Jiang De-en, University of California, Riverside
Yu Han, King Abdullah University of Science and Technology
Sudhir Kulkarni, Air Liquide
Nikhil Medhekar, Monash University
King Abdullah University of Science and Technology (KAUST)
EN04.01: Advanced Ionic Systems
Tuesday PM, April 03, 2018
PCC North, 100 Level, Room 126 A
10:30 AM - EN04.01.01
Porous Ionic Liquids—Challenges and Opportunities
Sheng DaiShow Abstract
Functional materials using or in the presence of ionic liquids represents a burgeoning direction in materials chemistry. Ionic liquids are a family of non-conventional molten salts that can act as both functional materials and solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility of both organic and inorganic molecules, and ion conductivity. The unique solvation environment of these ionic liquids provides new reaction and separation media for controlling many energy-related processes. We have recently developed a class of ionic liquids with intrinsic porosities based on nanoscopic building blocks.1 Challenges and opportunities in synthesizing and using these porous ionic liquids in energy-related applications will be discussed.
(1) Zhang, J.; Chai, S.-H.; Qiao, Z.-A.; Mahurin, S. M.; Chen, J.; Fang, Y.; Wan, S.; Nelson, K.; Zhang, P.; Dai, S. Porous Liquids: A Promising Class of Media for Gas Separation. Angew. Chem.-Int. Edit. 2015, 54, 932-936. 10.1002/anie.201409420
11:00 AM - EN04.01.02
Post-Combustion CO2 Capture with Encapsulated Ionic Liquids
University of Texas at Austin1Show Abstract
Ionic liquids (ILs) present intriguing possibilities for removal of carbon dioxide from a wide variety of different gas mixtures, including post-combustion flue gas, pre-combustion gases, air, and raw natural gas streams. Even by physical absorption, many ILs provide sufficient selectivity over N2, O2, CH4 and other gases. However, when CO2 partial pressures are low, the incorporation of functional groups to chemically react with the CO2 can dramatically increase capacity, while maintaining or even enhancing selectivity. Previously, we have shown how the reaction stoichiometry can be doubled over conventional aqueous amine solutions to reach one mole of CO2 per mole of IL by incorporating the amine on the anion, how we can virtually eliminate any viscosity increase upon complexation of the IL with CO2, by using aprotic heterocyclic anions (AHA ILs) that eliminate the pervasive hydrogen bonding and salt bridge formation that is the origin of the viscosity increase, and how the process energy can be further reduced by using ‘phase change’ ionic liquids, which are AHA ILs whose melting points when reacted with CO2 are more than 100 °C below the melting point of the unreacted material. Here, we show how mass transfer challenges of the relatively viscous ILs can be overcome by increasing the gas/liquid contact area by encapsulation of the ILs in silicone based shells. In particular, we show that the polymeric shells do not provide significant resistance to transport of CO2 and the capacity of the AHA ILs is maintained in the shells. The absorbent material in the shells can be cycled repeatedly without loss of capacity. Moreover, we show that the reaction of CO2 with the AHA ILs in the presence of water, which involves some reprotonation of the anion and formation of bicarbonate, is completely reversible and can be cycled for both the neat material and when it is encapsulated in the shells. Results on both the equilibrium and the rates of these reactions will be presented. Finally, we will show how the encapsulated phase change IL material works effectively in a fluidized bed reactor.
11:30 AM - EN04.01.03
Hybrid Polyimide-Ionene Architectures for Membrane Separations
Jason Bara1,Kathryn O'Harra1,Grayson Dennis1,John Whitley1,Marlow Durbin1,Brian Flowers1,Valerie Levine1,Ashgar Abedini1,Heath Turner1
University of Alabama1Show Abstract
Membranes offer improved energy efficiency in separations processes such as CO2 capture from combustion point sources, natural gas sweetening, syngas processing and air separation. To this end, a number of advanced polymer, inorganic and hybrid materials have been developed in recent years. Several distinct material classes have emerged, each with its respective set of benefits and limitations. Specifically, polyimides, ionic liquids (ILs), polymers of intrinsic microporosity (PIMs), metal-organic frameworks (MOFs) and thermally rearranged (TR) polymers are at the forefront of advanced membrane materials. We have identified a versatile approach which incorporates the benefits of these structurally diverse materials into a single platform through the synthesis of hybrid polyimide-ionene architectures, or “aromatic ionic polyimides”. This presentation will detail the design of these materials and their performances as gas separation membranes using both experimental data and computational studies.
EN04.02: Polymeric and Composite Membranes
Tuesday PM, April 03, 2018
PCC North, 100 Level, Room 126 A
1:30 PM - EN04.02.01
Toward Solubility Selective Polymer Membranes for High Flux Gas Separation
Tomonori Saito2,Tao Hong1,Pengfei Cao2,Bingrui Li2,Michelle Lehmann2,De-en Jiang3,Konstantinos Vogiatzis1,Brian Long1,Shannon Mahurin2,Alexei Sokolov2,1
University of Tennessee, Knoxville1,Oak Ridge National Laboratory2,University of California, Riverside3Show Abstract
Most of the world’s energy is presently derived from the burning of fossil fuels, which releases vast quantities of carbon dioxide (CO2) into the environment and results in undesirable climate change. Practical and cost-efficient methods of CO2 separation and capture would thus solve one of the most challenging problems today. This presentation summarizes our efforts on the development of novel polymer membranes functionalized with CO2-philic groups for high flux CO2 separation. Our strategy focuses on tuning solubility selectivity in addition to diffusivity selectivity for achieving high permeability membranes combined with good selectivity. Various synthetic techniques including ROMP, thiol-ene click reaction, and post functionalization were used and the careful design permits to prepare well-defined novel high permeable polymers containing CO2-philic groups. This study demonstrated the addition of CO2-philic groups (e.g. amidoxime and PEO) significantly increased the solubility selectivity of CO2 over N2. The membrane performance is also highly dependent on the balance of gas/functional group interaction, intra/inter- molecular interaction (H-bonding etc.) of membrane, packing, and polymer dynamics (degree of crosslinking). Tuning the balance of the interaction and dynamics enables to achieve the CO2 separation performance over the Robeson upper bound, e.g. CO2 permeability 6800 Barrer and CO2/N2 selectivity 19, or CO2 permeability 820 Barrer and CO2/N2 selectivity 39. The structure-property relationships especially on CO2 uptake, CO2 and N2 permeability, CO2/N2 selectivity to the polymer structure, as well as the effort on the selective layer coating will be discussed. Moreover, the other gas pair separation such as CO2/CH4, He/CH4 and He/N2 via tailoring solubility selectivity and diffusivity selectivity will also be discussed. Our membranes are rubbery-based and thus have no ageing issues, in contrast to glassy membranes.
1:45 PM - EN04.02.02
Gas Separation Properties of Novel Poly(benzimidazole)s
The University of Texas at Austin1Show Abstract
Gas and water vapor separation properties of a systematic series of sulfonyl-containing poly(benzimidazole)s are reported as a function of pressure and temperatrue. Gas separation properties are reported over temeratures ranging from ambient up to 190C. Additionally, separation properties of PBIs blended with polyimides are also reported, with some blends exhibiting transport properties above the 2008 upper bound.
2:15 PM - EN04.02.03
Separation of C3+ Hydrocarbon from Natural Gases Using Synthesized PAN/PDMS Composite Membranes
John Yang1,Daniel Harrigan1,Justin Vaughn1,Millind Vaidya2
Aramco Research Ctr1,R&DC, Saudi Aramco2Show Abstract
Saudi Aramco has a strategic interest in recovering valuable higher hydrocarbons (C3+). These higher hydrocarbons, also known as natural gas liquids (NGLs), can be used to reduce the Kingdom’s reliance on liquid fuel for power generation and can also be used as a feedstock for downstream chemical production. The conventional separation of NGLs from natural gas is typically accomplished through energy intensive refrigeration processes. Polymeric membranes that are selective for C3+ (e.g. propane and butane) relative to methane could provide a lower energy alternative to accomplish such a separation. Currently, polydimethysiloxane (PDMS), a commercially-available silicon-based rubbery membrane material, exhibits prohibitively low C3+//methane selectivities under rigorous testing conditions, hindering their application in industrial gas processing plants. To achieve significant recovery of NGLs from natural gas while reducing capital and operating expenditures, more efficient membranes with improved selectivity are required. This work describes progress to improve the C3+/methane separation efficiency of modified PDMS by incorporating bulky hydrocarbons into the polymer matrix. The effect of polymer backbone modifications and crosslinking agents on membrane physical properties and permeation performance is investigated. Modified PDMS membranes show enhanced gas permeation performance compared to commercial PDMS under industrially-relevant feed streams and testing conditions, including with multicomponent C1-C4 hydrocarbon mixtures up to 800 psi and in the presence of aggressive contaminants, including benzene, toluene, ethylbenzene, and xylene (BTEX). The results of this study aim to advance the rapid development of novel rubbery membrane materials for enhanced NGL recovery from natural gas.
3:30 PM - EN04.02.04
Polyethersulfone-Carbon Nanotubes Hollow Fiber Mixed Matrix Membranes—Development and Characterization for Enhanced Gas Separation Performance
Akshay Modi1,Surendra Verma1,Jayesh Bellare1
IIT Bombay1Show Abstract
Carbon nanotubes (CNTs) were incorporated in polyethersulfone hollow fiber mixed matrix membranes (P HFMs) to improve the gas separation performance. The P-CNTs (PC) HFMs were successfully developed using an indigenous spinning pilot plant. PC HFMs showed the improved thermal stability and mechanical strength as compared to that measured for the pristine P HFMs. The pure gas permeability of CO2, CH4, O2, and N2 gases for the developed HFMs were measured at 3 bar feed pressure and room temperature in a lab-scale gas permeation setup. It was observed that the presence of CNTs in PC HFMs significantly improved the CO2 permeability by four-fold to that measured for the pristine P HFMs. Furthermore, the ideal gas selectivity for CO2/CH4, O2/N2, and CO2/N2 gas pairs was also remarkably enhanced by almost 7-times, 1.5-times and 8-times, respectively, to that measured for P HFMs. The gas separation performance was better than or comparable to that of the literature-reported carbon nanomaterials-based membranes. Remarkably, the separation performance crossed or was almost closer to the upper bound curves drawn by Robeson in 2008 for these gas pairs. The improved separation performance can be attributed to the positive effect of doping of CNTs in HFMs, which resulted in selective transport of gases. Thus, the results, obtained in this study, experimentally demonstrated that the developed PC HFMs are a potential membrane material for industrially relevant CO2/CH4, O2/N2, and CO2/N2 gas separations.
3:45 PM - EN04.02.05
Unprecedented Size-Sieving Ability in Polybenzimidazole Doped with Polyprotic Acids for Membrane H2/CO2 Separation
State University of New York at Buffalo1Show Abstract
Membranes that permeate hydrogen and reject CO2 at temperatures above 150 °C are of great interest for low cost CO2 capture in pre-combustion processes. The current leading polymeric material for this application is poly[2,2’-(m-phenylene)-5,5’-bisbenzimidazole] (PBI), which exhibits good thermal stability, strong size-sieving ability and good H2/CO2 selectivity. In this study, we demonstrate that H2/CO2 selectivity in PBI can be significantly enhanced by doping with phosphoric acid (H3PO4). H3PO4 can bond strongly with imidazole rings in PBI, and the complexes are thermally stable up to 200 °C under vacuum. We prepares a series of H3PO4 doped PBI samples by immersing PBI thin films (12 µm) in solutions containing H3PO4 and methanol. The H3PO4 concentration can be varied from 0.05 wt.% to 1.0 wt.% to achieve different doping levels in the PBI films (0.3 - 1.0, defined as the molar ratio of H3PO4 to PBI repeating unit). Increasing the doping level increases H2/CO2 selectivity and decreases H2 permeability. For example, pure PBI exhibits pure-gas H2 permeability of 27 Barrers and H2/CO2 selectivity of 14 at 150 °C, while the PBI with a doping level of 0.44 exhibits H2 permeability of 6.1 Barrers and H2/CO2 selectivity of 59 at 150 °C. As the doping level increases to 1.0, the PBI shows an impressive H2/CO2 selectivity of 136, though the H2 permeability decreases to 1.3 Barrers at 150 °C. This performance is above the upper bound in the Robeson’s plot for H2/CO2 separation. This presentation will also discuss the effect of H3PO4 doping on structural changes such as free volume, as well as CO2 sorption and diffusion, and the structure/property relationships in these H3PO4 doped PBI thin films.
4:00 PM - EN04.02.06
Realistic Simulations of Membrane Separations at the Molecular Scale
University College London1Show Abstract
We recently developed a new non-equilibrium molecular dynamics simulation method  in order to simulate the permeation of pure fluids and mixtures through membranes, namely "Concentration Gradient Driven Molecular Dynamics" (CGD-MD). This new method works by employing bias forces to fix the concentration of fluids (pure or mixture) at the inlet and outlet of a membrane in order to maintain a concentration gradient and drive the diffusion of the molecules through the membrane. This is aimed at mimicking membrane separation experiments; for instance, high concentration/pressure at the feed side and vacuum at the permeate side. CGD-MD addresses two main shortcomings of previous non-equilibrium MD methods used for simulating membrane separation processes at the molecular scale. First, it avoids the feed depletion issue and allows running steady state and continuous simulations for unrestricted simulation times. Second, it maintains the feed composition at a target value without the need of any complex Monte Carlo-MD coupling. We demonstrate the new method for the separation of various gas mixtures in a MOF membrane as well as a composite MOF/Polymer mebrane.
 Ozcan, A., Perego, C., Salvalaglio, M., Parrinello, M., Yazaydin, O.*; "Concentration gradient driven molecular dynamics: a new method for simulations of membrane permeation and separation", Chemical Science, 2017, 8, 3858–3865.
4:30 PM - EN04.02.07
Synthesis and Gas Separation Performance of Novel Thermally Rearranged Polymer Membranes from Highly Contorted Precursors
Stephen Meckler1,2,Jonathan Bachman2,Benjamin Robertson1,Chenhui Zhu1,Jeffrey Long2,1,Brett Helms1
Lawrence Berkeley National Laboratory1,University of California, Berkeley2Show Abstract
Polymer membranes are the material of choice for many gas separations owing to their high performance, scalable synthesis, and easy processing. However, they suffer from a fundamental permeability/selectivity tradeoff that defines the “upper bound” limitations of this technology.1 Membranes that perform at or above the upper-bound can be achieved through the thoughtful design of polymers containing significant microporosity and rigid backbone chemistries.2
Thermally rearranged polybenzoxazoles excel in this regard.3 Produced through high-temperature solid-state reactions that alter the chain packing of a precursor polyimide, these polymers display enhanced porosity and narrow pore size distributions, placing their performance at or above the upper bound for many relevant gas pairs.
Here, we demonstrate the synthesis and gas separation performance of a novel family of thermally rearranged polybenzoxazoles containing a backbone contortion of exceptional rigidity. The design of these polymers incorporates chemical functionalities featured in other state-of-the-art gas separation membranes into polyimides with ortho-functional groups (PIOFGs), which are subsequently thermally rearranged. Synthesis of the precursor polyimides and the pore network evolution during thermal rearrangement will be discussed. Additionally, we will examine gaseous analyte-polymer matrix interactions in the context of gas separation performance. These findings offer new insights into the design of gas separation membrane polymers and provide a path forward for further optimization of thermally rearranged polymers.
1) Robeson, L. M. J. Membr. Sci. 2008, 320, 390–400.
2) Freeman, B. D. Macromolecules 1999, 32, 375–380.
3) Robeson, L. M.; Dose, M. E.; Freeman, B. D.; Paul, D. R. J. Membr. Sci. 2017, 525, 18–24.
4:45 PM - EN04.02.08
Chemically Robust Membranes with Nano Fabricated Polybenzimidazoles
Jung Ji Hye1,Moon Ki Jeong1,Sang Yong Nam1
Gyeongsang National University1Show Abstract
Polybenzimidazole is well known for having a superior heat resistance and has good mechanical properties as good as heat resistance. Due to an excellent various properties, PBI has been used a lot of fields such as gas separation, OSN and solvent-resistant nano filtration. PBI parts, which are produced by using a compression molding process, are promising materials in extreme environments. This work is focused on fabrication of meta-Polybenzimidazole(m-PBI) and control of morphology according to concentrations or manufacturing conditions. The membranes were prepared via the phase inversion method from casting solutions with predetermined amounts PBI, dimethylacetamide (DMAc) and tetrahydrofuran (THF). The polymer solutions were cast on a clean glass plate by using casting knife. The membrane was immersed in IPA to remove the residual solvent and dried in vacuum oven for 24h. Also, this membrane can be prepared by electro-spinning. Electro-spinning can make highly porous non-woven fabrics consisted of nanofibers with the small diameters and overall porous structure. Also, electrospun fabrics have high specific surface area. To observe morphology, Scanning electron microscope (SEM) was used. In case of gas transport properties, H2, CO2 Permeability and selectivity of this membrane was measured via pure gas.
Jiang De-en, University of California, Riverside
Yu Han, King Abdullah University of Science and Technology
Sudhir Kulkarni, Air Liquide
Nikhil Medhekar, Monash University
King Abdullah University of Science and Technology (KAUST)
EN04.03: Metal-Organic Frameworks
Wednesday AM, April 04, 2018
PCC North, 100 Level, Room 126 A
8:30 AM - EN04.03.01
MOF Design to Applications—Impact of Pore System Control on Gas Separations and Storage
King Abdullah University of Science and Technology1Show Abstract
Various key gas/vapors separations are accomplished using energy intensive processes as exemplified by the olefin/paraffin separation, an essential separation in chemical industry.
Here we present our progress in the development of functional metal-organic frameworks (MOFs) to address some energy-intensive separations. Successful practice of reticular chemistry had afforded the fabrication of a chemically stable fluorinated MOF adsorbent materials (NbOFFIVE-1-Ni, also referred to as KAUST-7 and AlFFIVE-1-Ni, also referred to as KAUST-8).
KAUST-7 fully split propylene from propane. The bridging of Ni(II)-pyrazine square-grid layers with (NbOF5)2- pillars permitted the construction of a 3-dimensional MOF, enclosing a periodic array of fluoride anions in a contracted square-shaped channels. The judicious selection of the bulkier pillar (NbOF5)2- caused the looked-for hindrance of the previously free-rotating pyrazine moieties, delimiting the pore system and dictating the maximum opening of the pore aperture-size. The restricted MOF window resulted in the selective molecular exclusion of propane from propylene at atmospheric pressure, as evidenced by multiple cyclic mixed-gas adsorption and calorimetric studies. Remarkably, KAUST-7 maintains its distinctive separation properties in the presence of water as a result of its high chemical and hydrolytic stability.1
The development of suitable storage and refining processes makes natural gas an excellent alternative fuel, but before its transport and use, natural gas must first be dehydrated. Conventional dehydration agents are energy intensive. KAUST-8 selectively removes water and requires just 105°C for regeneration of the dehydrating agent.2
The deliberate control of the pore aperture-size of various selected MOFs and its impact on various separations will be discussed.
1. Cadiau, A.; Adil, K.; Bhatt, P. M.; Belmabkhout, Y.; Eddaoudi, M. “A metal-organic framework-based splitter for separating propylene from propane” Science, 2016, 353, 137-140.
2 Cadiau, A.; Belmabkhout, Y.; Adil, K.; Bhatt, P. M.; Pillai, R. S.; Shkurenko, A.; Martineau-Corcos, C.; Maurin, G.; Eddaoudi, M. “Hydrolytically stable fluorinated metal-organic frameworks for energy-efficient dehydration” Science, 2017, 356, 731-735.
9:00 AM - EN04.03.02
Cooperative Adsorption and Gas Separations in Metal-Organic Frameworks
Jeffrey Long1,2,Thomas McDonald1,3,Douglas Reed1,Rebecca Siegelman1,2,Dianne Xiao1,Julia Oktawiec1,Miguel Gonzalez1,Lucy Darago1,Jonathan Bachman1,Zoey Herm1,3,Jarad Mason1,4,Eric Bloch1,5,David Gygi1,4,Phillip Milner1,2,Jeffrey Martell1,Tomce Runcevski1,2,Alex Forse1,Keith Keitz1,6
University of California, Berkeley1,Lawrence Berkeley National Laboratory2,Mosaic Materials, Inc.3,Harvard University4,University of Delaware5,The University of Texas at Austin6Show Abstract
Owing to their high surface areas, tunable pore dimensions, and adjustable surface functionality, metal-organic frameworks (MOFs) can offer advantages for a variety of gas storage and gas separation applications. In an effort to help curb greenhouse gas emissions from power plants, we are developing new MOFs for use as solid adsorbents in post- and pre-combustion CO2 capture, and for the separation of O2 from air, as required for oxy-fuel combustion. In particular, MOFs with diamine-functionalized metal sites are demonstrated to operate via an unprecedented cooperative insertion mechanism, leading to high selectivities and working capacities for the adsorption of CO2 over N2 under flue gas conditions. Multicomponent adsorption measurements further show these compounds to be effective in the presence of water, while calorimetry and temperature swing cycling data reveal low regeneration temperatures compared to aqueous amine solutions. In addition, a new spin transition mechanism will be elaborated as a means of achieving cooperative CO adsorption.
9:30 AM - EN04.03.03
Synthesis and Surface Modification of Metal Organic Frameworks Nanoparticles for the Processing of Mixed Matrix Membranes
Nathalie Steunou1,Marvin Benzaqui1,2,Nicolas Menguy3,Florent Carn4,Rocio Semino5,Guillaume Maurin5,Christian Serre2
University of Versailles- University of Paris-Saclay1,Ecole Normale Supérieure2,UPMC3,Université Paris Diderot4,Université Montpellier5Show Abstract
Membrane separation has emerged as a promising alternative to cryogenic distillation or amine-based wet scrubbing for the CO2 capture, with potentially high efficiency, lower energy consumption, ease of scale-up and environmental friendliness. However, these membranes typically derived from polymers suffer from an inherent trade-off between permeability and selectivity. To enhance their performance, composite membranes (or mixed matrix membrane, MMM) which consist of filler particles dispersed into an organic polymer phase were proposed since they potentially combine the gas transport and separation properties of the incorporated particles with the good processability and mechanical properties of the polymers. Metal Organic Frameworks (MOFs) were recently proposed as fillers since they present a high separation performance owing to their size/shape exclusion or selective adsorption of gas molecules. However, MOF-based MMMs still pose limitations, which are mainly related to the low MOF loading for numerous MMMs (< 30 wt%). While the permeability of such MOF-based MMMs is usually improved in comparison to pure polymer membranes, an improvement of selectivity is only rarely observed. This mainly results from the fact that the selectivity of this system is driven by the polymer matrix which is the dominant component. In addition, a possible physico-chemical mismatch between MOFs and polymers may lead to the aggregation of MOFs fillers in the polymer matrix and interphase defects (macro or nanovoids). Such voids provide new bypasses through the MMMs that reduce the separation efficiency and compromise performance. There is thus a need to design nanoparticles of MOFs with a good control of the surface chemistry and morphology (diameter and shape) for the shaping of MMMs.
This communication deals with the synthesis of microporous and water stable MOFs nanoparticles for the processing of MMMs. We focused mainly our attention on the aluminum trimesate MIL-96(Al) and the zeolitic imidazolate ZIF-8 which are attractive for the selective capture of CO2. The synthesis of MIL-96(Al) crystals of different morphology and diameter was achieved by using water as the main solvent. Monodisperse MIL-96(Al) nanoparticles were combined to polymers for the preparation of defect-free MMMs. The microstructure of MMMs and compatibility of MOFs nanoparticles within polymers were also investigated through a complete characterization of MOFs/polymer colloidal solutions by combining complementary experimental (DLS, SAXS, TEM, HAADF-STEM) and computational tools. This study has shown the influence of the surface chemistry of MOFs and the properties of polymers on the physico-chemical matching between MOFs and polymers.
 M. Benzaqui, R. Semino, N. Menguy, F. Carn, T. Kundu, J. M. Guigner, N. B. McKeown, K. J. Msayib, M. Carta, E. Malpass-Evans, C. LeGuillouzer, G. Clet, N. A. Ramsahye, C. Serre, G. Maurin, N. Steunou, ACS Appl. Mater Interfaces, 8, (2016), 27311-27321
9:45 AM - EN04.03.04
Density Functional Theory Investigation of Framework Flexibility and Gas Sorption in the Flexible Pillared Metal-Organic Framework Material Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)4] (PICNIC-60)
Eric Cockayne1,Andres Correa Hernandez2,Lan Li2
National Institute of Standards and Technology1,Boise State University2Show Abstract
Flexible metal-organic framework materials are of great interest for gas separation problems as the response of the framework to sorption or other stimuli can influence the further sorption of gas species. We use first-principles density functional theory GGA+U plus empirical van der Waals calculations to investigate the stability of one particular flexible system: the pillared metal-organic framework material Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)4] (Ni2(bpene)(CN)4 or PICNIC-60 for short) as a function of cell volume, bpene orientations and CO2 content. We find two types of stable orientations for individual bpene molecules: along the monoclinic axis (b) and perpendicular to it (c), with a rotational transition barrier of about 0.4 eV. The most stable pattern of bpene orientations for empty PICNIC-60 changes from all (b) to alternating (b) and (c) as the molar volume increases from 440 Å3 to 720 Å3, with the transition at about 500 Å3. The addition of CO2 changes the picture, with yet a third pattern of bpene orientations- all along (c)- favored for CO2 concentration greater than 3 CO2 per mole of bpene. A particularly stable arrangement of 5 CO2 per mole of bpene is found, beyond which CO2 sorption becomes much less favorable. The experimental hysteresis observed in CO2 sorption isotherms is explained in terms of the energy barriers to bpene reorientation and to CO2-CO2 interactions. Preliminary results are presented for other sorbant species, including comparisions of the binding energies and geometries for N2, H2 and CH3 .
10:30 AM - EN04.03.05
Pore Space Partitioning and Engineering of Metal-Organic Framework Materials
Pingyun Feng1,Xianhui Bu2
University of California, Riverside1,California State University Long Beach2Show Abstract
Metal-organic framework materials (MOFs) are among the most fascinating families of solid state materials, because of their highly tunable compositions, structures, and properties. In this presentation, strategies for the synthesis of new porous MOFs will be discussed, with the focus on the use of different metallic elements and their various combinations. The talk will cover our recent efforts on functionalizing MOF for enhancing gas sorption. The pore space of MOF can be engineered by using extra-framework ligands or nested cage-in-cage configurations to tune the gas sorption properties. The development of the optimum pore architectures for enhanced gas sorption will be covered. To maximize the pore space utilization, we are pursuing a unique synthetic paradigm that is based on the delicate pore space partition through nested pore architecture by using complementary coordination properties of multitopic ligands. In addition to focus on the application in gas adsorption, the potential application of these materials in energy related areas will also be covered.
11:00 AM - EN04.03.06
Molecular Modeling on Metal-Organic Frameworks for CO2 Capture and Hydrocarbon Separations
Ravichandar BabaraoShow Abstract
Metal-organic frameworks (MOFs) have emerged as a special class of hybrid nanoporous materials. The variation of metal oxides and the vast choice of controllable organic linkers allow the pore size, volume and functionality of MOFs to be tailored in a rational manner for designable architectures. MOFs thus provide a wealth of opportunities for engineering new functional materials and are considered as versatile candidates for storage, separation, sensing, catalysis, drug delivery, and other important applications. With ever-growing computational resources and advance in mathematical techniques, molecular simulations have become an indispensable tool for materials characterization, screening, and design. At a molecular level, simulations can provide microscopic insights from the bottom-up and establish structure-function relationships. An overview is presented here on how molecular modeling can a powerful tool in the intelligent design of new smart porous materials for CO2 capture and hydrocarbon separation.
A. Sharma, A. Malani, and R. Babarao, Journal of Physics D: Applied Physics, 2017, 50, 46.
R. Huang, M. R. Hill, R. Babarao, N.V. Medhekar, Journal of Physical Chemistry C, 120, 16658 - 16667, 2016.
R. Babarao, M. R. Martinez, M. R. Hill, A.W. Thornton, Journal of Physical Chemistry C, 2016, 120, 13013 – 13023.
S. Mukherjee, B. Manna, A. V. Desai, Y. Yin, R. Krishna, R. Babarao, and S. K. Ghosh, Chem. Commu., 2016, 52, 8215 – 8218 (Highlighted as Back Cover).
A.W. Thornton, R. Babarao, A. Jain, F. Trousselet, and F- X. Coudert, Dalton Trans., 2016, 45, 4352 – 4359, 2016.
W. Liang, R. Babarao, M, Michael and D. D’Alessandro, Chemical Communication, 2015, 51 (56), 11286-11289.
11:30 AM - EN04.03.07
Direct Synthesis of High-Aspect-Ratio Zeolite MFI Nanosheets for Membrane Separation Applications
Donghun Kim1,Mi Young Jeon1,Prashant Kumar1,Pyung Soo Lee1,K. Andre Mkhoyan1,Michael Tsapatsis1
University of Minnesota1Show Abstract
Molecular sieve membrane-based separation is a potentially energy-efficient alternative to conventional separation processes (e.g., distillation). In particular, the all silica zeolite with structure type MFI has been of interest, as, in addition to its superior thermal and chemical stability, its pore dimensions are close to the sizes of many valuable chemicals. The fabrication of high-performance zeolite MFI separation membranes requires control of microstructure that can be achieved by the secondary growth of a MFI nanosheet coating.
We have developed a direct synthesis method, which readily provides MFI nanosheets with increased lateral dimensions (~2 μm) and similar nano-scale thicknesses (5 nm) compared to the prior stste-of-the-art.2 This was enabled by seeded growth with bis-1,5(tripropyl ammonium) pentamethylene iodide (denoted as dC5) as a structure-directing agent. This dC5 SDA was reported to be able to yield high-aspect-ratio MFI crystals with thin dimensions along their b-axes.3 However, the formation of rotational intergrowths prohibits the formation of high aspect ratio flat nanosheets.4 We utilized a seeded growth method to suppress the rotational intergrowths in MFI crystals and to grow the MFI crystal in a single nanosheet morphology. Time-dependent growth investigations with TEM established that a nanosheet forms from a corner of the seed crystal and encircles the seed crystal. A single rotational intergrowth appears to trigger a morphology transition from a cylinder to a nanosheet. No additional rotational intergrowth was observed, allowing to achieve high-aspect-ratio MFI nanosheets with ~2-μm lateral dimensions. Upon the fabrication of seed coating with a filtration method, followed by a gel-free secondary growth, the membranes exhibit unprecedented combination of high p-xylene permeance (~5×10-7 mol Pa-1 s-1 m-2) and separation factor (2,000) for xylene isomer separation.2 The separation factor of the membrane was further improved (>10,000), when the membrane was fabricated from dense and uniform nanosheet coatings prepared from the monolayer transfer method.5
(1) Varoon et al., Science 2011, 334, 72–75.
(2) Jeon et al., Nature 2017, 543, 690–694.
(3) Bonilla et al., Chem. Mater. 2004, 16, 5697–5705.
(4) Chaikittisilp et al., Angew. Chem. Int. Ed. 2013, 52, 3355–3359.
(5) Kim et al., under review.
EN04.04: Novel Architectures
Wednesday PM, April 04, 2018
PCC North, 100 Level, Room 126 A
1:30 PM - EN04.04.01
Ion-Gated Gas Separation Through Porous Graphene
University of California, Riverside1Show Abstract
Porous graphene holds great promise as a one-atom-thin, high-permeance membrane for gas separation and water desalination, but to precisely control the pore size down to a few angstroms proves challenging. Here we demonstrate from classical molecular dynamics simulations that an ion-gated graphene membrane comprising a monolayer of ionic liquid coated porous graphene can dynamically modulate the pore size to achieve selective gas separation. This approach enables the otherwise non-selective large pores on the order of 1 nm in size to be selective for gases whose diameters range from three to four angstroms. We find that the anion serves as a gate to control gas permeation through the pore, while the strong cation-graphene and cation-anion interactions hold the gate in place.
1:45 PM - EN04.04.02
Graphene Oxide Membranes with Nanopockets
Jae Eun Shin1,Ho Bum Park1
Hanyang University1Show Abstract
Recently, a few-layered graphene oxide (GO) has been extensively investigated as a membrane material for gas and liquid separation. Although GO membrane is considered as one of promising membranes, it has a limitation to apply for practical application because of low gas permeability and low stability under dry condition. In general, small molecules such as gas, water, and ion are passed along the layered structure, which lead to increase of diffusion path. As such, in this study, we prepared porous GO sheets by generating and decorating the holes on the basal plane of GO sheets using simple modification method without any chemical or thermal reduction, as a result, maintaining original GO functional groups such as epoxy, hydroxyl and carboxyl groups. After stacking the porous GO sheets, we have found that empty holes could be formed between stacked GO layers. The empty holes (or pores) can be a route to reduce diffusion penalty for small molecules and then, it can lead to an increase of mass transport rate than that of pristine GO membranes with high aspect ratio. Especially, GO membrane derived from individual porous GO sheets have a ‘nanopocket’, which can contain large amount of water or CO2, surrounded by amine functionalized edges around nanopockets. From these reasons, the CO2 permeability was significantly increased by approximately 30 times compared to the pristine GO membrane and CO2/N2 selectivity was increased up to as high as 30. These results have the potential to open up new approaches for an improvement in the transport and absorption properties of porous two-dimensional membrane material for use in next-generation CO2-selective membranes.
2:00 PM - EN04.04.03
Creating CO2 Channels in Gas Separation Membranes
Tianjin University1Show Abstract
High CO2 permeability polymer-based membrane materials can address large-scale separations such as CO2 removal from flue gas and natural gas purification . We have explored several approaches to designing membranes having both high gas permeability and high permselectivity. The alignment of filler materials creates fast and selective gas transport channels to improve membrane performance. Two approaches we explored are:
The vertical alignment of highly CO2-permeable covalently-anchored Montmorillonite (MT) clay fillers is achieved by interspersing the filler with polymer. The resulting mixed matrix membrane is anchored to a supporting substrate, creating a membrane with transport channels that are selective for carbon dioxide . A high CO2 permeance is achieved combined with high mixed CO2/gas selectivity that is stable over a period of 600 h and is independent of water content in the feed gas.
The horizontal alignment of graphene oxide (GO) by deposition of a thin layer on membrane supports allows fast CO2 transport between the layers, when CO2 sorbing materials lie within the interlayer spaces [3,4]. These materials are also used to crosslink the GO spaces, thereby fixing the interlayer spacing and affording greater stability.
 Review: Advances in high permeability polymer-based membrane materials for CO2 separations, S. Wang, X. Li, H. Wu, Z. Tian, Q. Xin, G. He, D. Peng, S. Chen, Y. Yin, Z. Jiang, M. D. Guiver, Energy & Environ. Sci. 9, 1863 – 1890 (2016).
 A highly permeable aligned montmorillonite mixed-matrix membrane for CO2 separation, Z. Qiao, S. Zhao, J. Wang, S. Wang, Z. Wang, M. D. Guiver, Angew. Chem. Int. Ed., 55, 9321 – 9325 (2016).
 A highly permeable graphene oxide membrane with fast and selective transport nanochannels for efficient carbon capture, S. Wang, Y. Wu, N. Zhang, G. He, Q. Xin, X. Wu, H. Wu, X. Cao, M. D. Guiver, Z. Jiang, Energy & Environ. Sci. 9, 3107 – 3112 (2016).
 Graphene oxide membranes with heterogeneous nanodomains for efficient CO2 separations, S. Wang, Y. Xie, G. He, Q. Xin, J. Zhang, L. Yang, Y. Li, H. Wu, Y. Zhang, M. D. Guiver, Z. Jiang, Angew. Chem. Int. Ed., in press DOI: 10.1002/anie.201708048
3:30 PM - EN04.04.04
Integration of Ionic Liquid with Nitrogen-Doped Porous Carbon for Enhanced Pre and Post-Combustion CO2 Capture
Sreetama Ghosh1,Ramaprabhu Sundara1,R. Sarathi1
Indian Institute of Technology Madras1Show Abstract
Carbon dioxide is a major anthropogenic greenhouse gas produced primarily from the combustion of fossil fuels, automobile emission and from industrial exhausts that have posed a huge danger to the environment in recent times. One such way to capture CO2 in porous materials is by adsorption process. In recent times, a wide range of materials such as zeolites, porous carbon, organic polymers, metal−organic frameworks (MOFs) etc. have been extensively studied for CO2 capture. Porous carbonaceous materials are especially attractive because of their large specific surface area, regular porosity, and ease of synthesis, abundant availability and thermal stability. An effective CO2 adsorbent must possess high adsorption capacity, high selectivity, moderate heat of adsorption, fast adsorption and desorption kinetics and excellent chemical and mechanical stability. The nitrogen content of the samples also plays very important role in CO2 adsorption. One of the most important reasons is that the N content improves the electron density of the carbon framework and thereby increases the basicity of the framework. As a result, it becomes easier for the electron deficient C atom of CO2 to get anchored in the framework by Lewis acid (CO2)-Lewis base (N) interactions. Ionic liquids (ILs) are molten salts mainly composed of organic cations and organic or inorganic anions having melting point lower than 100 °C. Room temperature ionic liquids exhibit some significant properties such as low vapor pressure, high chemical and thermal stability, tunable properties, good ionic conductivity and high CO2 solubility. The interaction of IL with CO2 is quite fast that effectively increases the sorption kinetics. The present work basically focuses on a solvent-free facile synthesis of ionic liquid functionalized nitrogen doped porous carbon by a simple thermal decomposition technique. This ionic functionalized micro-mesoporous nanocomposites sample showed large CO2 adsorption capacity along with fast adsorption kinetics when compared to only porous carbon. The ionic liquid used in this particular work is 1-Butyl-3-Methylimidazolium bis(trifluoromethyl sulfonyl)imide ([BMIM][TFSI]). It has already been reported that surface functionalization with ionic liquids basically increases the anchoring sites which leads to a higher CO2 adsorption capacity. The CO2 adsorption-desorption studies were carried on at different temperatures and in both high as well as sub-ambient pressure conditions. These studies show that the nanocomposite exhibit excellent cyclic stability in storage performance. In addition, thermodynamic studies suggest that the adsorption takes place mainly by physicochemical adsorption mechanism and therefore easy regeneration process is also possible which is considered as another critical property of an adsorbent. Thus it can be concluded that this particular material has the potential to serve as a good CO2 adsorbent both in pre as well as post-combustion CO2 capture.
3:45 PM - EN04.04.05
Metal–Organic Frameworks Grown on a Porous Two-Dimensional Template with a High Surface Area—Promising Nanofiller Platforms for CO2 Separation
Ho Bum Park1,Hyunhee Lee1,Ji Soo Roh1
Hanyang Univ1Show Abstract
Porous nanosheets made of effectively aligned zeolitic imidazolate framework-8 (ZIF-8), dubbed ZPGO, with an exceptionally high surface area (2170 m2 g−1) were demonstrated. This composite was prepared by growing ZIF-8s on highly porous graphene oxide (PGO) and the mixed matrix membrane with such a nanofiller showed drastically improved size-selective CO2 transport even at very low filler concentration (0.02 wt%) especially under mixed gas conditions where both selectivity (CO2/N2 ∼57) and CO2 permeability (∼163 barrer) were significantly enhanced. In addition to this, ZPGO effectively suppressed CO2-plasticization, which indicates great potential in real operations. This new concept of nanofillers is expected to maximize the filler effect in other fields benefitting from a high surface area as well.
4:15 PM - EN04.04.06
Architecturing Nanospace for Highly Efficient Gas Separations
Anita Hill1,Aaron Thornton1,Cara Doherty1
Since their discovery over a decade ago, thermally rearranged polymers have become established as a new class of glassy polymer membrane with superior permeability-selectivity combinations for mixed gas transport compared to conventional glassy polymers. Permeability-selectivity combinations surpassing Robeson’s upper bound have been attributed to the porosity that is developed during thermal rearrangement resulting in nanospace reminiscent of bottlenecks connecting adjacent chambers, such as those found in nature in the form of ion channels and aquaporins. Applications of these polymer membranes for clean energy include CO2 separation to make existing power generation industries cleaner. In research designed to understand and optimize the performance of these membranes we have measured the development of free volume in thermally rearranged polymers using positron annihilation lifetime spectroscopy and small angle X-ray scattering. In addition, we have performed a theoretical study, based on the free volume elements, in order to explain why these membranes perform so well. The hour-glass shaped pores are shown to provide a series of size-selective necks connected with larger flux-assisting cavities. Remarkably, with the correct neck and cavity size, the upper bound can be exceeded for many different gas mixtures. The ability to measure and tailor free volume at the Angstrom scale is shown to be critical for prediction of membrane performance.
4:45 PM - EN04.04.07
Homogeneous Porous Organic Cage Mixed Matrix Membranes for Molecular Separation Processes
Guanghui Zhu1,Christopher Jones1,Ryan Lively1
Georgia Institute of Technology1Show Abstract
Porous organic cages (POCs) are individual molecules that are porous and soluble in certain common solvents. Compared to their extended framework counterparts, such as zeolites and metal-organic frameworks (MOFs), POCs offer the advantage of solution processability. Moreover, when fabricated into mixed matrix membranes, the soluble POC molecules have the potential to exhibit molecular-level intimate mixing with matrix polymer. The incorporation of POCs into mixed matrix membrane is still in its infancy and lacks demonstration of comprehensive improvement of membrane performance. In this work, we utilized vertex functionalized amorphous scrambled porous organic cages (ASPOCs) in mixed matrix membranes to study a series of key questions in this field. The dispersion of ASPOCs possessing different crystallization tendencies within a polymer matrix are probed using Raman imaging and Energy Dispersive X-Ray (EDX) mapping. Gas permeation experiments of N2, CO2, CH4 and SF6 were carried out as a function of ASPOC loading and crystallization tendency. A 4-8 fold of permeability increase was observed for N2, CO2 and CH4 compared to pure polymer membrane. Moreover, a clear molecular sieving effect was observed for SF6, resulting in 2-4 fold of increase of N2/SF6 selectivity compared to the pure polymer membrane. The membranes were further examined in organic solvent nanofiltration experiments using a cross-flow permeation approach. The Molecular Weight Cut Off (MWCO) of the membranes were calculated based on the polystyrene permeation tests. Overall, these membranes demonstrated homogeneous mixing between the POC molecules and the polymer matrix, and showed potential to be used in molecular separation processes.
EN04.05: Poster Session
Wednesday PM, April 04, 2018
PCC North, 300 Level, Exhibit Hall C-E
5:00 PM - EN04.05.01
Improving CO2 Capture Ability by Polyethylene Terephthalate Plastic-Derived Microporous Adsorbents with Chemical Activation Treatment
Xiangzhou Yuan1,Jong-Gyu Lee2,Ki Bong Lee1
Korea University1,Research Institute of Industrial Science and Technology (RIST)2Show Abstract
Adsorption is considered a promising technology for capturing CO2 and appropriate adsorbent is one of key factors for successful development of adsorption method. In this study, CO2 adsorption using polyethylene terephthalate (PET) plastic-derived porous carbon materials was investigated from both equilibrium and kinetic perspectives. The PET plastic was utilized for developing CO2 adsorbents by carbonization and chemical activation processes. The carbonization process was conducted under 600 °C and N2 atmosphere within 1 h. Both the KOH and NaOH were selected for activating the carbonized PET plastic, and the activation temperature was varied from 700 to 1000 °C. Varying the activation temperature had a dramatic effect on the textual properties of the prepared adsorbents. The adsorption isotherms were well fitted by the Langmuir isotherm model (R2 > 0.999), the experimental CO2 adsorption data were well described by the pseudo-second-order kinetic model (R2 > 0.999), compared with the Elovich and intra-particle-diffusion models, and CO2 adsorption appeared to be mainly controlled by physisorption. The PET-KOH-700 adsorbent exhibited the highest CO2 adsorption uptake of 4.75 mmol g-1 at 25 °C and 1 atm. The outcome of this study revealed that the PET-KOH-700 adsorbent, synthesized from easy recycling and obtainable PET plastic, showed remarkably high CO2 adsorption uptake, good CO2/N2 selectivity at relatively low CO2 pressures, excellent recyclability, easy regeneration, and rapid adsorption-desorption kinetics, which will be very promising for industrial CO2 separation applications.
5:00 PM - EN04.05.02
K2CO3-Catalyzed Steam Gasification and CO2 Capture Processes of Petroleum Coke—Improving H2 Concentration in Syngas
Xiangzhou Yuan1,Jingjing Jiang2,Ki Bong Lee1
Korea University1,Ajou University2Show Abstract
Catalytic steam gasification has been considered as one of the most promising clean technologies that could convert the solid fuel to obtaining an H2-rich syngas, which has long been an important source of hydrogen for various industrial sectors. K2CO3 was utilized as a catalyst due to that it has the ability to significantly increase gasification reaction rates and good mobility to disperse throughout the sample under gasification operating conditions. After conducting the K2CO3 catalyzed steam gasification of petroleum coke, the highest H2 content reached 19.38 vol.% (67.37 vol.% of N2) under 10 wt% K2CO3 loading and gasifying temperature of 900 oC, obtaining the carbon conversion of 92.91%. In this study, the CO2, mainly caused the hottest global warming issue, was also captured from the produced syngas for improving the H2 concentration in the final H2-rich syngas. Adsorption is considered a promising technology for capturing CO2 and appropriate adsorbent is one of key factors for successful development of adsorption method. N-doped microporous carbons derived from petroleum coke was developed for investigating the CO2 capture from the syngas, from both equilibrium and kinetic perspectives. The N-doped and KOH activated petroleum coke showed high CO2 capacity, excellent CO2/N2 selectivity, easy regeneration, and rapid adsorption-desorption kinetics, which will play a significant role in the petroleum coke-to-H2 rich syngas system and also be very promising for industrial applications.
5:00 PM - EN04.05.03
In Situ Observation of High-Temperature CO2 Capture Over NaNO3 Promoted Magnesium Oxide
Hyeongbin Jeon1,Minhee Cho1,Jeong Gil Seo1
Myongji University1Show Abstract
In industrial electric production, cogeneration and fossil fuel power plants occupy a high proportion, resulting in excessive carbon dioxide emissions in the atmosphere. As a result, environmental issues such as global warming have emerged as major problems of our society. Various studies have been conducted in order to solve this problem. Among them, a method of utilizing magnesium oxide (MgO) as an adsorbent to capture carbon dioxide has been extensively studied. MgO has several advantages such as excellent theoretical CO2 adsorption capacity, thermally stable MgCO3 form, and low regenerative energy. However, MgO has also disadvantages such as slow reaction kinetic and loss of basic site on MgO surface during regeneration, large lattice energy and irregular particle size. Thus it is difficult to exert excellent performance in capturing CO2 with MgO alone. Recently, it has been found that the promoter can utilize MgO toward CO2 adsorption by dissociating it into Mg2 + and O2-. In addition, hydrotalcite as a support can function as a framework for forming MgCO3 with high stability, CO2 capture ability, and economic efficiency, thereby further enhancing the CO2 adsorption ability of MgO. Fundamentally, CO2 capture on MgO begins with surface chemisorption and ends up with forming MgCO3 throughout the MgO body. Adsorption-mediated carbonation can be promoted due to the strong solvation effect when the promoter and support are mixed. However, the CO2 adsorption mechanism on neither pure MgO nor the MgO complex of promoter and support has not been explicitly described for the formation of surface specific MgCO3 (on pure MgO) and bulk MgCO3 (on MgO with promoter and support). In this study, adsorbents were prepared by using promoter (NaNO3) and hydrotalcite (MgO: Al2O3, the weight ratio of 30:70 and 70:30) as a promoter for dispersion of MgO and stability of adsorbent. Adsorption performance of hydrotalcite used as a support was investigated by non-isothermal test according to weight ratio of MgO: Al2O3. Adsorbent characteristics were analyzed by XRD, cyclic test, fixed bed adsorption test, and TGA. Also, adsorbents were subjected to in-situ transmission electron microscopy (TEM) for the direct observation of fundamental CO2 adsorption in a complex of MgO, promoter and support under non-vacuum (CO2 atmosphere) and high temperature (> 250oC) conditions. Morphological and crystallographical changes at the interface of synthesized mixture were observed in nano-scale by using SAED and EDS. The performance of the adsorbent and the surface change of complex by analysis of CO2 adsorption mechanism will be discussed in detail. This work was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRT-2016R1C1B2008694).
5:00 PM - EN04.05.04
Characterization of Interfacial Properties Between Ionic Liquids and Polymer Membranes for CO2 Absorbing Membrane Contactor
For the carbon dioxide capture and separation, lots of researches have been carried out. Most mature process for CO2 separation is an absorption technology consisting of an amine based absorbent and a pact column. Though this has high absorption efficiency, amine base absorbent is highly corrosive and degradable at operation temperature. Also it requires high energy consumption to regenerate absorbent and degassing CO2 from the absorbent. Pact column for CO2 absorption requires high building cost for its huge CO2 absorbing column. To overcome these problems, combination of membrane contactor and ionic liquid system for CO2 separation is having great attention. Because, these can make more compact and cost-effective system. Ionic liquid has an advantage of non-corrosive, non-volatile and low degradation sensitive nature compared with conventional amine based absorbent. And membrane contactor also has larger effect surface area than pack column system. To retain CO2 absorbing efficiency, membrane between liquid absorbent and CO2 gas should be intact without smearing from an absorbent to gas phase and without swelling of membrane by an absorbent. To prevent smearing and swelling, it needs to control membrane surface properties. Especially membrane should be hydrophobic to prevent wetting by hydrophobic ionic liquids. In this study, we used polypropylene (PP) membrane for a flat sheet membrane contactor(MSMC). Also PP membrane surfaces were modified using organosilanes or fluorosilanes and modified surfaces were confirmed using FT-IR and FE-SEM. Hydrophobicity of modified PP membrane was compared with water contact angle. Also contact angle between Ionic liquid and PP membrane was also investigated for the application to CO2 absorbing membrane contactor.
5:00 PM - EN04.05.05
Improving Hydrogen Uptake of Covalent Organic Frameworks via Ligand Engineering
Amy Keuhlen1,Wade Braunecker2,Justin Johnson2,Katherine Hurst2,Thomas Gennett2,1,Alan Sellinger1,2
Colorado School of Mines1,National Renewable Energy Laboratory2Show Abstract
Hydrogen is a potential sustainable and clean source of energy that can decrease reliance on hydrocarbons. Although advances in renewable sourcing of hydrogen are encouraging, safe storage for hydrogen gas remains a significant hurdle for widespread use in a hydrogen economy. Currently, hydrogen gas must be substantially compressed at low temperatures for safe storage, which poses a large problem for wide spread use. A simple solution lies in metal and covalent organic frameworks (MOF and COF): highly porous materials with promising gas storage capabilities at decreased pressure and higher temperature compared to traditional methods. Hydrogen uptake and operability for these frameworks do not yet meet the U.S. Department of Energy (DOE) 2020 targets of 0.03 kg H2/L of system and operating temperatures of -40-60°C. To reach these goals, key parameters to optimize are MOF/COF ligand design and surface area, as these correspond to improved hydrogen uptake. We have developed new COF ligands that result in high surface area COFs with potential enhanced hydrogen storage properties. We show hydroxy and fluorine groups on the linkers enhance hydrogen binding within the framework, while judicial solvent choice boosts surface area. Future work will test for metal integration into the framework to further augment hydrogen bonding capabilities. Progress in designing functional COFs with high surface area, preferential hydrogen bonding groups, and metal incorporation improves hydrogen’s potential as a clean, widespread energy source.
5:00 PM - EN04.05.06
Selective Adsorption of H2 on N-Doped ZnO Nano-Ribbons—First-Principle Analysis
Nacir Tit1,Alaa Shaheen1,Wael Othman1,Younes Aitladi1,Sultan Atatri1,Yahya Atatri1,Golibjon Berdiyorov2
UAE University1,Hamad bin Khalifa University2Show Abstract
Density functional theory combined with the non-equilibrium Green’s function formalism is used to study the adsorption and gas-sensing properties of H2 gas molecule on pristine and doped ZnO nano-ribbons (NRs). Substitutional doping of oxygen site with C, N and F have been tested versus adsorption of H2 molecule and other molecules (e.g., N2, O2, H2O, H2S). The results of relaxation show chemisorption to occur only on C-and N-doped samples. While all these molecules exhibit chemisorption on C-doped ZnO-NR, only H2 and O2 molecules are chemisorbed on N-doped ZnO-NRs. The chemisorption of O2 is associated with the breaking of one π-bond and thus desorption in reversal process is plausible. However, the chemisorption of H2 is associated with a complete dissociation and introduces donor states into the gap (i.e., it plays a role of n-type dopant) and consequently enhancing the conductivity. These characteristics made N-doped ZnO-NRs have high sensitivity and selectivity towards the detection of H2 gas. Furthermore, the calculated IV-curves have paved the way for estimating the sensitivity and consolidated our results. Since the change of conductance is one of the main outputs of sensors, our findings will be useful in developing Hydrogen-based solid-state sensors.
5:00 PM - EN04.05.07
Extremely Spatial Confinement Induced Charge Transfer Interactions at the Trapped Xenon Atoms
Jianqiang Zhong1,Mengen Wang2,1,Akter Nusnin2,1,Dario Stacchiola1,Deyu Lu1,Anibal Boscoboinik1
Brookhaven National Laboratory1,Stony Brook University2Show Abstract
Molecules confined in the nanoscale regions usually exhibit intriguing physical and chemical properties. The present paper reports on the direct observation of charge transfer behaviors in spatial confined xenon (Xe) atoms. Individual Xe atoms are trapped at 300 K in nano-cages consisting of silica hexagonal prisms forming a two-dimensional (2D) array on a planar surface. In-situ synchrotron-based ambient pressure X-ray photoelectron spectroscopy (AP-XPS) reveals that the charge transfer takes place at the Xe atoms which are extremely confined between the 2D framework and the Ru(0001) support, in which the interfacial distance can be controlled by the coverage of chemisorbed oxygen on Ru(0001). Density functional theory (DFT) calculations further corroborate these significant charge transfer interactions between the trapped Xe atoms and silica/Ru(0001) systems, opening exciting opportunities for the study of individual noble gas atoms in confinement.
5:00 PM - EN04.05.09
Theoretical Simulation of Dehydration of Natural Gas Using MOFs and Zeolite Molecular Sieve Composite Membrane
China University of Petroleum1Show Abstract
To solve the problem of dehydration in natural gas purification, several MOFs and zeolite molecular sieve membranes has been proposed. Behaviors of adsorption and diffusion for H2O in Natural Gas on HKUST-1 or LTA and T-Type Zeolite Molecular Sieve Membrane were investigated by grand canonical Monte Carlo (GCMC) method. It is found that the classical force fields are not suitable for the system of adsorptions of H2O in Natural Gas on these membranes. The optimized force field parameters were obtained by fitting the experimental data. Results showed that strong competitive adsorption behavior existed in HKUST-1 or LTA and T-Type zeolite for H2O/CH4 mixture. Water loading increased with water content of feed, it was in agreement with the trend of permeation flux for pervaporation dehydration. The diffusivity of pure water molecules was greater than that of pure CH4 . Furthermore, the diffusion behavior of H2O/CH4 mixture through membrane was prominently affected by the interaction between the two components. The CH4 molecules could slow down diffusion of water molecules significantly, thus it would affect permeation flux of these membranes.
Jiang De-en, University of California, Riverside
Yu Han, King Abdullah University of Science and Technology
Sudhir Kulkarni, Air Liquide
Nikhil Medhekar, Monash University
King Abdullah University of Science and Technology (KAUST)
EN04.06: Porous Polymers and Composite Systems
Thursday AM, April 05, 2018
PCC North, 100 Level, Room 126 A
8:30 AM - EN04.06.01
Rational Design and Synthesis of Covalent Triazine Frameworks Based on Novel N-Heteroaromatic Building Block for Efficient CO2 and H2 Capture and Storage
Guangbo Wang1,Karen Leus1,Shuna Zhao1,Yingya Liu2,Pascal Van Der Voort1
Ghent University1,Dalian University of Technology2Show Abstract
The development of effective technologies or strategies for capturing or eliminating CO2 produced from various processes in order to minimize its influence on climate change remains an urgent and challenging task. To address this issue, in this present study, we have designed and synthesized a novel nitrogen-rich heteroaromatic tetranitrile, namely 4,4',4'',4'''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzonitrile, to prepare a set of nitrogen-rich CTFs as high-performance platforms for selective gas sorption and storage. The influence of several parameters such as the ZnCl2/monomer ratio and reaction temperature on the structure and porosity of the resulting frameworks was systematically examined. Remarkably, the CTF material obtained using 20 molar equiv. of ZnCl2 at the reaction temperature of 400 oC exhibits an excellent CO2 adsorption capacity (3.48 mmol/g at 273 K and 1 bar) as well as a significant high H2 uptake (1.5 wt% at 77 K and 1 bar). These values are among the top levels for all the CTFs measured under identical conditions to date. In addition, the obtained CTFs also present a relatively high CO2/N2 selectivity (up to 36 at 298 K) making them promising adsorbents for gas sorption and separation.
8:45 AM - EN04.06.02
Evaluation of Amine Functionalized Porous Polymer Networks for Post-Combustion Carbon Capture
Zachary Perry1,Hong-Cai Zhou1,Gregory Day1
Texas A&M University1Show Abstract
Power plant fossil fuel combustion is a major source of anthropogenic CO2 emissions, and as such, much current research has focused on mitigating these CO2 emissions. As part of our continued research into porous materials we have begun investigating a series of porous polymer network (PPN) sorbents for post-combustion carbon capture. Our leading sorbent series, the PPN-150 series, are mesoporous melamine-formaldehyde resins which, upon loading with amines, can act as highly efficient sorbents for CO2 capture under flue gas conditions. The high nitrogen content of the parent polymer greatly improves the amine tethering ability of the material compared to porous carbon while still not requiring the extensive synthesis seen in amine functionalized sorbents. The tethering ability can also be tuned by adding in dopants, functionalized small molecules that are dispersed throughout the polymer structure and provide separate sites for amine tethering or CO2 chemisorption. By adjusting the loaded amines and dopants identities the sorbents are capable of CO2 uptakes greater than 0.1 g/g sorbent. In addition, cycling studies have been performed with these sorbents showing loss of CO2 uptakes less than 4.5% over 33 cycles under dry gas conditions, with no noticeable loss in cycling performance observed for wet gas cycling. The PPN-150 series can be produced at the bench scale, taking advantage of the low-cost reagents required for the synthesis, while still maintaining high gravimetric CO2 uptakes.
9:15 AM - EN04.06.03
Unprecedented Gas Separation Properties of Blends Containing Polymers of Intrinsic Microporosity
Ingo Pinnau1,2,Nasser Alaslai1,2,Xiaohua Ma1,2,Yingge Wang2,Mahmoud Abdulhamid1,2,Yu Han2
King Abdullah University of Science and Technology1,King Abdullah University of Science and Technology (KAUST)2Show Abstract
Membrane-based gas separation processes have been implemented for the past three decades in a variety of large-scale industrial applications, such as carbon dioxide removal from natural gas, hydrogen recovery from petrochemical off-gas streams and nitrogen production from air. Interestingly, only a few membrane types are currently in use made mostly from commercially available polymers, such as cellulose triacetate, bisphenol-A polysulfone, polyimides, poly(phenylene oxide) polydimethylsiloxane, polyether-polyamide block copolymers etc.
Intrinsically microporous polyimides (PIM-PIs) with pore size < 20 Å were recently introduced into by incorporating highly contorted building blocks to provide polymers with significantly enhanced permeability while maintaining acceptable selectivity and all other desirable properties of high-performance polyimides, such excellent mechanical strength and high thermal stability; however, development of these PIM-PIs is currently limited by the availability of building blocks, such as spirobisindane, ethanoanthracene and triptycene-based monomers. In this work, novel membrane materials for gas separation processes were custom-designed from binary polyimide blends of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) reacted with a contorted hydroxyl-functionalized diamine and a carboxyl-functionalized diamine. These PIM-PI blends exhibited exceptional gas separation properties, specifically extremely high gas-pair selectivity values with improved permeabilities compared to commercial glassy polymer membrane materials. This extraordinary performance resulted from strong hydrogen-bonding-induced interactions between the hydroxyl and carboxyl groups, which generated an ultra-microporous polymeric molecular sieve structure. XRD spectra of resulting blends confirmed creation of average interchain d-spacing of smaller than ~3.5 Å, which made these blends materials highly selective for small gases. An optimized blend displayed a permselectivity of 136 for CO2/CH4, 11.4 for O2/N2 and 636 for H2/CH4 with diffusivity selectivities of 48.5 and 11 for CO2/CH4 and O2/N2, respectively.
9:45 AM - EN04.06.04
Application of Porous Polymeric Scaffolds for Carbon Capture
Farid Akhtar1,Dariush Nikjoo1
Luleå University of Technology1Show Abstract
Porous polymers have received an increased interest as CO2 sorbents due to combining the properties of both porous structure and polymers. High internal phase emulsion (HIPE) as a template by Oil-in-Water (O/W) system and photopolymerization technique was used to prepare crosslinked Acrylamide-co-Acrylic acid (AAM-co-AAC) hydrogel monolith. Also, photopolymerization followed by freeze granulation was utilized for the fabrication of the AAM-co-AAC hydrogel granules. The structural analysis of synthesized scaffolds confirmed crosslinked copolymer. The scanning electron microscopy (SEM) micrographs presented porous structure for monolith consists of a “skeleton copy” of the O/W HIPE where granules revealed many severe wrinkles on the surface. Monoliths and granules exhibited BET surface areas around 24 m2/g and 28 m2/g respectively. The CO2 uptake ability of synthesized scaffolds for dry scrubbing as well in aqueous media (wet scrubbing) was investigated. The CO2 adsorption capacity of monoliths and granules reached to saturation at 25 kPa to 0.5 and 0.8 mmol/g, respectively which were higher than adsorption values reported for amide-based porous polymers [1,2]. The electron-rich groups like NH2, C=O, and R-O-R in the structure of block copolymer can interact with CO2 molecules and give rise to the higher adsorption capacity. The CO2 and N2 adsorption isotherms for granules and monoliths indicated the selectivity of AAM-co-AAC copolymer for CO2 gas. Furthermore, the granules were able of capturing CO2 in aqueous media where the absorption of CO2 on water-swollen granules increased with increasing the amount of water. The CO2 capture capacity reached to 1.8 mmol/g in completely swollen granules. The uptake of CO2 in aqueous solution contributes from the physical dissolution of CO2 in water along with interactions between the functional groups of the hydrogels and gas molecules. The results revealed the CO2 dry and wet scrubbing ability of the synthesized hydrogel copolymers .
1. S. Zulfiqar, et al., RSC Adv. 4 (2014) 52263-52269.
2. F. U. Shah, et al., Magn. Reson. Chem. 54 (2016) 734-739.
3. D. Nikjoo, et al., J. CO2 Utilization 21 (2017) 473–479.
10:30 AM - EN04.06.05
Advanced Mixed Matrix Membranes for CO2 Separation
Cafer T. Yavuz1,Shannon Mahurin1
Oak Ridge National Laboratory1Show Abstract
The removal of CO2 from combustion streams has become a global challenge with significant environmental implications. While a number of approaches have been explored to separate CO2 from mixed streams, membranes have emerged as a promising technology because of their small footprint, reliability and energy efficiency. Hybrid, or mixed matrix, membranes combine the advantages of a porous material with the stability and reliability of a dense matrix to form an advanced membrane material with enhanced permeance and selectivity. Hollow carbon spheres with a microporous shell incorporated into a polymer matrix will be presented as a unique strategy to fabricate high performance membrane materials. The empty space within the hollow spheres promotes fast gas transport while the symmetry of the carbon shell along with the strong interaction between the carbon surface and a unique block co-polymer allows for the formation of a mechanically robust membrane with enhanced permeance and selectivity compared to the dense polymer. In addition, graphene- and graphene-oxide-based hybrid membranes provide a distinct opportunity to enhance membrane performance through unique architectures. Incorporating ionic liquids into graphene and graphene-oxide membranes can lead to novel gas transport mechanisms that improve permeance and selectivity leading to a new class of ultrathin, hybrid membranes.
11:00 AM - EN04.06.06
Mixed Matrix Composites Based on PEI-Silica Sorbents for Direct Indoor CO2 Capture
Mei Chee Tan1,Yuanyuan Zhang1,Jinguk Kim1,Daniel Wirawan1,Him Cheng Wong1,Hong Yee Low1
Singapore Uni of Technology and Design1Show Abstract
There is a growing need to advance CO2 capture materials and technology to mitigate the impact of climate change especially due to the escalating levels of CO2 that is strongly tied to the rapid pace of urbanization. Cities are reportedly responsible for more than 80% of global greenhouse gases (GHG) and CO2 is the most prominent component of anthropogenic GHG emissions. The elevated CO2 levels leads to higher absorption and thermal trapping which contributes partly to the urban heat island effect. This has led to increased research efforts to remove CO2 directly from the atmosphere using technical means such as direct air capture, to keep up with the pace of urbanization. Since the efficiency of CO2 capture is proportional to the purity of the gas stream, key challenges of direct air capture are the relatively low atmospheric CO2 concentration and low air circulation in most dense urban environments. Amongst the existing forms of carbon capture materials (CCMs), such as liquid sorbents or bulky ceramic-based honeycomb structures, mixed matrix polymeric composites are attractive material system that allow us to tailor the carbon capture performance and yet remain in a form that is versatile and be easily adapted for eventual implementation. The separation performance and properties of the mixed matrix composites depends on intrinsic properties of filler and matrix, filler loading and filler-matrix interaction.
In this work, we will discuss the effects of surface modification and processing strategies on the carbon capture performance of polyethylenimine (PEI)-modified porous silica sorbents (PEI-SiO2) that were dispersed in an elastomeric Pebax® matrix. PEI functionalization of high surface area silica is required for CO2 capture by harnessing the high interaction affinity between the amine groups of PEI with CO2. In this work, we will discuss how the PEI molecular weight and solvents used during the modification affect the PEI-SiO2 interfacial interactions and its impact on the CO2 capture capacity. By controlling the PEI-SiO2 interfacial interactions, we have optimized our PEI-SiO2 sorbent chemistry to achieve a CO2 capture capacity of 167 mg of CO2/g material (75°C), which is comparable to existing reported benchmarks of 132 to 141 mg of CO2/g material (75°C). These PEI-SiO2 sorbents were next dispersed within Pebax® to form free-standing films to facilitate eventual wide implementation of these CCMs. The composite formulation and filler dispersion was subsequently tailored to control the capture capacity, CO2 permeability and CO2/N2 selectivity of mixed matrix composite. Our preliminary studies that show successful ambient CO2 capture in a simulated indoor environment. The captured CO2 was subsequently recovered through desorption by purging the system using an inert gas such as N2. The recovered CO2 could be used as an alternative feed source for other carbonation chemistries.
11:15 AM - EN04.06.07
2D MOF/Polymer Mixed-Matrix Membranes for CO2/CH4 Separation
Jie Zha1,Xueyi Zhang1
The Pennsylvania State University1Show Abstract
Two-dimensional (2-D) metal-organic frameworks (MOFs) combine the tunable structure and chemical functionality of MOF materials with the high aspect ratio of the 2-D morphology, which is beneficial for a wide range of applications, such as gas separation, surface sensing, and catalysis. In the field of gas separation, the presence of 2-D MOFs in MOF/polymer mixed-matrix membranes will lead to selective transport of preferably adsorbed species in MOFs, such as CO2, but not other gases, resulting in improved selectivity with uncompromised permeance. However, challenges still exist in the facile synthesis of 2-D MOFs due to the isotropic nature of most MOF structure building units. In this work, we demonstrated a one-step room-temperature synthesis of 2-D MOFs based on copper paddlewheel units, where intrinsically anisotropic building units were utilized to control the morphology of MOF nanoparticles. This synthesis method was successfully extended to functionalized 2-D MOFs by selecting ligands with functional groups targeted for CO2 separation applications. To illustrate the advantage of using 2-D MOFs, the synthesized 2-D MOFs were incorporated into polymer matrices and the resultant mixed matrix membranes (MMMs) exhibited improved CO2/CH4separation performance with ideal selectivity increased by approximately 400%. The mechanisms underlying the increased selectivity of MMMs can be attributed to the greatly enhanced sorption toward CO2 molecules as a result of the incorporation of functionalized 2D MOFs, which overwhelmed the impeded gas diffusion owing to reduced chain mobility. Due to the high tunability of MOF structure with retained 2-D morphology, this approach of making 2-D MOFs and its composite materials will be further developed in the separation of other industrially and environmentally important gases.
11:30 AM - EN04.06.08
Linking Microstructure and Structure to Sorption Properties During Selective Gas Adsorption in Advanced Gas Sorbent Materials
Andrew Allen1,Winnie Wong-Ng1,Laura Espinal1,Eric Cockayne1
National Institute of Standards and Technology1Show Abstract
To be effective in practical applications, advanced gas sorbent materials must selectively adsorb large quantities of the target gas usually from a flowing gas stream containing multiple gases. The capacity to adsorb, e.g., CO2 under different pressure and/or temperature conditions can frequently be linked to changes in sorbent structure, which must be understood if sorbents are to be improved and optimized by material development. In this connection, metal-organic frameworks (MOFs) and MOF-like materials show considerable promise and potential for future development. Obviously, a lack of selectivity to adsorb only the target gas will result in other gases or water molecules being adsorbed and occupying sites within the sorbent that cannot then be occupied by the target gas. Selective adsorption cannot simply be established by measuring sorption isotherms for different single gases; it is necessary to determine whether one gas being adsorbed (e.g., CO2), also lets in a second gas by some collective gate-opening effect. Such sorption selectivity (or lack of it) can frequently be related to sorbent structure and microstructural or structural changes during the adsorption/desorption cycle. Building on previous work to elucidate these issues, 1-4 we have carried out a range of in situ operando small-angle X-ray and neutron scattering (SAXS and SANS), X-ray and neutron diffraction (XRD & ND) studies on different MOF-like sorbent systems during adsorption and desorption of CO2 and CO2 gas mixtures under realistic pressure conditions. (Recent experimental advances actually allow the combined SAXS & XRD data to be obtained together with a time resolution of less than 5 minutes.5) Pressure conditions include both static and flowing gas environments, and also supercritical CO2 conditions. By combining these results with density functional theory (DFT) calculations, we have gained new insights in connecting features in the isotherm curves to underlying changes in sorbent microstructure or structure.
 K.L. Kauffman, J.T. Culp, A.J. Allen, L. Espinal, W. Wong-Ng, T.D. Brown, A. Goodman, M.P. Bernardo, R.J. Pancoast, D. Chirdon & C. Matranga; Angew. Chem. Int. Ed., 50, 10888-10892 (2011).
 L. Espinal, W. Wong-Ng, J.A. Kaduk, A.J. Allen, C.R. Snyder, C. Chiu, D.W. Siderius, L. Li, E. Cockayne, A.E. Espinal & S.L. Suib; J. Am. Chem. Soc., 134, 7944-7951 (2012).
 W. Wong-Ng, J.T. Culp, Y.S. Chen, P. Zavalij, L. Espinal, D.W. Siderius, A.J. Allen, S. Scheins & C. Matranga;” CrystEngComm, 15, 4684-4693 (2013).
 A.J. Allen, L. Espinal, W. Wong-Ng, W.L. Queen, C.M. Brown, S.R. Kline, K.L. Kauffman, J.T. Culp & C. Matranga; J. Alloys and Compounds, 647, 24-34 (2015).
 J. Ilavsky, F. Zhang, R.N. Andrews, I. Kuzmenko, P.R. Jemian, L.E. Levine & A.J. Allen; J. Appl. Cryst., submitted (2018).
11:45 AM - EN04.06.09
The Role of Hydrogen Bonding on Transport of Co-Adsorbed Gases in Metal Organic Frameworks Materials
Kui Tan1,Stephanie Jensen2,Hao Wang3,Jing Li3,Timo Thonhauser2,Yves Chabal1
The University of Texas at Dallas1,Wake Forest University2,Rutgers University3Show Abstract
Understanding co-adsorption in nanoporous materials such as metal organic framework (MOFs) is important for most applications since they are rarely used solely for pure gases and they are typically subject to gas contamination. Co-adsorption, however, leads to a variety of processes that complicate the analysis, such as molecular competition for adsorption and diffusion. Due to a lack of in situ characterization within these 3D nanoporous structures, these processes remain largely unknown. We report here a novel synergistic effect involving co-adsorption in a prototypical metal organic framework (MOF) material, i.e. MOF-74. We find that the addition of NH3 or H2O to MOF-74 previously loaded with a variety of small gases (e.g., CO, CO2, SO2) first displaces a certain amount of molecules always and then prevents the removal of the remaining small gases upon evacuation. We further show, with support of first-principles modeling, that this phenomenon is not due to guest-guest binding as usually being regarded as “cooperative binding effect”, but instead to an increase in diffusion barrier for these small molecules. Combining in situ infrared spectroscopic measurements and first-principles modeling, we demonstrate that hydrogen bonding is primarily responsible for the large increase of the diffusion barrier (by a factor of ~7 for CO and CO2) along the transport pathway. These relevant findings contribute to fundamental understanding of co-adsorption in porous materials and to dispel common assumptions. For instance, H2O and NH3 are usually regarded as impurities that are detrimental to the performance of gas adsorption and capture by poisoning active sorption sites. This is clearly not the case here. Therefore, the effect of H2O and NH3 (or other hydrogen containing molecules prone to hydrogen bonding) on the gas adsorption performance of MOF materials needs to be reevaluated.
EN04.07: Advanced Materials
Thursday PM, April 05, 2018
PCC North, 100 Level, Room 126 A
1:30 PM - EN04.07.01
Advanced Porous Materials for Hydrocarbon Separations
University of South Florida1Show Abstract
Advanced porous materials as represented by metal–organic frameworks (MOFs) and porous organic polymers (POPs) represent a new class of materials, and one of their striking features lies in the tunable, designable, and functionalizable nanospace, which allows designed incorporation of different functionalities for targeted applications, such as gas storage/separation, sensing, drug delivery, catalysis, conductivity. We will show how MOFs and POPs can be task-specifically designed and functionalized for applications in hydrocarbon separations, particularly paraffin/olefin separations.
2:00 PM - EN04.07.02
Enabling 10 mol/kg Swing Capacity in Post-Combustion CO2 Capture Processes
Ryan Lively1,Stephen DeWitt1,Rohan Awati1,Hector Rubiera Landa1,Eli Carter1,Jongwoo Park1,Matthew Realff1,Krista Walton1,David Sholl1
Georgia Institute of Technology1Show Abstract
The rapid increase in global industrialization necessitates technology shifts in energy production, manufacturing, and carbon management techniques. Large energy costs in refineries, power plants, and manufacturing facilities using traditional separation techniques are currently a major opportunity for innovation. Approximately 10% of global energy use can be attributed to separation processes, with the vast majority of separations being “thermal” in nature (e.g., distillation). Significant energy and cost savings can be realized using advanced separation techniques such as membranes and sorbents. One of the major barriers to acceptance of these techniques remains linking engineering materials to actual processes that are effective in the presence of aggressive industrial feeds.
The creation of robust materials-enabled advanced separators and their manufacturing into low-cost, energy-efficient devices to meet this global challenge will be the focus of the talk. Engineering novel materials—such as zeolitic imidazolate frameworks, polymers of intrinsic microporosity, and carbon molecular sieves—into hollow fiber separation devices shows promise for emerging separation applications. These include natural gas liquid fractionation, olefin/paraffin separation, carbon capture, and organic solvent purification. Specifically, a highly heat integrated sub-ambient pressure swing adsorption process that enables ultra-high swing capacities using robust metal-organic frameworks will be discussed. Synthesis and formation of advanced composite materials, mass transfer of small molecules through these materials, and an outlook for energy- and cost- efficient separations will be discussed. The dual advance of novel materials engineering and scalable separation device manufacturing will enable use of membranes and sorbents in critical industrial separation processes.
3:30 PM - EN04.07.03
Ceramic-Carbonate Dual-Phase Membranes for Carbon Dioxide Capture
Jerry Lin1,Oscar Ovalle-Encinia1,Ben Wu1
Arizona State University1Show Abstract
Most membranes show carbon dioxide perm-selectivity at low temperatures (such as the room temperature). High temperature carbon dioxide permeable membranes offer advantages for effective carbon dioxide capture from fossil fuel burning power plants at high temperatures. The paper will focus on a new group of dual-phase membranes that permeate only carbon dioxide at high temperatures (>500oC). These dual-phase membranes consist of a metal or oxygen ionic conducting oxide phase and a molten carbonate phase which conduct respectively electrons or oxygen ions and carbonate ions. The paper will summarize key properties of the dual-phase membranes, including the effects of the ionic conductivity of materials, pore structure of the ceramic phase, membrane thickness and the operation conditions on the permeance of carbon dioxide. Applications of these membranes in membrane reactors for water gas shift reaction or dry-reforming of methane for pre- or post-combustion carbon dioxide capture will be discussed. Finally, the paper will address the key issues of the stability of the membranes in industrially related atmospheres.
4:00 PM - EN04.07.04
The Influences of Pore Density and Pore Size of Nanoporous Graphene Membrane for Gas Permeation and Separation
University of California, Riverside1Show Abstract
Pore density and pore size are two factors for gas molecular permeation and separation in nanoporous membranes. The nanopores on the membranes can be tuned to control gas molecular permeation and separation. But how the pore density can influence the permeation and how the pore size of multilayer nanoporous membrane can be tuning to influence the selectivity have not been fully addressed from a computational simulation. Here we use molecular dynamics (MD) simulation to investigate gas molecular permeation and adsorption behaviors by changing the pore densities of a nanoporous graphene membrane from 0.01 nm-2 to 1.28 nm-2 and adjusting the effective pore size by tuning the offset of bilayer graphene membrane. We find that the higher pore density leads to higher permeation for both CO2 and He, but the increase rate slows down only for CO2. And We also find that offset can influence the effective pore size, which can be used to build bilayer gas separation membrane flexibly.
4:15 PM - EN04.07.05
High-Throughput Screening to Investigate the Relationship Between the Selectivity and Working Capacity of Porous Materials for Propylene/Propane Adsorptive Separation
Sang Soo Han1,Byung Chul Yeo1,Donghun Kim1
Korea Institute of Science and Technology1Show Abstract
An efficient propylene/propane separation is a very critical process for saving the cost of energy in the petrochemical industry. For separation based on the pressure-swing adsorption process, we have screened ~1 million crystal structures in the Cambridge Structural Database and Inorganic Crystal Structural Database with descriptors such as the surface area of N2, accessible surface area of propane, and pore limiting diameter. Next, grand canonical Monte-Carlo simulations have been performed to investigate the selectivities and working capacities of propylene/propane under experimental process conditions. Our simulations reveal that the selectivity and the working capacity have a trade-off relationship. To increase the working capacity of propylene, porous materials with high largest cavity diameters (LCDs) and low propylene binding energies (Qst) should be considered; conversely, for a high selectivity, porous materials with low LCDs and high propylene Qst should be considered, which leads to a trade-off between the selectivity and working capacity. In addition, for the design of novel porous materials with a high selectivity, we propose a porous material that includes elements with a high crossover distance in their Lennard-Jones potentials for propylene/propane such as In, Te, Al, and I, along with the low LCD stipulation.
4:30 PM - EN04.07.06
Recent Advances on Alkaline Ceramics as Possible Captors and Catalytic Materials for the CO2 Chemisorption and Conversion to Added Values Products
Universidad Nacional Autonoma de Mexico1Show Abstract
In the last two decades different lithium and sodium ceramics have been proposed as potential high temperature CO2 captors, under different physicochemical conditions. Moreover, in the last five years, it has been evidenced that some of these alkaline ceramics can be used as possible bifunctional materials for CO2 capture and subsequent catalytic conversion to added value products. This kind of alkaline ceramics have been tested in different catalytic reactions (where CO2 has been previously chemically trapped) such as methane reforming and water gas shift processes. These processes (capture reactions and the subsequent methane reforming process) are environmentally important, as CO2, CO and CH4 are catalytically converted into an added value product, the syngas. Moreover, it has been evidenced that the same alkaline ceramics can be used for CO oxidation-capture process, which would be highly useful in hydrogen enrichment process. Therefore, the aim of this presentation is to show the most recent advances obtained about the next three different aspects: 1) CO2 capture on alkaline ceramics; 2) the use of these ceramics as bifunctional materials for the CO oxidation-capture process; and 3) The methane reforming reaction for the syngas production, using the CO2 chemically trapped in the alkaline ceramics.
4:45 PM - EN04.07.07
The Role of a Liquid-Phase Interfacial Film on the Carbonation Performance of MgO Decorated with Eutectic Mixtures
Jacinto Lamud1,Nick Florin2,3,Dianne Wiley4,Mark Sceats5,May Lim1
University of New South Wales1,University of Technology Sydney2,Imperial College London3,University of Sydney4,Calix, Ltd.5Show Abstract
In recent years, sorbent-based CO2 capture technologies using metal oxides have been extensively studied. Among various metal oxides which can capture CO2 via adsorption, magnesium oxide (MgO) is among the most widely investigated because of its potential for pre-combustion CO2 capture applications such as coal gasification and natural gas reforming . While MgO has a theoretical CO2 capture capacity of ~24 mmol.g-1, its reaction with CO2 gas molecules is usually restricted by the surface product layer which limits its actual capacity to < 1 mmol.g-1 . In the last decade, much attention has been paid to improving the properties of MgO to realize its potential as a CO2 sorbent. Herein, we report a significant promoting effect of eutectic (binary, ternary and quaternary) alkali salt mixtures on the CO2 capture performance of MgO. The sorbents were prepared by wet impregnation of MgO with varying loadings of the eutectic mixtures. The physicochemical properties were characterized by various techniques such as BET, ICP-OES, XRD, FT-IR, CO2-TPD, SEM and TEM, and the capture capacity was evaluated using thermogravimetric analysis (TGA). The results suggest that the nature of the salt and its melting temperature (Tm) are crucial factors in the performance of the sorbent. The sorbent modified with NaNO3 (Tm ≈ 302 °C) exhibited the highest CO2 uptake of 11.9 mmol.g-1 (523.7 mg CO2 per 1 g of sorbent) after carbonation for one hour at 300 °C under ambient pressure while those modified with LiNO3 and KNO3 did not perform well. Interestingly, the use of eutectic mixtures of these salts not only improved the CO2 uptake but also broadened the operating temperature window. In the case of the (LiNaK)NO3- and (LiNaK)NO3-NaNO2-modified sorbents, the CO2 uptakes were better than that of the NaNO3-modified sorbent at temperatures below and above 300 °C. The results of the FT-IR spectroscopy reveal the presence of two types of carbonates (surface and bulk) while the XRD confirms the formation of well-crystallized MgCO3 after CO2 sorption. Based on these findings, a mechanism that involves a gas-liquid-solid interface as an alternative pathway for the reaction of gaseous CO2 and the solvated [Mg2+...O2-] ionic pairs will be discussed.
1. MacDowell, N., et al., An overview of CO2 capture technologies. Energy & Environmental Science, 2010. 3(11): p. 1645.
2. Wang, J., et al., Recent advances in solid sorbents for CO2 capture and new development trends. Energy & Environmental Science, 2014. 7(11): p. 3478-3518.