a DoE Energy Frontier Research Center

Ultra-Selective High-Flux Membranes from Directly Synthesized Zeolite Nanosheets

Porous crystalline materials with uniform pore sizes and high pore densities are promising for membrane separation applications, which are energy-efficient alternative to the conventional separation processes. However, the fabrication cost of such material is relatively high, and cost reduction or performance improvement is required for industrial applications. One promising approach is to fabricate a thin and intergrown membrane based on 2-dimensional crystals (nanosheets). In this work, we have, for the first time, developed a direct synthesis method of single MFI nanosheets and demonstrated their high separation performances. Previously, zeolite MFI nanosheets were prepared by exfoliation of multi-lamella MFI materials. This exfoliation process is costly and time-consuming and suffers from fracture of the nanosheets (<300 nm). In comparison, our direct synthesis method can yield larger (~2 µm) nanosheets with an improved production yield. This was enabled by seeded growth based on twining, which triggers the emergence of nanosheet from the seed crystal. These nanosheets with high aspect ratios can form high-density coating on porous supports, which are further intergrown into continuous membranes. These thin membranes exhibit superior separation performances, as established for xylene isomer mixtures, alcohol/water mixture, and linear/branched hydrocarbon mixtures.
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Continuous Flow Processing of ZIF-8 Membranes on Polymeric Porous Hollow Fiber Supports for CO2 Capture

Inorganic membranes can have very high gas permeability and selectivity compared to conventional polymeric membranes. But the fabrication of inorganic membranes is costly, time consuming and needs aggressive synthesis conditions. Also, scale-up and reproducibility are big problems, in part due to the use of expensive ceramic supports. In this work, we have successfully fabricated defect-free ZIF-8 membranes on polymeric hollow fiber supports using a continuous flow processing method that is simple, scalable, reduces manufacturing costs, and is environmentally friendly. The formation of a continuous ZIF-8 membrane that is ~8 µm thick was controlled by flowing an aqueous metal solution on the shell side of a polymer hollow fiber while flowing the 2-methylimidazole linker through the bore. The formation of ZIF-8 was confirmed using XRD and EDX. The ZIF-8 membrane was grown and anchored to the microporous region of the outer surface of supports for better mechanical properties and to avoid the delamination of membrane. These membranes demonstrated CO2 permeance of 22 GPU and CO2/N2 selectivity of 52. This method is very useful to scale up the fabrication of inorganic membranes for industrial applications, as the membrane can be formed in situ in a pre-assembled hollow fiber module.
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Chemical Conversion of Linkages in Covalent Organic Framework

Covalent organic frameworks (COFs) are ordered, porous polymers formed from the assembly of small molecular building blocks. The typical linking reactions employed are reversible so that any defects arising during COF synthesis can be dissolved and subsequently reformed. The inherent linkage reversibility leaves the frameworks subject to chemical degradation through this reverse reaction. This report describes a chemical modification of the framework from easily hydrolyzed imine linkages to more chemically stable amide functionalities. This reaction can be performed under mild oxidative conditions at room temperature, and leaves the underlying structure of the starting materials unchanged. The conversion of these materials can be confirmed can both infrared and solid state nuclear magnetic resonance (NMR) spectroscopy. In addition, the products maintain the crystallinity of the parent compounds, as measured by powder X-ray diffraction. While the amide-linked materials are permanently porous, their surface area is lowered by this transformation, probably due to included oligomeric species, whose existence is supported by preliminary NMR experiments. The improved chemical stability of these new materials was assessed by measurement of diffraction before and after treatment with strong aqueous acid and base.
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New Adsorbate-Induced Deformation of a Series of Metal-Organic Frameworks

Flexible metal-organic frameworks (MOFs) have unique adsorption properties. However, most simulation studies of adsorption in MOFs assume that the crystal lattice is rigid. The development of new flexible framework models is required to compare to and interpret experimental data. Recently, a new deformation pattern has been observed by the adsorption of argon in the IRMOF-74 series. To describe this behavior, we used a combination of Monte Carlo and molecular dynamics simulation techniques, which demonstrates that adsorbate molecules can induce a change in the crystal lattice associated with a lowering of the crystal symmetry. The simulations show that the crystal lattice changes from regular hexagons to a complex pattern of some regular hexagons surrounded by a spiral of irregular hexagons. Adsorption simulations show that irregular hexagons in the deformed lattice have a slightly smaller pore volume, which enhances adsorbate interactions. We compared the X-ray scattering data associated with the deformed lattice to results published in the journal Nature, and found that deformed lattice X-ray peaks corresponded with experimental observations. The conclusions indicate that lattice deformation is an alternative explanation for in situ small angle X-ray scattering data of this series of materials.
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New Method to Incorporate Alkylamine into Metal-Organic Frameworks for CO2 Capture

Inexpensive and effective CO2 adsorbents are highly desired to stabilize atmospheric CO2 levels. Alkylamine modified metal-organic frameworks (MOFs) are promising candidate sorbent materials, since they bind CO2 with strong affinity even in the presence of water and can be easily regenerated by moderate heating under reduced pressure. However, it is challenging to synthesize adsorbent materials replete with amine functionalities. In this work, we developed a simple method to synthesize alkylamine modified MOFs based on a Brønsted acid-base reaction through which alkylamines are tethered to sulfonic acid sites in the framework. By systematically optimizing the amine tethering process, we generated an adsorbent that demonstrates strong CO2 binding under conditions relevant for capture from both flue gas and air. Importantly, the CO2 uptake capacity was unchanged after 15 cycles of CO2 capture and regeneration, indicating good long-term stability for multiple cycles of use. The low-cost starting materials and simple synthetic procedure of this adsorbent make it a promising candidate for large-scale production as a carbon capture material.
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In silico Design and Screening of Hypothetical MOF-74 Analogs and Their Experimental Synthesis

Our in silico reticular chemistry study combines an application that has only been studied experimentally, the creation of MOF-74 analogs, with a computational method for the automated generation of hypothetical analogs of MOFs exhibiting a 1-D rod topology. With MOF-74 as the target system for our in silico structure generation, only 61 ligands (0.0001%) were identified to assemble valid MOF-74 analogs from the chemical space spanned by the PubChem compounds database. We necessarily developed a novel in silico building algorithm since MOF-74 exhibits 1-D secondary building unit (SBU) rods and complex connectivity between ligands and SBUs. Additionally, we utilized Density Functional Theory (DFT) and Grand Canonical Monte Carlo (GCMC) to simulate and understand the CO2 adsorption trends in this library of materials. One ligand in the library that was also identified as commercially available, known by its pharmaceutical name olsalazine or 3,3′-azobis(6-hydroxybenzoate)salicylic acid, was used to successfully synthesize a MOF-74 analog. We significantly increase the impact of our in silico screening by demonstrating that novel, predicted structures are indeed synthesizable.
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Reducing Plasticization Effects in Polymer Membranes using Metal-Organic Framework Nanocrystals

The efficient separation of CO2 from various gas streams, in processes such as natural-gas purification and post-combustion carbon capture, presents major opportunities for advancing clean energy technologies. Membrane-based gas separations are less energy intense compared to conventional CO2 separation methodologies, but new membrane materials with improved separation performance under realistic process conditions are needed. Here, we utilize strong metal-organic framework nanoparticle/polymer interactions to improve membrane performance under realistic feed environments, which tend to diminish the separation properties of neat polymer membranes. We demonstrate that the incorporation of Ni2(dobdc) metal-organic framework nanocrystals into various polyimides can improve the performance of membranes for separating CO2 from CH4 under mixed-gas conditions. Four upper-bound 6FDA-based polyimides, as well as the commercial polymer Matrimid®, show improved selectivity under mixed-gas feeds when loaded with 15-25 wt% Ni2(dobdc), while the neat polyimides show diminishing selectivity upon increasing feed pressure. This approach presents an alternative to chemical crosslinking for achieving plasticization resistance, with the added benefit of retaining or increasing permeability while simultaneously reducing chain mobility.
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Selective Gas Capture via Kinetic Trapping

The burning of carbon based fossil-fuels and the consequent release of carbon dioxide in the atmosphere poses a threat to the environment. Capture and sequestration of CO2 from a flue-gas mixture is therefore a pressing need. Adsorbents like metal-organic frameworks (MOFs) are used for this purpose, but gas uptake processes rely on equilibrium conditions, severely restricting the parameter space of conditions and materials available to industry. Furthermore, nonequilibrium aspects of gas capture in MOFs remains unexplored. Here, using a simple statistical mechanical model of gas diffusion and binding, parameterized by quantum mechanical data, we show that selective gas capture in MOFs can be effected under nonequilibrium conditions. Employing ideas of statistical mechanics, we uncover the emergent gas separation mechanism that arises due to different mobilities of different gas types within a crowded framework. We predict optimum nonequilibrium strategies for effective gas uptake. Our simulation study provides a new perspective on the problem of gas capture, and identifies a path toward using previously discounted or new materials and conditions to achieve it.
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About the CGS


Who We Are

The Center for Gas Separations is one of 32 Energy Frontier Research Centers funded by the Department of Energy to conduct fundamental research that addresses the five Basic Energy Sciences Grand Challenges:

  1. How do we control material processes at the level of electrons?
  2. How do we design and perfect atom- and energy-efficient synthesis of revolutionary new forms of matter with tailored properties?
  3. How do remarkable properties of matter emerge from complex correlations of the atomic or electronic constituents and how can we control these properties?
  4. How can we master energy and information on the nanoscale to create new technologies with capabilities rivaling those of living things?
  5. How do we characterize and control matter away -especially very far away- from equilibrium?

The Center is made up of researchers across the US, at the University of California, Berkeley (lead institution), Lawrence Berkeley National Lab, Texas A&M University, University of Minnesota, the National Energy Technology Laboratory, and the National Institute of Standards and Technology.


What We Do

Although it is challenging to calculate the energy used by all chemical separation processes, the best estimates indicate that they account for 10-15% of the energy consumed globally. Some of the largest offenders are the purification of oxygen (O2, 91% of energy input is for separating N2), petroleum refining (>50% energy expended is for separations), and the separation of carbon dioxide (CO2) from H2 necessary for ammonia production (25% of energy consumed). In the US alone, separations account for an even greater ~22% of the total national energy input. Furthermore, when faced with climate change resulting from continually-increasing anthropogenic CO2 emissions and the corresponding necessity of large-scale carbon capture and storage, the cost of separations is expected to increase significantly. Reducing the total energy costs of separations would therefore contribute substantially to minimizing wasteful energy consumption globally.

To address this need, the primary goal within the Center for Gas Separations (CGS) is to tailor-make novel materials for highly efficient gas separations, with an emphasis on adsorbents that are highly selective for CO2 capture. This strategy addresses the 2nd Grand Challenge and requires a fundamental understanding of materials properties, molecular interactions, and the design of adsorbents tuned precisely for interactions with specific gases.

Announcements


Date  
March
2017
The CGS team participated in the College & Career Day at Berkeley Arts Magnet elementary school on March 10.
November
2016
Carbon Capture and Storage: Carbon Capture and Storage themed issue, Faraday Discussions. [RSC website]
September
2016
Evok Innovations Announces First Round of Investments: Mosaic Materials, which is working to commercialize materials initially discovered in the CGS, is selected as one of five cleantech companies. [PDF]
September
2016
EFRC Program Booklet: BES has recently published a booklet that summarizes the history and mission of the EFRC program and highlights the accomplishments since 2009. [PDF]
June
2016
2016 All-Hands Meeting
Date: November 8-9, 2016
Location: DoubleTree Hilton at the Berkeley Marina
April
2015
Materials Science: The Hole Story (Nature: News Feature, 520, 148-150, April 8, 2015)
March
2015
Materials Chemistry: Cooperative Carbon Capture (Nature News & Views, 519, 294-295, March 19, 2015)
March
2015
Porous Crystal Supersuckers Capture Carbon (IEEE Spectrum, March 18, 2015)
March
2015
New Material Captures Carbon at Half the Energy Cost (Phys.org, March 11, 2015)
March
2015
New Material Captures Carbon at Half the Energy Cost (Science Daily, March 11, 2015)
March
2015
New Material Captures Carbon at Half the Energy Cost (Scicasts, March 11, 2015)
March
2015
A Better Way To Scrub CO2 (Science 2.0, March 19, 2015)
March
2015
A Better Way of Scrubbing CO2 (Newswise, March 17, 2015)
March
2015
A Better Way of Scrubbing CO2 (Lab Manager, March 19, 2015)
March
2015
Researchers Triple CO2-Scrubbing Capacity of MOFs by Appending a Diamine Molecule (Azonano, March 18, 2015)
March
2015
A Better Way of Scrubbing CO2 (Nanowerk, March 17, 2015)
March
2015
A Better Way of Scrubbing CO2 (EurekAlert! March 17, 2015)
March
2015
A Better Way of Scrubbing Carbon Dioxide (R&D Mag, March 17, 2015)
March
2015
Cooperative Insertion of CO2 in Diamine-appended Metal-organic Frameworks (Bioportfolio, March 11, 2015)
March
2015
A Better Way of Scrubbing CO2 (Innovations Report, March 18, 2015)
March
2015
New Material Captures Carbon at Half the Energy Cost (Health Medicinet, March 2015)
March
2015
Material Captures Carbon at Half the Energy Cost (Product Design & Development, March 13, 2015)
March
2015
Cooperative Capture (Nature podcast interview of Jeff Long on work reported in 3/12/15 Nature article)
March
2015
The Proof Is in the Pores (EFRC Newsletter, March 2015)
March
2015
Predicting Cheaper Routes for Carbon Capture (EFRC Newsletter, March 2015)
December
2014
Cover of Chemical Science (Chem. Sci., Dec. 2014)
November
2014
Playing Catch and Release with Molecules (Frontiers in Energy Research, Nov. 2014)
October
2014
New Carbon Capture Method is the Best of Both Worlds (Nature World News, Oct. 2014)
October
2014
Un captage de carbone (encore) plus rentable et plus efficace ? (Enerzine, Oct. 2014)
October
2014
MOF Slurry-Based Process May Revolutionize Carbon Capture (Azonano, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture (Science Newsline, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture (Phys.org, Oct. 2014)
October
2014
New 'Slurry' Could Make Carbon Capture More Efficient (Climate Central, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture (e! Science News, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture (Science Daily, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture (USA News, Oct. 2014)
October
2014
A Cost-effective and Energy-efficient Approach to Carbon Capture with MOFs (Nanowerk, Oct. 2014)
September
2014
New Sorbents for Greener Cooling (C&EN, Sept. 2014)
June
2014
An Inside Look at a MOF in Action (ALS Highlight, June 2014)
April
2014
MOFs (MRS-TV video, April 2014)
December
2013
Research Highlight: Cage Calculations (Nature Chemistry, Dec. 2013)
August
2013
New method predicts adsorption in carbon dioxide-scrubbing materials (R&D Magazine, Aug. 2013)
August
2013
Cover of Advanced Materials (Adv. Mat., Aug. 2013)
June
2013
Cover of the Journal of Physical Chemistry C (J. Phys. Chem. C, June 2013)
May
2013
Material That Sorts Molecules by Shape Could Lower the Price of Gas (MIT Technology Review, May 2013)
April
2013
Researchers discover materials to transform methane into fuel (The Daily Californian, April 2013)
April
2013
Methane-gobbling material found, scientists say (NBC News, April 2013)
April
2013
Inside back cover of Angewandte Chemie (Angewandte Chemie, April 2013)
December
2012
MOFiosos: Berkeley scientists make carbon a structure it cannot refuse (Berkeley Science Review, Dec. 2012)
November
2012
Cover of ChemPhysChem (ChemPhysChem, Nov. 2012)
October
2012
Nanosolutions for Grand Challenges (EFRC Newsletter, Oct. 2012)
October
2012
News and Views in Nature Chemistry: Force fields for carbon capture (Nature Chemistry, Oct. 2012)
October
2012
Cover picture on Angewandte Chemie (Angewandte Chemie, Oct. 2012)
September
2012
Biomimetic And Extreme Surface-Area Frameworks (C&EN, Sept. 2012)
August
2012
Cover of PCCP (PCCP, Aug. 2012)
May
2012
Computer Model Pinpoints Prime Materials for Efficient Carbon Capture (Science Daily, May 2012)
May
2012
New Materials could Reduce Parasitic Load of CO2 Capture by up to 40%, Researchers Say (GHG Monitor, May 2012)
May
2012
New Materials Could Cut Parasitic Energy Costs for CO2 Capture by up to 30-40% (Green Car Congress, May 2012)
April
2012
A Step Up for Separating Hydrocarbons (C&EN, April 2012)
March
2012
New Material Cuts Energy Costs of Separating Gas for Plastics and Fuels (e! Science News, March 2012)
March
2012
Cutting the Cost for Commercial Gas Purification -Theory Leads the Way for a Materials Solution (DOE-BES highlight, March 2012)
March
2012
Carbon Dioxide Catchers (Nanowerk, March 2012)
August
2011
Inside front cover of Advanced Materials (Advanced Materialds, Aug. 2011)
October
2010
Structure of the Week - # 10 October 25, 2010 (ACS, Oct. 2010)
September
2011
Metal Organic Frameworks (CEN Online video, Sept. 2011)
July
2010
Carbon Smackdown: Carbon Capture (Berkeley Lab video, July 2010)
May
2010
Hunt for Improved Carbon Capture Picks up Speed (Berkeley Lab video, May 2010)
February
2010
Carbon Cycle 2.0: Carbon Capture (Berkeley Lab video, Feb. 2010)