Metal–Organic Frameworks for Separations

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.

Membrane Technology and Applications

A ceramic fuel cell in an all solid-state energy conversion device that produces electricity by electrochemically combining fuel and oxidant gases across an ionic conducting oxide. Current ceramic fuel cells use an oxygen-ion conductor or a proton conductor as the electrolyte and operate at high temperatures (>600°C). Ceramic fuel cells, commonly referred to as solid-oxide fuel cells (SOFCs), are presently under development for a variety of power generation applications. This paper reviews the science and technology of ceramic fuel cells and discusses the critical issues posed by the development of this type of fuel cell. The emphasis is given to the discussion of component materials (especially, ZrO2 electrolyte, nickel/ZrO2 cermet anode, LaMnO3 cathode, and LaCrO3 interconnect), gas reactions at the electrodes, stack designs, and processing techniques used in the fabrication of required ceramic structures.

Ceramic Fuel Cells

The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Carbon Dioxide Capture: Prospects for New Materials

Sorption and diffusion of VOCs in DAY zeolite and silicalite-filled PDMS membranes

The catalytic properties of dense fluorite-structured Bi 1.5 Y 0.3 Sm 0.2 O 3– δ (BYS) pellets for oxidative coupling of methane (OCM) to ethane and ethylene (C 2 products) were studied in a packed-bed reactor in co-feed mode. The effects of temperature, feed flow rate, CH 4 /O 2 and He/(CH 4 +O 2 ) ratios on the OCM performance over BYS were systematically investigated. The appropriate operating conditions were found to be: temperature, 900–1000°C; total flow rate, 90–150 ml (STP)/g min; CH 4 /O 2 ratio, 2–3.5; He/(CH 4 +O 2 ) ratio, 0.75–1.75. Under these conditions, C 2 yields of 20–27%, C 2 selectivities of 50–62% and C 2 space–time yield of up to 6.9 μmol/g s were achieved. The good OCM catalytic properties of BYS are believed to be related to its fluorite-type phase structure and large oxygen ion mobility at high temperatures. OCM kinetics of BYS oxide was studied with the assumption that no C 2 products were converted to CO x under low to medium methane conversion range. Lumped rate equations for C 2 and CO x formation were obtained as functions of temperature, O 2 and CH 4 partial pressures. The solid phase oxygen ions are responsible for the C 2 formation, while the gas phase oxygen molecules enhance the CO x formation.

Oxidative coupling of methane on fluorite-structured samarium–yttrium–bismuth oxide

Chemical vapor deposition (CVD) with methyldiethoxysilane (MDES) for MFI zeolitic pore size reduction is an effective way to improve the H2/CO2 separation factor of zeolite membranes. However, only good membranes with few intercrystalline defects are able to show considerable improvement in H2/CO2 separation factor through CVD modification. It is unreliable to evaluate the membrane quality on the basis of the H2/SF6 or N2/SF6 ideal separation factor because the SF6 adsorption-induced crystal swelling causes shrinkage of the intercrystalline defects in the MFI zeolite membranes. In this study, the quality of MFI zeolite membranes was evaluated on the basis of their performance in separating equimolar H2/CO2 mixture gas at room temperature. High-quality membranes are more selective to CO2 molecules rather than H2 at room temperature due to the adsorption of CO2 into the zeolitic pores and blocking of the pore channels for H2 diffusion. The effectiveness of the quality evaluation method was confirmed by on-s...

Effect of the Membrane Quality on Gas Permeation and Chemical Vapor Deposition Modification of MFI-Type Zeolite Membranes

Effects of adsorption-induced microstructural changes on separation of xylene isomers through MFI-type zeolite membranes

Nanoscale, high surface area cerium oxide (ceria) powders and stable, high-concentration (>1 M) ceria sols were prepared by a new method based on homogeneous precipitation in an acidic environment using cerium(IV) nitrate as the precursor. The results are compared with ceria powders and sols prepared by a hydrothermal method in a basic environment with cerium(III) nitrate as the precursor. Hydrolysis and condensation of the cerium(IV) and cerium(III) nitrates yield the ceria precursor precipitates with molecular formula of CeO2·2H2O [or Ce(OH)4] and CeO2·H2O [or Ce(OH)2O], respectively. The dried ceria precursor powders from Ce(IV) and Ce(III) are well dispersed in the form of primary particles of about 4 nm in size. Calcination at 450 °C causes phase transformation of the amorphous portion accompanying growth of the Ce(IV)-derived ceria crystallite or aggregation of the Ce(III)-derived ceria particles. The Ce(III)-derived ceria crystallites have a smaller lattice parameter than the Ce(IV)-derived sample ...

Y.S. Lin

Papers

Sorption and diffusion of VOCs in DAY zeolite and silicalite-filled PDMS membranes

Oxidative coupling of methane on fluorite-structured samarium–yttrium–bismuth oxide

Effect of the Membrane Quality on Gas Permeation and Chemical Vapor Deposition Modification of MFI-Type Zeolite Membranes

Effects of adsorption-induced microstructural changes on separation of xylene isomers through MFI-type zeolite membranes

Synthesis and Characterization of Nanosized Ceria Powders and High-Concentration Ceria Sols