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In view of the increasingly severe global warming and ocean acidification caused by CO 2 emissions, we report a new procedure, named "reactive separation", to capture CO 2 . We used advanced Monte Carlo and molecular dynamics methods to simulate the water-gas shift reaction in single-walled carbon nanotubes. We found that (11,11) carbon nanotubes with a diameter of 0.75 nm have the best ability to capture CO 2 generated in the water-gas shift reaction. When the feed water-gas ratio is 1:1, the pressure is 3 MPa, and the temperature is 473 K, the storage capacity of CO 2 reaches 2.18 mmol/g, the molar fraction of CO 2 and H 2 inside the carbon nanotube is 0.87 and 0.09, respectively, the conversion of CO in the pore is as high as 97.6%, and the CO 2 /H 2 separation factor is 10.3. Therefore, utilizing the reaction and separation coupling effect of carbon nanotubes to adsorb and store the product CO 2 formed in the water-gas shift reaction, while separating the generated clean energy gas H 2 , is a promising strategy for developing novel CO 2 capture technologies.

Advancement of a hydrogen economy requires establishment of a whole supply chain including hydrogen production, purification, storage, utilization, and recovery. Nevertheless, it remains challenging to selectively purify hydrogen out of H 2 -containing streams, especially at low concentrations. Herein, a novel protonic ceramic electrochemical cell is reported that can sustainably separate pure H 2 out of H 2 -diluted streams over the temperature regime of 350-500 °C by mildly controlling the electric voltage. With the Faraday's efficiency above 96%, the measured H 2 separation rate at 0.51 V and 500 °C is 3.3 mL cm -2 min -1 out of 10% H 2 - 90% N 2 , or 2.4 mL cm -2 min -1 out of 10% H 2 - 90% CH 4 taken as an example of renewable hydrogen blended in the natural gas pipelines. Such high hydrogen separation capability at reduced temperatures is enabled by the nanoporous nickel catalysts and well-bonded electrochemical interfaces as produced from well-controlled in situ slow reduction of nickel oxides. These results demonstrate technical feasibility of onsite purification of hydrogen prior to their practical applications such as fuels for fuel cell electric vehicles.

The 3D metal-organic framework (MOF) structure UiO-66 [Zr 6 O 4 (OH) 4 (bdc) 6 ], featuring triangular pores of approximately 6 Å, has been successfully prepared as a thin supported membrane layer with high crystallographic orientation on ceramic α-Al 2 O 3 supports. The adhesion of the MOF layer to the ceramic support was investigated in different taxing conditions. Furthermore, by coating this UiO-66 membrane with a thin polyimide (Matrimid) top layer, we prepared a multilayer composite. Said membranes have been evaluated in the separation of hydrogen (H 2 ) from different binary mixtures at room temperature. H 2 as the smallest molecule (2.9 Å) should pass the UiO-66 membrane preferably since the kinetic diameters of all the other gases under study are larger. The gas mixture separation factors for the neat UiO-66 membrane were indeed found to be H 2 /CO 2 = 5.1, H 2 /N 2 = 4.7, H 2 /CH 4 = 12.9, H 2 /C 2 H 6 = 22.4, and H 2 /C 3 H 8 = 28.5. The coating with Matrimid led to a sharp cutoff for gases with kinetic diameters greater than 3.7 Å, resulting in increased separation performance.

Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to Pd 65.1 Cu 34.9 alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the Pd 65.1 Cu 34.9 alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the Pd 65.1 Cu 34.9 alloy under 1000 ppm of H 2 S + H 2 feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable H 2 S-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

Using the van-der-Waals-corrected density functional theory (DFT) and molecular dynamic (MD) simulations, we theoretically predict the H2 separation performance of a new two-dimensional sp(2) carbon allotropes-fused pentagon network. The DFT calculations demonstrate that the fused pentagon network with proper pore sizes presents a surmountable energy barrier (0.18 eV) for H2 molecule passing through. Furthermore, the fused pentagon network shows an exceptionally high selectivity for H2/gas (CO, CH4, CO2, N2, et al.) at 300 and 450 K. Besides, using MD simulations we demonstrate that the fused pentagon network exhibits a H2 permeance of 4 × 10(7) GPU at 450 K, which is much higher than the value (20 GPU) in the current industrial applications. With high selectivity and excellent permeability, the fused pentagon network should be an excellent candidate for H2 separation.

Addition of Ag is a promising way to enhance the H2 permeability of sulfur-tolerant PdCu membranes for cleanup of coal-derived hydrogen. We investigated a series of PdCuAg membranes with at least 70 atom % Pd to elucidate the interdependence between alloy structure and H2 permeability. Membranes were prepared via sequential electroless plating of Pd, Ag, and Cu onto ceramic microfiltration membranes and subsequent alloying at elevated temperatures. Alloy formation was complicated by a wide miscibility gap in the PdCuAg phase diagram at the practically feasible operation temperatures. X-ray diffraction showed that the lattice constants of the fully alloyed ternary alloys obey Vegard's law closely. In general, H2 permeation rates increased with increasing Ag and decreasing Cu content of the membranes in the investigated temperature range. Detailed examination of the permeation kinetics revealed compensation between activation energy and pre-exponential factor of the corresponding H2 permeation laws. The origin of this effect is discussed. Further analysis showed that the activation energy for H2 permeation decreases overall with increasing lattice constant of the ternary alloy. The combination of these correlations results in a structure-function relationship that will facilitate rational design of PdCuAg membranes.

In this work, the high quality Pd/SAPO 34 membranes were grown on the support using a secondary (seeded) growth hydrothermal technique followed by insertion of 11-mercaptoundecanoic acid capped palladium (MUA-Pd) nanoparticles (NPs) to the membrane surface. For this, first, the indigenous low cost clay-alumina support was treated with poly diallyldimethylammonium chloride (PolyDADMAC) polymer, and subsequently, a seed layer of SAPO 34 crystals was deposited homogeneously in a regular orientation. Since PolyDADMAC is a high charge density cationic polymer, it assisted in reversing the charge of the support surface and produced an attractive electrostatic interaction between the support and zeolite crystals. This may facilitate the zeolite grain orientation in the synthesized membrane layer. Here, the Pd NPs were deposited in the membrane matrix by a simple dip-coating method. After thermal treatment of the Pd/SAPO 34 membrane, the defects were formed because of the removal of the structure-directing agent (SDA) from the zeolite pores but the presence of Pd NPs, which were entrapped inside the nonzeolitic pores and clogged the defects of the membrane. Field emission scanning electron microscopy (FESEM) and elemental mapping of the membrane cross-section confirmed that most of the Pd NPs were deposited at the interface of the membrane and the support layer which may increase the membrane efficiency, i.e., separation factor, as well as permeability of H2 through the membrane. As the membrane structure was associated with the oriented crystal, the pores were more aligned and permeation adequacy of H2 through the membrane enhanced. These membranes have a relative hydrogen permeance of 14.8 × 10(-7) mol·m(-2)·s(-1)·Pa(-1). The selectivity of H2/CO2 based on single gas permeation was 10.6, but for the mixture gas (H2/CO2 55:45), the H2/CO2 mixture separation factor increased up to 20.8 at room temperature. It is anticipated that this technique may be useful for making a defect free membrane and also a hydrogen selective Pd loaded membrane with lower cost (as the quantity of Pd is low) which can be utilized for a "clean energy" related application.