Computational Studies on Holey TMC6 (TM = Mo and W) Membranes for H2 Purification

Abstract

The purification of hydrogen (H2) has been a vital step in H2 production processes such as steam–methane reforming. By first-principle calculations, we revealed the potential applications of holey TMC6 (TM = Mo and W) membranes in H2 purification. The adsorption and diffusion behaviors of five gas molecules (including H2, N2, CO, CO2, and CH4) were compared on TMC6 membranes with different phases. Though the studied gas molecules show weak physisorption on the TMC6 membranes, the smaller pore size makes the gas molecules much more difficult to permeate into h-TMC6 rather than into s-TMC6. With suitable pore sizes, the s-TMC6 structures not only show an extremely low diffusion barrier (around 0.1 eV) and acceptable permeance capability for the H2 but also exhibit considerably high selectivity for both H2/CH4 and H2/CO2 (>1015), especially under relatively low temperature (150–250 K). Moreover, classical molecular dynamics simulations on the permeation process of a H2, CO2, and CH4 mixture also validated that s-TMC6 could effectively separate H2 from the gas mixture. Hence, the s-MoC6 and s-WC6 are predicted to be qualified H2 purification membranes, especially below room temperature.

Unveiling the Potential of Ca/Cu Composite Sorbents for CO2 Capture: A Precursor Perspective

“…The CO 2 concentration in the atmosphere surged to 417 ppm in 2022, a concerning indication strongly linked to climate change. − Therefore, there has been a growing emphasis on controlling the atmospheric CO 2 concentration. − CO 2 capture, utilization, and storage (CCUS) is widely recognized as an effective and promising approach to mitigate anthropogenic CO 2 emissions on an industrial scale. − In this setup, CO 2 capture is the initial stage and significantly affects the technical and economic feasibility of the process. , Calcium looping (CaL) technology, which exploits reversible carbonation and calcination reactions (eq ), has great potential for the large-scale reduction of CO 2 emissions. , As depicted in Figure a, CO 2 -rich flue gases are introduced into the carbonation reactor, where the carbonation reaction occurs to decarbonize them. The resulting CaCO 3 is then transferred to the calcination reactor, where the calcination reactor is used for sorbent regeneration.…”