Zeolites for CO₂–CO–O₂ Separation to Obtain CO₂-Neutral Fuels

Abstract

Carbon dioxide release has become an important global issue due to the significant and continuous rise in atmospheric CO concentrations and the depletion of carbon-based energy resources. Plasmolysis is a very energy-efficient process for reintroducing CO into energy and chemical cycles by converting CO into CO and O utilizing renewable electricity. The bottleneck of the process is that CO remains mixed with O and residual CO. Therefore, efficient gas separation and recuperation are essential for obtaining pure CO, which, via water gas shift and Fischer-Tropsch reactions, can lead to the production of CO-neutral fuels. The idea behind this work is to provide a separation mechanism based on zeolites to optimize the separation of carbon dioxide, carbon monoxide, and oxygen under mild operational conditions. To achieve this goal, we performed a thorough screening of available zeolites based on topology and adsorptive properties using molecular simulation and ideal adsorption solution theory. FAU, BRE, and MTW are identified as suitable topologies for these separation processes. FAU can be used for the separation of carbon dioxide from carbon monoxide and oxygen and BRE or MTW for the separation of carbon monoxide from oxygen. These results are reinforced by pressure swing adsorption simulations at room temperature combining adsorption columns with pure silica FAU zeolite and zeolite BRE at a Si/Al ratio of 3. These zeolites have the added advantage of being commercially available.

Incorporation of trivalent cations in NaX zeolite nanocrystals for the adsorption of O2 in the presence of CO2

“…The selective adsorption of O2 in the presence of CO2 is very challenging, as most of zeolites will adsorb preferably CO2. [10][11][12][13][14] The experimental results were supported by DFT calculations, which in turn highlight that the adsorption selectivity of O2 towards CO2 may be largely enhanced if Ce 3+ cations pairs are embedded in the nanosized zeolites.…”

Molecularly Imprinted Porous Aromatic Frameworks for Molecular Recognition

“…(1) The ultra-micropores in zeolites allow us to rationally adjust to arrange multiple small gas molecules exclusively by size, which can be used to achieve gas separation into high purity grades for practical industrial applications. 27 , 28 (2) MOF samples are gifted with open metal sites that can strongly interact with guest molecules such as hydrogen and acetylene. 29 − 33 Therefore, they could potentially be capable of separating gas molecules and sensing neutral and ionic species.…”

“… (a) Zeolites for CO 2 /CO/O 2 separation. Reprinted with permission from ref ( 27 ). Copyright 2018, American Chemical Society.…”

“…Two remarkable examples demonstrate the conventional strategies for achieving specific objectives in porous materials (Figure ). (1) The ultra-micropores in zeolites allow us to rationally adjust to arrange multiple small gas molecules exclusively by size, which can be used to achieve gas separation into high purity grades for practical industrial applications. , (2) MOF samples are gifted with open metal sites that can strongly interact with guest molecules such as hydrogen and acetylene. − Therefore, they could potentially be capable of separating gas molecules and sensing neutral and ionic species. However, these materials have many drawbacks, such as low selectivity, complicated synthesis procedures, and limited universality.…”

“…gas separation into high purity grades for practical industrial applications. 27,28 (2) MOF samples are gifted with open metal sites that can strongly interact with guest molecules such as hydrogen and acetylene. 29−33 Therefore, they could potentially be capable of separating gas molecules and sensing neutral and ionic species.…”