A Fine-Tuned MOF for Gas and Vapor Separation: A Multipurpose Adsorbent for Acid Gas Removal, Dehydration, and BTX Sieving

Abstract

The development of highly stable separation agents is recognized as a decisive step toward the successful deployment of energy-efficient and cost-effective separation processes. Here, we report the synthesis and construction of a metal-organic framework (MOF), kag-MOF-1, that has adequate structural and chemical features and affords a stable adsorbent with unique and appropriate adsorption properties for gas processing akin to acid gas removal, dehydration, and benzene-toluene-xylene (BTX) sieving. A combination of X-ray diffraction experiments, adsorption studies, mixed-gas breakthrough adsorption column testing, calorimetric measurements, and molecular simulations corroborated the exceptional separation performance of kag-MOF-1 and its prospective use as a multifunctional adsorbent. The unique adsorption properties of kag-MOF-1, resulting from the contracted pore system with aligned periodic array of exposed functionalities, attest to the prominence of this new generation of ultra-microporous material as a prospective practical adsorbent toward cost-effective and more simplified gas and vapor processing flowcharts for natural gas upgrading and flue gas scrubbing. Various key gas and vapor separations require highly energy-intensive processes with an associated exorbitant cost, namely CO2 and H2S removal from valuable industrial gases, benzene-toluene-xylene (BTX) elimination before the production of elemental sulfur, and the compulsory dehydration of gases before transport. Deployment of advanced solid-state adsorbent materials offers great prospects of introducing efficient separation processes with less or no parasitic energy associated with the regeneration of the sorbent. Markedly, the development of innovative separation agents that capture CO2, H2O, and H2S while excluding BTX is highly desirable because it allows access to a simplified gas processing flow chart for processing valued industrial gases. A highly stable kag-MOF-1, produced by easy and economical synthesis, has a high affinity for H2O, CO2, and H2S and sieves impurities such as benzene, toluene, and xylene completely. This material has the potential to carry out many industrially important separations such as acid gas removal, dehydration, and benzene-toluene-xylene (BTX) sieving in an energy-efficient manner.