Synergistic conversion of acid gases (H2S and CO2) to valuable chemicals: Carbonyl sulfide synthesis over vacancy-defective CoMo sulfide catalysts

Abstract

Synergistically convert acid gases to valuable chemicals is meaningful. Herein, unsupported CoMo sulfide catalysts with abundant sulfur vacancies were fabricated to attain synergistical conversion of H2S and CO2 to COS. Various metal sulfides were obtained, such as Co3S4, Co9S8 and vacancy-defective MoS2. Besides, simultaneous sulfidation of Mo with Co prompted formation of CoMoS phase, which enhanced catalytic performance. Among them, CoAlMo-S catalyst exhibited superior activity, allowing for equilibrium COS yield (6%, 300 ℃). DFT calculations indicate that chemisorbed H2S induced CO2 activation via van der Waals interaction between C atom in CO2 and S atom in H2S, contributed to efficient C–S bond formation. Sulfur vacancy significantly promoted dissociative adsorption of H2S while Co atom in CoMoS phase was beneficial for CO2 adsorption and facilitated C–S bond construction. This work not only achieves H2S pollution control and carbon emission reduction, but also provides an alternative approach to synthesis COS.