Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over modified microwave coal-based active carbon catalysts at low temperature

A series of microwave coal based active carbon catalysts loaded by metal oxides were prepared by a sol gel method and tested for the simultaneous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 50-70 degrees C. The influences of preparation conditions on catalytic activity were studied, which were the kinds and amount of additive, calcination temperatures, and types and content of alkali. The results show that catalysts with 5.0% Fe2O3 after calcining at 300 degrees C have superior activity for the simultaneous catalytic hydrolysis of COS and CS2. It also indicated that the catalytic hydrolysis activity increased with the basic intensity, following the order of KOH > K2CO3 > Na2CO3 > NaHCO3, and the optimum amount of KOH was 13%. The structure and surface properties were characterized by Xray diffractometry (XRD), Brunauer-Emmett-Teller measurements (BET), Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XRD and BET results revealed that the calcination temperature controlled the crystalline phase and generation of Fe2O3 and affected the properties of specific surface area and pore structure. The XPS results showed that most of COS and CS2 hydrolysis products were sulfate ion (SO42-) species, which accumulated on the active carbon's surface and had a negative effect on the hydrolysis activity.