Adsorption and catalytic decomposition of dimethyl sulfide on H-BEA zeolite

Catalytic direct decomposition of dimethyl sulfide (DMS) was performed using solid acid catalysts to develop an on-site hydrogen-free desulfurization system for utilization in small systems, such as fuel cells. DMS was decomposed to CH₃SH and H₂S at 500 °C on SiO₂–Al₂O₃ and various zeolite catalysts. Among the catalysts, H-BEA zeolite with Si/Al = 18.5 (H-BEA-18.5) showed the highest performance for DMS decomposition at 500 °C. While the catalytic activity at 500 °C maintained a DMS conversion of greater than 30% for up to 114 h, a large amount of carbon deposition caused gradual deterioration. At a low temperature of 400 °C, DMS decomposition to CH₃SH on H-BEA-18.5 continued for 100 h with a stable conversion of approximately 30%, although the adsorption of DMS on the catalyst surface was also confirmed. To achieve a high performance for the DMS decomposition, high temperatures were required to avoid the adsorption of sulfur species.