Insights into the different catalytic behavior between Ce and Cr modified MCM-41 catalysts: Cr2S3 as new active species for CH3SH decomposition

High sulfur resistance and high stability of catalysts are crucial for the catalytic decomposition of sulfurcontaining volatile organic compounds. In this work, compared to 5Ce-MCM-41, the 5Cr-MCM-41 catalyst exhibited ultra-stability (no activity loss at 600 h) and higher sulfur resistance. The physical structure and chemical characteristics of the catalysts were analyzed by XRD, H2-TPR, NH3-TPD, CO2-TPD, XPS, and TEM. Combining the characterization results, we found that the 5Cr-MCM-41 catalyst presented outstanding catalytic performance due to superior reducibility and appropriate acidity, which results in the conversion of most of the C and S elements in the CH3SH to the gas-phase coke- and sulfur-containing products rather than accumulating on the catalyst surface. Meanwhile, the catalytic performance, reaction path, and deactivation mechanism of rare earth metal (Ce) and transition metal (Cr) modified MCM-41 catalysts were systematically investigated by in situ DRIFTS and DFT calculations. Additionally, a new active phase (sulfide state Cr2S3) was proposed and proved via accurately designed experiments, which plays a significant role in the collaborative removal of CH3SH with hexavalent chromium (Cr(VI)). These findings are beneficial for designing high sulfur resistance catalysts for the removal of CH3SH and other sulfur-containing products.