Support Effects on Water Gas Shift Activity and Sulfur Dependence of Mo Sulfide Catalysts

Abstract

Molybdenum (Mo) sulfide catalysts supported on ZrO2, Al2O3, TiO2, CeO2, and SiO2 were prepared by the incipient wetness impregnation method and explored with respect to their catalytic activity and H2S dependence in the water gas shift (WGS) reaction. The highest WGS activity at 450 °C and S/Mo atomic ratio among all Mo sulfide catalysts investigated were observed for the Mo–S/ZrO2 catalyst. Moreover, the WGS activity of the Mo–S/ZrO2 catalyst was stable for 72 h of reaction, regardless of the presence of H2S in the feed. The extent of sulfidation of supported Mo–S catalysts increased with decreasing MoO3 reduction temperature in temperature-programmed reduction, which indicated a decreased strength of MoO3–support interactions. A comparison of fresh and used supported Mo catalysts suggested that the active Mo–S sites of the Mo–S/ZrO2 catalyst maintained their catalytic activity without the crystallization of Mo–S species during 72 h of WGS reaction. Therefore, ZrO2 was indicated by this study as a promising support for the Mo-based WGS catalysts.

Spectroscopic Identification of Active Centers and Reaction Pathways on Mos2 Catalyst for H2 Production Via Water-Gas Shift Reaction

“…However, even the widely accepted redox mechanism that supports the MoS 2-x O x site as active center does not allow to understand why sulfide catalysts would exhibit poor stability under H 2 S-free condition, which is often interpreted as poor antioxidation capability for the formation of oxy-sulfide phase during the WGS reaction. On the contrary, the catalytic performance and stability would be significantly enhanced in H 2 S-containing atmosphere [22,23]. These highly divergent results indicate that redox mechanism is not well understood, especially for the role of MoS 2-x O x sites.…”

“…Furthermore, the role of the support also requires special consideration [24]. On one hand, CO adsorbed on sulfide sites could spill over to the support [25], implying that the support could be involved in catalytic reaction whereas only sulfide phase is considered in DFT calculation; on the other hand, the interaction between the sulfide phase and the support results in varying the proportion of M-edge to S-edge sites [26], also affecting the catalytic activity [22].…”

Improving the Performance of a Co-CeO2 Catalyst for Hydrogen Production via Water Gas Shift Reaction by Addition of Transition Metal Oxides

“…Humanity is facing significant climate change, which adversely affects its survival, owing to the indiscriminate use of fossil fuels and the waste of resources. Therefore, 136 countries have declared a net-zero emission target, , which requires the production of clean and renewable energy. Each country has set a Nationally Determined Contribution (NDC) and aims to reduce carbon emissions by developing various methods based on advanced science and technology .…”

Understanding the Role of Potassium Addition on the Active Centers and Reaction Pathway of MoS2Catalysts for Water Gas Shift Reaction

“…Sulfides are considered good candidates for the sulfur-tolerant WGS catalysts. Indeed, the most active component of such catalysts is sulfide phase and thus this catalyst is not only sulfur tolerant but its activity is actually enhanced by sulfur, [5,6] which prolongs the useful life of catalysts.…”