Catalytic decomposition of methanethiol to hydrogen sulfide over TiO sub(2)

• Published in: Fuel processing technology 2015-03, Vol.131, p.117-124
• Main Authors: Mukoyama, Takashi, Shimoda, Naohiro, Satokawa, Shigeo
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Decomposition; Decomposition reactions; Hydrogen sulfide; Mathematical analysis; Metal oxides; Specific surface; Titanium dioxide
• ISSN: 0378-3820
• DOI: 10.1016/j.fuproc.2014.11.013

As a new desulfurization process for fuel cell systems, catalytic direct decomposition of methanethiol into hydrogen sulfide on various metal oxides without hydrogen addition has been examined. Methanethiol was decomposed into hydrogen sulfide over several metal oxide catalysts at 300 [degrees]C. Major metal oxide catalysts used in this study decomposed methanethiol completely at 500 [degrees]C. However they would be sulfurized immediately by the decomposed products. Among them, titania (TiO sub(2) catalyst exhibited a remarkable methanethiol decomposition activity and it was hardly sulfurized. The methanethiol conversion of TiO sub(2) catalyst depended on the specific surface area. Hydrogen sulfide and dimethyl sulfide were produced with the same amount at below 250 [degrees]C. The methanethiol seems to be decomposed by the following equation at low temperature range: 2CH sub(3)SH [arrowright] H sub(2)S + (CH sub(3)) sub(2)S. In contrast, hydrogen sulfide and methane were produced as gas phase products and carbon species were also formed on TiO sub(2) surface above 400 [degrees]C. The methanethiol seems to be decomposed by the following equation at high temperature range: 2CH sub(3)SH [arrowright] 2H sub(2)S + CH sub(4) + C. We conclude that the direct decomposition of methanethiol on TiO sub(2) surface proceeds via different reaction pathways depending on the reaction temperatures.