Oxidation of Thiophenes over Silica Gel Using Hydrogen Peroxide and Formic Acid

Abstract

Thiophene (C₄H₄S) and 3-methylthiophene (3-MC₄H₄S) are typical thiophenenic sulfur compounds that exist in gasoline from the fluid catalytic cracking (FCC) process. C₄H₄S and 3-MC₄H₄S were oxidized on silica gel by hydrogen peroxide (H₂O₂) and formic acid. The silica gel loaded with copper and cobalt (1:1) was very active catalyst for the oxidation of these sulfur compounds, while the silica gel unloaded with metal was less active. Oxidation of these sulfur compounds was taken place under mild reaction conditions and high conversion was achieved by increasing the reaction time. The sulfur removal rate of C₄H₄S and 3-MC₄H₄S was enhanced when the emulsifier OP or tetrabutylammonium bromide (TBAB) was added. It is interesting to find that a bromine substitution appeared as TBAB was added in the oxidation system.

Keywords:

• 3-methylthiophene
• oxidative desulfurization
• silica gel
• thiophene

Acknowledgments

The authors are grateful for the financial support from the National Science Foundation of China (20276015) and the Natural Science Foundation of Hebei Province (203364).