The Feasibility of Mo2C Catalysts for the Reforming of Sulfur-Laden Transportation Fuels

Abstract

Abstract : The objective of this project is to investigate the feasibility of using molybdenum carbide catalysts for the reforming of transportation fuels (gasoline and diesel) in the presence of sulfur. Using trimethyl pentane (TMP) and hexadecane (HD) as model fuels and thiophene and benzothiophene as model sulfur compounds, all of the original objectives of the project were successfully accomplished. We have found that the steam reforming (SR) of sulfur-free TMP can be carried out over bulk Mo2C catalysts at essentially stoichiometric feed conditions without coking, as long as the temperatures are at about 1000 C. However, the stable operating temperature can be lowered to 900 C, by adding molecular oxygen (oxidative-steam reforming (OSR)). The activity of a bulk molybdenum carbide catalyst for the steam (SR) of sulfur free hexadecane was found to be stable under very low steam:carbon ratios at temperatures as low as 885 degrees C under OSR conditions, and at 965 degrees C under SR conditions. For both TMP and HD, the degree of deactivation in the presence of sulfur was dependent on the sulfur concentration but was minimal at concentrations below 100 ppmw. While deactivation was completely reversible in the case of TMP steam reforming, spent catalysts from OSR could only be partially reactivated. However, sulfur poisoning was totally reversible for HD under both SR and OSR conditions.