Hydrodesulfurization and hydrogenation of radioactive 35S-labeled dibenzothiophene on alumina-supported chromium and promoted chromium catalysts

Abstract

Hydrodesulfurization (HDS) reactions of radioactive ³⁵S-labeled dibenzothiophene ([³⁵S]DBT) were carried out over a variety of Cr/Al₂O₃ with 5.5–33.3 wt.% CrO₃ and over promoted Me-Cr/Al₂O₃ (Me/Cr = 0.4, 0.6; Me = Ni, Co and Cu) catalysts at temperatures in the range of 300–380°C and under a reaction pressure of 5.0 MPa. The HDS activity of Cr/Al₂O₃ catalysts increased with increasing Cr loadings to 33.3 wt.% CrO₃. Moreover, both HDS and hydrogenation (HYD) activities of Cr/Al₂O₃ catalysts were enhanced with the addition of Ni and Co. In contrast, adding Cu to Cr/Al₂O₃ catalyst decreased its catalytic activity inversely. Further, the results obtained from the HDS reaction of ³⁵S-labeled dibenzothiophene indicated that the amount of labile sulfur increased on adding Ni and Co to Cr/Al₂O₃ catalysts whereas it decreased on adding Cu. It is suggested, therefore, that the addition of Ni and Co weakens the strength of the chromium–sulfur bond on the sulfided Cr/Al₂O₃ catalyst, and brings about increases in amount of labile sulfur and in catalytic activity of the Cr catalyst.