Production of middle distillate through hydrocracking of paraffin wax over Pd/SiO 2–Al 2O 3 catalysts

Abstract

Pd/SiO 2–Al 2O 3 catalysts (Pd/SA- X) with different SiO 2 contents ( X, wt%) were prepared for use in the production of middle distillate (C 10–C 20) through hydrocracking of paraffin wax. The effect of SiO 2 content of Pd/SA- X catalysts on their physicochemical properties and catalytic performance in the hydrocracking of paraffin wax was investigated. High surface area and well-developed mesopores of Pd/SA- X catalysts improved the dispersion of Pd species on the SiO 2–Al 2O 3 support. Acidity of Pd/SA- X catalysts determined by NH 3-TPD experiments showed a volcano-shaped trend with respect to SiO 2 content. Conversion of paraffin wax increased with increasing acidity of the catalyst, while selectivity for middle distillate decreased with increasing acidity of the catalyst. Yield for middle distillate showed a volcano-shaped curve with respect to acidity of the catalyst. This indicates that acidity of Pd/SA- X catalysts played an important role in determining the catalytic performance in the hydrocraking of paraffin wax. Among the catalyst tested, Pd/SA-69 with moderate acidity showed the highest yield for middle distillate.