Effect of acidity and metal content on the activity and product selectivity for n-decane hydroisomerization and hydrocracking over nickel-tungsten supported on silica-alumina catalysts

Ni-W/silica-alumina based catalysts with different nickel and tungsten concentration (nickel ranging from 12 to 17% and tungsten ranging from 8 to 30%) were prepared by sol-gel method. The BET, temperature-programmed desorption of ammonia (TPDA) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) techniques were used to characterize the prepared solids. Afterwards, the catalysts were screened for activity and selectivity in the hydroconversion of n-decane. Under the experimental conditions, yields of isomers as well as cracking products were a function of both metal content and amount of acid sites. Up to 15% Ni content, nickel increased isomerization selectivity, afterwards, the catalytic selectivity decreased. Moreover, the higher the amount of medium acid sites present on the catalyst, the higher its activity and its deactivation. After running on stream for 100 min, the catalysts with 15% of nickel and 10% of tungsten (WT(15,10) catalyst) showed the best results (42.3% of conversion and 55% selectivity) at 250 degrees C. (c) 2004 Elsevier B.V. All rights reserved.