Hydroisomerization of n-decane over Ni–Pt–W supported on amorphous silica–alumina catalysts

Abstract

A series of NiPtW/silica–alumina catalysts (wt.%: Ni, 12–17; W: 10, Pt: 0.1–1) were prepared via a hybrid method: sol–gel and incipient wetness impregnation and characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), BET, temperature-programmed desorption of ammonia (NH 3-TPD), pyridine adsorption followed by FTIR and TPO techniques. On these catalysts, n-decane hydroisomerization was carried out under the following conditions: fixed bed reactor, atmospheric pressure, temperature ranging from 150 to 300 °C, weight hourly space velocity of 4 h −1 and molar hydrogen/hydrocarbon ratio of 5. Pt was found to promote activity and stability, the effect being optimal for 0.2 wt.% Pt. Isomers and cracking products yields were a function of both metal (Ni and Pt) content and conversion. Whatever n-decane conversion, monobranched isomers were found to be predominant. Besides, up to 10% conversion, the cracked products were not produced in significant amounts. For a time on stream of 100 min, the best results (47% conversion and 56% isomerization selectivity) were obtained at 250 °C over the catalyst containing 12% Ni, 10% W and 0.2% Pt).