Research Of N-Octane Isomerization Over Tungsten Based Catalysts

Tungsten catalyst system, including reduced tungsten trioxide and tungsten carbide, that can be used in catalyzing n-alkane isomerization and have the advantages of simple preparation, cheap raw materical, non-pollution. so tungsten catalyst system have important study value and application perspeetive.In this study, we investigate the hydroisomerization of n-octane over Co/WO₃/ZrO₂, Ni/WO₃/SiO₂-Al₂O₃ catalysts, which were prepared by coprecipitation and impregnation methods, respectively. The hydroisomerization of n-octane over Co/WO₃/ZrO₂ and Ni/WO₃/SiO₂-Al₂O₃ catalysts was investigated in a conventional fixed bed reactor. The effect of the preparation, reduction and reaction conditions on the conversion and isomerization selectivity of n-octane over Co/WO₃/ZrO₂ and Ni/WO₃/SiO₂-Al₂O₃ catalysts was studied carefully.For the Co/WO₃/ZrO₂ catalyst, it is found that a high isomerization selectivity of over 93.96% with an overall conversion of nearly 21.98% can be achieved when W content of the catalyst is 15%, Co content is 2%, calcination temperature of WO₃/ZrO₂ is 800℃, reduction temperature is 500℃, reduction time is 4 h, reaction temperature is 250℃, WHSV is 3.52 h?1, and n(H2)/n(n-Octane) is 12.For the Ni/WO₃/SiO₂-Al₂O₃catalyst, it is found that the isomerization selectivity of over 52.65% with an overall conversion of nearly 21.55% can be achieved when W content of the catalyst is 10%, Co content is 15%, calcination temperature is 500℃, reduction temperature is 425℃, reduction time is 4 h, reaction temperature is 260℃, WHSV is 7.04 h?1, and n(H2)/n(n-Octane) is 6.