Activity of shaped Pt/AlSBA-15 catalysts in n-hexadecane hydroisomerization

Abstract

In this study, AlSBA-15 supported Pt catalysts were tested for activity in hydroisomerization of n-hexadecane. Experiments were carried out in a continuous-flow system at 5MPa 320–360°C (WHSV=3.5h−1, H2:CH=350Nm3/m3). Shaped Pt/AlSBA-15 catalysts were prepared by two methods: (i) where the powders of AlSBA-15 materials (obtained with aluminium sulphate, aluminium nitrate or aluminium isopropoxide; Si/Al gel ratio of 20) were impregnated with H2PtCl6 solution and then shaped with binder into the extrudates and (ii) where the powders of AlSBA-15 materials (obtained with aluminium isopropoxide; Si/Al gel ratio of 20 and 7) were firstly shaped with binder into the extrudates and then impregnated with Pt precursor. The method of catalyst preparation where the binder was combined with AlSBA-15 before impregnation with the Pt precursor yielded a 1.0wt% of Pt catalyst with a comparable activity and isomerization selectivity as 1.5wt% of Pt catalyst obtained by adding the binder to the Pt/AlSBA-15 powder. The results have also revealed that the Pt catalyst with moderate acid strength, i.e. that prepared with AlSBA-15 using aluminium isopropoxide, displayed better isomerization selectivity than that one possessing strong acid sites, i.e. obtained with AlSBA-15 using aluminium sulphate; the last one displayed the highest n-C16 hydroconversion but it simultaneously provided the highest yield of hydrocracking products.