Hydrodearomatisation of Diesel Fuels Using Zeolite Based Catalysts

摘要

Results of preparation and activity tests of zeolite based catalysts for diesel fuel hydrodearomatisation and hydrodecyclization are presented. The catalysts were prepared using NH_4Y and USY zeolites as supports and palladium, platinum, nickel and tungsten as active metals. Deep desulphurized diesel fuel, with a sulphur content of 50 ppm, was applied as feed. In a first series of experiments palladium (0.57 wt%) and platinum (0.19 wt%) were supported on carriers containing 50 wt% of zeolites (obtained by ion exchange and dealumination) and the same quantity of alumina. In the second series, nickel-tungsten catalysts were used which had been prepared with support containing only ca 10 wt% zeolite. It is shown that in comparison to a relatively low activity of the nickel-tungsten catalysts the noble metal containing catalysts exhibited very high hydrogenation and at the same time high undesirable hydrocracking activity. Zeolite dealumination resulted in lower zeolite acidity and respectively lower hydrocracking activity of the catalyst. The results obtained indicate that besides activity and resistance to deactivation by sulphur and nitrogen, the selectivity of the catalyst is the main problem in designing of catalysts for dieselfuel hydrodearomatisation.