n-Butane hydroisomerization over Pd/HZSM-5 catalysts. Palladium loaded by ion exchange

The influence of the preparation method, the nature of the precursor compou nd and acid treatment on hydroisomerization of It-butane over bifunctional Pd/HZSM-5 catalysts was investigated to obtain active and highly selective catalysts. Temperature-programmed desorption of ammonia, atomic absorption spectroscopy, chemisorption, temperature-programmed reduction and transmiss ion electron microscopy techniques were used to characterize the catalysts. Pd(NO3)(2) was selected as metal precursor, because calcination of this co mpound can be carried out in a furnace under static air atmosphere without needing careful temperature control. A catalyst with a palladium loading of 0.53 wt.% exhibited good isomerization performance, which was further impr oved by severe acid treatment, as a higher strong acid-site density was obt ained. The selected catalyst led to a total conversion of 35.3 mol% and a h igh selectivity of 78%. (C) 2001 Elsevier Science B.V. All rights reserved.