n-Pentane and 3-Methylpentane Conversions on Differently Pretreated Supported Palladium Catalysts

摘要

Metal-support interactions in silica-and alumina-supported palladium catalysts have been investigated by using n-pentane and 3-methylpentane conversions as test reactions.High temperature reduction(HTR)at 600 deg C results in a considerable increase of the selectivity towards isomeric and cyclic products,i.e.causes a similar effect as in the case of previously studied reactions of 2,2-dimethylpropane and various C_6-alkanes.However,the silica-supported palladium catalysts behave differently from the Pd/Al_2O_3.For the former catalysts subjected to HTR,the selectivity for cyclic products is enhanced,whereas a similarly pretreated Pd/Al_2O_3 gives mainly isomers.This observation,and the changes in both the hydrogen reaction order and in the activation energy caused by different catalyst pretreatment,were both analyzed in detail.All mentioned quantities appeared to be new convenient diagnostic parameters towards determining whether or not palladium interacts with a support.