Isomerization of n-butane:conversion as a function of sulfate loading on sulfated zirconia catalysts

摘要

Sulfur loading on a sulfated zirconia catalyst was studied as a function of H_2SO_4 concentration.The resulting catalytic activity was tested using the isomerization of n-butane as a reaction probe at 200 deg C.Optimum catalytic activity was observed for a catalyst prepared using 0.5 N H_2SO_4.The amount of carbon required to completely deactivate the catalyst was determined using a TGA/FTIR technique.For all of the catalysts synthesized in this study it was found that two active sulfate sites were poisoned by a single deposited carbon atom.Using this information,an active site composed of two coupled sulfate sites,perhaps a surface pyrosulfate site,is suggested.Using a TGA/FTIR technique it was found that the number of catalytically active sulfate sites never exceeded 14% of the total sulfate loading.These results were also supported by calorimetric studies.