The influence of carrier structure on the reaction performance of the catalyst for isobutane dehydrogenation
Four types of alumina carriers were obtained with pseudo-boehmite as the main raw material through different treatment methods,and further supported PtSnNa/Al2O3 dehydrogenation catalysts were prepared.The test results of XRD and N2 adsorption demonstrate that the treatment process of pseudo-boehmite had a significant effect on the structural characteristics of alumina support.An alumina support withγ-Al2O3 crystal phase can be obtained by refluxing the pseudo-boehmite with ethanol solvent and subsequent calcining in a nitrogen atmosphere.This γ-Al2O3 support has a specific surface area of 248 m2·g-1,a total pore volume of 0.89 mL·g-1,an average pore size of 15.5 nm.However,the specific surface area,total pore volume,and average pore size of the alumina sample obtained by direct calcination in air are relatively small.Four PtSnNa/Al2O3 dehydrogenation catalysts were used for catalyzing the reaction of isobutane dehydrogenation to isobutene.The PtSnNa/Al2O3 catalyst made of alumina support with larger pore volume and pore size shows the optimal catalytic performance in isobutane dehydrogenation reaction.The average conversion of isobutane on this catalyst is as high as 47.2％,the average selectivity of isobutene is as high as 96.3％,and the lifetime of the catalyst exceeds 100 hours.The carbon-deposited catalyst after the reaction was investigated by thermal analysis method.The characterization results indicate that a smooth pore structure is conducive to the migration of intermediate species and the removal of reaction products,while improving the carbon capacity of the catalyst.
catalytic chemistryalumina precursorAl2O3precious metal catalystC4 alkaneC4 olefin
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