Lanthanum-containing(LaX)and cerium-containing X zeolites(CeX)were prepared by a double-exchange,double-calcination method.By changing the calcination atmospheres between nitrogen and air,the CeⅣ contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established.The crystallinity of CeX zeolite was found to be negatively correlated with the CeⅣ content.This i s believed to be due to the water formed during the oxidation of CeⅢ,which facilitates the framework dealumination.As a consequence,calcining in air resulted in a great elimination of strong Br?nsted acid sites while under nitrogen protec-tion,this phenomenon was mostly hindered and the sample's acidity was preserved.When tested in a continuously flowed slurry reactor,the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Br?nsted acid concentration.In addition,Ce3+was found more benefit for the hydride transfer compared with La3+,which is ascribed to the stronger polarization effect on the CH bond of isobutane.Moreover,the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules.Based on the product distribution,a new catalytic cycle of dimethylhex-anes(DMHs)involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.

Zhiqiang Yang;Ruirui Zhang;Honghua Zhang;Hongguo Tang;Ruixia Liu;Suojiang Zhang

School of Chemical Engineering&Technology,Tianjin University,Tianjin 300072,China;Beijing Key Laboratory of Ionic Liquids Clean Process,State Key Laboratory of Multiphase Complex Systems,CAS Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Sciences,100049 Beijing,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China

中国化学工程学报（英文版）

[1]Zhiqiang Yang;Ruirui Zhang;Honghua Zhang;Hongguo Tang;Ruixia Liu;Suojiang Zhang-.Comparative catalytic study on butene/isobutane alkylation over LaX and CeX zeolites:The influence of calcination atmosphere)[J].中国化学工程学报（英文版）,2022(06):173-183

LaX,CeX,dealumination,Ce3+was,dimethylhex,DMHs,carbocation

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