Deactivation Of Solid Acid Catalyst For Isobutane/Butene Alkylation

Solid acid catalysts can replace the liquid acids used in alkylation.HY zeolite,for example,is one of the most studied solid acid catalysts for isobutane/butane alkylation.However,it is also easily deactivated by the deposition of coke precursors.Therefore,the study on the deactivation of solid acid alkylation catalyst is helpful to understand the alkylation reaction mechanism.Meanwhile,it is of great significance to the development of the regeneration method of solid acid alkylation catalysts.In this paper,the reasons for the deactivation of the catalyst,the influence of different reaction conditions on the activity of the HY zeolite catalyst and possible molecular cluster of the coke precursor were investigated.XRD,TG,BET,NH3-TPD,Py-IR characterization results show that:The deactivation of the catalyst is mainly due to the microporous blockage of the catalyst by the coke precursor and the reduction of the medium strong acid sites.The chromatographic-mass spectrometry(GC-MS)and 1H NMR spectra of the deactivated catalyst extract showed that the coke precursor was mainly composed of highly branched alkene.The results of the alkylation experiments under different reaction conditions show that there is an optimum reaction temperature at which the HY catalyst achieves the longest lifetime.Although the activity of the HY zeolite catalyst is best at this temperature,the tendency of pore blocking,the consumption of acid,and the deposition of coke precursor are still increasing with the increase of the reaction temperature;and with the increase of the reaction space velocity and the reduction in the amount of feed alkane will aggravate the deposition of coke precursors on the catalyst and the consumption of acid,thereby accelerating the deactivation of the catalyst.