Characterization of the deposits on deactivated TS-1 catalyst in cyclohexanone ammoximation process

Organic compounds deposited on titanium silicalite catalyst(TS-1) are one of the main reasons that cause the catalyst deactivation during cyclohexanone ammoximation process.The molecular structure and physicochemical properties of deposits on deactivated TS-1 are recognized and identified by means of various characterization approaches,including FT-IR,TG-DTA,GC-MS,XRD,NMR,N_2 physisorption and SEM.According to the characterization results,the deposits,which locate on the pores of zeolite and result in the catalyst deactivation,consist of the ether-soluble compounds including the products of cyclohexanone oxidation/reduction,dimers of cyclohexanone,continuous reaction products of cyclohexanone oxime,tert-butylcyclohexanone as well as the insoluble deposits due to their further polymerization.The overall amount of deposits accounts for 5.0% of deactivated TS-1 in mass.The deposits closed to Ti centers can be removed preferentially at lower temperatures during the TPO process,but the removal of others needs a higher temperature and can be completed at 650℃.The catalytic activity of deactivated catalyst can be recovered after it was calcined at 700℃ in air.