环己酮氨肟化反应中失活TS-1催化剂上沉积物的物化表征

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, N2 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.