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

在液相环己酮氨肟化反应中，有机物在钛硅分子筛催化剂（TS-1）上的沉积是造成失活的原因之一。采用傅里叶变换红外光谱、热重-差热、色谱-质谱联用、X-射线衍射、固体核磁共振、N2物理吸附和扫描电镜等分析手段，对失活TS-1的骨架结构及表面沉积物分子的结构和物化性质进行了表征。结果表明，引起催化剂失活的沉积物富集在分子筛的孔道内，主要有环己酮的氧化或还原产物、环己酮的二聚物、环己酮肟深度反应产物、叔丁基环己酮等可溶性沉积物以及它们缩聚而成的不溶性沉积物，其量可占失活催化剂总质量的5.0%。TPO烧炭时靠近Ti中心处的沉积物可以在较低温度下脱除，而孔道内的其他沉积物需要在较高温度下脱除，650℃沉积的炭可完全脱除。失活催化剂经700℃煅烧再生后，催化活性可恢复到新鲜催化剂的水平。

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, 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.