Nature and location of deposit on beta zeolite catalyst for isopropylationof benzene with propene to cumene

The modified beta zeolite catalyst showed excellent performance (e.g. activ ity, selectivity and stability) in isopropylation of benzene with propene t o cumene in liquid phase. C-13 NMR, IR, GC-MS and TG combined with some tec hniques including solvent-extraction method, TPO and structure characteriza tion were applied to determine the components of the deposit on the coked b eta zeolite catalyst after reaction for 8 000 h in pilot-plant scale. It wa s shown that the composition of the deposit consists mainly of multi-isopro pyl benzene (55.3%) and tetrahydronaphthalene (17.3%), locating in the pore s and channels of the zeolite instead of on the surface of the catalyst. Th e activity of the regenerated zeolite catalyst can be restored to 92% of th at of the fresh one after TPO (in 3%Q(2)-97%N-2 from 30 to 500 degreesC at a heating rate of 15 degreesC/min and then kept at 500 degreesC for 1 h). T he higher heating rate in TPO is suitable for the regeneration of the catal yst rather than the lower rate.