Abstract
Vapor phase Beckmann rearrangement over new type zeolite (SSZ-31) with medium pore size and weak acid sites were carried out to elucidate the effects of acid strength and micro pore size on the selectivity to ε-caprolactam (CL) and the catalyst deactivation. Furthermore, the titanosilicate with ZSM-5 type structure (TS-1) was used for the rearrangement to clarify the effect of Si/Ti ratio on the CL selectivity and catalyst deactivation rate. The results obtained from the new catalysts were compared with the results over HZSM-5.The selectivity to the CL over the catalyst with strong acid sites was lower than that over high silica HZSM-5 with weak acid strength. The CL selectivity over the catalyst with large micro pore was lower than that over the catalyst with MFI structure. These results indicate that the CL produced in medium pore (about 1.0 nm) changes to oligomers and the deposited oligomer in the pore gradually changes to coke or its precursor. The oligomerization should be accelerated by the strong acid sites. The SSZ-31 with medium pore is not suitable to the Beckmann rearrangement, whereas TS-1 with small pore was good catalyst for the rearrangement.
