Regeneration of Lamina TS-1 Catalyst in the Epoxidation of Propylene with Hydrogen Peroxide

The deactivation and regeneration of the lamina titanium silicalite (TS-1) catalyst for the epoxidation of propylene with dilute H2O2was investigated in a fixed-bed reactor. In the scale-up experiment, the dosage of the lamina TS-1 catalyst is 2. 5 kg, after 1000 h reaction the catalyst still exhibits good performance and further increases the reaction time, the conversion of H2O2begins to decrease. TG and BET analyses of the deactivated catalysts show that the main species occluded within the zeolite pore are propylene oxide oligomers, and these species occupying the active Ti site and blocking the pores of the lamina TS-1 are the main reason for the deactivation of catalyst. The deactivated catalyst can be regenerated by different regeneration methods. The activity of deactivated catalysts regenerated by dilute H2O2or heat treatment by using air or nitrogen as a calcination media can be fully recovered, but a decline in propylene oxide (PO) selectivity of the regenerated catalyst has been observed during the first hours of reaction. However, water vapor treatment of the deactivated catalyst can improve the PO selectivity with the same activity as that of the fresh lamina TS-1 catalyst.