Investigations on TPSR-TPD of H2O2, O-2 and allyl chloride species adsorbed on Ti-Si zeolites

In the TPSR-TPD curves of allyl chloride, there are multiple desorption peaks (amount to triplet) on TS-1 zeolites, however there is only a single desorption peak on TiO2/silicalite. After the adsorption of H2O2 or molecular O-2 separately, O(16) atoms are discovered in the desorbed species by MS. It is found that the activity of the samples dissociating molecular O-2 into atomic O(16) is low, TS-1 zeolites can simultaneously adsorb H2O2 and allyl chloride, but the adsorption of both of them on TiO2/silicalite surface is relevant to adsorptive sequence. The order of epoxidation activity is as follows: TS-1(TPAOH)>TS-1 (TPABr+NaOH)>TiO2/silicalite. It is postulated that the higher oxidation activity of Ti-Si zeolites is related to the formation of surface O(16) atoms adsorbed on the zeolites after the adsorption of H2O2.