The TS-1/diatomite catalyst was prepared for the hydroxylation of phenol with H2O2 in the fixed-bed reactor and the effects of pretreatment on the properties of TS-1/diatomite were studied by FT-IR, XRD, UV-vis, ICP-AES, BET surface area and NH3-TPD techniques. It is shown when the catalyst is pretreated by the KAc, NaAc, NH4Ac, NH4Cl or HNO3 aqueous solution, the framework structure of TS-1 is not destroyed and titanium in the framework is not removed. The surface area of catalyst has no obvious change compared with that of the untreated catalyst. But the extra-framework TiO2 can be removed partly, which leads to the slight increase of the crystallinity of catalyst and the decrease of acid concentration on the surface of the TS-1/diatomite catalyst. As a result, the activity, selectivity and utilization of H2O2 for hydroxylation of phenol are improved. After the TS-1/diatomite catalyst is pretreated by the NH3•H2O, Na2CO3 or Na3PO4 solution, its framework silicon is dissolved partly in the base solution and the framework structure of TS-1 is destroyed. While the crystallinity and surface area of catalyst decrease and the concentration of acid sites on the surface of catalyst increased slightly. As a result, the catalytic activity of the TS-1/diatomite catalyst for hydroxylation of phenol descended or deactivated completely.

Direct gas-phase epoxidation of propylene to propylene oxide (PO) by molecular oxygen was studied over the MoO3-modified supportedsilver catalyst. The effect of promoter and support on the performance of the Ag-MoO3 catalyst and their role were investigated by XPS, XRD, SEM, BET surface area, NH3-TPD, CO2-TPD techniques and so on. As the promoter, MoO3 plays a great role of electron- and structure-type bi-functional promoter. Of all the supports studied, ZrO2 is the most suitable one for the Ag-MoO3 catalyst. The presence of support can regulate the size of the Ag-MoO3 particles and the pore radii of catalyst, and decrease the loading of MoO3 from ∼50wt.% in the unsupported Ag-MoO3 catalyst to ∼4wt.% in the Ag-MoO3/ZrO2 catalyst. The properly weak Lewis acidic sites, the larger size of the Ag-MoO3 particles and pore channel on the Ag-MoO3/ZrO2 catalyst are beneficial to improve epoxidation performance of the catalyst. The effect of the reaction temperature and space velocity on the catalytic epoxidation of propylene was also investigated. The low temperature or high space velocity can decrease the deep oxidation of propylene oxide to improve the selectivity to PO. Over the 20%Ag-4%MoO3/ZrO2 catalyst at 400℃, 0.1MPa and space velocity of 7500h−1, the selectivity to PO of 60.3% was achieved with the O2 conversion of 4.8%; under the space velocity of 12 000h−1, the selectivity to PO was 71.5% with 2.5% O2 conversion.