Gas-phase Epoxidation Of Propylene With TS-1Based On The Atomization Of Hydrogen Peroxide

Gas-phase epoxidation of propylene with TS-1based on the atomization of H2O2was carried out in a small fixed-bed reactor. A series of experiments were conducted over it equipped with an on-line chromatographic technique. Firstly, technical feasibility of the PO synthesis method above was proved, and then the effect of epoxidation conditions were investigated, which include reaction temperature, space velocity of propylene, catalyst amount, reactor inside diameter, concentration of H2O2and different catalysts. The effect of different kinds of trace additives such as alcohols, acetonitrile, amines and earth metal salts on the gas-phase epoxidation was studied. The conclusions obtained are as follows:1. The technical route of gas-phase epoxidation based on the ultrasonic atomization of H2O2was feasible.2. Direct gas-phase epoxidation of propylene with hydrogen peroxide on TS-1was performed, it can be found that the reaction temperature and space velocity of propylene can significantly improve the the utilization of H2O2. The suitable reaction conditions was reaction temperature150℃, space velocity of propylene8.10h-1, catalyst amount0.4g, space velocity of H2O20.24h-1, inside diameter of reactor15mm, nC3H6/nH2O2=33.5/1. PO selectivity can reach to99%and propylene conversion was about2.4%, catalyst productivity330gPOKg-1(cat)h-1and H2O2utilization can acheive to80%under the reaction conditions above.3. The effect of different kinds of trace additives such as alcohols, acetonitrile, amines and earth metal salts on the gas-phase epoxidation. The methanol, isopropanol and acetonitrile can obviously encreaced the TS-1catalytic activity, but PO selectivity remain unchanged. However, trace ethanol decreased PO selectivity significantly. PO selectivity enhanced obviously by the introduction of trace alkaline substances such as ammonia, methylamine, trimethylamine, sodium hydroxide and potassium hydroxide, but propylene conversion, catalyst productivities and H2O2utilization significantly reduced. The introduction of TPAOH not only improved PO selectivity,, but also promoted catalytic activity, catalyst productivities and H2O2utilization in the process of epoxidation. Besides, PO selectivity increased and propylene conversion, catalyst productivities and H2O2utilization unchanged with trace earth metal salts such as sodium chloride and potassium chloride were added. 4.The catalytic activity of TS-1after TPAOH treatment was significantly improved and modification times lead the different results.The TS-1catalyst modified twice could get the highest catalytic activity.Meanwhile,the catalytic activity of TS-1[add salt] was more ingher than TS-1[add acid].