丙烯环氧化反应组分在TS-1中吸附行为的分子模拟

 摘要：利用巨正则蒙特卡罗方法研究了钛硅分子筛（TS-1）催化丙烯环氧化反应中丙烯(C3H6)及过氧化氢(H2O2)在TS-1上的吸附行为。计算了压力为400kPa时，不同温度下丙烯和H2O2在TS-1中的吸附量和吸附能；探讨了主体相中不同n(C3H6)/n(H2O2)（进料比）下丙烯和H2O2的混合吸附行为，包括两者的吸附量及吸附位。结果表明，H2O2的吸附量明显高于丙烯；丙烯的吸附量随着温度的升高而降低，而H2O2的吸附量则随着温度升高而增加；H2O2的吸附能也高于丙烯。在混合吸附中，丙烯的吸附量随着进料比的增加而增加，而H2O2吸附量则随着进料比的增加而降低；当n(C3H6)/n(H2O2)=45时，二者在TS-1上的吸附量之比接近1，与两者反应的化学计量比相同，因此确定该反应的最佳进料比为45。还发现，丙烯优先被吸附于TS-1的直孔道和曲折孔道的交叉处，进而吸附于直孔道和曲折孔道中，同时H2O2被逐渐挤出孔道。

MOLECULAR SIMULATION FOR THE ADSORPTION OF PROPYLENE EPOXIDATION REACTANTS IN TS-1

Abstract：Adsorption of reactant molecules of propylene epoxidation on titanium silicalte zeolite (TS-1) was studied by grand canonical Monte Carlo simulation. The adsorption amounts and adsorption energies of propylene (C3H6) and hydrogen peroxide (H2O2) on TS-1 were obtained at different temperature under the pressure of 400 kPa. The effects of temperature on the adsorption amounts and adsorption energies of C3H6 and H2O2 were investigated. The adsorption behaviour of C3H6-H2O2 binary mixture at different molar ratios of C3H6/H2O2 was discussed, including adsorption amount and adsorption locations of C3H6 and H2O2 in TS-1. The simulation results indicated that on TS-1 the adsorption amount of H2O2 was obviously greater than that of C3H6, which increased with the temperature rising, being opposite to C3H6. Furthermore, the adsorption energy of H2O2 was higher than that of C3H6. The equimolecular adsorption of C3H6 and H2O2, similar to the stoichiometric proportion for the reaction of C3H6 with H2O2, was reached in TS-1 at about 45 of n(C3H6)/n(H2O2), which was the optimal feed ratio for the propylene epoxidation. Moreover, it was found that C3H6 molecules were adsorbed on the interconnections of the sinusoidal and straight channels in TS-1 at first, then on these two channels, at the same time, H2O2 was extruded out gradually.