MnO2负载量对MnO2/HBeta分子筛催化二甲醚制六甲基苯反应性能的影响

摘要

The MnO2/HBeta catalysts with different MnO2 loadings were prepared by impregnation method, and characterized by Abstract: The fundamental thermodynamic data of the substances in the reactions of dimethylamine with acetic acid or acetic anhydride were calculated by Benson group contribution method and Waston empirical formula. The reaction enthalpy, Gibbs free energy change and equilibrium constant of the main reactions were calculated. The results show that the enthalpy changes of both reacions are negative at 20-160℃, indicating that both reactions are exothermic; with the increase of reaction temperature, the heat release will decrease gradually; the Gibbs free energy changes of both reactions are negative, meaning that both reaction can occur spontaneously; and the equilibrium constants of both reactions decreases with the increase of reaction temperature, and they are pretty large at 20-40℃, which is suitable for the reaction.%在连续流动固定床反应器上考察了不同MnO2负载量的MnO2/HBeta分子筛催化二甲醚制六甲基苯的性能,结果表明:10%MnO2改性HBeta有利于提高六甲基苯选择性.在常压、反应温度为280℃、空速为100h-1条件下,10%MnO2/HBeta催化二甲醚反应,二甲醚转化率达76.36%,HMB选择性为25.1%.利用NH3-TPD,Py-IR,BET及XRD等对催化剂的结构和性质进行表征,结果表明,随着MnO2负载量的增加,MnO2在催化剂中逐渐以晶体结构存在,且催化剂表面强酸中心逐渐增加,而催化剂B酸酸性呈现出先减弱后增强的趋势.10%MnO2改性HBeta催化剂具有适宜的表面酸性,有利于HMB的生成.