硅钛比对TS-1分子筛催化甲醇羰基化反应性能的影响

Effect of Si/Ti Ratio on Performance of TS-1 Zeolite Catalytic for Methanol Carbonylation

对TS-1分子筛而言,它的各种物理性质影响其反应活性.通过调节和控制催化剂的物理性质能够提高产物选择性和收率,降低副产物,从而提高反应活性.本文考察了TS-1分子筛的硅钛比对甲醇羰基化反应性能的影响.在合成TS-1分子筛时,通过控制硅源和钛源的比值得到了不同硅钛比的TS-1分子筛.结果表明:硅钛比大时(例如:硅钛比为64),TS-1沸石分子筛的非骨架钛含量和锐钛矿含量较少,甲醇羰基化反应效果较好;反应温度为300℃时,甲醇转化率为30%,乙酸甲酯和甲酸甲酯选择性之和为26%,反而硅钛比较小(例如:硅钛比为34和41)时,TS-1沸石分子筛的非骨架钛含量和锐钛矿含量较多,甲醇羰基化反应性能较差.甲醇转化率仅为5%,乙酸甲酯和甲酸甲酯选择性之和仅为4%.产生以上结果的原因之一是硅钛比大,TS-1沸石分子筛结晶完全、杂质少、孔道通畅;其二为钛分布合理,其三为所生成的中间产物可能继续进行反应生成二甲醚、乙醇及裂解生成CO2、CO、干气等副产物.

For TS-1 molecular sieve,its various physical properties affect its reaction activity.By adjusting and controlling the physical properties of the catalyst,the selectivity and yield of the products can be improved,and the by-products can be reduced,so as to improve the reaction activity.The effect of Si/Ti ratio of TS-1 molecular sieve on methanol carbonylation was investigated in this paper.In the synthesis of TS-1 zeolites,TS-1 zeolites with different Si/Ti ratios were obtained by controlling the ratio of Si to Ti,the result shows that when the ratio of Si to Ti is high(e.g.the ratio of Si to Ti is 64),the content of non framework titanium and anatase in TS-1 Zeolite is less,and the effect of methanol carbonylation is better,when the reaction temperature is 300℃,the conversion of methanol is 30%,and the total selectivity of methyl acetate and methyl formate is 26%,and when the ratio of Si to Ti is low(e.g.the ratio of Si to Ti is 34 or 41),TS-1 zeolites have high content of non framework titanium and anatase,and poor performance of methanol carbonylation.The conversion of methanol is only 5%,and the selectivity of methyl acetate and methyl formate is only 4%.One of the reasons for the above results is the high ratio of Si to Ti,complete crystallization,less impurities and smooth pore channels of TS-1 Zeolite;the second is that the titanium distribution is reasonable;the third is that the intermediate products may continue to react to produce dimethyl ether,ethanol and pyrolysis to produce CO2,CO,dry gas and other by-products.