载体及NiO负载方法对乙炔加氢酯化合成丙烯酸甲酯反应的影响

EFFECT OF SUPPORT AND METHOD OF LOADING ON THE CATALYTIC PERFORMANCE OF SUPPORTED NICKEL CATALYST FOR ACETYLENE HYDROESTERIFICATION TO METHYL ACRYLATE

在 5～ 6MPa、2 2 0℃下考察了用浸渍法制备的NiO/SiO2 (NiO/SiO2 (imp .) )和NiO/Al2 O3(NiO/Al2 O3(imp .) )催化剂及用离子交换法制备的NiO/SiO2 (NiO/SiO2 (ex .) )催化剂上乙炔加氢酯化合成丙烯酸甲酯 (MA)的催化活性和选择性。试验结果表明用离子交换法制备的NiO/SiO2 (ex .)催化剂 ,其催化活性和选择性均高于浸渍法制备的NiO/SiO2 (imp .)。从TPR谱图看 ,NiO/SiO2 (ex .)和NiO/SiO2(imp .)都只有一个还原峰 ,而前者的还原温度较后者高。NiO/Al2 O3(imp .)在NiO含量低时只有一个高温还原峰 ,含量高时出现两个还原峰 ,其低温还原峰对应的是与载体作用较弱的NiO晶粒的还原 ,而高温还原峰相当于与载体作用较强的NiO晶粒的还原。

The catalytic hydroesterification of acetylene over supported NiO/Al_2O_3 and NiO/SiO_2 catalysts prepared by impregnation and ion-exchange (NiO/Al_2O_3(imp.), NiO/SiO_2(imp.),and NiO/SiO_2(ex.))has been studied in a fixed bed reactor at the conditions of 220 ℃ and 5～6 MPa.The results show that the NiO/Al_2O_3(imp.) catalyst is very active and selective to methyl acrylate,but the NiO/SiO_2(imp.) catalyst is less active and selective than that prepared by ion-exchange NiO/SiO_2(ex.).TPR results show that NiO/Al_2O_3(imp.),NiO/SiO_2(imp.)and NiO/SiO_2(ex.) have different reduction temperature,which suggests that the dispersion degree of NiO over support is different.