Vapor-phase Synthesis Of3-methylindole Over SiO₂-supported Cu-based Catalyst: Effects Of Promoters And Catalyst Preparation Methods

3-Methylindole, an important indole derivatives, can be widely applied in the fields ofindustry, agriculture and medicine. For many years, the synthesis of3-methylindole is an areaof focus for the chemists.We reserch the vapor-phase synthesis of3-methylindole，regarding glycerol and anilineas the raw material. Investigating the effect of MgO, ZrO₂and Al₂O₃promoter on the activityand selectivity of Cu/SiO₂catalyst, focusing on the effect of Al₂O₃promoter content andpreparation method on the catalytic properties of Cu-Al₂O₃/SiO₂catalyst. The catalysts arecharacterized by XRD, TEM, H2-TPR, NH3-TPD and TG-DTA techniques.The results show that the addition of MgO, ZrO₂and Al₂O₃promoter are conducive toimprove the activity and selectivity of Cu/SiO₂catalyst, because the promoter both canenhance the interaction between copper and support, improving the dispersion of the copperparticles. The Al₂O₃promoter show the best promoting effect. The activity and selectivity ofCu-Al₂O₃/SiO₂catalyst increase first and then decrease with the increment of Al₂O₃content,and the optimum Al₂O₃content is1.1mmol/g. Compared with the catalysts prepared byincipient wetness impregnation （IWI） or ultrasonic impregnation（UI）, Cu-Al₂O₃/SiO₂catalystprepared by co-precipitation （COP） exhibits better catalytic performance, because the catalystnot only possesses a good dispersion of Cu particles, a better resistance to the sintering, butalso has a substantial weak acid sites. When the content of Al₂O₃is1.1mmol/g, the3-methylindole yield reaches44%at the third hour, and the yield can be kept to41%evenafter regeneration and the reaction time of51h. There is difference between carbon type of theCu-Al₂O₃/SiO₂catalysts prepared by IWI, UI and COP.