Vapor-phase Synthesis Of3-methylindole From Glycerol And Aniline Over Zeolites-supported Cu-based Catalysts

3-Methylindole, known as a C3-alkyl indole derivative and intermediate ofchemical synthesis, can be widely applied in the fields of industry, agriculture andmedicine. One of the most promising routes, from an economic point of view, is directvapor-phase synthesis of3-methylindole by feeding glycerol and aniline as reactants，because the route is not only low price but also green environmental-protection.The objective of this work is to research zeolites （NaY,5A, HZSM-5andMCM-41）–supported copper catalysts for the vapor phase synthesis of3-methylindoleand Na₂O, K₂O promoter was introduced into the optimal zeolite–supported coppercatalyst. The Cu-based catalysts were prepared by sequential incipient wetnessimpregnation. BET, XRD, NH₃-TPD and TG-DTA techniques were used toinvestigate and explain the relationship between the structure of Cu-based catalystsand their catalytic performances.The results indicated that Cu/NaY catalyst exhibited higher activity and selectivitydue to the better dispersion of copper and larger amount of weak acid sites on thesurface of the catalyst, which the yield of3-methylindole reached37%at the secondhour. The addition of Na₂O or K₂O to Cu/NaY decreased the amount of middle-strongacid sites of the catalyst obviously and inhibited the formation of the coke, as a result,the selectivity of the catalyst improved greatly. Optimization the reaction conditionsinhibited the formation of carbon effectively, meanwhile, the deactivation rate of thecatalyst was decelerated. When the amount of Na₂O or K₂O was0.6and0.4mmol/g,the reaction was carried out at220℃, the flow rate of H2, steam or N2was20,6or54ml/min, the yield of3-methylindole could be up to48%and49%at the second hour.The addition of Na₂O or K₂O did not change the texture of the coke. Furthermore, aprobable mechanism for the synthesis of3-methylindole over zeolites-supportedCu-based catalysts was proposed.