Vapor-phase synthesis of 3-methylindole from glycerol and aniline over zeolites-supported Cu-based catalysts

• Zeolites-supported Cu-based catalysts were used in the synthesis of 3-methylindole.
• Cu/NaY exhibited higher activity and selectivity than Cu/5A, Cu/HZSM-5 or Cu/MCM-41.
• The addition of Na2O to Cu/NaY improved the selectivity of the catalyst remarkably.
• Over Cu/NaY–Na2O, the selectivity and yield of 3-methylindole reached 72.3 and 50.4%, respectively.
• The catalytic mechanism for the synthesis of 3-methylindole was proposed.

Zeolites-supported Cu-based catalysts for the vapor-phase synthesis of 3-methylindole from glycerol and aniline were investigated. The catalysts were characterized by N2 adsorption, XRD, NH3-TPD and TG–DTA techniques. The results indicated that Cu/NaY catalyst exhibited higher activity and selectivity than Cu/5A, Cu/HZSM-5 or Cu/MCM-41 due to better dispersion of copper particles and larger amount of weak acid sites on the catalyst. The addition of Na2O to Cu/NaY not only improved the selectivity of the catalyst efficiently, but also inhibited the deactivation of the catalyst. Over Cu/NaY–Na2O, the selectivity of 3-methylindole reached 72.3% and the yield of the aim product was up to 50.4%. The characterizations revealed that Na2O promoter could decrease the amount of middle-strong acid sites of the catalyst remarkably as well as prevent from the formation of the coke. Furthermore, a probable catalytic mechanism for the synthesis of 3-methylindole from glycerol and aniline was proposed.

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