The vapor-phase synthesis of 3-methylindole from glycerol and aniline over Cu/NaY modified by K2O was investigated. The catalysts were characterized by X-ray diffraction (XRD) and the temperature-programmed desorption of ammonia (NH3-TPD). The effect of the reaction temperature on the activity and selectivity of Cu/NaY-K2O catalyst was also investigated. The results indicated that the addition of K2O to Cu/NaY increased the selectivity of the catalyst remarkably because the amount of middle-strong acid sites decreased clearly. The decrease of the reaction temperature was beneficial for the increase of 3-methylindole selectivity. Over Cu/NaY-K2O, the selectivity of 3-methylindole reached 75% and the yield of the target product was up to 47% at 220 °C. A probable catalytic mechanism for the synthesis of 3-methylindole from glycerol and aniline was proposed.Cu/NaY-K2O exhibited high selectivity for the vapor-phase synthesis of 3-methylindole from glycerol and aniline, which the selectivity of 3-methylindole reached 75% and the yield of the target product was up to 47% at 220 °C.

•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.

An Al2O3-modified Cu/SiO2 catalyst was used in the vapor-phase synthesis of 3-methylindole from glycerol and aniline. The effect of Al2O3 and the preparation method of the Cu–Al2O3/SiO2 catalyst on the activity and selectivity of the catalyst were investigated. The catalysts were characterized by XRD, TEM, H2-TPR, NH3-TPD and TG techniques. The results indicated that the addition of Al2O3 to Cu/SiO2 increased the activity and selectivity remarkably. Cu–Al2O3/SiO2 prepared by co-precipitation (COP) exhibited better catalytic performance compared with the catalyst prepared by incipient wetness impregnation (IWI) or ultrasonic impregnation (UI), because the catalyst possessed a good dispersion of Cu particles, a better resistance to the sintering of Cu particles as well as a larger amount of weak acid sites. Over Cu–Al2O3/SiO2 (COP) with the Al2O3 content of 1.1 mmol/g, the yield of 3-methylindole reached 44 % at the third hour of reaction, and the yield could be kept to 41 % even after the reaction time of 51 h.

Adding La2O3 or CeO2 to the Ag/SiO2–ZnO catalyst can improve the catalytic performance in the synthesis of indole and CeO2 exhibits more efficiency than La2O3. La2O3 can improve the dispersion of silver on SiO2. CeO2 can improve the reduction of Ag2O. Both La2O3 and CeO2 can suppress the formation of coke.

A series of metal oxide catalysts for catalytic oxidative degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) were prepared, and the supported CuO catalysts were studied particularly. The supported CuO catalysts were characterized by XRD and NH3-TPD techniques, in which CUO/γ-AI2O3 exhibited high degradation activity. The addition of Na20 or K2O into CUO/γ-AI2O3 improved the oxidative degradation of CPs remarkably, in which Na20 was more efficient than K2O. Over CuO/γ-Al2O3-Na20, CPs were completely converted and the liberation of the inorganic chloride from 2-CP or 4-CP reached 97% or 100% respectively at 30 °C for 2 h. The supported CuO catalysts with good dispersion of CuO particles and less acid sites were favorable for the efficient oxidative degradation of CPs. In addition, the initial pH of the reaction solution was found to be an important factor which influenced the catalytic oxidative degradation of CPs and the initial pH of 11.2 and 9.8 was preferred for the oxidative degradation of 2-CP and 4-CP respectively over CUO/γ-AI2O3 catalyst.

The Cu/SiO2 catalyst prepared by incipient wetness method exhibited very high activity and selectivity for the vapor-phase synthesis of N-butylaniline from aniline and 1-butanol. When Cu loading was 0.70 mmol/g-SiO2 and the catalyst precursor was calcined at 500 °C, 1-butanol conversion reached 99%, and the selectivity of N-butylaniline exceeded 97%.

Cu-based catalysts, such as Cu/SiO2, Cu/γ-Al2O3 and Cu/SiO2-Al2O3, for the vapor phase synthesis of N-butylaniline from aniline and 1-butanol were investigated and the catalysts were characterized by BET, H2-TPR, XRD and NH3-TPD techniques. The results indicated that the dispersion of copper on support was greatly influenced by the interaction between Cu and the support. Copper-based catalyst with larger amounts of acidic sites did not favor the synthesis of N-butylaniline because more by-products were produced. Among the tested catalysts, Cu/SiO2 showed excellent catalytic activity and stability with a yield of N-butylaniline above 90% during the reaction time of 200 h.

The vapor-phase synthesis of 3-methylindole over Ag/SiO2 doped with ZnO was investigated. The catalysts were characterized by XRD, H2-TPR, NH3-TPD and TG techniques. The results indicated that ZnO promoter greatly enhanced the initial activity of the catalyst but disfavored its stability. H2-TPR and XRD results showed that the reduction peak of Ag2O shifted to higher temperature and the intensity of silver diffraction peaks was much weaker after the addition of ZnO promoter to Ag/SiO2. This indicated that there existed the interaction between Ag2O and SiO2-ZnO which promoted the silver particles dispersing on the support and inhibited the sintering of silver during the reaction. NH3-TPD and TG results revealed that the acid amounts of the catalyst and coking increased after adding ZnO to Ag/SiO2, which resulted in the deactivation of Ag/SiO2-ZnO catalyst rapidly.

An efficient environment-friendly synthesis of N-phenylpiperidine was developed from aniline and 1,5-pentanediol over γ-Al2O3 catalyst under atmospheric pressure. The conversion of 1,5-pentanediol reached 97% and the selectivity for N-phenylpiperidine attained 94%. The structure of the catalyst was characterized by NH3-TPD and BET. The influences of calcination temperature of the catalyst and reaction temperature on activity and selectivity of the catalyst were investigated.

A novel efficient method for vapor-phase synthesis of 3-methylindole from aniline and glycerol has been developed over Cu-based catalysts. The catalysts were characterized by BET, XRD, H2-TPR and NH3-TPD techniques. The results indicated that Cu/SiO2-Al2O3 catalyst exhibited high activity. The yield of 3-methylindole could be up to 40% when the Cu loading was 5.41 wt% and the reaction temperature was 240 °C. Moreover, the catalyst could be reused without obvious loss of the yield even after reaction time of 46 h. Copper-based catalyst with good dispersion and large amount of weak acid sites was favorable for producing 3-methylindole. A possible reaction pathway for the catalytic synthesis of 3-methylindole was proposed.A novel efficient method for the vapor-phase synthesis of 3-methylindole from aniline and glycerol has been developed over Cu/SiO2-Al2O3 catalyst with the yield of 3-methylindole up to 40%.Download full-size imageResearch Highlights► 3-Methylindole was synthesized from aniline and glycerol. ► Cu/SiO2-Al2O3 showed high activity and good stability. ► The yield of 3-methylindole was up to 40%. ► The weak acid sites and small copper particles on the catalyst facilitated the reaction.