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对丙三醇和苯胺在Co或Ni促进的Cu/SiO2-Al2O3催化剂上气相合成3-甲基吲哚进行了研究.采用N2吸附、氢气程序升温还原(H2-TPR)、电感耦合等离子体(ICP)发射光谱、X射线衍射(XRD)、透射电子显微镜(TEM)、氨程序升温脱附(NH3-TPD)及热重(TG)分析等技术对催化剂进行了表征.结果表明,向Cu/SiO2-Al2O3催化剂加入钴或镍助剂改善了催化剂的催化性能,钴比镍更加有效.在催化剂Cu-Co/SiO2-Al2O3和Cu-Ni/SiO2-Al2O3上,反应第3 h,3-甲基吲哚收率分别达到47%和45%,而且催化剂经过6次再生收率仍能达到44%和42%.各种表征表明,向Cu/SiO2-Al2O3催化剂加入钴或镍助剂能增强铜和载体之间的相互作用,其结果不仅促进了铜粒子在载体表面的分散度,而且有效减少了反应过程中铜组分的流失.另外,加入钴或镍助剂还能减少催化剂的中强酸中心数,从而提高3-甲基吲哚的选择性,并且抑制积炭的形成.此外,钴助剂还能增加催化剂的弱酸中心数,促进3-甲基吲哚的生成.提出了金属铜与弱酸中心共同促进3-甲基吲哚合成的催化反应机理.
Gas-phase synthesis of 3-methylindole over glycerol and aniline catalyzed by Co or Ni over Cu / SiO2-Al2O3 catalyst was investigated by N2 adsorption, hydrogen temperature programmed reduction (H2-TPR), inductively coupled plasma ) Emission spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), ammonia temperature-programmed desorption (NH3-TPD) and thermogravimetric analysis (TG) were used to characterize the catalysts. -Al2O3 catalyst added cobalt or nickel promoter to improve the catalytic performance of the catalyst, cobalt is more effective than nickel.On the catalyst Cu-Co / SiO2-Al2O3 and Cu-Ni / SiO2-Al2O3, the reaction 3 h, 3-methyl The yields of indoles reached 47% and 45%, respectively, and the regeneration yields of the catalysts reached 44% and 42% after 6 cycles respectively. Various characterizations indicate that the addition of cobalt or nickel promoter to the Cu / SiO2-Al2O3 catalyst can enhance the copper And the carrier interaction, the results not only promote the dispersion of copper particles in the carrier surface, but also effectively reduce the loss of copper components during the reaction.In addition, cobalt or nickel additives can also reduce the catalyst medium strong acid The number of centers, thereby increasing the selectivity of 3-methylindole and inhibiting the formation of coke. In addition, cobalt additives Can increase the number of weak acid sites of the catalyst and promote the formation of 3-methylindole. A catalytic reaction mechanism of copper and weak acid centers to promote 3-methylindole synthesis was proposed.