Promoting Effect Of Fe, Co Or Ni On Cu/SiO₂-Al₂O₃for The Vapor-phase Synthesis Of3-methylindole From Glycerol And Aniline

The chemistry and biological activity of indole derivatives3-indolylcarbinol,3,3-diindolylmethane and3-methylindole have attracted considerable attention of manyfields，from biology to industry or environment.3-Methylindole, not only one of the mostimportant indole derivatives and intermediate of chemical synthesis, but also can be used invarious applications. So, how to efficient synthesis of3-methyl indole has become veryimportant.In this paper, the promoting effect of Fe, Co or Ni on Cu/SiO₂-Al₂O₃for the vapor-phasesynthesis of3-methylindole was investigated （glycerin and aniline as materials）. The catalystswere characterized by H2temperature programmed reduction （H2-TPR）, X–ray photoelectronspectroscopy （XPS）, X–ray diffraction （XRD）, transmission electron microscopy （TEM）,temperature-programmed-de sorption of ammonia （NH3-TPD）, thermogravimetric （TG-DTA）analysis techniquesinductively and coupled plasma （ICP） emission spectroscopy. The resultsindicated that adding Fe, Co or Ni to Cu/SiO₂-Al₂O₃improved the catalytic performance ofthe catalyst and Fe and Co exhibited more efficiently. Over Cu-Fe/SiO₂-Al₂O₃,Cu-Co/SiO₂-Al₂O₃and Cu-Ni/SiO₂-Al₂O₃, the yield of3-methylindole reached48%,47%and44%at the third hour of reaction. In addition, catalyst stability is improved and the reactionproducts yield was not significantly reduced after43h.The characterizations of XPS, TPR,ICP and XRD revealed that the addition of Fe, Co or Ni to Cu/SiO₂-Al₂O₃could reinforce theinteraction between copper and the support which promoted the dispersion of Cu particles onthe surface of the support. So, Fe, Co or Ni to Cu/SiO₂-Al₂O₃could decrease the loss ofcopper component during the reaction. Furthermore, Fe, Co or Ni promoter could decrease theamount of the middle-strong acid sites of the catalyst, which was conducive to the high yieldof3-methylindole, and inhibit the formation of coke. DTA analysis techniques spectraindicating that Co or Ni could change the texture of the coke.