La2O3对Ag／SiO2催化剂气相合成3-甲基吲哚的促进作用

3-甲基吲哚作为一种重要的氮杂环化合物在工业、农业及医药等领域应用非常广泛．以苯胺和1，2-丙二醇为反应原料，研究了La2 O3助剂对Ag/SiO2催化剂气相合成3-甲基吲哚的促进作用，采用X射线衍射（XRD）、氢气程序升温还原（H2-TPR）和氨气程序升温脱附（NH3-TPD）技术对催化剂进行了表征．结果表明，向Ag/SiO2催化剂加入适量的L a2 O 3助剂能明显提高银在载体表面的分散度、显著减少催化剂的强酸中心数，从而大大提高了催化剂的选择性．在 Ag/SiO2-La2 O3催化剂上，当 La2 O3含量为0．03 mmol/g时，3-甲基吲哚收率达到45％．

Promoting effect of La2O3 on Ag/SiO2 for the vapor-phase synthesis of 3-methylindole

3-Methylindole ,an important nitrogen-containing heterocyclic chemical ,can be widely ap-plied in the fields of industry ,agriculture and medicine .This paper investigated the promoting effect of La2 O3 on the catalyst of Ag/SiO2 for vapor-phase synthesis of 3-methylindole from aniline and 1 ,2-propanediol .The catalysts were characterized by X-ray diffraction（XRD） ,the temperature-pro-grammed reduction of hydrogen and the temperature-programmed desorption of ammonia（N H3-TPD） .The results indicated that the greatly enhanced selectivity of the catalyst due to adding appro-priate amount of La2 O3 into Ag/SiO2 is associated with the significantly enhanced dispersion of Ag on the support as well as the remarkably decreased strong acid sites in amount being caused by the addi-tion of La2 O3 .Over Ag/SiO2-La2 O3 ,the yield of 3-methylindole reached 45% w hen the amount of La2 O3 was 0 .03 mmol/g .