【摘要】 采用Zr(NO3)4为Zr源,水为溶剂,浸渍法制备了负载型ZrOx/MCM-41介孔分子筛催化剂,考察了其在以异丙醇为氢源,苯甲醛为模型反应物,经氢转移法还原为苯甲醇的反应(MPV反应)中的催化性能,同时对样品进行XRD、N2吸附-脱附、IR、UV等表征分析,并与水合ZrO2、骨架掺杂Zr-MCM-41进行对比研究。结果表明:ZrOx/MCM-41分子筛性能最为优异,负载范围为2.5%～20%时,Zr负载量对性能影响较不明显,最佳负载量为5%;焙烧温度对性能影响较明显,最佳焙烧温度是300℃,以300℃焙烧8h的5%ZrOx/MCM-41分子筛为催化剂,在76℃、反应8h后,苯甲醛的转化率为88%,苯甲醇的选择性>99%。该类催化剂具有较好的抗水性、抗活性组分流失性和再生性能。ZrO2负载于MCM-41上时可能形成表面Si-O-Zr-OH基团,其可能是该催化剂性能优异的主要原因,催化剂表面少量存在的NO3-可能增加了其酸性,使其活性进一步提高。更多还原

【Abstract】 The zirconia catalysts supported on MCM-41 were prepared by impregnation method using Zr(NO3)4 as zirconia source and water as solvent.The catalysts prepared were used for hydrogen transfer reaction of benzyl aldehyde to benzyl alcohol with 2-propanol as reducer(Meerwein-Pondorf-Verley reduction),and they were characterized with XRD,N2 sorption,TG-DTA,IR,and UV.The catalytic activities of the prepared catalysts were compared with hydrous zirconia and doped Zr-MCM-41,and the results show that among them the supported ZrOx/MCM-41 catalysts demonstrate the highest activity.It was found that the optimal Zr content for ZrOx/MCM-41 catalysts is 5%,and with Zr loading from 2.5% to 20%,the effect of Zr content on the activity of ZrOx/MCM-41 catalysts isn’t very obvious,.In the range of 200～500℃,the activity of ZrOx/MCM-41 catalysts is markedly affected by calcination temperature,and the optimal calcination temperature is 300℃.When reaction was carried out at 76℃ for 8 h,using catalyst of 5%ZrOx/MCM-41 calcinated at 300℃,the conversion of benzyl aldehyde is 88%,and the selectivity of benzyl alcohol is higher than 99%.The abilities of regeneration,resist-water and resist-leaching of the active component of the catalysts prepared are all good.It was found that the excellent catalytic performance of ZrOx/MCM-41 catalysts may originate from the Si-Zr-OH radicals formed on its surface during loading ZrO2,and a few residual NO3- on the catalyst surface may enhance its acidity,thus improving its catalytic activity further.更多还原