大颗粒SiO_2载体负载Ir/FeO_x催化剂的巴豆醛加氢性能

选择粒径(1~3)mm的Si O2为载体,采用浸渍法制备Ir/Fe Ox/Si O2催化剂,考察Fe含量对催化剂气相巴豆醛选择加氢反应性能的影响,采用X射线粉末衍射、拉曼光谱及光电子能谱等对催化剂进行表征。结果表明,随着Fe添加量的增加,反应1 h时巴豆醛转化率和反应10 h时巴豆醇选择性呈现先提高后下降趋势,n(Fe)∶n(Ir)=1.0时,反应1 h时巴豆醛转化率最高(达67%);n(Fe)∶n(Ir)=0.3时,反应1 h时巴豆醛转化率和反应10 h时巴豆醇选择性分别达88%和95%,反应过程中催化剂表面积炭是导致巴豆醛转化率降低的主要原因。对于同种催化剂,反应后电子结合能往低结合能方向偏移可能是导致选择性提高的原因。

Selective hydrogenation of crotonaldehyde over Ir/FeO x catalysts with large particle SiO2 support

Using SiO₂ with particle size of (1-3) mm as the support,Ir/FeO_x/SiO₂ catalysts were prepared by impregnation method.The influence of FeO_x contents on the performance of Ir/FeO_x/SiO₂ catalysts for crotonaldehyde selective hydrogenation was investigated.The as-prepared Ir/FeO_x/SiO₂ catalysts were characterized by X-ray powder diffraction,Raman spectroscopy and X-ray photoelectron spectroscopy.It was found that when the reaction time were 1 h and 10 h,both crotonaldehyde conversion and selectivity to crotyl alcohol increased first and then decreased with the content increase of iron in Ir/FeO_x/SiO₂ catalysts.The highest crotonaldehyde conversion rate was 67% when n(Fe)∶n(Ir) was 1 and reaction time was 1 h;the selectivity to crotyl alcohol for reaction 1 h and 10 h were 88% and 95%,respectively when the molar ratio of Fe to Ir was 0.3.Carbon deposition formed on the catalyst surface during hydrogenaton process was the main reason for the decrease of crotonaldehyde conversion.For the same type of catalysts,the binding energy after reaction shifted to lower value,which could result in the selectivity enhancement.