采用浸渍法制备了负载型Ir/ZrO2催化剂,详细考察了H2还原温度对Ir/ZrO2催化剂上气相巴豆醛选择性加氢反应性能的影响.结果表明,随着还原温度的升高,Ir/ZrO2催化剂上巴豆醛转化率和巴豆醇选择性均先升后降,400℃下还原时,Ir/ZrO2催化剂性能最佳,巴豆醛转化率和巴豆醇选择性分别达32.2％和74.3％.X射线光电子能谱结果表明,催化剂表面系Ir0和Ir3+共存,且随着还原温度的升高,Ir0的比例逐渐增加,至600℃时,表面Ir物种大部分以Ir0存在.NH3程序升温脱附结果表明,随着还原温度的升高,催化剂表面Lewis酸中心的数目减少,强度下降.这是由于催化剂中C1含量下降所致.Ir0和Ir3+共存和中等强度的表面Lewis酸中心有利于提高巴豆醇选择性.%The Ir/ZrO2 catalyst was prepared by impregnation, and the effect of reduction temperature on its catalytic performance for hy-drogenation of crotonaldehyde in gas phase was measured. With increasing reduction temperature, the crotonaldehyde conversion and selectivity for crotyl alcohol over the Ir/ZrO2 catalyst first increase and then decrease. The catalyst reduced at 400 °C exhibits the highest crotonaldehyde conversion, reaching a value as high as 32.2%, and the selectivity for ctotyl alcohol is 74.3%. The results of X-ray photoelectron spectroscopy indicated that both Ir° and Ir3+ species coexist on the catalyst surface after reduction at 400 °C. With increasing reduction temperature, the ratio of I0/Ir3+ increases, and the surface Ir species exists mainly as Ir° when the reduction temperature is 600 °C. Additionally, NH3 temperature-programmed desorption indicated that the amount and intensity of Lewis acid sites show a downward trend with increasing reduction temperature, which is attributed to the decline of Cl element in the catalyst. Therefore, it is concluded that the coexistence of Ir° and Ir3+ and moderate-intensity of surface Lewis acid help improve the yield and selectivity of crotyl alcohol.
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