焙烧温度对苯甲酸加氢用Mn/Zn/Al催化剂性能的影响

采用共沉淀法制备了Mn/Zn/Al系列催化剂，考察了焙烧温度对苯甲酸加氢制备苯甲醛反应中催化剂性能的影响，采用DSC-TGA、BET、XRD和H₂-TPD等手段对催化剂进行表征，并与催化剂活性和苯甲醛选择性关联。研究表明，焙烧温度对Mn/Zn/Al催化剂性能影响显著，影响了催化剂对H₂的吸附能力及比表面积。经500 ℃焙烧处理的催化剂苯甲酸转化率为92.1%，苯甲醛选择性达89.3%，此时，活性组分分散较好，催化剂对H₂的吸附强度适中，吸附量较大，催化剂活性较高。随着焙烧温度增加，MnO分散度下降，催化剂比表面积相应降低，苯甲醛选择性下降。

Effect of calcination temperature on Mn/Zn/Al catalysts for hydrogenation of benzoic acid

A series of Mn/Zn/Al catalysts were prepared with co-precipitation method. The catalytic performance of Mn/Zn/Al catalyst for vapour-phase hydrogenation of benzoic acid to benzaldehyde was investigated in a continuous flow and fixed-bed reactor. The catalyst was characterized by DSC-TGA, BET, XRD and H₂-TPD. It was found that calcination temperature showed significant effects on the catalytic performance of Mn/Zn/Al catalyst, such as H₂ adsorption capacity and the specific surface area of the catalyst. The proper calcination temperature for Mn/Zn/Al catalyst was 500 ℃. The conversion of benzoic acid and the selectivity of benzaldehyde were 92.1% and 89.3%, respectively，over the catalysts calcined at 500 ℃, which had better dispersion of the active component, moderate H₂ adsorptive intensity and maximal H₂ adsorption. With the increase of calcination temperature, the dispersancy of MnO descendted and the specific surface area reduced, which resulted in a decrease in the selectivity of benzaldehyde.