焙烧温度对Pd／TiO2催化剂加氢性能的影响

Effect of Calcination Temperature on Hydrogenation Performance of Pd/TiO_2 Catalysts

以自制TiO2成型载体采用浸渍法制备了0.5%Pd/TiO2催化剂,考察了催化剂前驱体的焙烧温度对粗对苯二甲酸(CTA)中的主要杂质对羧基苯甲醛(4-CBA)的加氢性能的影响,并用XRD、BET、XPS等手段对催化剂进行了表征。结果表明,Pd在催化剂中呈均匀分散状态,随着焙烧温度的增加,催化剂的BET比表面积无明显变化,但催化剂表面的Pd/O原子比和Pd的比表面积先增大而后降低。焙烧温度400℃时,催化剂表面Pd的比表面积最大,4-CBA的转化率最高。在反应温度280℃～290℃,H2分压0.6～1.5MPa,反应时间0.5～2.0h的条件下,0.5%Pd/TiO2催化剂上4-CBA转化率可在99.2%以上。研究结果可为粗对苯二甲酸加氢精制催化剂的研究提供一个新的方向。

0.5%Pd/TiO2 catalysts were prepared by the impregnation method using TiO2 as supports.Effects of calcination temperature of the catalyst precursors on the hydrogenation performance of p-carboxy benzaldehyde(4-CBA),the main impurity in crude terephthalic acid(CTA),were investigated.These catalysts were characterized by XRD,BET and XPS techniques.The results showed that palladium was highly dispersed on the TiO2 support.The BET surface area of catalysts changed slightly,however,the surface Pd/O atomic ratio,and the surface area of Pd increased firstly and then decreased with the increase of calcination temperature.The surface area of Pd and the conversion of 4-CBA were both reached their maximum values when the catalyst precursor was calcined at 400℃.The conversion of 4-CBA over Pd/TiO2 catalyst was over 99.2% at the reaction condition of reaction temperature of 280℃～290℃,H2 partial pressure of 0.6～1.5MPa,and reaction time of 0.5～2.0 h.The research points to a new direction for improving the hydropurification catalyst of crude terephthalic acid.