化学还原法制备胶体Pd/γ-Al_2O_3催化剂及其催化性能

Preparation of Colloidal Pd/γ-Al_2O_3 Catalyst by Chemical Reduction and Its Catalytic Properties for Furfural Decarbonylation

采用化学还原法制备了高分散的胶体Pd/γ-Al2O3催化剂,考察了保护剂、还原剂和制备方法等对其催化性能的影响。实验结果表明,最佳保护剂为聚乙烯吡咯烷酮(PVP),PVP的最佳用量为n(N)∶n(Pd)=40∶1;最佳还原剂为乙醇/NaOH,NaOH的最佳用量为n(NaOH)∶n(Pd)=3∶1。X射线光电子能谱和X射线衍射表征结果显示,催化剂中的Pd以零价态存在;同时根据Debye-Scherrer公式估算,Pd在催化剂中以胶体状态存在。将胶体Pd/γ-Al2O3催化剂用于糠醛液相脱羰反应,实验结果表明,该催化剂比常规方法制备的Pd/γ-Al2O3催化剂具有更高的活性,糠醛的转化率为97.6%,呋喃的选择性为95.1%。

Highly-dispersed colloidal Pd/γ-Al2O3 catalyst for decarbonylation of furfural was prepared by chemical reduction method. Effects of protecting agent, reducing agent, and different preparation methods on catalyst activities were investigated. Poly （N-vinyl-2-pyrrolidone） （PVP） was the best protecting agent with appropriate PVP dosage of n （N） ： n （Pd） 40 ： 1. Ethanol/NaOH was the best reducing agent with appropriate NaOH dosage of n （NaOH） ： n （Pd） 3 ： 1. XPS and XRD studies showed that Pd was reduced to elementary valence state in the catalysts. Crystalline form of palladium particles was of face-centered cubic system. By estimation with Debye-Scherrer formula, colloidal particles of Pd were highly dispersed in catalyst. The catalyst prepared by this method is more active than those prepared by conventional methods. Conversion of furfural is 97.6% and selectivity to furan is 95.1% in decarbonylation of furfural on the catalyst.