Catalytic Performance Of Pt-based Catalysts For Vapor Phase Selective Hydrogenation Of Crotonaldehyde To Crotyl Alcohol

Selective hydrogenation ofα,β-unsaturated aldehyde such as crotonaldehyde is an important and challenging work in fields of heterogeneous catalysis.In this work,Pt catalysts supported on two types of reducible oxides were synthesized and the effects of preparation method and reaction conditions were investigated for model reaction of vapor phase hydrogenation of crotonaldehyde to crotyl alcohol.In our paper,Pt/Ce_xSm_1-xO_2-δ and Pt/ZrO₂ catalysts were synthesized and characterized by XRD,N₂-sorption,H₂-TPR,TG-DTA,TEM techniques.The effect of preparation method,Pt content in the catalyst,dispersion of Pt and surface property of the support on the catalytic performance was systematically studied.The main results were summarized as follows:A Pt/Ce_0.8Sm_0.2O_2-δ catalyst prepared by an impregnation method showed good performance for hydrogenation of crotonaldehyde.The crotyl alcohol selectivity was 76.5 %and conversion of crotonaldehyde was 16.8%at a reaction temperature of 80℃.The composition of support and preparation method showed significant effect on the catalytic perforrnance.It was found that the Ce_0.8Sm_0.2O_2-δ oxide was the most suitable support which gave the highest activity and selectivity,meanwhile,the impregnation method resulted in the catalyst with better performance.By optimizing the preparation conditions, it was found that the most active catalyst contained 3%of Pt loading,with H₂PtCl₆ as the precursor.A higher activity was obtained when the catalyst was directly reduced,compared to the catalyst that underwent a calcination-reduction process.The highest selectivity and yield to crotyl alcohol was achieved under a reduction temperature of 500-600℃and a reduction time of 1 h.ZrO₂ supports were prepared with different methods and Pt/ZrO₂ catalysts were tested for the selective hydrogenation of crotonaldehyde.The results show that catalyst Pt/ZrO₂ whose support was prepared by template method behaves better than that preapared by calcination and deposition methods.The study of the influence of reduction temperature shows that high temperature reduction pretreatment favors selective hydrogenation of C=O band.