The vapor-phase selective hydrogenation of crotonaldehyde, a classical α, β-unsaturated aldehyde, to crotyl alcohol over heterogeneous catalysts is an appealing green process of great importance from both industrial and academic points of view. This paper reviews the latest progresses of the heterogeneous catalysts for selective hydrogenation of crotonaldehyde to crotyl alcohol in the past ten years. Noble metal catalysts such as platinum, silver, gold and iridium and non-noble metal catalysts such as cobalt and copper employed for selective hydrogenation of crotonaldehyde are summarized. The parameters influencing the catalytic behaviors of the catalyst system such as active sites, metal particle size, support type, promoters are discussed. Also, catalyst deactivation and reaction mechanism are investigated. Finally, the current problems of the vapor-phase selective hydrogenation of crotonaldehyde are summarized and development trend of catalyst systems for this reaction is proposed. It is pointed out that the vapor-phase selective hydrogenation of crotonaldehyde over non-noble metal catalysts will be a main research direction because its much lower cost compared to the noble metal catalysts. As the catalyst deactivation is the main obstacle for this reaction, the research should be focused on the understanding of the reaction and deactivation mechanism. Contents
1 Introduction
2 Noble metal catalysts
2.1 Platinum catalysts
2.2 Gold catalysts
2.3 Other noble metal catalysts
3 Non-noble metal catalysts
3.1 Cobalt catalysts
3.2 Copper catalysts
4 Reaction mechanisms
5 Deactivation of catalysts
6 Conclusions and outlook