Layered Double Hydroxides And Mixed Metal Oxides Supported Pt Catalyst For The Hydrogenation Of α, β-unsaturated Aldehydes

Selective hydrogenation of α, β-unsaturated aldehydes at the carbonyl(C=O) and olefinic(C=C) group is highly desirable in the fine chemical industry, because most products of them are important intermediates for the syntheses of many chemicals. Cinnamaldehyde(CAL) and citral is particularly important representatives of α, β-unsaturated aldehyde, their research of the selective hydrogenation are of great significance in scientific and industrial applications. It is well known there is an interaction between the support and active metal sites that can modify the catalytic properties of the metal catalyst. It is a feasible way to search for appropriate materials used as catalyst supports for preparing highly active and selective catalysts. Layered double hydroxides(LDH) and derived mixed metal oxides(MMO) are widely employed as promising heterogenerous catalysts and supports, due to their high specific surface area, thermal stability and tunable surface acidic/basic properties. Especially Co, Ni LDH and other transition metal-based catalytic materials are be preferred.In this paper, catalyst are fabricated with LDH and derived MMO as catalyst and Pt metal as active component and employed to research the promotion of the support on Pt metal for catalytic hydrogenation of the cinnamaldehyde as a representative of α, β-unsaturated aldehydes. Details are as follows: 1. Platinum nanocrystals supported on CoAl-MMO nanosheets derived from LDH for selective hydrogenation of cinnamaldehydeDifferent Pt nanoparticles supported on sheet-like MMO derived from LDH are prepared using using a reduction-deposition method with NaBH4 as reductant and uesd to research the catalytic performance on the selective hydrogenation of CAL. A series of characterization such as FT-IR,XRD,BET,SEM,TEM,XPS and TGA, are employed to investigate the structure and composition of the support and catalyst. The effect of support on the catalyyic reaction performance is invertegated and CoAl-MMO supported catalyst achieves an increase in both conversion and selectivity to cinnamylalcohol(COL) due to the forming of PtCo alloy on the surface of catalyst during the preparation. The effects of recation time, reaction temperature, Co/Al ratio and calcination temperature on the catalytic performance are researched in this work. and the possible reaction path is proposed. 2. Highly selective hydrogenation of α, β-unsaturated aldehydes by Pt catalysts supported on Fe-based LDH and MMO.In this section, Fe-based LDH derived MMO supported Pt catalyst are prepared using the sanme method and uesd as catalyst for the selective hydrogenation of CAL. Compared with an Al-based support, Fe-based support exhibits an improvement in both activity and selectivity than Al-based support. Among them, Pt/ZnFe-LDH shows the best activity and COL selectivity in the CAL hydrogenation reaction. The catalysts performed well in CAL hydrogenation and fully hydrogenation catalyst are to used in the hydrogenation reaction of citral, the results indicate that citral was mostly transformed into citronellol over the Pt/NiFe-LDH catalyst.