ZIF-8 decorated Au/Al2O3 hybrid material for highly selective hydrogenation of cinnamaldehyde

Abstract

Recycling of supported Au catalysts is challenging because of aggregation or loss of Au. Here, we report a strategy for introducing ZIF-8 into traditional Au/Al2O3 surface. The introduction of ZIF-8 can not only provide higher selectivity for the reaction products, but also prevent the loss or aggregation of the Au catalyst. From a series of characterizations, it can be seen that the ZIF-8 decorated Au/Al2O3 hybrid material Au@ZA (Z refers to ZIF-8, A refers to Al2O3) was successfully prepared. Au nanoparticles have better dispersion on the composite carrier, and the particle size is smaller. In the hydrogenation reaction of cinnamaldehyde (CAL), the Au@ZA composite catalyst has both the high chemical stability and the high selectivity of cinnamyl alcohol (COL) due to the micropore size effect of ZIF-8. The Au@ZA catalyst has ∼ 85 % COL selectivity when the CAL conversion is close to 100 %. And after 8 times of repeated use, the conversion of CAL and the selectivity of COL did not decrease significantly. It should be noted that just when a small amount of ZIF-8 is present, the synergistic catalytic effect mentioned above can be produced.