Boosting selective hydrogenation of α,β-unsaturated aldehydes through constructing independent Pt and Fe active sites on support

Abstract

The alloy catalysts usually exhibited excellent catalytic synergy owing to the electronic and ensemble effect. However, the process of alloying makes the displacement of the d-band center from the Fermi level, decreasing the adsorption strength of reactant molecules. Herein, we constructed the spatial separation catalyst in which the independent Pt and FeOx nanoparticles were uniformly distributed on SBA-15 support (denoted as Pt = Fe/SBA-15), which exhibits remarkable efficiency in the hydrogenation of α,β-unsaturated aldehydes, i.e. with a 4 fold higher than the corresponding alloy catalyst in reaction rate, and a 4 fold increase in selectivity for cinnamalcohol production compared to the single Pt catalyst. It is found that Pt primarily catalyzes the H2 dissociative adsorption into H*, while FeOx mainly catalyzes the reaction between H* and aldehydes, forming alcohols. Assuming that the rate-determining-step is the H-spillover from Pt to Fe, the two cascade reactions are interconnected. To confirm this mechanism, we employ a physical mixture catalyst of Pt/SBA-15 and FeOx/SBA-15, where its catalytic activity lies between Pt = Fe/SBA-15 and alloy materials. The catalysts’ structures are well characterized by STEM and EDS mapping analysis, and the mechanism is supported by experimental data and DFT calculations. The research we conducted offers a new perspective into the cooperative catalysis, achieved by coupling independent active centers in thermos-hydrogenation reactions.