Metal-support Interactions Of Ir/H-MoO_x In Furfural Hydrogenation

As one of biomass-drived platform molecules,furfual?FAL?has received much attention due to the versatile production of various down stream chemicals free from petroleun-derived sources.In furan ring,the lone pair electrons are conjugated to an oxygen atom to form a large?bond,and the oxygen atom in the carbonyl of the straight chain is more negative than the carbon atom.FAL hydrogenation delivers rich chemistry in catalyst design far beyond the hydrogenation of simple?,?-unsaturated aldehydes.Because of the complex reaction network,selective C=O hydrogenation usually requires mild reaction conditions with low catalytic turnover to avoid side reactions,such as furan ring hydrogenation,C-O hydrogenolysis,rearrangement,C-C dissociation,and polymerization,which cause unsatisfactory hydrogenation efficiency.In this dissertation,we introduced in-situ H₂ spillover to vary H doping into MoO₃,affording strong metal-supports interactions to achieve efficient FAL hydrogenation on Ir/H-MoO_x catalysts.Firstly,a controlled H-doping into Mo O₃ nanorods via H₂ spillover was introduced to optimize the metal-support interactions in Ir/H-MoO_x,resulting in highly active and selective furfural hydrogention to furfuryl alcohol.The temperature?T?for catalyst reduction is varied from 200 to 600 ^oC to realize a simple control on H-doping.The controlled H-doping into H-MoO_x remarkably alters the contents of low-valence Mo species(Mo⁵⁺and Mo⁴⁺),and thus charge redistribution on loading Ir NPs due to electronic metal-support interactions.Accordingly,the Ir/H-MoO_x with varied Ir⁰/Ir^?+on surface exhibits the different adsorption and activation of molecular H₂,which will contribute to the hydrogenation activity.As expected,the optimal Ir/H-MoO_x-400 with controlled H-doping delivers high activity(TOF:4.62 min^-1)and selectivity?>99%?in hydrogenating FAL to FOL at a mild condition(T=30 ^oC,P_H2=2 MPa),performing among the best of current catalysts.Secondly,the mesoporous Ir/meso H-MoO_x was one-pot prepared,employing in-situ H-doping to address the rigidity of MoO₃ crystals and there by remaining the rich nanoporosity.As compared with the counter parts synthesized via typical calcination in air flow,the Ir/meso H-MoO_x well retained the high surface area,identifying the effect of H₂ spillover during catalyst preparation.Ir/meso H-MoO_x catalyst exhibits high activity and selectivity in catalytic hydrogenation of furfural.In summary,this work elucidates the easy modulation on the surface structures and electronic configuration of MoO_x supports,resulting in the modulated metal-support interactions to boost FAL hydrogenation to value-added FOL.It's envisioned that future research with better control over the nanostructures of metal oxide supports and relative H doping would further boost their catalytic application.