Hydrogen Spillover Assisted By Organic Oxygenate Molecules Over Inert Solid Supports

Hydrogen spillover plays an important role in hydrogenation/hydrogenolysis on solid catalysts,while effective hydrogen spillover over non-reducible metal oxide support surfaces?e.g.aluminium oxide and silicon dioxide?is still a huge challenge.This was primarily owing to the lack of well-defined model catalysts to reveal the mechanism and catalytic function of hydrogen spillover.In this work,hierarchically structured SiO₂ supports with both micropores and macropores were prepared,and two types of metals with distinct abilities on hydrogenation and HZ dissociation?i.e.Pt and Fe?were selectively deposited into the micropores and macropores,respectively.The prepared Pt@-Fe@SiO₂ catalysts were used for methanol steam reforming and guaiacol hydrodeoxygenation cascade reaction to elucidate the existence and catalytic functions of hydrogen spillover for non-reducible supports.Influences of organic oxygenate molecules on hydrogen spillover were investigated in detail with cofeeding C₁-C₃ oxygenate molecules?alcohol,aldehydes,ketones,lipids and esters?in guaiacol hydrodeoxygenation reaction.Combined experimental and theoretical studies show that the presence of oxygenate molecules,including those in situ produced,which contain carbonyl group can increase the rate of hydrogen spillover.Such oxygenate molecules can capture and stabilize hydrogen radicals formed during catalysis,promote their spillover over the surface of the non-reducible carrier,and significantly improve the activity and selectivity of the catalyst in the hydrodeoxygenation reaction.Applying this strategy,the yield of complete deoxygenation product?BTX?of guaiacol on Pt@-Fe@SiO₂ catalysts was increased by nearly 40%.This study provides a deeper understanding on hydrogen spillover and also theoretical basis for the use of this effect in catalytic hydrogenation/hydrogenolysis reactions.