Rational design of palladium single-atoms and clusters supported on silicoaluminophosphate-31 by a photochemical route for chemoselective hydrodeoxygenation of vanillin

摘要

Chemoselective hydrodeoxygenation of vanillin is of great importance in converting biomass into high value-added chemicals.Herein,we describe a facile photochemical route to access palladium single atoms and clusters supported on silicoaluminophosphate-31(SAPO-31)as a highly active,chemoselective,and reusable catalyst for hydrodeoxygenation of vanillin.Characterizations by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy,extended X-ray absorption fine structure measurement,and CO-absorbed diffuse reflectance infrared Fourier transform spectroscopy reveal the atomically dispersed palladium single atoms and clusters are loosely bonded and randomly dispersed,without forming strong palladium-palladium metallic bonding,over the SAPO-31 support.This catalyst,with a full metal availability to the reactants,exhibits exceptional catalytic activity(TOF:3,000 h^(−1),Yield:>99%)in the hydrodeoxygenation of vanillin toward 2-methoxy-4-methylphenol(MMP)under mild conditions(1 atm,80°C,30 min),along with excellent stability,scalability(up to 100-fold),and wide substrate scope.The superior catalytic performance can be attributed to the synergistic effect of the positively charged palladium single atoms and fully exposed clusters,as well as the strong metal-support interactions.This work may offer a new avenue for the design and synthesis of fully exposed metal catalysts with targeted functionalities.