Pd Nanoparticles Supported on Activated Carbon and Their Application in the Oxidative Condensation Reaction of Furfural: Effect of Base and Oxidizing Agent on Catalytic Behavior and Deactivation

Catalysts with different Pd loading (0.5–2 wt.%) supported on an activated carbon were synthesized and tested in the oxidative condensation reaction of furfural using absolute ethanol, sodium carbonate as base, and hydrogen peroxide as oxidizing agent. The characterization of the catalysts reveals a high dispersion of the Pd-species in the form of Pd⁰. The catalytic results reported that furan-2-acrolein is the main product with a maximum yield of 52% after 6 h of reaction at 130 °C for the catalyst with the highest Pd content. To obtain this product, it is necessary to have the presence of an oxidant as hydrogen peroxide, to promote the oxidation of ethanol to acetaldehyde, and then a base, which promotes its condensation reaction with the furfural molecule. The progressive decay of the furan-2-acrolein yield and the conversion values after several cycles suggests the formation of carbonaceous deposits on the surface of the catalysts, which block the metallic sites involved in the reactions, as was observed by X-ray photoelectron spectroscopy and CO-chemisorption studies.