Selective Furfural Hydrogenation to Furfuryl Alcohol Using Cu-Based Catalysts Supported on Clay Minerals

Copper supported on clay minerals (bentonite and sepiolite) catalysts, with copper loading between 15 and 60 wt%, have been synthesized by precipitation-deposition, calcination and subsequent reduction. The catalysts were characterized by X-ray diffraction, H₂ temperature programmed reduction (H₂-TPR), N₂ adsorption–desorption at −196 °C and X-ray photoelectron spectroscopy, being detected spherical metal Cu-particles with variable size, mainly located on the surface of clays. The evaluation of their catalytic performance in the furfural (FUR) hydrogenation in gas phase has demonstrated that the use of bentonite as support allows attaining conversion values of 83% for 45Cu-Bent, whereas only a 52% is reached by the 45Cu-Sep catalyst. All catalysts were highly selective towards furfuryl alcohol (FOL), reaching yields of 72% for 45Cu-Bent and 45% for 45Cu-Sep after 5 h of time-on-stream (TOS) at 210 °C, by using a H₂:FUR molar ratio of 11.5 and a WHSV of 1.5 h⁻¹. However, all catalysts suffer a progressive deactivation with TOS, by deposition of reactants and product (FOL and FUR), as well as the oxidation of the active phase.