RuO2–Ru/Hβ zeolite catalyst for high-yield direct conversion of xylose to tetrahydrofurfuryl alcohol

Abstract Tetrahydrofurfuryl alcohol (THFOL), a valuable biomass-derived chemical, is an important precursor for producing linear diols and biodegradable solvents. Herein, we present the one-pot cascade conversion of xylose to THFOL over an Hβ zeolite-supported RuO2–Ru (RuO2–Ru/Hβ) catalyst. To elucidate the structure–property correlation of the RuO2–Ru/Hβ catalyst and achieve a high THFOL yield via sequential isomerization, dehydration, and hydrogenation, several synthesis methods, namely incipient wetness impregnation, reductive deposition, activated reductive deposition, and post-oxidative activated reductive deposition (ARD-O) were used. The best catalytic performance was obtained over the RuO2–Ru/Hβ-ARD-O catalyst. An almost complete conversion of xylose and a high THFOL yield of 61.8% were achieved after 1 h at 180 °C under an initial H2 pressure of 3.0 MPa in tetrahydrofuran. In-depth analyses of the RuO2–Ru/Hβ-ARD-O catalyst furfural (FFA)- and CO-probed diffuse reflectance infrared Fourier transform spectra indicated the formation of RuO2 at the corner and edge sites of Ru nanoparticles. The direct conversion of FFA to THFOL at interfacial RuO2–Ru sites without furfuryl alcohol (FOL) readsorption hindered the contact of FOL with the acidic support, which suppressed the formation of humin and other byproducts and led to a high THFOL yield.