Catalytic Aqueous Phase Conversion of Cellulose to Ethanol over Multifunctional Pt/WOX/SiO2 Catalysts

Abstract

Cellulosic ethanol is a pivotal biofuel, and its chemocatalytic production from lignocellulosic biomass is crucial for addressing global energy challenges. In this study, a series of Pt-loaded catalysts were developed by sequentially loading varying weight percentages (wt %) of Pt and W onto SiO₂ carriers using the impregnation method. The catalysts were comprehensively characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy to analyze the metal dispersion and active oxidation states on the SiO₂ support. Under hydrothermal conditions (240 °C and 4 MPa H₂), cellulose was directly converted to ethanol in the aqueous phase, achieving an ethanol yield of 37.5 C%. The catalysts demonstrated excellent stability, maintaining high activity over at least five consecutive reaction cycles. Notably, the WO₃ component played a key role in facilitating C–C bond cleavage and hydrolyzing cellulose into glucose and ethanal intermediates. These intermediates were swiftly transferred to the Pt active sites, further promoting the formation of ethylene glycol. Among the catalysts, 3%Pt-15%WO₃/SiO₂ exhibited optimal performance due to its well-balanced ratios of Pt⁰ and Pt²⁺, which enabled selective C–O bond activation and significantly enhanced ethanol production.