Supported Bifunctional Molybdenum Oxide-Palladium Catalysts for Selective Hydrodeoxygenation of Biomass-Derived Polyols and 1,4-Anhydroerythritol

Abstract

Selective removal of oxygen from biomass-derived polyols is critical toward bridging the gap between biomass feedstocks and the production of commodity chemicals. In this work, we show that earth-abundant molybdenum oxide based heterogeneous catalysts are active, selective, and stable for the cleavage of vicinal C–O bonds in biomass-derived polyols. Catalyst characterization (Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)) shows that partially reduced MoO x centers are responsible for C–O bond cleavage and are generated in situ by hydrogen dissociated atoms over palladium (Pd) nanoparticles. We find that the support, TiO2, facilitates communication between the hydrogen dissociating metal and dispersed MoO x sites through hydrogen spillover. Reactivity studies using a biomass-derived model substrate (1,4-anhydroerythritol) show the effective removal of vicinal hydroxyls over MoO x -Pd/TiO2 producing tetrahydrofuran with >98% selectivity at 29% conversion. Catalyst stability is demonstrated upon cycling. These studies are critical toward the development of low-cost heterogeneous catalysts for sustainable hydrodeoxygenation of biobased polyols to platform chemicals.

Hydrodeoxygenation of potential platform chemicals derived from biomass to fuels and chemicals

“…144,145 ReO x -Ag/CeO 2 catalyzed the DODH of 1,4-AHERY with H 2 to produce 2,5-dihydrofuran in high yield (∼88%) with 5% yield of 2,3-dihydrofuran. 147 It was also reported recently that MoO x -Au/ TiO 2 and MoO x -Pd/TiO 2 emerged as good catalysts for the DODH of 1,4-AHERY with H 2 to form 2,5-dihydrofuran (77% yield) 148 and tetrahydrofuran, 148,244 respectively. Although high selectivity was reported, the activity of the MoO x -M/TiO 2 -catalyzed system was significantly lower than that of the ReO x -M/ CeO 2 -catalyzed systems (higher reaction temperature or lower initial reaction rate), because of the intrinsic lower activity of Mo species in DODH than that of Re.…”

Utilization of Ni as a Non-Noble-Metal Co-catalyst for Ceria-Supported Rhenium Oxide in Combination of Deoxydehydration and Hydrogenation of Vicinal Diols

“…In spite of the high activity and large turnover number (TON) of ReO x –M/CeO 2 (M = Pd, Au, and Ag) catalysts, the catalyst cost is still a severe problem. Substitution of Re with Mo is one method to decrease the cost of the DODH catalyst; − however, the DODH performance of reported Mo catalysts is inferior to that of Re catalysts: a higher reaction temperature, a lower maximum yield, and a narrower substrate scope (Table S1). Utilization of inexpensive base metals for M is another method.…”

Bio-based 1,4-butanediol and tetrahydrofuran synthesis: perspective

“…Among them, the higher activity of Au catalyst prepared by deposition-precipitation method than the impregnation method was due to the better dispersion of Au by the deposition-precipitation method. In addition, Albarracin-Suazo et al 106 investigated the hydrodeoxygenation of 1,4-AHERY to THF over a bifunctional catalyst consisting of metal centers (Pd, Rh, Pt) to dissociatively activate hydrogen and redox metal oxide centers (MoO x , ReO x , WO x ). The highest THF production rate of 0.22 mol mol co −1 min −1 was produced and the selectivity of THF was >98% at 140 °C and 5.2 MPa of H 2 with 2 wt% MoO x -0.3 wt% Pd/TiO 2 as the catalyst, but the 1,4 AHERY conversion was only 29% after 8 h. Multiple characterization proves that partially reduced MoO x centers are responsible for C-O bond cleavage, which are generated in situ by dissociated hydrogen atoms over Pd nanoparticles; while the support, TiO 2 , facilitates communication between the hydrogen dissociating metal and dispersed MoO x sites through hydrogen spill-over.…”