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Abstract: The conversion of propanoic acid under high hydrogen pressure has been studied over zirconia-supported monometallic Ru and bimetallic Ru–Mo catalysts. The cleavage of C–C bond of propanoic acid to methane and ethane is improved and the formation of Cnation products (propanol and propane) is decreased with increasing the temperature. Upon addition of Mo, both the overall activity and the C–C bond cleavage selectivity decrease while the selectivity of Cnation increases. With increase of Mo contents, the C–C bond cleavage reaction is significantly inhibited, especially at high temperature. This is also confirmed by the DRIFTS of propanoic acid, showing that the propanoyl intermediate species on Ru–Mo bimetal catalysts is more difficult to dissociate to CO compared with Ru monometal catalyst. Based on H2-TPR, CO-FTIR and DRIFTS of propanoic acid characterizations, the reaction mechanisms and the resulting selectivity towards the possible reaction paths (C–C bond cleavage/Cnation) are discussed in terms of the formation of Ru–MoO x and the stability and variety of propanoyl intermediate species occurring on the Ru–Mo bimetal catalysts. It is suggested that the interaction of Ru and MoO x species and the formation of Ru–MoO x interface are the important factors for the decrease in the TOF of propanoic acid and the C–C bond cleavage selectivity. [Copyright &y& Elsevier]

The selective hydrogenolysis of 5-hydroxymethylfurfural (HMF) platform molecule to 2,5-dimethylfuran (DMF) has attracted increasing attention due to its broad range of applications. However, HMF, with multiple functional groups, produces various byproducts, hindering its use on an industrial scale. Herein, a bimetallic Pt-FeOx/AC catalyst with low Pt and FeOx loadings for selective HMF hydrogenolysis to DMF was prepared by incipient wetness impregnation. The structures and properties of different catalysts were characterized by XRD, XPS, TEM, ICP-OES and Py-FTIR techniques. The addition of FeOx enhanced Pt dispersion and the Lewis acidic site density of the catalysts, and was found to be able to inhibit C=C hydrogenation, thereby im-proving DMF yield. Moreover, the presence of Pt promoted the reduction of iron oxide, creating a strong interaction between Pt and FeOx. This synergistic effect originated from the activation of the C–O bond over FeOx species followed by hydrogenolysis over the adjacent Pt, and played a critical role in hydrogenolysis of HMF to DMF, achieving a yield of 91% under optimal reaction conditions. However, the leaching of Fe species caused a metal–acid imbalance, which led to an increase in ring hydrogenation products. [ABSTRACT FROM AUTHOR]

Abstract: Inexpensive non-sulfided Ni-based catalysts were evaluated for hydrodeoxygenation (HDO) using guaiacol as model compound. SiO2–ZrO2 (SZ), a complex oxide synthesized by precipitation method with different ratio of Si/Zr, was impregnated with Ni(NO3)2·6H2O and calcined at 500°C. Conversion rates and product distribution for guaiacol HDO at 200–340°C were determined. Guaiacol conversion reached the maximum at 300°C in the presence of Ni/SZ-3. When HDO reaction was carried out with real lignin-derived phenolic compounds under the optimal conditions determined for guaiacol, the total yield of hydrocarbons was 62.81%. These hydrocarbons were comprised of cyclohexane, alkyl-substituted cyclohexane and alkyl-substituted benzene. They have high octane number, would be the most desirable components for fungible liquid transportation fuel. [Copyright &y& Elsevier]

The orbital modulation and surface lattice reconstruction represent an effective strategy to regulate the interaction between catalyst interface sites and intermediates, thereby enhancing catalytic activity and selectivity. In this study, the crystal surface of Au-K/CeO 2 catalyst can undergo reversible transformation by tuning the coordination environment of Ce, which enables the activation of the C β -H bond and the oxidative cleavage of the C β-O and C α -C β bonds, leading to the cleavage of 2-phenoxy-1-phenylethanol. The t 2g orbitals of Au 5d hybridize with the 2p orbitals of lattice oxygen in CeO 2 via π-coordination, modulating the coordination environment of Ce 4 f and reconstructing the lattice oxygen in the CeO 2 framework, as well as increasing the oxygen vacancies. The interface sites formed by the synergy between Au clusters in the reconstructed Ce-O L1 -Au structure and doped K play dual roles. On the one hand, it activates the C β -H bond, facilitating the enolization of the pre-oxidized 2-phenoxy-1-phenylethanone. On the other hand, through single-electron transfer involving Ce 3+ 4f 1 and the adsorption by oxygen vacancies, it enhances the oxidative cleavage of the C β-O and C α -C β bonds. This study elucidates the complex mechanistic roles of the structure and properties of Au-K/CeO 2 catalyst in the selective catalytic oxidation of lignin β-O-4 bond., (© 2024 Wiley-VCH GmbH.)

Metal-oxide interaction was widely observed in supported metal catalysts, playing a significant role in tuning the catalytic performance. Here, we reported that the interaction of Ru and MnO x was able to facilitate the hydrodeoxygenation of levulinic acid (LA) to 2-butanol with a high turnover frequency (1.99 × 10 6 h -1 ), turnover number (4411), and yield (98.8%). Moreover, this catalyst was capable of removing the hydroxymethyl group of lactones and diol with high yields of products. The high activity of the Ru-MnO x catalyst was due to the strong Ru-MnO x interaction, which facilitated reduction of Ru oxide to Ru 0 and Mn oxide to Mn 2+ . The increased fractions of Ru 0 and Mn 2+ provided metal and Lewis acid sites, respectively, and therefore facilitated LA hydrodeoxygenation. A linear correlation between the hydrodeoxygenation activity of the Ru-MnO x catalyst and [Mn 2+ ]ln([Ru 0 ]) was observed.

Herein, WO x -decorated Ir/SiO 2 (W/Ir = 0.06) and HZSM-5 were coupled to selectively convert microcrystalline cellulose (MCC) into C 6 alkanes. A 92.8% yield of liquid alkanes including an 85.3% yield of C 6 alkanes was produced at 210 °C. Cellulose hydrolysis, glucose hydrogenation and sorbitol hydrodeoxygenation were integrated to produce alkanes via a sorbitol route. Ir-WO x /SiO 2 showed high performance for hydrogenation and hydrodeoxygenation reactions after hydrolysis catalyzed by HZSM-5. The intimate contact between WO x and Ir enhanced the synergistic interaction through the electron transfer from Ir to WO x . The interaction strengthened the reduction capability of Ir for hydrogenations, as well as improved the adsorption and activation of C-O bonds on reduced WO x for deoxygenations. The monotungstate WO x species provided moderate Lewis acids to cooperate with Ir to accelerate hydrodeoxygenations with alleviated retro-aldol condensation to yield more C 6 alkanes., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Novel catalytic material with high catalytic activity and hydrothermal stability plays a key role in the efficient conversion of levulinic acid (LA) to γ-valerolactone (GVL) in water. In this study, mixed oxides Al 2 O 3 -TiO 2 , Al 2 O 3 -MoO 3 and Al 2 O 3 -Co 3 O 4 were synthesized by co-precipitation using aqueous solution of NaOH as precipitant. Ru catalysts supported on mixed oxides were prepared by impregnation method and their catalytic performances were tested in the hydrogenation of LA to GVL on a fixed bed reactor. The physicochemical properties of the catalysts were characterized by XRD, H 2 -TPR, NH 3 -TPD, and BET techniques. The TiO 2 component significantly affected the acidity of the catalyst, and thus its catalytic activity for the GVL yield was affected. The desired product GVL with a yield of about 97% was obtained over the Ru/Al 2 O 3 -TiO 2 catalyst under mild conditions (WHSV = 1.8 h -1 , T = 80 °C). Moreover, the catalyst Ru/Al 2 O 3 -TiO 2 exhibited excellent thermal stability in the test period of time., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)