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BACKGROUND: Syngas to dimethyl oxalate (DMO) followed by hydrogenation to methyl glycolate (MG) is considered to be an environmentally friendly and economical route. However, the catalyst with super performance and low cost for this route is still challenging. In this work, a simple and low‐lost fabrication method was developed to prepare a Ru/activated carbon (AC) catalyst and was used for DMO hydrogenation to MG under mild reaction conditions. RESULTS: The Ru/AC catalyst showed the best performance in the low‐temperature hydrogenation of DMO to MG compared to Ru/SiO2 and Ru/Al2O3. A series of characterization results showed that the super catalytic properties of Ru/AC catalyst might be attributed to the higher dispersion of Ru on support and its smallest nanoparticles size, weak surface acidity and electron‐deficient state of Ru species. The key parameters such as Ru loading, temperature, weight hourly space velocity, and pressure, were comprehensively investigated. MG selectivity of 94.6% with DMO conversion of 97.2% were obtained over the 4.0 Ru/AC catalyst at 90 °C. The 4.0Ru/AC catalyst showed excellent stability and there was no obvious deactivation after 1032 h test. CONCLUSIONS: The Ru/AC catalyst is effective for the DMO hydrogenation to MG under mild conditions and has great promise for industrial applications because of its low cost, simple preparation, high efficiency, and long life. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-8 derived ZnO@NC can anchor Ru nanoparticles to create Ru-O-Zn interface. • Ru/ZnO@NC achieved complete conversion and 99.2% GVL yield in LA hydrogenation. • Ru/ZnO@NC achieved excellent reaction activity with a TOF of 6032 h−1 at 40 °C. • Reaction mechanism of LA hydrogenation to GVL has been revealed by DFT calculation. • Ru-O-Zn interface can remarkably decline activation energy of rate-determining step. Highly efficient synthesis of valuable γ-valerolactone (GVL) by levulinic acid (LA) hydrogenation is of interest for biomass refinery, but it suffers from great challenge to design highly active Ru-based catalyst at low temperature. ZIF-8 derived ZnO@NC nanocomposite can firmly anchor Ru nanoparticles to create strong Ru-ZnO interfacial structure, as revealed by characterization techniques and DFT calculations. By optimizing Ru content and ZnO particle size, Ru/ZnO@NC achieved excellent reaction activity with a turnover frequency (TOF) of 6032 h−1 at low temperature of 40 °C, which is never reported before. After etching the accessible ZnO, the TOF value was significantly declined to 125 h−1 on Ru/ZnO@NC-HF owing to the lack of effective Ru-ZnO interface. DFT calculation results demonstrate that the Ru-ZnO interfacial structure can facilitate the activation of intermediate CH 3 CHOCH 2 CH 2 COOH* and remarkably decline the activation energy barrier of rate-determining step (CH 3 CHOCH 2 CH 2 COOH + H = HPA) from 1.28 eV to 0.82 eV, thus leading to excellent activity of LA hydrogenation at low temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Few-layer graphene encapsulated hexagonal closed-packed Co particles were prepared. • The hcp-Co@G400 achieved outstanding performance in carboxylic acid hydrogenation. • The TOF values of hcp-Co@G were one magnitude higher than that of fcc-Co countparts. • DFT calculation elucidates reaction mechanism of carboxylic acid hydrogenation. • Acetic acid vertically adsorbs at hcp-Co (0 0 2) facet with low adsorption energy. Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH 2 CO* followed by consecutive hydrogenation to RCH 2 CH 2 OH through RCH 2 COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation. [ABSTRACT FROM AUTHOR]

• Rod, cube and octahedral CeO 2 exposed (1 1 0), (1 0 0) and (1 1 1) facets in Ru/CeO 2. • Ru/CeO 2 -rod with exposed (1 1 0) facet achieved 99.4% GVL yield in EL hydrogenation. • DFT calculation elucidates reaction mechanism of EL hydrogenation to GVL on Ru/CeO 2. • The concentration of oxygen vacancy is linearly proportional to GVL production rate. • Surface CeO 2 structure and concentration of oxygen vacancy determine facet effect. Three Ru/CeO 2 catalysts with different CeO 2 morphology (nanorod, nanocube and nano-octahedra) mainly exposed (1 1 0) + (1 0 0), (1 0 0) and (1 1 1) facets for hydrogenation of biomass-derived ethyl levulinate (EL) to valuable γ-valerolactone (GVL). Ru/CeO 2 -rod with exposed (1 1 0) crystal plane obtained the highest GVL yield (99.4%) and best productivity (13140 h−1). The surface facets of CeO 2 supports not only affect the chemical states of Ru species but also tune the concentration of oxygen vacancy in Ru-CeO 2 interface. The concentration of oxygen vacancy shows a linear relationship with GVL production rate. DFT calculations indicate that the lactonization of CH 3 CHOCH 2 CH 2 CO* to produce GVL is the rate-determining step in EL hydrogenation, and Ru 10 /CeO 2 (1 1 0) with more oxygen vacancy has low activation energy barrier, compared to Ru 10 /CeO 2 (1 0 0) and Ru 10 /CeO 2 (1 1 1). [ABSTRACT FROM AUTHOR]

Highlights: [•] Addition of SiO2 to PtW/Zr greatly enhanced activity and 1,3-propanediol selectivity. [•] 54.3% conversion and 52.0% 1,3-propanediol selectivity were achieved over 5PtW/ZrSi. [•] A model scheme of WO x transformation due to SiO2 doping has been built. [•] Pt and polytungstate have been identified as the dominant active phases. [•] Glycerol hydrogenolysis conforms to the dehydration–hydrogenation mechanism. [Copyright &y& Elsevier]

• TiO 2 nanosheets supported Ru nanoparticles form strong interfacial Ru O Ti structure. • Ru/TiO 2 reached the highest TOF of 19,045 h−1for levulinic acid (LA) hydrogenation. • 99.1% yield of γ-valerolactone (GVL) was achieved over Ru/TiO 2. • DFT calculations clearly elucidate reaction mechanism of LA hydrogenation to GVL. • Ru/TiO 2 interface tunes rate-determining step from LA hydrogenation to cyclization. Highly efficient synthesis of valuable γ-valerolactone (GVL) by levulinic acid (LA) hydrogenation is still a challenge for Ru-based catalysts under mild condition. In this work, we have reported that ultrathin TiO 2 nanosheets supported Ru nanoparticles showed extraordinarily high catalytic activity, GVL yield (99.1%) and reusability owing to the formation of Ru O Ti interfacial structure. The turnover frequency (TOF) reached as high as 19,045 h−1 at 100 °C, much higher than those of Ru/SiO 2 , Ru/GO, Ru/MoS 2 , and commercial Ru/C. DFT calculation elucidates that the dominant reaction pathway of LA hydrogenation to GVL is preferentially hydrogenated to CH 3 CHOCH 2 CH 2 COOH*, followed by cyclization to CH 3 (OH)C 4 OH 4 OH* (GVL − OH) and final dehydroxylation, irrespective of surface structure. Compared to Ru (0 0 2) facet, Ru/TiO 2 interfacial structure changes the rate-determining step from initial hydrogenation to cyclization, which greatly declines the activation barrier from 0.81 eV to 0.48 eV. [ABSTRACT FROM AUTHOR]