Search

[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: [•] Ag1PW presented the best activity for glycerol esterification with acetic acid. [•] The TON of Ag1PW was up to 2189.9h−1. [•] Ag-exchanged HPW exhibited outstanding water-tolerant property. [•] A mechanistic scheme for glycerol esterification with acetic acid was proposed. [•] Ag1PW catalyst did not suffer from deactivation in five consecutive reaction tests. [ABSTRACT FROM AUTHOR]

Highlights: [•] B2O3 can promote the dispersion of copper species and stabilize copper particles. [•] Addition of B2O3 to Cu/SiO2 greatly enhanced activity and stability. [•] 100% Conversion and 98.0% 1,2-propanediol selectivity were achieved over 3CuB/SiO2. [•] 1,2-Propanediol yield was proportional to Cu specific surface area. [•] Glycerol hydrogenolysis is a structure-sensitive reaction. [ABSTRACT FROM AUTHOR]