•Two kinds of Co3O4 with different morphologies (nanorods and naoplates) were used to prepared Pt/Co3O4 catalysts.•The catalyst activity was studied in higher alcohol synthesis from CO2 hydrogenation in fixed-bed reactor.•The highest space time yield of higher alcohol (0.69 mmol gcat−1 h−1) was achieved at 200 °C and 2 MPa for Pt/Co3O4-p catalyst.Two kinds of Co3O4 with different morphologies (nanorods and naoplates) were used to support Pt nanoparticles to prepared Pt/Co3O4 catalysts. The properties of the nano-structured Co3O4 and Pt/Co3O4 were characterized by XRD, SEM, TEM, H2-TPR and XPS techniques. The catalyst activity was studied in higher alcohol synthesis from CO2 hydrogenation in fixed-bed reactor operated at 2 MPa and 190–230 °C. The catalyst gave a stable and relative higher CO2 conversion and alcohol selectivity during 50 h under mild reaction condition. The morphology of Co3O4 affected the catalyst’s CO2 conversion and production selectivity. The active surface of Pt/Co3O4-p catalyst was high dispersed Pt and Co nanoparticles anchored on Co3O4 support with some oxygen vacancies, evidenced by XRD results. The highest space time yield of higher alcohol (0.56 mmol gcat−1 h−1) was achieved at 200 °C and 2 MPa for Pt/Co3O4-p catalyst.Two kinds of Co3O4 with different morphologies (nanorods and naoplates) were used to support Pt nanoparticles to prepared Pt/Co3O4 catalysts. The catalyst activity was studied in higher alcohol synthesis from CO2 hydrogenation in fixed-bed reactor operated at 2 MPa and 190–230 °C. The morphology of Co3O4 affected the catalyst’s CO2 conversion and production selectivity. The active surface of Pt/Co3O4-p catalyst was high dispersed Pt and Co nanoparticles anchored on Co3O4 support with some oxygen vacancies. The synergic effect of Pt, Co nanoparticles and oxygen vacancies of Co3O4-x improved the adsorption of H2 and CO2, gave the highest space time yield of higher alcohol (0.69 mmol gcat−1 h−1) at 200 °C and 2 MPa.Download high-res image (93KB)Download full-size image

•Fe3O4@C-Pd showed high activity towards the transfer hydrogenation of nitro compounds.•Full nitrobenzene conversion and high selectivity (>99%) of aniline were produced.•The active energy was calculated to be 20.93 kJ K− mol.•The catalyst was very stable without the loss of its catalytic activity.Catalytic reduction of nitro compounds to the amines is of high importance in modern synthetic chemistry. In this study, an efficient method was developed for the transfer hydrogenation of nitro compounds over a magnetic Pd catalyst by the use of NaBH4 as the hydrogen donor. Full nitrobenzene conversion and high selectivity (>99%) of aniline were produced after 1 h at 60 °C in ethanol. The reductions are successfully carried out in presence of a wide variety of other reducible functional groups in the molecule, except halogen and vinyl substitute nitrobenzene. Kinetic studies indicated the active energy for the transfer hydrogenation of nitrobenzene was 20.93 KJ mol−1. The transfer hydrogenation of nitrobenzene was confirmed to proceed via azobenzene as the intermediate. More importantly, the catalyst was very stable without the loss of its catalytic activity.

In this study, Pd nanoparticles were immobilized on the core–shell structure C@Fe3O4 (carbon is the shell and Fe3O4 is the core) magnetic microspheres via in situ adsorption and reduction to generate the magnetically separable Pd/C@Fe3O4 catalyst. In this method, no excess reductant and capping reagents were required, and it is a clean, simple and green process for the preparation of the magnetic Pd nanocatalyst. The Pd/C@Fe3O4 catalyst showed high activity and extraordinary stability during the oxidation of biomass derived 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) under mild conditions. A study aimed at optimizing the reaction conditions such as reaction temperature, reaction solvent and base amount has been performed. Under optimal reaction conditions, HMF conversion of 98.4% and FDCA yield of 86.7% were achieved after 6 h at 80 °C. After reaction, the Pd/C@Fe3O4 catalyst could be easily recovered by an external magnet and reused without the loss of its activity.

In this study, magnetically separable, graphene oxide-supported palladium nanoparticles (C–Fe3O4–Pd) were successfully prepared via a one-step solvothermal route. The C–Fe3O4–Pd catalyst showed excellent catalytic performance in the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA). The base concentration and reaction temperature significantly affected both HMF conversion and FDCA selectivity. High HMF conversion (98.2%) and FDCA yield (91.8%) were obtained after 4 h at 80 °C with a K2CO3/HMF molar ratio of 0.5. The C–Fe3O4–Pd catalyst was easily collected by an external magnet and reused without significant loss of its catalytic activity. The developed method is a green and sustainable process for the production of valuable FDCA from renewable, bio-based HMF in terms of the use of water as solvent, the use of stoichiometric amount of base, high catalytic activity under atmospheric oxygen pressure, and facile recyclability of the catalyst.

•The iongel catalyst showed high catalytic activity for low temperature WGS reaction.•Ru nanoparticles with particle size of 2.4 nm presented the best catalytic activity.•The iongel catalyst gave the highest CO conversion of 37.8% at 140 °C.•The iongel catalyst also showed a high stability.In this study, two different kinds of iongel catalysts were prepared by the dispersion of Ru nanoparticles in 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) with a particle size of 2.4 nm in tetraethoxy orthosilicate (TEOS), followed by the hydrolysis of TEOS under acidic or basic conditions. The iongel catalyst prepared under acidic conditions had larger surface area, pore volume and higher stability to confine the active component in the silica matrix than that prepared under basic conditions. Thus, the iongel catalyst prepared under acidic conditions showed much higher catalytic activity. The highest CO conversion of 37.8% was achieved at 140 °C over the iongel catalyst prepared under acidic conditions, significantly higher than the 10% achieved on the iongel catalyst prepared under basic conditions. More importantly, it also showed high stability. Besides the superior texture properties of the iongel catalyst prepared under acidic conditions, the stability of Ru nanoparticles also contributed to its high catalytic activity and stability over the iongel catalyst prepared under acidic conditions.The iongel catalyst prepared by the confinement of Ru nanoparticles in ionic liquids (IL) in silica matrix under acidic conditions showed high catalytic activity for low temperature water-gas shift reaction.

The present study reported the results on the water–gas shift (WGS) reaction over a series of Ru/C catalysts. It was found that the reduction method showed a remarkable effect on the catalytic activity of Ru/C catalysts over WGS reaction, which increased in an order of the reduction by NaBH4, ethylene glycol, H2. It has been shown that alkali additives with K2CO3 significantly improved the activity of the Ru/C catalysts. XPS results indicated that Ru species were further oxidized by the addition of K2CO3, which indicated an electron transfer from the alkali metal to the substrate, resulting in stronger bonding of the adsorbed gas. FTIR results showed that the absorption peak intensity of H2O and hydroxyl group increased with the increase of K2CO3 content, due to the strong hygroscopic ability of K2CO3. Through the addition of K2CO3 to the Ru/C catalyst, much more water was adsorbed around the catalytic active sites, reducing the strong adsorption of CO on the active sites. Thus the addition of K2CO3 balanced the concentration of water and CO on the active sites, which was considered to be the key step for low temperature WGS reaction over Ru supported on irreducible activated carbon.

The paper deals with oxidation of the biomass-derived model molecule 5-(hydroxymethyl)furfural (HMF) catalyzed by the trimetallic mixed oxide RuCo(OH)2CeO2. The catalyst RuCo(OH)2CeO2 was prepared through alkali hydrolysis of RuCl3, Co(NO3)2, and Ce(NO3)2 and characterized by X-ray diffraction and transmission electron microscopy techniques. RuCo(OH)2CeO2 showed high catalytic activity for aerobic oxidation of HMF under mild conditions (in the case of atmospheric oxygen pressure). Various reaction parameters such as the reaction temperature, catalyst amount, solvent, and oxidant were explored. Results demonstrated that the oxidant and solvent showed a remarkable effect on the aerobic oxidation of HMF to 2,5-diformylfuran (DFF). Under optimal conditions, DFF was obtained in a high yield of 82.6% with HMF conversion of 96.5% after 12 h at 120 °C. More importantly, the catalyst could be reused several times without significant loss of its catalytic activity.

In this study, a series of iongel catalysts were prepared and studied for the low temperature water–gas shift (WGS) reaction. Compared to the supported ionic liquid (IL) phase catalysts, Ru-iongel catalysts showed better WGS activity and stability. This was mainly because of the strong interaction between the IL and the silica support by the hydrogen bonds in the iongel catalysts. The IL loading and structure both had a remarkable effect on the catalyst's texture, and thus, affected the catalytic activity. It was found that the activity of iongel catalysts increased with the increase of the IL loading and the iongel catalysts with larger anions showed higher catalyst activity over the WGS reaction. The iongel catalysts showed certain activity over the WGS reaction in the temperature range from 120 °C to 200 °C, and the highest turnover frequency (66.7 h−1) was obtained at 160 °C over 2%Ru/30%[BDMIM]BF4@SiO2 catalyst. Through the control experiments and Fourier-transform infrared spectroscopy, a ruthenium carbonyl complex was shown to be the active component.

In this study, a new ruthenium catalyst was used for the oxidation of biomass derived 5-hydroxymethylfurfural (HMF) under mild conditions, which was prepared by the exchange of Ru3+ with H+ in the structure of the zirconium phosphate (ZrP). The as-prepared ZrP–Ru catalyst showed high catalytic activity towards the oxidation of HMF, affording 100% of HMF conversion at 130 °C after 12 h under atmospheric oxygen pressure. 2,5-Furandicarboxylic acid (FDCA) and 2,5-diformylfuran (DFF) were detected to be the major oxidation products.Download high-res image (120KB)Download full-size image

•Ru nanoparticles in ionic liquids deposited on ZnO was studied for WGS reaction.•The shape/crystal plane of ZnO showed a great effect on the catalyst activity.•The rodlike ZnO supported catalyst showed the highest catalytic activity.•{100} planes improved the catalyst activity by lowering the activation energy.In this study, four kinds of Ru-[BMIM]BF4/ZnO catalysts were prepared by the deposition of Ru nanoparticles in ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF4 on the different types of ZnO supports with specific shape. A strong shape/crystal plane effect of ZnO on the activity of Ru-[BMIM]BF4/ZnO catalysts was observed for the water-gas shift (WGS) reaction. The rodlike ZnO supported catalyst enriched by {100} planes showed higher WGS catalytic activity than dislike ZnO supported catalyst enriched {002} planes. Kinetic studies indicated that the activation energy of the Ru-[BMIM]BF4/ZnO-rod3 (43 kJ/mol) was much lower than that of Ru-[BMIM]BF4/ZnO-disk catalyst (60 kJ/mol). Physically experiments and control experiments indicated that the {100} planes of ZnO in the Ru-[BMIM]BF4/ZnO catalyst improved the adsorption of CO and increased the concentration of steam around the catalytic sites, and much more metallic Ru nanoparticles were present. In situ DRIFT experiments indicated that Ru-[BMIM]BF4/ZnO-disk catalyst showed a stronger adsorption ability toward CO2 than that of Ru-[BMIM]BF4/ZnO-rod catalysts, and the adsorbed CO2 might cover some active sites, lowering the catalytic activity of Ru-[BMIM]BF4/ZnO-disk catalyst, while formates were much easier formed in Ru-[BMIM]BF4/ZnO-rod catalysts, improving its catalytic activity.

The present study reported the results on the water–gas shift (WGS) reaction over a series of Ru/C catalysts. It was found that the reduction method showed a remarkable effect on the catalytic activity of Ru/C catalysts over WGS reaction, which increased in an order of the reduction by NaBH4, ethylene glycol, H2. It has been shown that alkali additives with K2CO3 significantly improved the activity of the Ru/C catalysts. XPS results indicated that Ru species were further oxidized by the addition of K2CO3, which indicated an electron transfer from the alkali metal to the substrate, resulting in stronger bonding of the adsorbed gas. FTIR results showed that the absorption peak intensity of H2O and hydroxyl group increased with the increase of K2CO3 content, due to the strong hygroscopic ability of K2CO3. Through the addition of K2CO3 to the Ru/C catalyst, much more water was adsorbed around the catalytic active sites, reducing the strong adsorption of CO on the active sites. Thus the addition of K2CO3 balanced the concentration of water and CO on the active sites, which was considered to be the key step for low temperature WGS reaction over Ru supported on irreducible activated carbon.

In this study, magnetically separable, graphene oxide-supported palladium nanoparticles (C–Fe3O4–Pd) were successfully prepared via a one-step solvothermal route. The C–Fe3O4–Pd catalyst showed excellent catalytic performance in the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA). The base concentration and reaction temperature significantly affected both HMF conversion and FDCA selectivity. High HMF conversion (98.2%) and FDCA yield (91.8%) were obtained after 4 h at 80 °C with a K2CO3/HMF molar ratio of 0.5. The C–Fe3O4–Pd catalyst was easily collected by an external magnet and reused without significant loss of its catalytic activity. The developed method is a green and sustainable process for the production of valuable FDCA from renewable, bio-based HMF in terms of the use of water as solvent, the use of stoichiometric amount of base, high catalytic activity under atmospheric oxygen pressure, and facile recyclability of the catalyst.