Selective 5-Hydroxymethylfurfural Hydrogenolysis to 2,5-Dimethylfuran over Bimetallic Pt-FeOx/AC Catalysts

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

Efficient production of ethyl levulinate from cassava over Al-2(SO4)(3) catalyst in ethanol-water system

One-pot achievement of ethyl levulinate from cassava was conducted in ethanol-water system over several simple sulfate salt catalysts. Al-2(SO4)(3) catalyst had the best performance in synthesizing ethyl levulinate comparing with those of a series of sulfate salts. The highest yields of ethyl levulinate was up to 39.27% as well as 7.78% levulinate acid when cassava was catalyzed in ethanol medium by adding 10 wt% water. C-13 and H-1 NMR spectroscopic investigations confirmed that isomerization of glucose to fructose over Al-2(SO4)(3) catalyst is an important step in producing ethyl levulinate and levulinate acid. Due to aggregations of Al3+ under hydrothermal conditions, tiny amount of Al3+ were detected in filtrate at the percentage of 0.32% even if in absolute water. Bronsted and Lewis acids could improve the yield of ethyl levulinate and levulinate acid by synergistic effect. All results suggested that Al-2(SO4)(3) was a simple and efficient catalyst for ethyl levulinate and levulinate acid production. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved

Reactivity and structural changes of asphaltene during the supercritical water upgrading process

Experiments on the reactivity and structural changes of asphaltene in the SCW upgrading process were conducted with a batch reactor. The reactivity and structural changes of asphaltene was evaluated with the yield of products (gas, maltene and coke) and the characterizations of remaining asphaltene with elemental analysis (C, H, N, and S), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) H-1 and nuclear magnetic resonance (H-1 NMR). As shown from the transformation of asphaltene, the enhance of severity condition would increase the conversion of asphaltene but resulted in the secondary reaction of maltene and the formation of more coke and gases. And the characterizations fully illustrated that the size was greatly reduced, the ratios of H/C, N/C and S/C were seriously lowered, the alkyl side chains were much shorted and the aromaticity and condensation degree were significantly enhanced as for remaining asphaltene obtained from the SCW upgrading process. Finally, the transformation pathway of asphaltene was analyzed with the reconstruction of asphaltene macromolecular model at various severity condition and the results showed that the reactivity and structural changes of asphaltene was closely related to the cracking of asphaltene macromolecular into smaller one, the fracture of alkyl side chains and the reaction of dehydrogenation and polymerization

Hydrodeoxygenation of lignin-derived phenolic compounds to hydrocarbons over Ni/SiO2-ZrO2 catalysts

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)center dot 6H(2)O and calcined at 500 degrees C. Conversion rates and product distribution for guaiacol HDO at 200-340 degrees C were determined. Guaiacol conversion reached the maximum at 300 degrees 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. (C) 2013 Elsevier Ltd. All rights reserved

Facile synthesis of Pd@MOF catalyst and its application for High Selective Hydrogenation and Hydrodeoxygenation of Biomass-Derived Compounds

High selective hydrogenation and hydrodeoxygenation of biomass-derived compounds are still challenging especially under mild reaction conditions using heterogeneous catalysis. Here, we reported a one-step synthesis method that successfully prepared Pd species immobilized on NH2-MIL-125 (Ti) MOF frameworks which were named Pd@MOF and used as a highly efficient hydrodeoxygenation catalyst for the reduction of vanillin to 2-methoxy-4-methyl phenol in excellent yield with an atm of H2 pressure at room temperature. Pd(PPh3)4 was dispersed in a solvent containing the MOF precursors. Among them, the PPh3 ligand could be oxidized to remove and Pd particles in situ doped in MOF framework during the solvothermal process. Compare to immersed-Pd/MOF and Pd-MOF, Pd@MOF has higher catalytic efficiency because the smaller Pd particles encapsulated in MOF inhibit Pd over oxidation. Moreover, the different reduction products could be obtained selectively by tuning reaction time, and the catalyst realized to catalyze the highly effective transformation of a variety of biomass-derived compounds

A review of conversion of lignocellulose biomass to liquid transport fuels by integrated refining strategies

Due to the limitations on carbon emissions, many countries are seeking potential clean, renewable and sustainable energy and fuels. Conversion of lignocellulose biomass to liquid fuel is one of the research hotpots because biomass is a renewable and sustainable resource. This paper outlines an attractive strategy for the production of liquid transport fuels from lignocellulose biomass. Specifically, hemicellulose and cellulose are converted to C5 and C6 alkanes (bio-gasoline) and C8-C15 alkanes (aviation fuel) via C5/C6 platform molecules, and lignin is converted to arenes and cyclanes via phenolic monomers and dimers through hydrodeoxygenation. The focus is to review the state-of-the-art technologies for the preparation of platform molecules, the synthesis of light/heavy alkanes, lignin depolymerization and catalytic hydrodeoxygenation. In addition, major challenges and promising prospects are also pointed out for the future development of the conversion of lignocellulose biomass to liquid transport fuels

effectofcalcinationtemperatureofnisio2zro2catalystonitshydrodeoxygenationofguaiacol

采用化学沉淀法合成了SiO2-ZrO2复合氧化物载体，并以浸渍法制备了Ni/SiO2-ZrO2双功能催化剂，考察了焙烧温度对催化剂结构及其催化愈创木酚加氢脱氧制环己烷性能的影响.结果表明，经500℃焙烧催化剂的加氢脱氧活性最高，在Ni金属中心和SiO2-ZrO2载体材料的协同作用下，愈创木酚转化率为100%，环己烷选择性为96.8%.对催化剂进行N2物理吸附、H2化学吸附、X射线衍射分析、H2程序升温还原、NH3程序升温脱附与Raman光谱等表征后发现，合成的SiO2-ZrO2为无定形的酸碱两性氧化物；经500℃焙烧的催化剂样品的有效比表面积和孔体积均明显增大，表面酸量最多，硝酸镍分解成小颗粒的NiO较易被H2还原，这些特性是该催化剂样品具有高效加氢脱氧活性的原因

One-Pot Hydrogenation of Furfural into Tetrahydrofurfuryl Alcohol under Ambient Conditions over PtNi Alloy Catalyst

Furfural (FAL), a promising renewable platform compound from biomass, can be totally hydrogenated to an industrially important platform chemical, tetrahydrofurfuryl alcohol (THFA). In this work, a high yield of THFA was obtained by one-pot hydrogenation of FAL over a PtNi catalyst under mild reaction conditions. Small PtNi alloy particles were well distributed on active carbon. The catalysts were characterized by several physical-chemical technologies (transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and inductively coupled plasma spectroscopy). Temperature-programmed reduction with hydrogen and in situ X-ray photoelectron spectroscopy demonstrate the presence of PtNi alloy. The electron-rich metal Pt could facilitate the heterolytic dissociation of hydrogen and promote the hydrogenation of FAL. Pt sites on the surface facilitate the adsorption at aldehyde (C=O) groups, and the furan ring strongly adsorbs on the Ni surface. Low reaction temperature is advantageous to reduce side reactions. Various metal concentrations were employed in this reaction; Pt(3)Ni(3)/C catalyst exhibits the best performance, achieving 99% FAL conversion and 93% THFA yield at 35 degrees C and under 2 MPa H-2

Ni/Co@NDC Modulates the Highly Selective Conversion of Vanillin in Flow Reactor under Mild Conditions

Vanillin is currently the most abundant aromatic molecule produced from lignin on an industrial scale and one of the few renewable resources that can be readily catalyzed to obtain alkanes. The hydrogenation of vanillin as a lignin model has been a hot research topic in the catalytic community. Vanillin has the potential to be upgraded to value-added compounds by catalytic hydrogenation, and its valuable hydrogenation products are usually vanillinol (VA) and 4-methylguaiacol (MMP). The difficulty of this reaction lies in the selectivity control of the hydrogenation products. Complete conversion of both products cannot be achieved with either noble or non-precious metal catalysts in the same catalytic system. For the hydrogenation of vanillin, the usual catalysts can achieve complete conversion of one product or partial conversion of both products. In our work, we developed a novel bimetallic catalyst encapsulated in nitrogen-rich carbon to achieve, for the first time, the selective and regulated conversion of two products, i.e., 96.06% vanillin and 99.99% MMP, in the same system. The use of nitrogen-doped carbon (NDC) as a carrier for Ni nanoparticles allows the charge transfer from Ni to the carrier, i.e., NDC, resulting in the oxidation potential is corrected. Combined with the more favorable deoxidation activity of Co, our catalysts are inexpensive, simple to prepare, stable in performance, easy to separate, high in activity, and have the advantage of being tunable to the target product. Due to the synergistic effect of Ni and Co bimetals, the vanillin hydrogenation reaction can be almost completely stopped at the step of VA generation and the catalytic activity of the active center can be adjusted by controlling the temperature in a continuous flow to achieve the conversion of the other product MMP at 99.99%, which has never been reported before

Mechanistic insights into the effects of support on the reaction pathway for aqueous-phase hydrogenation of carboxylic acid over the supported Ru catalysts

Several supported Ru catalysts, Ru/TiO2, Ru/ZrO2, Ru/SiO2, Ru/gamma-Al2O3 and Ru/SiO2-Al2O3, were prepared and investigated for propanoic acid aqueous-phase hydrogenation. H-2-TPR, NH3-TPD, pyridine-FTIR and propanoic acid-DRIFTS techniques were performed to explore the metal-support interaction, acid sites and key adsorption species. The effect of support on the reaction pathway of C=O hydrogenation and decarbonylation of acyl species was discussed. Compared with Ru/ZrO2 and Ru/SiO2 catalysts, high selectivity of C=O hydrogenation was obtained over the catalysts with more Lewis acid sites, such as Ru/gamma-Al2O3 and Ru/SiO2-Al2O3 catalysts. The DRIFTS results suggest that the formation of adsorption species (acyl, carboxylate and carboxylic acid) is strongly depended on the nature of support. The metal-acid bifunctional sites are indispensable for the C=O hydrogenation of acyl. However, the decarbonylation of acyl on the metal sites requires the relatively weak metal-support interaction and few of Lewis acid sites. (C) 2014 Elsevier B.V. All rights reserved