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The isomerization of glucose to fructose is the rate determining step in many techniques for chemo‐catalytic conversion of cellulosic biomass to highly value‐added biochemicals. However, current techniques are generally challenging by poor process efficiency, low fructose yield and selectivity, etc. Therefore, the exploitations of novel catalytic systems for the efficient isomerization of glucose are important and highly desired. Herein, a series of biodegradable guanidinium ionic liquids were synthesized and employed in the selective isomerization of glucose to fructose. The results demonstrated that the performance of the isomerization of glucose was significantly influenced by the basic strength of the ionic liquids and the reaction conditions involving catalyst dosage, reaction temperature, time, and solvent. At the optimized conditions of 80 °C for 30 min, an impressive fructose yield of 34.1 % could be obtained in the presence of tetra methyl guanidinium proline ([TMG]Pro). Furthermore, the kinetic behavior of the process was further studied, and the apparent activation energy was 57±2 KJ/mol, which is lower than most current base‐catalyzed glucose isomerization systems. Moreover, the results of isotope labeling experiments showed that this aqueous isomerization of glucose was proceeded via a deprotonation mechanism. Therefore, this work provides a new insight on the selective isomerization of glucose. [ABSTRACT FROM AUTHOR]

In this study, we propose a novel and efficient process for bagasse liquefaction in subcritical water over the solid alkali catalyst of MgMOx (M = Mn, Ni, Fe, Cr, Zn and Al). The intensification effect of the catalyst was investigated via hydrothermal liquefaction, where the product distribution and composition of volatiles and residue were compared using GC–MS, GPC, FT-IR and elemental analysis. The results show that the materials substantially promote bagasse liquefaction. Under optimized conditions (250 °C for 15 min), MgMnO 2 liquefied 93.7% of the bagasse yielding a water-soluble fraction of 59.5%. Of particular note, lignin, the most recalcitrant fragment in biomass hydrothermal liquefaction, is efficiently depolymerized to volatile phenolic monomers with these catalysts. Furthermore, the MgMnO 2 catalyst shows good recyclability, where no significant activity loss is demonstrated even after the fifth run. [ABSTRACT FROM AUTHOR]

Efficient conversion of lignin depolymerization products to more stable chemicals has attracted increasing attention during last few years. Here, we reported a novel and efficient method for lignin depolymerization products valorization on the simple and economic catalyst Ni x Mg 1 − x O. In which, the unsaturated ingredients were converted to thermal and chemical stable products, resulting in the obvious decreasing of the unsaturated degree of the products and the repolymerization of the phenolic oligomer. The results showed that more than 98% of phenol, a model chemical of lignin depolymerization products, could be converted to cyclohexanol with 100% selectivity. Further investigation demonstrated that it was also efficient for the real lignin depolymerization products, where a significant decrease on the oxygen content and the average molecular weight were shown. Moreover, the Ni x Mg 1 − x O catalyst was recyclable, and no significant loss of the catalytic activity was exhibited even after 5 runs. [ABSTRACT FROM AUTHOR]

Bio oil, for its simple preparation and low cost, had the potential to be one kind of substitute liquid fuel. In view of its high temperature, H2pressure, and high oxygen content, hydrodeoxygenation (HDO) is very critical for hydrocarbon fuel. Upgrading the light phase of bio-oil might be a potential method and stable oxygenated compounds might be a kind of potential fuel for the application of bio-oil. In this paper, a Raney Ni catalyst was used for hydrogenating bio oil to saturated alcohols in the high pressure reaction kettle. The influences of temperature (100-180°C), initial pressure of hydrogen (4-8 MPa), the dosages and the recycle usage of the catalyst on the hydrogenation of bio-oil over the self-made Raney-Ni catalyst were discussed. X-ray Diffraction, Brunauer Emmett Teller, and a scanning electron microscope were used to investigate the deactivation mechanism. The results indicated that the reaction temperatures and the initial pressures of the hydrogen gas had an obvious effect on the conversion of the light composition of the bio oil. With the increasing of the reaction temperature to 140°C and the initial pressure to 6 MPa, the yield of saturated alcohols increased and reached the highest point of 53.51%. Meanwhile, the total content of stable alcohols and esters reached 64.62%. At this condition, there was no aldehyde detected in the product, and nearly 40% of the ketones were hydrogenated to alcohols. And also there was 1.77% of ether detected in the products which accounts for the dehydration happening from alcohols. With the increasing of temperature, the conversion of phenol increased. When the dosage of the catalyst increased from 0.5 g to 1 g, the content of saturated alcohols in the product increased from 25.42% to 51.89%. Over 0.5 g of Raney Ni catalyst, there were some unstable ketone compounds such as 1-hydroxy-butanone, 3-hydroxy-butanone, and hydroxyl-acetone in the products. When the dosage of Raney Ni catalyst increased, the content of saturated alcohols in the upgraded bio oil was little changed. Over fresh and once-used Raney Ni catalysts, the content of saturated alcohols decreased from 53.51% to 29.20%. The XRD results showed that the three characteristics of the diffraction peak intensity decreased significantly, and the heterogeneous metal skeleton crystal structure of the Raney Ni catalyst collapsed after use. The SEM results showed that after the hydrogenation reaction, the catalyst presented a black honeycomb solid surface and the activity on the surface was covered by coking. The deactivation of the catalyst may relate to the covering of the catalyst pore and the coking on the catalyst channel, which leads to a decrease of the catalyst's activity and a reduction of the reaction efficiency. During the upgrading process, the ketones and the aldehydes compounds could be hydrogenated to alcohols, and the phenols could be hydrogenated to cyclohexanol and its derivatives. Apart from the hydrogenation reaction, the esterifications existed during the process, and the contents of acids decreased after hydrogenation to some extent. Compared with hydrocarbon fuel, oxygenated fuel for its good combustion performance becomes more popular. It might be a potential and novel way of upgrading bio-oil to oxygenated fuel. [ABSTRACT FROM AUTHOR]

Highlights: [•] An efficient and economic process for lignin depolymerization was achieved. [•] THF advantaged excellent lignin dissolution ability and catalyst promotion effect. [•] 13.2% yield of phenolic monomer was obtained under optimized condition. [•] This base-catalyzed process can inhibit char formation significantly. [Copyright &y& Elsevier]

Abstract: Liquefaction is a process for the production of biofuel or value-added biochemicals from non-food biomass. SO3H-, COOH-functionalized and HSO4-paired imidazolium ionic liquids were shown to be efficient catalysts for bagasse liquefaction in hot compressed water. Using SO3H-functionalized ionic liquid, 96.1% of bagasse was liquefied and 50.6% was selectively converted to low-boiling biochemicals at 543K. The degree of liquefaction and selectivity for low-boiling products increased and the average molecular weight of the tetrahydrofuran soluble products decreased with increasing acidic strength of ionic liquids. Analysis of products and comparative characterization of raw materials and residues suggested that both catalytic liquefaction and hydrolysis processes contribute to the high conversion of bagasse. A possible liquefaction mechanism based on the generation of 3-cyclohexyl-1-propanol, one of the main products, is proposed. [Copyright &y& Elsevier]

Abstract: Esterification of aliphatic acids with alcohols was studied using a series of Brønsted acidic ionic liquids as catalysts. The results indicate that five SO3H-functionalized ionic liquids show high catalytic activity and fair reusability even at very low catalyst loadings, while the conventional non-functionalized ionic liquids show poor activity. Hammett method was used to determine the acidity of the ionic liquids and the results were found to be relevant to the catalytic activity observed in the esterification reactions. [Copyright &y& Elsevier]