Quan Cao

Conversion of hexose into 5-hydroxymethylfurfural in imidazolium ionic liquids with and without a catalyst.

Conversion of fructose and glucose into 5-hydroxymethylfurfural (HMF) was investigated in various imidazolium ionic liquids, including 1-butyl-3-methylimidazolium chloride (BmimCl), 1-hexyl-3-methylimidazolium chloride (HmimCl), 1-octyl-3-methylimidazolium chloride (OmimCl), 1-benzyl-3-methylimidazolium chloride (BemimCl), 1-Butyl-2,3-dimethylimidazolium chloride (BdmimCl), and 1-butyl-3-methylimidazolium p-toluenesulfonate (BmimPS). The acidic C-2 hydrogen of imidazolium cations was shown to play a major role in the dehydration of fructose in the absence of a catalyst, such as sulfuric acid or CrCl(3). Both the alkyl groups of imidazolium cations and the type of anions affected the reactivity of the carbohydrates. Although, except BmimCl and BemimCl, other four ionic liquids could only achieve not more than 25% HMF yields without an additional catalyst, 60-80% HMF yields were achieved in HmimCl, BdmimCl, and BmimPS in the presence of sulfuric acid or CrCl(3) in sufficient quantities.

Selective dehydration of fructose to 5-hydroxymethylfurfural catalyzed by mesoporous SBA-15-SO3H in ionic liquid BmimCl

Mesoporous SBA-15 materials functionalized with propylsulfonic acid groups (SBA-15-SO(3)H) were synthesized through a conventional one-pot route. It was used as a catalyst for the selective synthesis of 5-hydroxymethylfurfural (HMF) from the dehydration of fructose using BmimCl as solvent. Reaction time, temperature and fructose concentration were investigated during the HMF synthesis procedure. The catalyst SBA-15-SO(3)H exhibits high fructose conversion (near 100%) and HMF selectivity (about 81%) with good stability in the HMF synthesis. It was a suitable catalyst to produce HMF from renewable carbohydrates in potential industrial process.

Acidic resin-catalysed conversion of fructose into furan derivatives in low boiling point solvents

Conversion of fructose into furan derivatives 5-hydroxymethylfurfural (HMF) and 5-methoxymethylfurfural (MMF) is performed in tetrahydrofuran (THF) and methanol-organic solvent systems, catalysed by an acidic resin Amberlyst-15. The melted fructose can be converted into HMF on the surface of the solid resin catalyst in the presence of THF as an extracting phase, which is a good solvent for HMF and other by-products. The solid resin catalyst can be reused eleven times without losing its catalytic ability, with an average HMF yield of approximately 50%. Upon the addition of methanol, the generated HMF can further react with methanol to form MMF, and the total yield of HMF and MMF could be promoted to 65%. GC-MS analysis confirms the formation of a small amount of methyl levulinate in methanolorganic solvent system.

Iridium nanoparticles supported on hierarchical porous N-doped carbon: an efficient water-tolerant catalyst for bio-alcohol condensation in water

Nitrogen-doped hierarchical porous carbons were synthesized successfully by a controllable one-pot method using glucose and dicyandiamide as carbon source and nitrogen source via hydrothermal carbonization process. The nitrogen-doped materials, possessing high nitrogen content (up to 7 wt%), large surface area (>320 m2 g−1) and excellent hierarchical nanostructure, were employed as catalyst supports for immobilization of iridium nanoparticles for bio-alcohol condensation in water. The introduction of nitrogen atoms into the carbon framework significantly improved iridium nanoparticles dispersion and stabilization. The novel iridium catalysts exhibited superior catalytic activity in the aqueous phase condensation of butanol, offering high butanol conversion of 45% with impressive 2-ethylhexanol selectivity of 97%. The heterogeneous catalysts had great advantages of easy recovery and high catalytic stability. The outstanding catalytic performance could be attributed to excellent dispersion of iridium nanoparticles, stronger iridium-support interactions and interaction of nitrogen species with alcohol substrates.

Role of ReOx in Re-modified Rh/ZrO2 and Ir/ZrO2 catalysts in glycerol hydrogenolysis: Insights from first-principles study

The thermodynamics of glycerol hydrogenolysis to produce 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO) over Ru/ZrO2, Rh/ZrO2, ReOx-Rh/ZrO2, and ReOx-Ir/ZrO2 were studied using density functional theory calculations, with a special focus on the mechanism controlling the activity and selectivity of the reactions. It is found that the decomposition of glycerol on Ru/ZrO2 and Rh/ZrO2 proceeds through a dehydration-hydrogenation mechanism. The formation of 1,2-PDO is thermodynamically favored, and the activity of the Ru-based catalyst is higher than that of the Rh-based one. In contrast, a direct hydrogenolysis mechanism is proposed for the Re-modified Rh and Ir catalysts, in which a dissociated H atom on the Rh(Ir) metal surface attacks the C-O bond neighboring the alkoxide species on the ReOx cluster. In the presence of ReOx-Rh/ZrO2, the modified catalyst favors the production of 1,2-PDO, and 1,3-PDO production becomes competitive. However, the ReOx-Ir/ZrO2 catalyst significantly improves 1,3-PDO selectivity. The direct hydrogenolysis pathway, as opposed to the indirect hydrogenolysis mechanism for monometallic catalysts, may be the key to the high 1,3-PDO selectivity on the modified catalysts, where the hydroxylated Re group facilitates the formation of terminal alkoxide species rather than secondary alkoxides. Steric effects are important in preferential terminal alkoxide formation on the ReOx-Ir/ZrO2 catalysts because of the growth of large Ir-Re clusters, resulting in high selectivity for 1,3-PDO. 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Sorbitol hydrogenolysis to glycerol and glycols over M-MgO (M = Ni, Co, Cu) nanocomposite: A comparative study of active metals

The activities and selectivities of MgO-supported Ni, Cu, and Co catalysts have been compared in aqueous-phase hydrogenolysis of sorbitol to glycerol and glycols. All catalysts effectively catalyzed the sorbitol conversion into C2 and C3 polyols like glycerol, 1,2-propylene glycol, and ethylene glycol, but with different product distributions. The differences in activities and selectivities are ascribed to their different dehydrogenation/hydrogenation activities. The influences of base promoter, temperature, H-2 pressure, and reaction time were also studied. Added base promoter and prolonged reaction time enhanced sorbitol conversion for the three catalysts, but led to product degradation and decreased selectivity over Ni-MgO and Co-MgO, whereas selectivity maintained almost unchanged over Cu-MgO

Chemical Conversion of Biomass to Green Chemicals

Biomass has the potential to serve as a sustainable source of energy and organic carbon for our industrial society. The focus of this chapter is to provide a survey of different strategies to achieve chemical catalytic conversion of biomass-derived oxygenated feedstocks to value-added chemicals and fuels. The key reactions involved in the processing of biomass are hydrolysis, dehydration, isomerization, aldol condensation, reforming, hydrogenation/hydrogenolysis, and oxidation. Here, a few specific examples, namely efficient hydrolysis of cellulose over novel solid acids and synthesis of polyols by hydrogenation/hydrogenolysis of cellulose and sugar have been chosen for this review. Further, the selective conversion of platform molecules, such as furan, HMF, and biogenic carboxylic acids into intermediates, specialties, and fine chemicals has been considered. While many challenges are involved in biomass processing, understanding of fundamental reaction chemistry for different types of reactions can lead to the development of new approaches for specific processes.

Combined chemo- and bio-transformations from non-fossil fuel raw materials

At present, Chinas petrochemical industry is facing significant challenges of resources and environment. In the future, the bulk chemical manufacture is moving towards high resources utilization efficiency, usage of multiple raw materials, design of high value-added product, green and low-carbon processes. In the present situation, the develop-ment of novel industry by integrated chemo-and bio-transformation, i.e., combining the green, specifity characteristics in biotechnology with the high-efficiency, scaled separation and catalysis in current chemistry industry in one process, is very important in promoting the sustainable development in bioenergy and modern petrochemical industry. This article gives some examples of innovation practices on combined chemo-and bio-transformation systems from non-fossil fuel raw materials, including combined raw materials, processes and products. Finally, outlook and suggestions are given on enhancing technological development for sustainable combined chemo-and bio-transformation for bulk chemicals.