Jifeng Pang

Catalytic conversion of cellulose to hexitols with mesoporous carbon supported Ni-based bimetallic catalysts

Robust and highly active Ni-based bimetallic catalysts supported on mesoporous carbon have been developed for catalytic conversion of cellulose to hexitols, over which the maximum hexitol yield reached 59.8%.

Catalytic Conversion of Cellulose to Ethylene Glycol over a Low‐Cost Binary Catalyst of Raney Ni and Tungstic Acid

Following our previous report on the selective transformation of cellulose to ethylene glycol (EG) over a binary catalyst composed of tungstic acid and Ru/C, we herein report a new low-cost but more effective binary catalyst by using Raney nickel in place of Ru/C (Raney Ni+H(2 WO(4) ). In addition to tungstic acid, other W compounds were also investigated in combination with Raney Ni. The results showed that the EG yield depended on the W compound: H(4)SiW(12)O(40) <H(3 PW(12)O(40) <WO(3) <H(2)WO(4) , but all the investigated W compounds were selective towards EG. Moreover, both WO(3) and H2 WO(4) were dissolved partially under the reaction conditions and transformed into Hx WO(3) , which is the genuinely active species for the C-C bond breakage of cellulose. This result further confirmed that the reaction that involves the selective breakage of the C-C bonds of cellulose with W species is homogenous. Among various binary catalysts, the combination of Raney Ni and H(2)WO(4) gave the highest yield of EG (65 %), which could be attributed to the high activity of Raney Ni for hydrogenation and its inertness for the further degradation of EG. Moreover, Raney Ni+H(2)WO(4) showed good reusability; it could be reused at least 17 times without any decay in the EG yield, which shows its great potential for industrial applications.

Synthesis of ethylene glycol and terephthalic acid from biomass for producing PET

There have been considerable efforts to produce renewable polymers from biomass. Poly(ethylene terephthalate) (PET) is one of the most versatile bulk materials used in our daily lives. Recent advances in the new catalytic process for conversion of biomass have allowed us to design more technically effective and cheaper methods for the synthesis of green PET monomers. This review analyses recent advances in the synthesis of PET monomers from biomass. Different routes for ethylene glycol (EG) and purified terephthalic acid (PTA) synthesis are systematically summarized. The advantages and drawbacks of each route are discussed in terms of feedstock, reaction pathway, catalyst, economic evaluation and technology status, trying to provide some state-of-the-art information on green PET monomer synthesis. Finally, an outlook is presented to highlight the challenges, opportunities and on-going trends, which may serve as guidelines for designing novel synthetic routes to green polymers from fundamental science to practical use.

One-pot catalytic conversion of cellulose to ethylene glycol and other chemicals: From fundamental discovery to potential commercialization

Abstract The one-pot catalytic conversion of cellulose to ethylene glycol (CEG) is a highly attractive way for biomass utilization to lessen the consumption of fossil energy resources. In this paper, we reviewed the disclosure of the CEG process and the rapid progress in the development of highly efficient and robust catalysts for it. Based on our study of tungstenic catalysts, we discuss the reaction mechanism, in which the reaction routes, catalyst states, and catalytic roles of the tungsten species and hydrogenation sites in the cascade reactions are understood clearly. With future applications in mind, the conversion of raw cellulosic biomass and the strategy to develop an efficient CEG process for commercialization are discussed, and a model where the CEG process is incorporated into a bio-refinery process of acetone- n -butanol-ethanol (ABE) production is presented.

Synthesis of 1,6-hexanediol from HMF over double-layered catalysts of Pd/SiO2 + Ir–ReOx/SiO2 in a fixed-bed reactor

1,6-Hexanediol (1,6-HDO) was effectively prepared from 5-hydroxymethylfurfural (HMF) over double-layered catalysts of Pd/SiO2 + Ir–ReOx/SiO2 in a fixed-bed reactor. Under optimal reaction conditions (373 K, 7.0 MPa H2, in solvent mixtures of 40% water and 60% tetrahydrofuran (THF)), 57.8% yield of 1,6-HDO was obtained. The double-layered catalysts loaded in double-layered beds showed much superior performance compared to that of a single catalyst of Pd–Ir–ReOx/SiO2, even when the same amount of active components were used in the catalysts. The reaction solvent significantly affected product distributions, giving a volcano-shape plot for the 1,6-HDO yield as a function of the ratio of water to THF. Bronsted acidic sites were generated on the catalyst in the presence of water which played determining roles in 1,6-HDO formation. A high pressure of H2 contributed to 1,6-HDO formation by depressing the over-hydrogenolysis of reaction intermediates and products to form hexane and hexanol. The reaction route was proposed for HMF conversion to 1,6-HDO on the basis of conditional experiments.

Catalytic conversion of cellulosic biomass to ethylene glycol: effects of inorganic impurities in biomass.

The effects of typical inorganic impurities on the catalytic conversion of cellulose to ethylene glycol (EG) were investigated, and the mechanism of catalyst deactivation by certain impurities were clarified. It was found that most impurities did not affect the EG yield, but some non-neutral impurities or Ca and Fe ions greatly decreased the EG yield. Conditional experiments and catalyst characterization showed that some impurities changed the pH of the reaction solution and affected the cellulose hydrolysis rate; Ca and Fe cations reacted with tungstate ions and suppressed the retro-aldol condensation. To obtain a high EG yield, the pH of the reaction solution and the concentration of tungstate ions should be respectively adjusted to 5.0-6.0 and higher than 187ppm. For raw biomass conversion, negative effects were eliminated by suitable pretreatments, and high EG yields comparable to those from pure cellulose were obtained.

Catalytic conversion of Jerusalem artichoke stalk to ethylene glycol over a combined catalyst of WO3 and Raney Ni

Jerusalem artichoke stalk (JAS) was employed as the feedstock for the production of ethylene glycol (EG) with a combined catalyst comprising commercial WO3 and Raney Ni. The raw JAS contains 51.6 wt% cellulose, 10.3 wt% hemicellulose, 17.2 wt% lignin, 1.7 wt% ash, and 19.2 wt% water-soluble substances. It was found that the lignin component in the JAS had little effect on the conversion of hemicellulose while the water-soluble substances caused a negative effect, which led to an EG yield of only 29.9%. After a simple hot water pretreatment, most of the water-soluble substances were removed, and the EG yield was increased to 37.6%. Moreover, the hot water pretreatment also led to an improvement in the durability of the catalyst. The effects of reaction temperature and reaction duration were also investigated

Chemocatalytic Conversion of Cellulosic Biomass to Methyl Glycolate, Ethylene Glycol, and Ethanol

Production of chemicals and fuels from renewable cellulosic biomass is important for the creation of a sustainable society, and it critically relies on the development of new and efficient transformation routes starting from cellulose. Here, a chemocatalytic conversion route from cellulosic biomass to methyl glycolate (MG), ethylene glycol (EG), and ethanol (EtOH) is reported. By using a tungsten-based catalyst, cellulose is converted into MG with a yield as high as 57.7 C % in a one-pot reaction in methanol at 240 °C and 1 MPa O2 , and the obtained MG can be easily separated by distillation. Afterwards, it can be nearly quantitatively converted to EG at 200 °C and to EtOH at 280 °C with a selectivity of 50 % through hydrogenation over a Cu/SiO2 catalyst. By this approach, the fine chemical MG, the bulk chemical EG, and the fuel additive EtOH can all be efficiently produced from renewable cellulosic materials, thus providing a new pathway towards mitigating the dependence on fossil resources.

Production of renewable 1,3-pentadiene from xylitol via formic acid-mediated deoxydehydration and palladium-catalyzed deoxygenation reactions

A two-step synthetic approach for the production of renewable 1,3-pentadiene was reported: xylitol deoxydehydration (DODH) by formic acid to 2,4-pentadien-1-ol, 1-formate (2E), followed by deoxygenation to 1,3-pentadiene over Pd/C. The overall carbon yield of 1,3-pentadiene reached 51.8% under the optimized conditions.

Catalytic conversion of Jerusalem artichoke tuber into hexitols using the bifunctional catalyst Ru/(AC-SO3H)

Jerusalem artichoke tuber OAT) was employed as a feedstock for production of hexitols under mild conditions over a sulfonated activated carbon supported Ru catalyst (Ru/(AC-SO3H)). In comparison with conventional Ru/AC catalyst, the sulfonation process of the carbon support was observed to create abundant surface acid groups, which in turn function as the anchoring sites for Ru nanoparticles, thus increasing the dispersion of Ru. Consequently, the bifunctional Ru/(AC-SO3H) catalyst displayed significantly enhanced activity in one-pot production of hexitols from JAT; the hexitols yield achieved 92.6% over the 3%Ru/(AC-SO3H) catalyst when the reaction was conducted at 373 K and 6 MPa H-2 for 3 h. The stability of the catalyst was also investigated, which showed a decreasing trend in the yield of sorbitol with the run number due to poisoning of Ru surface by the impurity in the JAT feedstock. In contrast, when pure inulin was used as the feedstock, the catalyst presented excellent stability in the successive four runs