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Using raw lignocellulosic biomass as feedstock for sustainable production of chemicals is of great significance. Herein, we report the direct catalytic conversion of raw woody biomass into two groups of chemicals over a carbon supported Ni-W 2 C catalyst. The carbohydrate fraction in the woody biomass, i.e., cellulose and hemicellulose, were converted to ethylene glycol and other diols with a total yield of up to 75.6% (based on the amount of cellulose & hemicellulose), while the lignin component was converted selectively into monophenols with a yield of 46.5% (based on lignin). It was found that the chemical compositions and structures of different sources of lignocellulose exerted notable influence on the catalytic activity. The employment of small molecule alcohol as a solvent could increase the yields of phenols due to the high solubilities of lignin and hydrogen. Remarkably, synergistic effect in Ni-W 2 C/ AC existed not only in the conversion of carbohydrate fractions, but also in lignin component degradation. For this reason, the cheap Ni-W 2 C/AC exhibited competitive activity in comparison with noble metal catalysts for the degradation of the wood lignin. Furthermore, the catalyst could be reused at least three times without the loss of activity. The direct conversion of the untreated lignocellulose drives our technology nearer to large-scale application for cost-efficient production of chemicals from biomass.

The hydrolysis of cellulose over sulfonated carbons was promoted greatly by elevating the sulfonation temperature. With 250 degrees C-sulfonated CMK-3 as a catalyst, the cellulose was selectively hydrolyzed into glucose with the glucose yield as high as 74.5%, which is the highest level reported so far on solid acid catalysts.

Currently, the human race faces two important issues: energy and the environment. Obtaining energy and chemicals in a sustainable and environmentally friendly manner has been the target of many chemists. Among many potential approaches, biomass conversion has been considered as one of the most important ones because of its renewable and carbon-neutral properties. Cellulose is the most abundant source of biomass and generally accounts for 30-60 wt % of dried plants. Much effort has been devoted to the development of a green and effective process for cellulose conversion, such as fermentation with enzymes to produce ethanol, [1] thermo-pyrolysis to biooils [2] and syn-gas, [3] and hydrolysis with dilute acids in ionic liquids to yield oligomers, [4] glucose, [5] and HMF.[6]An alternative green process for cellulose conversion is to use solid catalysts to convert cellulose into polyols in an aqueous solution. Yan et al. [7] found that cellubiose, the simplest model molecule for cellulose, can be converted into sorbitol by using a Ru nanocatalyst in an aqueous solution. Fukuoka and Dhepe, [8] and Luo et al., [9] disclosed that cellulose can be converted into hexitols under hydrothermal and hydrogen conditions over noble-metal catalysts. These studies opened up a green route for the conversion of cellulose. On the other hand, the yields of polyols in these processes were not very high; generally less than 40 %. Furthermore, expensive noblemetal catalysts were used. Therefore, the development of lessexpensive but efficient catalysts for cellulose conversion is highly desirable.Recently, we successfully achieved the direct conversion of cellulose into ethylene glycol (EG) by a heterogeneous catalytic reaction under hydrogen atmosphere and hydrothermal conditions.[10] Over an active-carbon-supported tungsten carbide catalyst (W 2 C/AC), cellulose was completely depolymerized and EG was produced with a yield of 27 %. More importantly, upon the addition of a small amount of Ni to the W 2 C catalyst, the EG yield was significantly increased to as high as 61 %. EG is an important bulk chemical and sourced dominantly from petroleum resources.[11] Thus, this work provided a novel route for EG production as well as for cellulose conversion.However, there are some very intriguing questions about this novel process yet to be answered. For example, besides the W 2 C catalysts, are there any other catalysts effective for the conversion of cellulose into EG? With the Ni-modified W 2 C catalysts, a remarkable synergistic effect was observed. Which effect caused this synergy in the conversion process? Herein, based on the element W, we develop a series of bimetallic catalysts for the cellulose conversion, including Ni-W, Pd-W, Pt-W, Ru-W, and Ir-W, supported on different carriers. A remarkable synergy is observed between tungsten and metals of groups 8, 9, and 10 [M(8,9,10)]. Moreover, it is found that the product selectivity can be tuned effectively by changing the weight ratio of W to M(8,9,10). The maximum yield of EG, 75.4 %, was ...

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A temperature-controlled phase-transfer catalyst-tungsten acid, which in combination with a robust heterogeneous catalyst Ru/C shows a high activity and exceptional reusability for the one-pot conversion of cellulose to ethylene glycol. This binary system can be reused more than 20 times with ethylene glycol yield over 50%.The efficient utilization of biomass for the sustainable production of energy and chemicals is an important way towards both decreasing the dependence on fossil resources and reducing CO 2 emissions. Cellulose is the most abundant biomass on earth, and its non-food nature and rich hydroxyl groups in its molecules make it an ideal feedstock for the production of polyols.

The use of whole lignocellulosic biomass as the feedstock for cellulose conversion is of great significance for largescale, low-cost biomass conversion to biofuel and other useful chemicals. We recently achieved the direct conversion of cellulose (pure microcrystalline cellulose) into ethylene glycol at high yields over tungsten carbide catalysts. Here, corn stalk, an agricultural residue available in large quantities, was used as a lignocellulosic feedstock for conversion over nickel-promoted tungsten carbide catalysts under hydrothermal conditions and a hydrogen atmosphere. Nine different pretreatment methods were employed to convert the raw corn stalk to cellulosic feedstock with different chemical components and structures before the catalytic reaction. We found that corn stalks pretreated with 1,4-butanediol, NaOH, H 2 O 2 , and ammonia produced much higher yields of ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG) compared to raw corn stalks, whereas pretreatments with ethanol solution, hot water, hot limewater, and supercritical CO 2 just slightly improved the EG and 1,2-PG yields and corn stalk conversion. The hemicellulose in the corn stalk can be effectively converted to EG and 1,2-PG without hindering the cellulose conversion. In contrast, the lignin was resistant to degradation in the reaction and also inhibited EG and 1,2-PG production. The crystallinity of cellulose did not appear to have notable influence on the EG and 1,2-PG production. In view of the environmental benignity and low cost, pretreatment with ammonia and/or diluted H 2 O 2 solution might be a practical method for corn stalk conversion, after which the derived cellulosic feedstock is readily converted into EG and 1,2-PG at an overall yield of 48% in the reaction.

This review presents recent advances in typical routes for drop-in replacement of poly(ethylene terephthalate) monomers from biomass.