Biomass is broadly defined as everything that can be grown organically. In a narrow sense, it refers to the main components of the plant: cellulose, hemicellulose, and lignin. The annual global biomass produced by photosynthesis is about 170 billion tons, and the energy contained is equivalent to 535.5 billion barrels of crude oil, which is much higher than the consumption of crude oil in 2015 (about 35 billion barrels). At present, the utilization of biomass is limited, only 3% -4%, and its development and utilization are promising. At present, the research on biomass conversion is mainly focused on conversion to fuels and chemicals. It has been found that the hydrothermal method can convert biomass into functionalized carbon materials and can be effectively used in the adsorption and electrochemical fields of heavy metal ions. This method is usually performed at about 200°C, and has significant advantages such as mild conditions and low energy consumption. However, since the hydrothermally prepared carbon material generally has a very low specific surface area, it is difficult to use in the catalytic field.
Recently, the researcher of the Department of Catalysis Materials at the National Institute of Materials Science, Shenyang Institute of Materials Science and Technology, Su Dangsheng and Dr. Wen Guodong, cooperating with Tian Zhijian, a researcher at the Dalian Institute of Chemical Physics, recently discovered that high specific surface area can be prepared by hydrothermal carbonization. Functionalized carbon catalyst material enriched with oxygen-containing surface. In the preparation process, the initial material concentration, the addition of surfactant, the change of carbonization temperature, and the addition of functional small molecules can control the morphology and size of the carbon material. The carbon material enriched in carbonyl and hydroxyl groups on the surface can efficiently catalyze the liquid phase reduction of nitrobenzene, and its performance is superior to many common carbon materials such as carbon nanotubes, nanodiamonds and graphite. It has been found that the spherical morphology has better catalytic performance, and the smaller the sphere size, the better the performance, which may be related to the smaller sphere size conducive to the exposure of active sites. The carboxyl acid group functionalized carbon material can be preferably used in the Beckmann liquid phase rearrangement reaction of cyclohexanone oxime, which is given as compared with conventional solid acid catalysts such as HY and ZSM-5 molecular sieves. Significantly high product selectivity. It has been found that weak Brønsted acids such as carboxyl groups are easily reacted, and the strong acid sites on the molecular sieves and the weak Lewis acid sites lead to the formation of by-products. These results indicate that although the acidic nature of the intrinsic oxygen-containing acidic groups on the carbon material is weak, it is suitable for reactions catalyzed by some weak Brønsted acids and can give superior performance over conventional solid acid catalysts. These results are published online in "Guodong Wen, Bolun Wang, et. al. Angew. Chem. Int. Ed. DOI: 10.1002/anie.201609047".
In recent years, the research group has done a series of work in this area (Angew Chem Int Ed, 2015, 54, 4105; ACS Catal, 2015, 5, 3600; ChemCatChem, 2014, 6, 1558; Phys Chem Chem Phys, 2015, 17 , 1567; Catal Sci Technol, 2014, 4, 4183; Chinese Journal of Catalysis, 2014, 35, 914). The research work was supported by the National Natural Science Foundation of China, the Liaoning Province Doctoral Startup Fund and the Chinese Academy of Sciences Strategic Pilot Fund.
Figure: Schematic representation of the preparation of carbon-enriched carbon catalytic materials on the surface by means of hydrothermal carbonization of biomass glucose. Carbon materials rich in carbonyl groups and hydroxyl groups on the surface can be effectively used in the nitrobenzene reduction reaction, and carbon materials rich in carboxyl groups on the surface can be used in the Beckmann rearrangement reaction.
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