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Study on Alcoholysis of Bamboo in Subcritical and Supercritical Methanol

Author: JiangZuo
Tutor: ChenJiZhong
School: Zhejiang University
Course: Chemical Engineering
Keywords: Phyllostachys pubescens subcritical alcoholysis supercriticalalcoholysis molecular sieve alcoholysis products
CLC: TQ351.0
Type: PhD thesis
Year: 2012
Downloads: 47
Quote: 0
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Abstract


Along with the fossil fuel being used up and the global environment being destroyed badly, it is extremely urgent to develop a clean and renewable energy. If biomass is utilized reasonably, it is not only a renewable energy, but also a clean energy. In recent years, the liquefaction technology of supereritical fluid taking methanol as the solvent and reaction medium has got extensive research. Bamboo is an ideal renewable resource as one of the most important forest resources in China with wide distribution and large amount. Based on summarizing of many literatures, an experimental scheme that bamboo was liquefied in subcritical and supercritical methanol with or without K2CO3and MCM-41has been worked out, and then, a series ofexperimental researches have been carried out. Results here will contribute to the understanding the disciplines of alcoholysis, also provide guide for product processing design and high value-added product development.Firstly, Bamboo powder (BP) collected from Shengzhou, Zhejiang. were deploymerized with supercritical methanol in a stainless-steel magnetically stirred autoclave. The alcoholysis products were analyzed with GC-MS system. The effect of reaction temperature, reaction time, and on the yields of the alcoholysis products was examined. The experiment results show that BP were more deeply deploymerized by methanol under supercritical condition than under subcritical condition and the yields of the alcoholysis products are proportional to reaction time. Dozens of organic compounds were detected by GC-MS analysis from supercritical alcoholysis products, and most of the species detected are furfural which is the main product of the cellulose and the hemicellulose and oxygen-containing organic chemicals, especially the methoxy compounds. A large number of phenol derivatives which can be used as high-value-added chemicals and farty acid esters which can be used to produce high class lubricating oils and bio-oil with high quality were detected from supercritical alcoholysis products. Moreover, the results show that the big molecule of BP, especially the cellulose and the hemicellulose, can be deploymerized under relatively gentl℃e condition(<300癈)by using supercritical alcoholysis, which will offer an important means to understanding the molecule structure of the bamboo. Simultaneity, it will provide theoretical basis of exploiting new technology for the effective utilization of bamboo.Secondly, in this paper, mesoporous molecular sieve MCM-41was perpared hydrothermally with TEOS, CTBA, NaOH as source materials and then used as supports for mesoporous molecular sieve Zr-MCM-41with Zr(NO3)4·5H2O as Zr source and H2O as solvent via impregnation method.Finally, in this paper, as catalyst. MCM-41and K2CO3were added into the subcritical and supercritical alcoholysis system of bamboo, the effects of reaction temperature, reaction time, bamboo powder and solid-liquid ratio of methanol and catalyst content were examined. The results show that the reaction rate with this two catalysts can be improved to varying degrees, of which the catalytic effect of K2CO3is better, and MCM-41can be recycled, which is an ideal catalyst to create an environment friendly; the catalytic mechanism of this two catalysts is different, such as MCM-41zeolite whose pore size is uniform, ordered the six-party, with the rapid proliferation of high specific surface area and adsorption capacity, can make it optional type for the macromolecular favorable space and effective acid active centers of reaction, and make the C10alcohols, ethers, esters liquid product increased significantly, especially the methyl acetate content, but it has little contribution to the degradation of lignin; K2CO3serves to dissolve the lignin, and reduce the generation of oxygen heterocycles. By using the model function to fit the isothermal kinetics of catalytic alcoholysis process, it is found that with K2CO3, more lignin begin to degrade, and alcoholysis mechanism is more complex, which can not be described with a simple step reaction; with MCM-41, no matter in the subcritical or supercritical process, the activation energy has reduced to varying degrees, the reaction is affected by temperature less, and the reaction reaches the equilibrium quickly.

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