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木质纤维素生物质水热液化的研究进展 总被引:1,自引:0,他引:1
对木质纤维素生物质的模型化合物(纤维素、半纤维素和木质素)的水热液化机理进行了剖析。纤维素和半纤维素降解路径主要是水解成单糖并进一步生成酸类、醛类、酮类等。木质素结构较复杂,液化产物中含有大量苯系化合物,具体木质纤维素生物质的水热液化反应更为复杂,不同的木质纤维素生物质原料水热液化产生的生物油含量不同;分析了原料种类、催化剂、反应温度、反应压力、对水热液化过程以及产品组成和收率的影响;对生物质水热液化制备生物油的研究进行了展望,认为发展木质纤维素生物质水热条件下降解的数学模型,开发新型反应器、研制催化剂,是今后生物质水热液化工程实验的发展方向。 相似文献
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超临界水直接液化褐煤是高湿低阶褐煤高效转化与资源化利用的一个重要的发展方向。阐述了超临界水液化制油的优势,总结了液化过程中的热解反应、脱杂反应、缩聚反应等关键反应;重点论述了操作条件(温度、停留时间、压力、溶剂等)对反应过程的影响机理;针对油品质的升级,总结了催化剂在液化油升级中的应用,分析了煤本身所含的铁系催化剂的催化特点,总结了贵金属在催化升级中的研究现状及部分过渡金属合金的高效催化特性;强调了煤与生物质共同液化的协同作用。对液化过程中存在的问题进行了总结,并展望了未来的工业放大应用。 相似文献
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含氧过多是限制藻类液化油实际应用的最大障碍,高含氧量意味着热值低、稳定性差、酸性强等,因此必须经过脱氧改质才能使其转化为高品位燃油。结合最新研究进展,首先选取藻类液化油中具有代表性的成分脂肪酸为模型化合物,总结了催化剂组成和反应气氛对脂肪酸脱氧机理及反应活性的影响。其次对目前国内外藻类液化原油及其轻馏分的催化脱氧改质研究现状进行综述。最后指出藻类液化生物油催化改质存在的问题,并对改进方法及未来的发展进行了展望。 相似文献
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生物质是种天然可再生资源,近些年来学者们对其加工利用技术做了大量研究工作,常压催化液化技术就是其中之一。对国内外生物质常压催化液化技术的发展和研究现状进行了介绍,分析了液化剂和催化剂对液化过程及产品组成的影响,提出了生物质常压催化液化技术存在的主要问题及未来研究的方向,展望了生物质利用的发展前景。 相似文献
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Kátia D. Oliveira Pedro H. G. Cademartori Graciela I. B. Muniz Luiz F. L. Luz-Junior Cícero N. Ávila-Neto 《加拿大化工杂志》2023,101(5):2403-2422
Kraft pulp production generates residues and by-products of significant importance to the mill. Solid residues from forestry activities are commonly used to generate steam in power boilers. In the recovery cycle, black liquor generates steam (and subsequently energy) by burning in the Tomlinson boiler, while white liquor is regenerated. Well-developed alternative technologies can use these residues and by-products to generate different types of biofuels. This review addresses the use of such technologies integrated with Kraft mills, in the concept of biorefineries, showing advantages, disadvantages, and successful examples. Solid residues from forestry can be used to produce bio-oil through processes such as fast pyrolysis and hydrothermal liquefaction. Bio-oils are currently used for heating through combustion in commercial/industrial boilers, but greater appreciation occurs if used as biofuels, which is done through catalytic upgrading processes. Black liquor gasification generates synthesis gas, which can be burned for energy co-generation, used to produce synthetic fuels, or as a hydrogenating agent for bio-oil or crude tall oil catalytic upgrading. Kraft biorefineries are gradually being implemented, justifying efforts to improve existing and new biomass conversion technologies. 相似文献
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生物炭具有环境友好、来源广泛、成本低廉等优点,作为催化剂及催化剂载体被广泛应用于热转化过程,但存在易结焦失活、产物定向调控机理尚不明确等问题。对生物质炭基催化剂应用于热转化过程的研究进行了综述,介绍了生物质炭基催化剂制备、改性(杂原子掺杂和金属负载)方案的研究现状。从常规催化热解、微波辅助热解、焦油脱除、酯化合成运输燃料和水热液化5个方面对炭基催化剂的应用进行讨论,并指出探索催化剂深层次的催化机理以及构建具有多级孔隙结构的炭基催化剂以定向生产高值化学品是未来的研究方向。 相似文献
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在过去的二十年里,利用常压催化液化法将木质生物质尤其是纤维素转化为小分子化学品的研究已经取得了一定的成果,近年来,常压催化液化法开始被应用于甲壳素生物质向小分子化学品转化的研究,极大地丰富了液化产物的种类尤其是含氮小分子化学品的类型。本文对常压下酸催化的纤维素与甲壳素在不同溶剂中液化生成的小分子化学品进行了总结,并重点对其液化机理的研究进展进行了阐述。提出了纤维素与甲壳素液化制备小分子化学品及机理研究中存在的一些问题及解决途径的建议,并对甲壳素的液化研究进行了展望。 相似文献
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Decomposition of the tar residue from oil distillation was carried out under hydrothermal conditions using a batch reactor at 623–673 K and 25–40 MPa, with and without K2CO3 as a catalyst. The reaction scheme for tar decomposition was determined as follows: the liquefaction and dissolution process of tar occur first and then intermediate chemical compounds are transformed into lighter molecular weight species. The presence of K2CO3 activates the dissociation of molecular hydrogen to facilitate hydrogenation reactions. The main products from the decomposition of tar were phenol, biphenyl, diphenylether (DPE), and diphenylmethane (DPM). These results indicate that hydrolysis was important in the cleavage of the macromolecular structure of tar under both catalytic and non‐catalytic hydrothermal conditions. This method can be developed for efficient tar liquefaction to generate high yields of valuable chemicals in an environmentally friendly way. 相似文献
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At the Paul Scherrer Institut (PSI) a continuous process for the catalytic hydrothermal gasification of wet biomass to synthetic natural gas (SNG) has been developed. The catalytic reactor is operated at temperatures of 400–450 °C and pressures of 25–30 MPa. Salts contained in the biomass and released during the liquefaction step are continuously withdrawn in the supercritical salt separation step and recovered as a concentrated brine upstream of the catalytic reactor. The recovered salts may be recycled as valuable nutrients or fertilizers after a certain work-up.Salt management was identified as critical issue in many different hydrothermal processes such as supercritical water oxidation (SCWO) and in catalyzed or non-catalyzed gasification technologies in near- and supercritical water. In this article we focus on the influence of organics, in this case glycerol and its hydrothermal degradation products, on the continuous salt separation performance. In the presence of organics higher temperatures are needed in the salt separator for an efficient salt separation and recovery due to a higher overall fluid density in the presence of glycerol compared to the density of pure water at the same conditions. Increasing temperatures in the salt separator lead to an increased degradation and, in particular, gasification of the glycerol. The salt studied, i.e. K3PO4, catalyzed the gasification of the glycerol to CO, H2, CO2, and CH4 as well as the water gas shift reaction. Due to the increased glycerol gasification at 460 °C in the salt separator, the fluid mixture density was lowered to similar values of pure water under the same conditions. Hence, at the fluid temperature of 460 °C in the salt separator the same salt separation performance was observed for water–K3PO4 and for an aqueous mixture of 20 wt.% glycerol with K3PO4. 相似文献
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Changwei HU Yu YANG Jia LUO Pan PAN Dongmei TONG Guiying LI 《Frontiers of Chemical Science and Engineering》2011,5(2):188
Biomass is considered as a renewable and alternative resource for the production of fuels and chemicals, since it is the only carbon and hydrogen containing resource that we can find in the world except for fossil resources, capable of being converted to hydrocarbons. The pyrolytic liquefaction of biomass is a promising way to convert biomass to useful products. This paper briefly surveys the present status of the direct catalytic pyrolysis for the liquefaction of biomass. The direct use of catalysts could decrease the pyrolysis temperature, increase the conversion of biomass and the yield of bio-oil, and change the distribution of the pyrolytic liquid products then improve the quality of the bio-oil obtained. The fact that biomass is in solid state present great challenges for its conversion and for the effective use of catalysts due to the bad heat transfer characteristics and bad mass transfer properties. These barriers appeal for the development of a new catalyst and new catalytic process as well as the integration of both. Process design and process intensification are of significant importance in the catalytic conversion of biomass. 相似文献
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Hydrothermal Liquefaction of Cypress: Effect of Water Amount on Structural Characteristics of the Solid Residue 下载免费PDF全文
Hydrothermal liquefaction of cypress was performed in an autoclave with various amounts of water. The obtained acid‐soluble and acid‐insoluble solid residues were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, sugar analysis, elemental analysis, and nuclear magnetic resonance to help understand the reaction mechanisms of this process. The characteristics of solid residues were significantly affected by the water amount. Cellulose was more stable at high water amount and hemicelluloses were much more reactive than cellulose. Comparison of nuclear magnetic resonance spectra of milled wood lignin and milled solid residues indicated a significant cleavage of the side chains. The components of milled solid residues were mainly derived from decomposition and repolymerization of lignin. The decomposition of the side chains was substantial for lignin depolymerization during hydrothermal liquefaction. 相似文献
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Mariko Yoshioka Yoshiyuki Nishio Daisuke Saito Hironori Ohashi Masayuki Hashimoto Nobuo Shiraishi 《应用聚合物科学杂志》2013,130(1):622-630
The liquefaction of starch in the presence of commercial polyol resulted in liquefaction products (LPs) with much lower hydroxyl values compared to those resulting from glycerol liquefaction. With the use of the obtained LPs (as initiators) and a catalytic amount of potassium hydroxide, oxypropylation was conducted under mild conditions (at 120°C, inner pressure generation of <0.2 MPa). Urethane resin foams were prepared from the obtained biopolyols. The reactivities of the biopolyols toward isocyanates were almost the same as those of commercial polyols. The physical properties of the obtained foams were as good or better than the ones obtained with the commercial polyols, including the sucrose/glycerol polyol GR‐84T. The biomass content values of the foams prepared with the biopolyols ranked among the highest in the world. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
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B. N. Kuznetsov 《Catalysis in Industry》2009,1(3):250-259
Increasing interest in the use of resources of organic raw materials alternative to petroleum stimulates researchers to study
the catalytic intensification of fossil coal and vegetable biomass conversion. The industrial use of the developed technologies
is restricted by the problem of enhanced catalyst deactivation. The main reasons for catalyst deactivation in solid organic
raw materials conversion are considered in the review. The possible ways of the successful solution of the problem of catalyst
deactivation in the processes of coal and biomass liquefaction and gasification and wood delignification and hydrolysis are
exemplified by the studies accomplished over the last decade. In the case of technologies using the synthetic catalysts, the
methods of their regeneration developed for the catalytic processing of heavy petroleum residues can be applied. The catalyst
regeneration is not demanded for the processes accomplished in a fluidized catalytic bed under the conditions of catalyst
loss as a result of its attrition and in the case of the application of melted catalysts, cheap iron-containing catalysts,
catalytically active slag materials, and natural minerals. The substitution of dissolved catalytic systems for solid catalysts
allows for the diminishing of their deactivation in the processes of wood delignification and hydrolysis. 相似文献