预处理生物质催化热解制取生物油的研究进展

总结了常见的生物质预处理方法,分析了不同催化剂的添加对生物油特性的影响,最后讨论将生物质预处理和催化热解联合作用对热解过程及产物的影响。认为合理的生物质预处理方法能改善生物油的品质,应结合生物质原料特性"因材施教";同时应深入探究催化剂在热解过程中的作用机理,从而选择最佳的预处理方法和催化剂进行联合热解,达到优化生物油特性的目的。     

酸洗-烘焙预处理对生物质热解产物的影响

选用稻壳为原料,进行酸洗-烘焙联合预处理后,于550℃下热解,详细分析了固、液、气热解三相产物,考察酸洗-烘焙联合预处理对稻壳热解产物特性的影响。结果表明联合预处理移除了生物质中大部分碱金属和碱土金属,并且C元素含量增加,H和O元素含量逐渐减小,高位热值增加,因此样品的燃料特性得到了提高;酸洗后,热解生物油收益率显著提高,并随着烘焙温度的升高减小,生物焦则相反;热解产物中,不可凝气中可燃成分含量增加;生物油含水率减少,但是,pH和高位热值明显增加,化学成分中糖类产量增加,酸类、酮类和呋喃类产量减少,生物焦孔隙结构得到发展,比表面积增加,稻壳灰中二氧化硅的相对含量增加,达到98.91%。根据上述实验结果,提出了一种新的稻壳资源综合利用系统。     

富氮生物质热解气的分级冷凝特性研究

采用固定床热解反应系统对稻壳负载尿素进行了热解耦合分级冷凝的研究,实验采用三级冷凝的方法,对比了热解温度(400、500、600℃)和冷凝温度(30、60、90℃)对产物分布和富集的影响,研究了生物质富氮热解和分级冷凝的机理。结果表明:富氮热解促进了Maillard反应产生含氮杂环物;分级冷凝富集规律明显,一级生物油富集了高露点的酚类,二级生物油富集了低露点的含氮杂环物;提高热解温度可以增加二级生物油中含氮杂环物的含量和降低二级生物油水分含量,热解温度为500℃时,液体产物产率和酚类产物产率最大;提高冷凝温度能增强各级油组分的富集效果,并降低一级生物油水分含量,一级冷凝温度为90℃时,水分几乎完全富集在第二级中,且一级生物油酚类产物含量最高。     

预处理法提高生物质热解产物品质的研究进展

生物质水分含量高、能量密度低、储存运输成本高等缺点制约着其转化利用。预处理技术是提高生物质热解产物品质的有效方法之一。为了研究高效经济的预处理技术,本文总结了国内外生物质预处理技术的研究,对干燥法、稀酸法、水热法、烘焙法和生物法等预处理技术进行了重点分析,发现干燥法和烘焙法等技术极具潜力,但是目前的研究仍存在不足,今后还需研究成本低、产率高、污染小的预处理技术,并对预处理技术的发展提出了建议。     

富氮生物质热解气的分级冷凝特性研究

采用固定床热解反应系统对稻壳负载尿素进行了热解耦合分级冷凝的研究，实验采用三级冷凝的方法，对比了热解温度(400、500、600℃)和冷凝温度(30、60、90℃)对产物分布和富集的影响，研究了生物质富氮热解和分级冷凝的机理。结果表明：富氮热解促进了Maillard反应产生含氮杂环物；分级冷凝富集规律明显，一级生物油富集了高露点的酚类，二级生物油富集了低露点的含氮杂环物；提高热解温度可以增加二级生物油中含氮杂环物的含量和降低二级生物油水分含量，热解温度为500℃时，液体产物产率和酚类产物产率最大；提高冷凝温度能增强各级油组分的富集效果，并降低一级生物油水分含量，一级冷凝温度为90℃时，水分几乎完全富集在第二级中，且一级生物油酚类产物含量最高。     

预处理催化法对生物质热解的影响研究进展

叙述了国内外生物质预处理技术和催化剂的选择研究现状,分析了干燥法、粉碎法、酸洗法和烘焙法等一系列预处理技术的优缺点,总结了金属盐、金属氧化物、分子筛等催化剂在生物质热解过程中的应用。认为可以根据不同生物质的基本特性,扬长避短,进行物理、化学、生物预处理方法的交叉式研究,逐步完善预处理方法的作用机理;应先对生物质热解催化剂的作用机理展开全面研究,再配合最佳的催化剂和预处理技术,从而实现预处理技术与催化剂在生物质热解过程中的完美结合。     

水洗-烘焙联合预处理对稻壳微波热解产品特性的影响

预处理技术能提高生物质热解产物的品质。本文研究了水洗-烘焙联合预处理技术对稻壳微波热解的产物特性的影响,结果表明:水洗-烘焙联合预处理技术增加了固体产率,而减少了液体和气体的产率;联合预处理技术提高了稻壳微波热解气体产物的品质,气体产物中CO₂含量减少,CH₄和H₂的含量增加,气体产物的热值提高到13MJ/m³;联合预处理技术提高了稻壳微波热解液体产物的品质,增大了液体产物中苯酚类和糖类的含量,减少了液体产物中酸的含量,简化了液体产物的成分。     

四种原料生物油-酚醛树脂胶粘剂特性研究

利用生物质快速热解液化产物制备燃料或化工产品已成为国内外的研究热点。将四种生物质原料(落叶松、杨木、棉秸秆和玉米秸秆)快速热解液化产物作为苯酚替代物,由此制备出不同种类的热解生物油-PF(酚醛树脂)胶粘剂,并探讨了胶粘剂胶接强度与热解生物油组成的关系。结果表明:落叶松热解生物油-PF胶粘剂的胶接强度最大(1.277 MPa),玉米秸秆热解生物油-PF胶粘剂的胶接强度最小(1.021 MPa);胶粘剂的胶接强度主要与热解生物油中酚类物质含量有关。     

生物质微波热解产生物油的影响因素研究进展

生物质作为可再生资源具有低成本、分布广泛且易得等优点,生物质能的开发利用可有效缓解能源压力,减少环境污染。微波热解技术是生产燃料油和高附加值化学品的有效方法之一,与传统的热解相比,微波热解具有加热速率快、均匀性好、选择性加热、节能与易于控制等优点。在简单分析微波热解产物分布的基础上,详细综述了近年来微波热解生物油产率的影响因素,主要包括热解温度、功率、吸波剂、催化剂、原料预处理、加热时间、原料性质和物料尺寸等因素;最后,总结和展望了微波技术在生物质催化热解制备生物油领域应用中存在的问题、解决途径和发展前景。     

生物质热解制备高品质生物油研究进展

生物质热解制备生物油是能源富集的有效途径,是实现碳闭路循环的重要方式,作为一种环境友好型技术受到广泛关注和研究。然而,生物质热解反应过程复杂,生成的生物油热值低、含氧量高及强酸性等特点,制约了生物油的分离提纯、制备合成气以及燃烧等方面的应用,生物油品质的提升迫在眉睫。本文从生物质三组分、原料预处理、反应参数、催化剂、反应器等方面综述了影响生物油品质的主要因素,分析了生物油的特点,不同预处理下生物质特性的变化与生物油的关系,催化剂参与的热解行为对提升生物油品质的导向作用以及常用生物质热解反应器的特点,并对影响生物油品质的主要因素进行了总结。最后,针对影响制备高品质生物油的诸多因素提出建议,以期为制备高品质生物油提供参考和借鉴。     

微波对生物质原料预处理及热解的作用研究进展

综述了生物质通过微波裂解转化制备生物燃料的新方法,重点比较了微波干燥预处理与常规干燥方法,分析了微波干燥后的生物质特性、微波作为热源对生物质裂解的影响及微波裂解机理. 对生物质微波裂解未来的发展方向作了预测,包括寻找低耗的生物质原料、高效的催化剂、开发高品位的生物油及对微波裂解的机理进行深入研究.     

Liquid phase equilibrium of phenol extraction from bio-oil produced by biomass pyrolysis using thermodynamic models

Utilization of biomass as a new and renewable energy source is being actively conducted by various parties. One of the technologies for utilizing or converting biomass as an energy source is pyrolysis, to convert biomass into a more valuable product which is bio-oil. Bio-oil is a condensed liquid from the vapor phase of biomass pyrolysis such as coconut shells and coffee shells. Biomass composition consisting of hemicellulose, cellulose, and lignin will oxidize to phenol which is the main content in bio-oil. The total phenolic compounds contained in bio-oil are 47.03% (coconut shell) and 45% (coffee shell). The content of phenol compounds in corrosive bio-oils still quite high, the use of this bio-oil directly will cause various difficulties in the combustion system due to high viscosity, low calorific value, corrosivity, and instability. Phenol compounds have some benefits as one of the compounds for floor cleaners and disinfectants which are contained in bio-oil.The correlation between experimental data and calculations shows that the UNIQUAC Functional-group Activity Coefficients (UNIFAC) equilibrium model can be used to predict the liquid–liquid equilibrium in the phenol extraction process of the coconut shell pyrolysis bio-oil. While the Non-Random Two Liquid (NRTL) equilibrium model can be used to predict liquid–liquid equilibrium in the extraction process of phenol from bio-oil pyrolysis of coffee shells.     

生物质快速裂解液化技术的研究进展

综述了生物质能转化的技术途径,生物质热裂解的４种方式,着重介绍了生物质快速裂解直接液化的各种著名工艺和生物质燃料油的特点及其开发和利用。指出了目前生物质裂解技术以及生物质油深加工的难点和发展方向。     

蔗渣纤维素乙醇的预处理技术研究进展

从蔗渣的物化特性及预处理的必要性出发,综述了近年来国内外预处理蔗渣方面发展的不同技术途径(包括物理法、化学法、生物法和联合法)及其研究进展,对各种技术的作用效果和特点进行了总结和对比分析,并对蔗渣预处理技术的发展方向予以展望。蔗渣作为糖厂的主要副产物,具有量大、集中且纤维含量高等特点,是生产第二代生物乙醇的重要潜在原料之一,对其进行有效预处理是利用其制取生物乙醇的关键,直接影响着后续的酶解糖化和乙醇发酵效果。     

Pyrolysis of microalgae biomass over carbonate catalysts

Microalgae are seen as potential biomass to be used in a biorefinery concept. Several technologies can be used to convert microalgal biomass, but pyrolysis is viewed as a unique pathway to obtain valuable chemicals distributed in three phases: liquid (bio-oil), gas (bio-gas) and solid (bio-char). The liquid phase, bio-oil, usually presents higher heating value than raw biomass, but acidity and oxygen content are major drawbacks. In situ catalyzed pyrolysis can help to decrease the oxygen content and acidity of pyrolytic bio-oils. Chlorella vulgaris and Scenedesmus obliquus were pyrolyzed in a fixed-bed reactor using commercial carbonate catalysts (Li₂CO₃, Na₂CO₃, K₂CO₃, MgCO₃, SrCO₃ and MnCO₃). The catalysis pyrolysis temperature (375 °C) was selected from thermal degradation profiles obtained using thermogravimetry under nitrogen flow and corresponds to the maximum degradation rate for both microalgae. In spite of similar volatile and fixed carbon contents, microalgae performed differentially during pyrolysis mainly due to the different contents of carbohydrates, oils and proteins. Chlorella vulgaris and Scenedesmus obliquus showed bio-oil yield in the range 26–38 and 28–50 wt%, respectively. Only sodium carbonate was able to decrease the bio-char yield, confirming that carbonate catalysts prompt simultaneously gasification and carbonization reactions. Fourier transform infrared spectra of produced bio-oils showed a net decrease of acidity, associated with carbonyl species when carbonate catalysts were used. Bio-char morphology, for both microalgae, showed evidence of melting and resolidification of cell structures, which might be due to the lower melting points of the pyrolysis products obtained from proteins and lipids. © 2020 Society of Chemical Industry     

The influence of temperature on the yields of compounds existing in bio-oils obtained from biomass samples via pyrolysis

The influence of temperature on the compounds existing in liquid products obtained from biomass samples via pyrolysis were examined in relation to the yield and composition of the product bio-oils. The product liquids were analysed by a gas chromatography mass spectrometry combined system. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiacol and their alkylated phenol derivatives. Thermal depolymerization and decomposition of biomass structural components, such as cellulose, hemicelluloses, lignin form liquids and gas products as well as a solid residue of charcoal. The structural components of the biomass samples mainly affect the pyrolytic degradation products. A reaction mechanism is proposed which describes a possible reaction route for the formation of the characteristic compounds found in the oils. The supercritical water extraction and liquefaction partial reactions also occur during the pyrolysis. Acetic acid is formed in the thermal decomposition of all three main components of biomass. In the pyrolysis reactions of biomass: water is formed by dehydration; acetic acid comes from the elimination of acetyl groups originally linked to the xylose unit; furfural is formed by dehydration of the xylose unit; formic acid proceeds from carboxylic groups of uronic acid; and methanol arises from methoxyl groups of uronic acid     

生物油储存稳定性的研究进展

保持良好的储存稳定性是生物油作为替代能源进入市场应用的关键之一。本文介绍了生物油的基本特性、储存稳定性的研究现状以及测量评价生物油储存稳定性的参数和方法,并重点介绍了目前提高生物油储存稳定性的方法,分析了不同方法的优缺点以及目前所面临的问题,并提出了深入生物质快速热解机理并制定关于生物油储存稳定性及应用的标准将有助于生物油的市场商业应用。     

Microstructure development of chars derived from high-temperature pyrolysis of barley (Hordeum vulgare L.) hulls

Fast pyrolysis of biomass is a thermochemical conversion process that provides an economic production of pyrolysis oils/bio-oils. The process also results in a residual solid residue, char, that comprises carbon and mineral ash that can be a potential source of fuel or a valuable co-product. Depending on the exposure time and temperature, pyrolysis can increase the interfacial surface areas of the residual char thereby enhancing its absorptive capacity. Char residues can be used for physical or chemical absorption and as catalyst support or base material for fertilizers. The reactions that occur during char combustion or gasification are heterogeneous hence the reaction rates are microstructure dependent. Ashes from biomass derived chars can be high either in calcium or silica with the latter exceeding 90% levels in certain grain hull residues. Depending on the microstructural transformations which occur during thermal degradation of the biomass, silica-laden ashes can be a potential source of pozzolan for the construction industry. In this study, the microstructure of the chars derived from fast pyrolysis of barley-hull was studied using environmental scanning electron microscopy under low vacuum conditions. The results indicate a gradual increase in convoluted microstructure related to the superficial organization of epidermal cells, including stomata and trichomes that eventually assume the form of various morphotypes of phytoliths. Characterization of the temporal events of high temperature evolution of the hull microstructure provides practical implications of its combustion reactivities and also provides information useful for predicting potential masonry applications for the resulting ash.     

Pretreatment and feeding of biomass for pressurized entrained flow gasification

In our contribution we have compared advantages and disadvantages of four different methods for biomass (wood) thermal pretreatment and grinding for feeding of the biomass-fuel to pressurized entrained flow gasifier. The four methods of pretreatment and feeding involve drying, torrefaction, flash pyrolysis and dissolution of wood in organic solvents.