Production and characterization of bio-oil and biochar from ablative pyrolysis of lignocellulosic biomass residues

Abstract

Agricultural residues are one of the large untapped sources of bio-energy in Thailand, with over 30 million tons available per year. They may be utilized to generate renewable liquid and solid fuels. In this work, pyrolysis of lignocellulosic biomass residues (corncobs, coconut shells, and bamboo residue) was carried out in an ablative pyrolysis reactor with rotating blades. Influences of inert carrier gas flows (5–15?L/min) and rotating frequency (4–8?Hz) at a fixed hot plate temperature of 500?°C on generating bio-oil were investigated. Characterization of bio-oil as well as biochar products was performed. Maximum bio-oil yield was found to be about 50% w/w for coconut shell at 5?L/min of flowrate and 8?Hz of the rotating frequency, and 45% w/w for bamboo residues at the same condition. For corncob, the highest bio-oil yield was 72% w/w at 5?L/min of flowrate and 6?Hz of the rotating frequency. Solid char yields were around 23–28% w/w. The heating values of the liquid oil and solid char were about 20–25 and 23–30?MJ/kg, respectively. Rotating blade ablative reactor was able to generate high yields of bio-oil for agricultural residues. The main compounds of the bio-oil obtained were phenolics, including furfuran, organic acids, aldehydes, alcohols, ethers, and ketones.     

生物油分离技术的研究进展

生物质是唯一可储存的、能实现CO2零排放的清洁可再生资源。通过快速热解将其转化为液态生物油是生物质利用的一种高效途径。生物油通过精制改性可制备生物柴油,而从中分离出高价值化学品是实现生物油快速商业化的方法。生物油的分离具有重要意义,本文综述了近年来用蒸馏、萃取、柱层析、分子蒸馏和超临界萃取方法分离生物油的研究进展及生物油中不同组分的化学用途。总结了生物油分离技术存在的主要问题,并展望了生物油分离研究的发展方向。     

Recent advances in the catalytic hydrodeoxygenation of bio-oil

Owing to the increasing interest in alternative energy, there is a focus on bio-oil production from biomass because it is an abundant and renewable energy source. Among the various kinds of biomass conversion technologies, pyrolysis has been investigated widely to produce bio-oil. However, the direct use of bio-oil is difficult because of its poor quality due to the large amounts of oxygen-containing compounds, such as acids, ketones, and esters. Therefore, an additional suitable upgrading process for bio-oil is required. Hydrodeoxygenation (HDO) is considered effective for the deoxygenation of bio-oil. This paper reviews the recent progress in the catalytic HDO of bio-oil. In addition, the effects of the solvent and catalyst applied to the HDO of bio-oil are reviewed intensively together with a discussion of the deactivation behavior of the catalyst during HDO.     

生物质热解气分级冷凝对生物油特性的影响

利用分级冷凝手段对成分复杂的生物质热解气在不同冷凝温度下的分离特性进行研究,将成分复杂的混合物依据自身露点的不同,通过控制冷凝温度,实现生物油的分组富集。对热解气在不同冷凝温度(300℃、100℃、0℃和-20℃)下生成的各级液体产物的物理特性和化学成分进行系统分析。生物质热解气经过分级冷凝处理后得到4组生物油样品,其中0℃时得到的生物油产率最大,超过液体总量的50%;其次是100℃时的冷凝产物,为分子量80~200的有机物,以杂酚类物质为主;300℃冷凝得到的产物为沥青类物质,不含水分,状似固体碳,没有流动性。分级冷凝能够很好地将水分和有机酸成分从生物油中分离出来,几乎所有的有机酸和超过80%的水分都富集在0℃和-20℃冷凝组分中。结合各组分GC-MS的分析结果,对乙酸、苯酚、愈创木酚和多环芳烃等生物油中典型有机组分的分布特性进行分析总结,得到各类物质在分级冷凝过程中的富集规律。     

生物质能源转化技术与应用(Ⅲ)——生物质热解液体燃料油制备和精制技术

生物质能源是唯一可再生、可替代化石能源转化成气态、液态和固态燃料以及其它化工原料或者产品的碳资源。随着化石资源的枯竭和人类对全球性环境问题的关注,生物质能源替代化石能源利用的研究和开发,已成为国内外众多学者研究和关注的热点。本系列讲座主要讲述以生物质资源为主要原料,通过不同途径转化为洁净的、高品位的气体、液体或固体燃料。本讲主要综述了生物质高压液化、快速热解液化制备液体燃料油技术现状、工艺及设备,并在总结生物质热解液体燃料油特性的基础上,总结了生物热解液体燃料油的物理法精制技术(包括脱水、添加溶剂和乳化)和化学法精制技术(包括催化加氢、催化裂解、催化酯化、水蒸气重整)的研究现状,并对其精制机理、优缺点进行了分析。随着制备和精制技术的深入研究,生物质热解液体燃料油可望替代汽油、柴油等化石燃料而越来越受到人们的关注。     

生物质连续裂解能源转化工艺与装置实验研究

介绍了连续热解生物质,使之产生出可燃气和生物燃油的裂解装置.试验表明,该装置可用于各种固体生物质的热解转化,并且以秸秆为例,研究了裂解过程的最佳操作工艺条件.对裂解所得的固体、液相和气相产物作了初步分析,获知生物油和可燃气的构成为可燃组分混合物.     

椰壳、椰壳渣与脱灰椰壳渣热解及热解动力学

用热重技术分析了椰壳类活性炭原料的热解过程，采用Coats-Redfern积分法求解了热解反应动力学模型。椰壳渣及脱灰椰壳渣热解失重过程主要集中在280~370℃之间，在热失重速率曲线上呈单峰，而椰壳热解失重主要集中在230~300℃和300~350℃两个温度范围，在热失重速率曲线上呈双峰。在低温段三者热解反应表观活化能差别较大，高温段差别较小，且最大反应速率均出现高温段。     

生物质热解制生物油及其提质研究现状

生物质能源作为可再生能源的重要组成部分,其综合高效利用在能源替代与补充、保护生态环境等方面具有重要的战略意义。生物油是生物质通过热裂解技术获得的液体产物,具有能量密度较高、环境友好、可再生及可直接输送等优点,可替代传统化石燃料推广使用,解决日益严重的能源紧缺与环境污染等问题。生物质热解制油技术的开发与利用,已成为新世纪可持续能源研究领域的重要课题之一。总结了近年来生物质热解制油技术的主要研究进展,重点关注热解反应器、催化热解技术与生物油的提质利用方面的研究,介绍了碱金属、氧化物和分子筛3种生物质热解催化剂,以及乳化、催化加氢、催化裂解、催化酯化和重整制氢5种生物质提质方法,最后对生物质热解技术的现状及发展趋势进行了总结和概括。     

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。     

蒙脱石的催化生物质热解特性

以纤维素和橡树叶为研究对象,探索了蒙脱石催化作用下热解产物的变化规律及机理。结果表明:蒙脱石负载促进纤维素向β-消除路径转化,导致活化能增加、DTG (微商热重分析曲线)峰值温度升高和热解速率降低,而对橡树叶的热解过程影响较小;蒙脱石可催化热解液体的2次裂解,使液体产率降低,气体产率增加,而对固体产物产率的影响较小,其中热解气体以H₂、CH₄和CO₂为主。蒙脱石表面和层间含有许多强酸性和弱酸性的Lewis (L)和Bronsted (B)酸性位点,可原位催化羧酸类物质发生脱羧基反应;同时对热解液体产物中糠醛和左旋葡聚糖酮的富集有明显的促进作用。     

Prediction of Biomass Pyrolysis Mechanisms and Kinetics: Application of the Kalman Filter

In order to predict the pyrolysis mechanisms of four different biomasses (Asbos (Psilocaulon utile), Kraalbos (Galenia africane), Scholtzbos (Pteronia pallens), and palm shell), a novel method called Kalman filter was investigated and the results were compared by regression analysis. Both analyses were applied to five different generalized biomass pyrolysis models consisting of parallel and serial irreversible-reversible reaction steps. The models consisting of reversible reactions in addition to parallel pyrolysis steps demonstrated a better fit with the experimental results. The pyrolysis step from biomass to bio-oil has the highest reaction rates compared with the other pyrolysis steps defined in the models. The Kalman filter is thus defined as a promising filtering and prediction method for the estimation of detailed pyrolysis mechanisms and model parameters, using minimum experimental data.     

ZSM-5/SBA-15复合催化剂制备及其对生物质热解制生物油

通过表面响应法，以Box-Behnken试验原理，对生物质（玉米秸秆）的非催化热解进行三因素试验，其中生物油产率为响应值，温度、升温速率、氮气流速为自变量，确定最大生物油产率的工艺参数进行催化热解。以硅酸四乙酯为硅源，通过水热合成法合成了复合催化剂ZSM-5/SBA-15，并进行玉米秸秆的微波催化热解产物分析。通过XRD、SEM、TEM、NH3-TPD进行催化剂表征，得到复合催化剂不仅具有介孔催化剂SBA-15的性质，且兼备微孔催化剂ZSM-5的性质。通过GC-MS分析，复合催化剂ZSM-5/SBA-15的加入，相比非催化热解烃类收率（6.42%）和酚类收率（39.65%）都有所增加。     

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。     

生物质能源转化技术与应用(Ⅰ)

生物质能源是唯一可再生、可替代化石能源转化成液态和气态燃料以及其它化工原料或者产品的碳资源。随着化石能源的枯竭和人类对全球性环境问题的关注,生物质能替代化石能源利用的研究和开发,已成为国内外众多学者研究和关注的热点。本文综述了我国年可获得生物质资源量达到3.14亿吨煤当量,其中秸秆和薪材分别占 54% 和 36%;现有180多亿吨林木生物质资源量、8~10亿吨可获得量和3亿吨可作为能源的利用量。生物质能转化利用的主要途径是:热化学高效转化利用的热解气化发电(供热、供气)、快速热解制备液体燃料和生物质气化合成液体燃料,以及生物化学转化技术等。同时,论述了目前已经进行的生物质研究开发技术和产业化利用进展。     

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     

生物油气化技术的研究进展

概述了国内外关于生物油水蒸气重整、裂解气化和超临界水气化以及其模型化合物气化和生物油气化制备合成气的净化等技术的研究进展,指出无论从经济方面还是技术方面,生物质热解油气化制备合成气都优于生物质直接气化制备合成气,但目前这一技术还处于实验室研究阶段。     

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。     

Development of process model of a rotary kiln for volatile organic compound recovery from coconut shell

The volatile organic compounds (VOCs) contained in coconut shell are wasted in the carbonization process of coconut shell due to the difficulty of recovery. The VOCs recovery is useful and necessary, because the VOCs are a sustainable energy source, and the recovery is an economically feasible project. A simulation model of the VOC recovery process from coconut shell using a rotary kiln is developed to investigate the process characteristics and the role of model parameters. The model includes the energy and material balances for the processing solid and the gas in the kiln. The validity of the proposed model is partially examined with the experimental results. From the simulation, the dominant heat transfer mechanism is determined for the understanding of the process operation. In addition, the optimal operating conditions of the rotary kiln are found for the use in the design and control of the kiln.     

Pyrolysis of coconut shells for the manufacture of carbon sorbents

Data on the effect of coconut shell pyrolysis conditions on the yield and properties of pyrolysis products and the results of pilot tests are considered. Coconut shells from Tra Vinh province (Vietnam) were used for the experiments.     

椰衣微波热解工艺的响应面法优化及液体产物组成分析

利用Box-Behnken试验设计，采用响应面法对椰衣微波热解工艺进行优化，考察了热解温度、氮气流速、升温速率和热解时间对液体产物产率的影响。试验结果表明：回归方程模型拟合较好且显著。各个因素对液体产物的产率影响的主次顺序为热解温度>氮气流速>热解时间>升温速率。最佳热解条件为热解温度550℃、氮气流速80 mL/min、升温速率20℃/min、热解时间25 min，在此条件下液体产物产率为38.28%。对液体产物的性质和组成分析发现：优化条件下得到的液体产物中含水量为14.32%，pH值为3.78，热值为24.61 MJ/kg。通过GC-MS对液体产物进行分析，最佳条件下得到的液体产物中主要含有酚、醛、酸、酮类化合物，分别为84.35%、6.01%、3.37%、2.05%，其中酚类化合物的量最高，包括苯酚（33.51%）、对甲酚（9.71%）、2-甲氧基苯酚（10.99%）和4-乙基-2-甲氧基苯酚（5.57%）。