生物质与烟煤程序升温共热解产物特性分析

研究了富含半纤维素的玉米芯(CB)和富含木质素的松木屑(SD)分别与烟煤(YL)程序升温共热解产物产率和组成变化规律,并对焦油族组成进行分析。结果表明:生物质与煤共热解造成热解产物组成和产率显著变化,且其变化程度与生物质的组成和结构有关。对于富含纤维素的玉米芯与烟煤共热解过程,玉米芯质量掺混质量比为75%时,共热解气体产率减小18.87%,其中CO2产率减少29.15%,而热解水产率增加16.77%。由于半焦和玉米芯中碱/碱土金属,尤其是K对焦油中重质组分裂解具有催化作用,共热解焦油中沥青质产率减小43.40%,而极性组分增加63.21%。与富含半纤维素类的玉米芯不同,富含木质素的松木屑与烟煤共热解造成气体和焦油产率增加,而半焦和热解水产率略有减小,气体中CO2和CO略有增加。松木屑中活性H的转移作用,造成共热解焦油中脂肪烃产率增加,极性组分产率减少。松木屑掺混质量比为50%时,脂肪烃增加89.30%,而极性组分减小17.40%。     

高硫煤与生物质共热解时有机硫的迁移规律

选取晋南和宁东地区的两种高硫煤作为研究对象,用HCl-HF-CrCl_2对煤样进行脱矿物质处理。将脱矿物质煤与稻壳和木屑两种生物质分别按不同质量比进行混合,在不同温度下共热解,研究了混合半焦收率的实验值与计算值的差异,以及脱矿物质煤与生物质共热解对煤中有机硫逸出的促进作用,并对有机硫逸出率最大的样品进行了FTIR,XPS,BET表征,探讨了生物质促进煤热解过程中有机硫逸出的机理。结果表明:当升温速率为15℃/min,温度低于700℃时,脱矿物质煤与生物质共热解存在明显的协同效应,使得混合样热解的有机硫逸出率高于煤单独热解时的有机硫逸出率。FTIR分析表明脱矿物质晋南煤与生物质共热解过程中—■键消失,说明协同效应促进亚砜的分解;XPS分析表明最大有机硫逸出率下有机硫的种类及含量都减少,变化最明显的是脂肪族硫化物和砜类。     

生物质与塑料共热解技术的分析方法及反应器研究进展

共热解技术是生物质与塑料高质化转化和高值化利用的重要方向。掌握生物质与塑料共热解分析技术及发展趋势,有利于加快对生物质、废塑料等废弃物的处理和利用。通过介绍生物质与塑料共热解技术的最新研究进展,归纳共热解过程动力学模型以及各组分之间的协同效应,讨论生物质与塑料在不同方法和反应器下共热解的表征。生物质和塑料共热解可降低热转化所需活化能,共热解协同效应可促进液态和气态产物生成。热解温度、加热速率和热解时间是影响共热解过程和产物的主要因素。文章为生物质与塑料共热解反应器类型的选择和相关技术分析提供参考。     

基于正交实验的低阶粉煤与玉米芯微波共热解研究

生物质协助低阶粉煤微波热解可改善热解产物的分布和特性,尤其是油气收率和品质。采用四因素四水平正交实验法研究了微波功率(420 W,280 W,700 W,560 W)、热解时间(30min,20min,10min,40min)、玉米芯粒径(0.250mm~0.420mm,0.177mm~0.250mm,0.841mm~1.680mm,0.420mm~0.841mm)和玉米芯添加量(10%,40%,30%,20%,质量分数)对低阶粉煤与玉米芯微波共热解中焦油收率的影响,对比分析了低阶粉煤、玉米芯单独微波热解和微波共热解的升温特性和产物特性。结果表明:影响焦油收率由主到次的因素分别为玉米芯添加量、微波功率、玉米芯粒径、热解时间。在本实验参数范围内,正交实验得到的最佳工艺条件为:微波功率700W、热解时间40min、玉米芯粒径0.841mm~1.68mm、玉米芯添加量40%,此时的半焦和气体产物收率分别为51.22%和32.17%,焦油收率达到最大,为8.85%。与低阶粉煤单独微波热解相比,微波共热解生成的焦油中轻油含量提高了11.89%,而杂原子化合物含量降低了7.09%,实现了热解焦油的轻质化和高品质化。     

生物质与聚合物、煤共热解研究进展

综述了近几年来生物质与其它物质如煤和聚合物共热解的研究进展。通过对生物质、煤和聚合物的单独热解以及同煤和其它聚合物共热解的大量文献报道结果进行比较发现:生物质与许多聚合物共热解具有协同作用,可以降低液体产物的含氧量,提高热解液相产率等。显示出生物质与某些聚合物共热解比单独热解具有一定的优势;并比较了煤和生物质共热解产生的现象,得到煤和生物质共热解难以产生协同作用。本文作者结合现阶段的研究成果,提出生物质与煤采用两步法热解工艺的思路,使生物质材料的氢有可能转移到热解煤的产物中,以改善煤热解过程中液体的性质,对今后生物质与煤及聚合物共热解的研究方向提出了自己的建议。     

褐煤与秸秆共热解的研究

选用小麦秸秆与褐煤进行共热解实验。主要考察生物质掺混比对共热解产物及热解特征参数的影响。结果表明:生物质与煤具有不同的热解温度范围。从DTG曲线可知,共热解过程中生物质先于煤进行热解。随着生物质掺混比的增加,生物质的热解特征增强,且共热解产物收率与掺混比呈线性关系。因此可初步判断:在慢速热解条件下,生物质与煤在共热解过程中不存在协同作用。     

共热解过程中煤与生物质相互作用的研究进展

煤炭与生物质共热解是实现煤炭高效清洁利用的重要途径之一。共热解可改善煤炭单独热解产生的污染问题和生物质单独利用时能源密度低、季节性供应不平衡的问题,不仅能提高煤炭转化效率,还能获得更高品质油品。本文从煤与生物质共热解的影响因素、研究方法和共热解过程中组分间相互作用等方面出发,对近期国内外煤与生物质共热解的研究进行综述。总结了生物质种类、热解工艺参数和热解反应器的类型对煤与生物质共热解过程的影响规律以及煤与生物质在共热解过程中的相互作用过程,即半焦与挥发分间的相互作用、挥发分间的相互作用、生物质中碱金属对共热解的催化作用,并针对如何进一步认识煤与生物质相互作用机理、提高共热解效率等问题和发展方向作了展望。     

陕北油房梁煤与生物质共热解研究

在N2气氛下,利用热重分析仪对生物质与陕北油房梁煤混合热解特性进行研究,重点考察了生物质混掺比对煤热解的影响。结果表明:相同升温速率下,生物质与煤在热解过程中表现出明显不同的热解特征;生物质与煤以不同掺混比进行共热解时,得到的共热解曲线分段呈现出生物质与煤单独热解的特性,且热解残余固体量与掺混比呈线性关系;此外,对比混合物共热解的实际特征曲线与理论计算曲线,发现实际DTG曲线也与理论计算的DTG曲线基本重合。从上述结果可预测,在热重反应器同步升温情况下,生物质与煤在共热解过程中不存在协同作用。     

农业生物质与塑料共热解技术进展

共热解技术是将多种原料通过热化学方法转化为清洁能源的重要手段。本文综述了以农业生物质为主要原料与塑料(聚丙烯PP、高密度聚乙烯HDPE、低密度聚乙烯LDPE、聚氯乙烯PVC、聚苯乙烯PS、聚对苯二甲酸乙二醇酯PET等)共热解技术的发展现状和研究进展。分析农业生物质与塑料共热解的动力学模型以及各组分之间的协同效应,阐述农业生物质与塑料的共热解机理;总结了温度、升温速率、滞留时间、原料混配比等因素对共热解协同作用的影响规律;探究生物质与塑料共热解固、液、气三相产物特性及分布规律,总结共热解技术优势及存在问题,展望未来发展方向,可为生物质与塑料共热解制备高附加值产品提供参考,同时也为农业生物质和农膜处理问题提供新方法、新思路。     

煤与生物质的共热解液化研究进展

煤与生物质共热解液化将是燃料与化学品重要的转化技术之一。本文从共热解液化机理、共热解液化反应动力学、煤与生物质的协同作用、催化剂、共热解液化工艺、共热解液化产物等方面对煤与生物质共热解液化研究进展进行了综述,指出煤与生物质的快速共热解液化将是重要的发展方向,催化剂的应用和液化产物的精制将对提升液化油的品位和降低成本,对实现共液化油替代现行石化液体油具有更重要的意义。     

低阶煤与玉米芯低温共热解的产物特性分析

采用低温干馏装置对不同玉米芯加入量的褐煤/玉米芯混合物进行低温共热解实验。结果表明：当玉米芯加入量为30%时,焦油产率最大为11.70%,比褐煤单独热解提高了53.75%。随着玉米芯的加入量增加,热解气中CO、CH₄和H₂含量逐渐增大。对热解焦油进行GC-MS检测,发现添加30%玉米芯后脂肪族质量分数从褐煤单独热解的24%提高到了30.67%,酚类质量分数从6.29%提高到了18.49%,杂原子质量分数从29.75%降低到了13.33%,一定程度上实现了焦油的轻质化和高品质化。对热解半焦进行SEM、比表面积分析和热值测定,发现共热解半焦表面变粗糙,孔隙结构得到改善,热值明显高于褐煤单独热解半焦热值。     

Synergies in co-pyrolysis of Thai lignite and corncob

The results from TGA experiments at the temperature range of 300–600 °C evidently distinguished the different pyrolysis behaviours of lignite and corncob; however, no clear synergistic effects could be observed for the mixture. The investigation of co-pyrolysis in a fixed-bed reactor, however, found significant synergies in both pyrolysis product yields and gas product compositions. The solid yield of the 50:50 lignite/corncob blend was much lower (i.e. 9%) than expected from the calculated value based on individual materials under the range of temperatures studied, and coincided with the higher liquid and gas yield. The synergistic effect in product gas composition was highly pronouncing for CH₄ formation, i.e. three times higher than the calculated value at 400 °C. Possible mechanisms were described including the interaction between corncob volatiles and lignite particles, and the effect of the heat profiles of lignite and corncob pyrolysis on the temperature dependent reactions. The enhanced devolatilisation of the blend was explained by the transfer of hydrogen from biomass to coal as well as the promotion of low-temperature thermal decomposition of lignite by exothermic heat released from corncob pyrolysis. Moreover, water, which was one of the major components in corncob volatiles produced mainly at around 200–375 °C, can also be expected to act as a reactive agent to promote the secondary tar cracking producing more CH₄.     

基于Py-GC×GC-qMS的玉米芯热解产物在线检测

利用热裂解-全二维气相色谱-质谱联用（Py-GC×GC-qMS）仪对玉米芯不同温度下热解产物进行在线分析。研究结果表明：玉米芯在550℃下热解18 s,GC×GC-qMS共检测到191种化合物,包括醇、酸、醛、酮、酯、呋喃类、碳氢化合物、酚类、含氮类和糖类等。主要化合物包括2,3-二氢-苯并呋喃、1,6-脱水-β-d-吡喃葡萄糖和糠醛,其GC含量分别为9.15%、8.80%和5.21%;而GC-qMS仅检测到58种化合物,且未检测到糖类化合物。玉米芯热解产物的种类随着温度的升高逐渐增加,在550℃时达到稳定值。温度对醛类、酮类和呋喃类化合物的影响并不明显,GC含量分别在450、550和500℃时达到最大,分别为4.80%、13.57%和21.01%;醇类、酸类和酯类化合物易在低温条件下形成;碳氢化合物易在高温条件下形成,600℃时GC含量为10.77%;酚类呈现出先增加后减少的趋势,450℃时GC含量最大为23.77%;温度的升高对含氮类和糖类GC含量的影响并不明显。     

Thermal pretreatment of kudzu biomass (pueraria lobata) as filler in cost‐effective pla biocomposite fabrication process

This article aims on the fabrication of cost‐effective polylactic acid (PLA) biocomposites using kudzu biomass derivatives as new filler. In this way, it has been realized that pretreatment of the filler was an essential requirement. We demonstrated thermal pyrolysis process that targeted to extraction and isolation of all extractable and unnecessary compounds such as intracellular water and bio‐oil from the biomass. Also, to further improve the compatibility of the filler with PLA, noncatalytic thermal esterification reactions of kudzu after thermal pyrolysis (called char) were carried out as second pretreatment stage in the presence of phthalic anhydride. Kudzu derivatives obtained from either first or second pretreatment reactions were melt‐blended with PLA in various rates. The blends were then compression molded into dumbbell specimens. Physicomechanical properties of the prepared biocomposites were evaluated using several analytical techniques. It was found that biocomposites containing treated biomass had higher values of physicomechanical properties than untreated ones. The final rate of filler to PLA with acceptable properties was set up to 50%. Obviously, the cost of PLA can be reduced using higher rates of low‐cost filler on a finished‐product basis. Extracted valuable compounds from biomass via thermal pyrolysis could be another benefit of the process. POLYM. ENG. SCI., 55:340–348, 2015. © 2014 Society of Plastics Engineers     

Flash co-pyrolysis of biomass with polylactic acid. Part 1: Influence on bio-oil yield and heating value

High amounts of water present in bio-oil are one of the major drawbacks for its utilisation as a fuel. One technology that shows the potential to satisfy the demand for bio-oil with a reduced water content is the flash co-pyrolysis of biomass with polylactic acid, PLA. The influence of PLA on the pyrolysis of willow is investigated with a semi-continuous home-built pyrolysis reactor. Flash co-pyrolysis of willow/PLA blends (10:1, 3:1, 1:1 and 1:2) show synergetic interaction. A higher bio-oil yield and a lower water content as a function of the willow/PLA ratios are obtained. Among the tested blends, the 1:2 willow/PLA blend shows the most pronounced synergy: a reduction in the production of pyrolytic water of almost 28%, accompanied by an increase of more than 37% in the production of water-free bio-oil. Additionally, PLA shows to have a positive influence on the energetic value of the bio-oil produced and on the resulting energy recuperation.     

ABS增韧PLA生物降解材料的制备与性能研究

采用丙烯腈-丁二烯-苯乙烯共聚物(ABS)弹性体对聚乳酸(PLA)进行熔融共混改性,制备出具有一定韧性的PLA/ABS生物降解材料,并研究了该共混体系的热性能、力学性能和生物降解性能。结果表明:ABS弹性体的加入降低了PLA/ABS共混材料的玻璃化转变温度、冷结晶温度和熔点,提高了共混材料的高温分解温度和断裂伸长率,改善了PLA的热稳定性和韧性。土壤掩埋实验表明,纯PLA和ABS含量为10%的PLA/ABS共混薄片具有良好的生物降解性能。     

基于TG/FT-IR, Py-GC/MS的聚乳酸塑料热降解研究

采用TG/FT-IR、Py-GC/MS联用技术研究了可降解塑料聚乳酸的气体释放过程及其热解产物.研究表明,聚乳酸在320～370℃区间发生剧烈热解反应,DTG曲线在359℃时出现最大值.热解气体的逸出情况由FT-IR进行实时检测,并且定性分析了CH_4, CO_2, CO 和有机物等产物的析出情况.通过比较TG/DTG曲线和FT-IR数据,发现DTG和FT-IR分析结果较为一致.Py-GC/MS联用技术用来分析聚乳酸热解产物,结果表明醛、酮、酯及低聚物是主要降解产物.Py-GC/MS方法快速、简便、准确,不失为聚合物热解研究的良好方法.     

生物质与聚乳酸共热解行为及其动力学研究

Thermal decomposition of polylactic acid （PLA） was studied in the presence of pine wood sawdust （PS）, walnut shell （WS）, corncob （CC） in order to understand the pyrolytic behavior of these components occurring in waste. A thermogravimetric analyzer （TGA） was applied for monitoring the mass loss profiles under heating rate of 10℃·min^-1. Results obtained from this comprehensive investigation indicated that PLA was decomposed in the temperature range 300 -372℃, whereas the thermal degradation temperature of biomass is 183-462℃. The difference of mass loss （AW） between experimental and theoretical ones, calculated as algebraic sums of those from each separated component, is about 17%-46% at 300-400℃. These experimental results indicated a significant synergistic effect during PLA and biomass copyrolysis. Moreover, a kinetic analysis was performed to fit thermogravimetric data, the global processes being considered as one to two consecutive reactions. A reasonable fit to the experimental data was obtained for all materials and their blends.     

Influence of temperature and alumina catalyst on pyrolysis of corncob

Corncob has been investigated as an alternative feedstock to obtain fuels and chemicals via pyrolysis in fixed-bed reactor. The influence of pyrolysis temperature in the range 300-800 °C as well as the catalyst effects on the products was investigated in detail and the obtained results were compared. The results indicated that a maximum oil yield of 22.2% was obtained at a moderate temperature of 600 °C. The oil yield was reduced when the temperature was increased from 600 to 800 °C, whereas the gas yield increased.Pyrolysis oils were examined by using instrumental analysis, ¹H NMR spectroscopy and GC/MS. This analysis revealed that the pyrolysis oils were chemically very heterogeneous at all temperatures. It was determined that the most abundant compounds composing the bio-oil were phenolics.It was observed that the catalyst decreased the reaction temperature. Most of the components obtained using a catalyst at moderate temperatures was close to those obtained at high temperatures without using a catalyst. Moreover, the use of a catalyst and the high temperatures of the reactions also decreased the amount of oxygenated compounds produced.According to these results, corncob bio-oils can be used as fuel and constitute a valuable source of chemical raw materials.