Importance of oxygen-containing functionalities and pore structures of biochar in catalyzing pyrolysis of homologous poplar

Biochar and bio-oil are produced simultaneously in one pyrolysis process,and they inevitably contact and may interact,influencing the composition of bio-oil and modifying the structure of biochar.In this sense,biochar is an inherent catalyst for pyrolysis.In this study,in order to investigate the influence of functionalities and pore structures of biochar on its capability for catalyzing the conversion of homologous volatiles in bio-oil,three char catalysts(600C,800C,and 800AC)produced via pyrolysis of poplar wood at 600 or 800℃or activated at 800℃,were used for catalyzing pyrolysis of homologous poplar wood at 600℃,respectively.The results indicated that the 600C catalyst was more active than 800C and 800AC for catalyzing cracking of volatiles to form more gas(yield increase by 40.2%)and aromatization of volatiles to form more light or heavy phenolics,due to its abundant oxygen-containing functionalities acting as active sites.The developed pores of the 800AC showed no such catalytic effect but could trap some volatiles and allow their further conversion via sufficient aromatization.Nevertheless,the interaction with the volatiles consumed oxygen on 600C(decrease by 50%),enhancing the aromatic degree and increasing thermal stability.The dominance of deposition of carbonaceous material of a very aromatic nature over 800C and 800AC resulted in net weight gain and blocked micropores but formed additional macropores.The in situ diffuse reflectance infrared Fourier transform spectroscopy characterization of the catalytic pyrolysis indicated superior activity of 600C for removal of -OH,while conversion of the intermediates bearing C=O was enhanced over all the char catalysts.

Study on pyrolysis and gasification of wood in MSW

In order to develop municipal solid waste（MSW） pyrolysis/gasification and melting technology with low emission and high efficiency, it was planed that all the main components in MSW and some typical kinds of MSW were pyrolyzed/gasified to propose an expert system for raw MSW. In this paper, wood, which was a prevalent component in MSW, was pyrolyzed and gasified in fluidized-bed reactors at different apparent excess air ratios （EARs）, temperatures and fluidizing velocities. For pyrolysis, with tem- perature increasing from 400℃ to 700℃, the yield of pyrolysis char decreased while that of pyrolysis gas increased （in this paper respectively from 28% to 20% and from 10% to 35%）, and when temperature was 500℃, the yield of pyrolysis tar reached the highest, up to 38% in this paper. It was the optimum for gasification when temperature was 600℃ and apparent EAR was 0.4. Under the experimental conditions of this paper, gasification efficiency achieved 73%, lower heat value（LHV） reached 5800 kJ/（Nm^3） and yield of syngas was 2.01 Nm^3/kg. Lower fluidizing velocity was useful to upgrade gasification efficiency and LHV of syngas for wood gasification. Based on the results, the reactive courses and mechanism were analyzed respectively for wood pyrolysis and gasification.

Experimental Researches on Milled Wood Lignin Pyrolysis Based on Analysis of Bio-oil

The structure of milled wood lignin（MWL）, isolated via the Bjrkman procedure, was studied by means of 1H NMR spectroscopy and Fourier transform infrared spectroscopy, and then its pyrolytic product distribution was investigated on a pyrolysis device. MWL obtained from Manchurian Ash（MA） contained more methoxyl and free phenolic hydroxyl groups per C9 unit than MWL from Mongolian Pine（MP） due to the existence of both guaiacyl and syringyl units, which have a major influence on the pyrolysis behavior of lignin. The results of pyrolysis show that MWL from MA generated a higher yield of bio-oil, mainly composed of phenols, guaiacols, syringols and catechols, and a less yield of char, in addition to the gaseous products CO, CO2, methane and methanol, compared with MWL from MP. Guaiacol and syringol were the typical products from G-lignin and S-lignin, probably attributed to the easier cleavage of the aryl-alkyl linkage in the side chain compared with the C―OCH3 bond in the benzene ring. The degradation of MWL from MP was dominated by the demethylation reaction and the cleavage of aliphatic ―CH2OH at the γ-position, followed by the cracking of the Cα―Cβ and C4―Cα bonds.

Kinetics and FTIR characteristics of the pyrolysis process of poplar wood

The pyrolysis characteristics of residues of poplar （Populus sp.） wood were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared （TG-FTIR） spectrometer. The pyrolysis process was sub- divided into four stages at a rate of 10℃.min-1, varying from 30 to 650℃. Below 180℃, a mass loss occurred for drying and preheating the sample and the onset temperature of pyrolysis ranged between 180-260℃. A significant mass loss 3f 61.4 wt.% occurred between 260-380℃, followed by a slow and continuous mass change with lignin devolatilization. The analysis of kinetic reactions showed that the activation energy （78.29 kJ.mol-1） in the low-temperature section was much larger than that （6.40 kJ-mol-1） in the high-temperature section. The evolved gases formed by thermal degradation 3f poplar wood were simultaneously analyzed by FTIR. It was observed from the main peaks that the emissions evolved during poplar wood pyrolysis were acetic acid, carbon dioxide, carbon monoxide, methane, water, some volatile com- 3ounds of esters, alcohols and aldehydes. The emissions gradually increased with rising temperatures before a strong 3eak around 360℃ and then decreased. Most gaseous products were emitted in the 320-380℃ range, while CO2 was =ontinuously emitted in a wide range from 140-550℃.

Wood Pyrolysis in Pre-Vacuum Chamber

Climate change, global warming, and energy crisis are critical issues to be solved urgently in a global framework. Alternative energy and renewable energy technologies must be quickly developed to be substituted for fossil fuels like oil, gases, and coal. USA, UE, and Japan invested huge budgets to develop biomass renewable energy technology. Their target is to develop a commercial base large-scaled plant. On the other hand, in developing countries, especially in rural areas, people who can access electricity is still less than 70%, To decelerate or prevent global warming and improve electrification in rural areas, a new technology for wood pyrolysis, which requires low manufacturing cost and less maintenance, and of which gases are directly applicable to the gas engine generator, is developed in a laboratory scale. This paper reports the performance of this new plant and effects of several parameters on the performance. It is concluded that the new technology is quite feasible in rural areas, and upgrading of the plant is easily possible.

Smoldering charcoal detection in forest soil by multiple CO sensors

Cleaning up residual fires is an important part of forest fire management to avoid the loss of forest resources caused by the recurrence of a residual fire.Existing residual fire detection equipment is mainly infrared temperature detection and smoke identification.Due to the isolation of ground,temperature and smoke characteristics of medium and large smoldering charcoal in some forest soils are not obvious,making it difficult to identify by detection equipment.CO gas is an important detection index for indoor smoldering fire detection,and an important identification feature of hidden smoldering ground fires.However,there is no research on locating smoldering fires through CO detection.We studied the diffusion law of CO gas directly above covered smoldering charcoal as a criterion to design a detection device equipped with multiple CO sensors.According to the motion decomposition search algorithm,the detection device realizes the function of automatically searching for smoldering charcoal.Experimental data shows that the average CO concentration over the covered smoldering charcoal decreases exponentially with increasing height.The size of the search step is related to the reliability of the search algorithm.The detection success corresponding to the small step length is high but the search time is lengthy which can lead to search failure.The introduction of step and rotation factors in search algorithm improves the search efficiency.This study reveals that the average ground CO concentration directly above smoldering charcoal in forests changes with height.Based on this law,a CO gas sensor detection device for hidden smoldering fires has been designed,which enriches the technique of residual fire detection.

Naturally Nitrogen-Doped Biochar Made from End-of-Life Wood Panels for SO_(2) Gas Depollution

Reconstituted wood panels have several advantages in terms of ease of manufacturing,but their shorter life span results in a huge amount of reconstituted wood panels being discarded in sorting centers yearly.Currently,the most common approach for dealing with this waste is incineration.In this study,reconstituted wood panels were converted into activated biochar through a two-step thermochemical process:(i)biochar production using pilot scale fast pyrolysis at 250 kg/h and 450℃;and(ii)a physical activation at three temperatures(750℃,850℃ and 950℃)using an in-house activation furnace(1 kg/h).Results showed that the first stage removed about 66% of the nitrogen from the wood panels in the form of NO,NH3,and trimethylamine,which were detected in small amounts compared to emitted CO_(2).Compared to other types of thermochemical conversion methods(e.g.,slow pyrolysis),isocyanic acid and hydrogen cyanide were not detected in this study.The second stage produced activated biochar with a specific surface area of up to 865 m^(2)/g at 950℃.The volatile gases generated during activation were predominantly composed of toluene and benzene.This two-step process resulted in nitrogen-rich carbon in the form of pyrrolic and pyridinic nitrogen.Activated biochars were then evaluated for their SO_(2) retention performance and showed an excellent adsorption capacity of up to 2140 mg/g compared to 65 mg/g for a commercial activated carbon(889 m^(2)/g).End-of-life reconstituted wood panels and SO_(2) gas are problematic issues in Canada where the economy largely revolves around forestry and mining industries.

Charcoal Production via Multistage Pyrolysis

Interests in charcoal usage have recently been re-ignited because it is believed that charcoal is a muchbetter fuel than wood. The conventional charcoal production consumes a large amount of energy due to the prolonged heating time and cooling time which contribute to the process completing in one to several days. Wood py-rolysis consists of both endothermic and exothermic reactions as well as the decomposition of the different components at different temperature range （hemicellulose： 200-260℃; cellulose： 240-350℃ and lignin： 280-500℃）. Inthis study we propose a multistagepyrolysis which is an approach to carry out pyrolysis with multiple heating stages so as to gain certain processing benefits. We propose a three-stage approach which includes rapid stepwise heating stage to a variable target temperatures of 250 ℃, 300℃, 350 ℃ and 400 ℃, slow and gradual heatingstage to a tinal temperature of 400℃ and adiabatic with cooling stage. The multi-stage pyrolysis process can save 30% energy and the processing time by using a first temperature target of 300 ℃and heating rate of 5℃.min-1 to produce a fixed-carbon yield of 25.73% as opposed to the base case with a fixed-carbon yield of23.18%.

Experimental and Modelling Studies of Biomass Pyrolysis

The analysis on the feedstock pyrolysis characteristic and the impacts of process parameters on pyrolysis outcomes can assist in the designing,operating and optimizing pyrolysis processes.This work aims to utilize both experimental and modelling approaches to perform the analysis on three biomass feedstocks—wood sawdust,bamboo shred and Jatropha Curcas seed cake residue,and to provide insights for the design and operation of pyrolysis processes.For the experimental part,the study investigated the effect of heating rate,final pyrolysis temperature and sample size on pyrolysis using common thermal analysis techniques.For the modelling part,a transient mathematical model that integrates the feedstock characteristic from the experimental study was used to simulate the pyrolysis progress of selected biomass feedstock particles for reactor scenarios.The model composes of several sub-models that describe pyrolysis kinetic and heat flow,particle heat transfer,particle shrinking and reactor operation.With better understanding of the effects of process conditions and feedstock characteristics on pyrolysis through both experimental and modelling studies,this work discusses on the considerations of and interrelation between feedstock size,pyrolysis energy usage,processing time and product quality for the design and operation of pyrolysis processes.

生物质基木醋液的制备工艺和增效技术研究进展

木醋液是生物质热解制炭产生的高价值酸性副产物,具有来源丰富、无污染、成本低等特点。如果将木醋液中的成分进行转化并加以利用,对促进生物质资源利用具有重要意义。木醋液的主要成分为有机酸、醇类、酚类、醛类和酮类等多种有机物和微量金属元素,具有刺激作物生长、抑制病原菌生长和抗氧化的作用,通过不同的制备工艺和增效技术将木醋液应用于植物上是目前的研究热点。通常,木醋液生产途径可分为工业生产木醋液和实验室制备木醋液,但初步制备出的木醋液含有某些有毒物质,需要进一步精制,精制的过程主要采用过滤法、活性炭吸附法、蒸馏法、静置法、低温法、萃取法等。笔者基于近年来国内外木醋液的研究动态,简述了木醋液的制取和精制,分析了目前木醋液精制方法的优缺点,介绍了木醋液对植物生长的作用机理;概述了木醋液在粮食、水果、蔬菜和其他作物上的增效技术和应用效果,总结出木醋液具有促进种子发芽和植物生长、抑制作物病原菌、提高作物产量和抗逆性以及改良土壤等功能。然而,木醋液在开发和利用方面尚无明确的统一标准,且对植物的增效机制尚不明确。今后,研究重点应主要集中在不同原料和不同工艺制备的木醋液对植物促生的作用机理和土壤的改良机理等方面,研究结果将为木醋液开发、高效利用及农业绿色发展提供参考。

传统熏烤木材中木质素结构表征及其热解特性

为探究传统熏烤肉制品熏烤时所采用不同化学组成及结构的木材类型对产生有害物质多环芳烃的种类和生成量的影响,以传统熏烤肉制品生产时常用的松木、杨木、榉木、枣木、苹果木5种木材为研究对象,通过红外光谱、拉曼光谱、热重及热重-红外联用分析,考察5种木材中木质素的结构特征及其热解特性。结果表明:5种木材中木质素含量,以及木质素中愈创木基结构单元(G)、紫丁香基结构单元(S)含量均存在差异;热解过程基本可分为3个阶段,主要发生在200~500℃范围内,但是5种木质素的质量损失速率、质量损失温度、热解速率、热解温度均不同,说明不同木质素的热稳定性存在显著差异。熏烤木材中木质素含量,S/G结构含量及侧链结构上差异可导致其热稳定性的不同,而热解特性的不同则进一步影响多环芳烃等有害物的生成。

聚氯乙烯/松木粉低温共热解脱氯提质特性

掌握聚氯乙烯(PVC)和木质纤维素类生物质共热解过程中脱氯提质特性,对开发生活垃圾脱氯预处理技术和实现其无害化具有重要意义。研究了PVC与松木粉(WP)在低温(200~450℃)共热解过程的提质和Cl的迁移转化特性。结果表明,在热解温度为300~350℃时,PVC和WP混合物的脱氯效率可以达到98%以上,对应的能量回收率约为76%。在300℃热解温度下停留15min,超过90%的Cl以HCl形式释放,且HCl释放量随着热解温度升高和停留时间的延长而增加。热解焦油中氯的含量很低,仅为1.80%~3.04%。低温共热解过程中,WP中木质素产生的酚羟基可以促进氯的取代反应,提高脱氯效率。

水热过程中杉木屑组分的演变对木醋液的影响

以杉木屑为研究对象,经180~280℃水热预处理后热解制备木醋液。采用范氏法定量分析了不同水热温度下杉木屑组分的演变,并利用气相色谱-质谱联用仪(GC-MS)、酸度计等测试手段考察了水热预处理后杉木屑组分演变对木醋液产率、有机组分和理化性质的影响。结果表明:随水热温度升高,水热杉木屑中的半纤维素含量持续降低;纤维素含量呈先升高后降低趋势;木质素含量逐渐升高。随水热温度升高至230℃,木醋液中酚类和醛类化合物含量逐渐增加,分别与木质素和纤维素含量变化趋势一致;酸类化合物含量略微减少,与半纤维素和纤维素总含量变化呈正相关趋势,半纤维素和纤维素是酸类化合物的主要来源。当水热温度为180~230℃时,水热杉木屑中半纤维素的大量分解导致纤维素和木质素含量增加使得木醋液密度更高、pH更低,而产率仅在200℃前增加。通过水热预处理优化杉木屑三组分占比,可制取更高品质的木醋液。

温和条件下ZnCl_(2)原位催化松木粉快速热裂解制生物油及生物炭应用

生物质快速热裂解是生物质转化利用的有效途径,但常因是非催化过程,裂解温度高导致生物油成分复杂难控。本实验以ZnCl_(2)为催化剂,研究了木质素、纤维素、玉米芯和松木粉的热解过程,旨在探索原位催化对快速热裂解的强化作用。本实验通过热重曲线拟合,获得了热裂解的活化能;通过快速热裂解实验,研究了催化作用下热解油组成变化。结果表明,ZnCl_(2)催化可显著降低生物质裂解温度,简化生物油组成。在350℃快速热裂解松木粉获得了47%生物油产率,主要成分是纤维素和半纤维素的衍生物。ZnCl_(2)可显著降低纤维素裂解的活化能(由304.78 kJ/mol降低至112.46 kJ/mol),而对木质素的裂解影响不大。裂解后的碳渣在600℃二次碳化可获得性能良好的活性炭,苯酚吸附容量可达165 mg/g。

微波裂解木粉生物质制混合可燃气的研究

生物质是化石燃料的一种很有前途的替代品,随着世界能源消耗的持续增加,研究如何高效利用生物质已经成为了一个极具前景的方向。本研究提出了一种高效快速的方法,利用木粉生物质催化分解产出主要成分为CO与H_(2)的混合气。使用自主设计的压缩波导以及廉价的铁基催化剂催化裂解生物质,得到了较好的结果,其中CO产率约为28.15 mmol/g,H_(2)产率约为18.29 mmol/g。探索了物料中木粉与催化剂的不同配比、催化剂内铁铝元素配比及电磁场分布情况对气体产率的影响,并得到了能以较高产率裂解木粉生物质的反应条件,展示了以木粉为原料生产可燃气的潜力。

废弃板式家具材料热解产物分析

为实现高效回收废旧板式家具,研究废弃板式家具材料热解温度对热解产物的影响。以废弃板式家具拆解获得的胶合板、中密度板、刨花板为实验材料,在升温速率为100℃/h,热解温度为400,500和600℃的热解条件下进行热解处理,并对产物进行分析。结果表明,随着热解温度升高,固态产物得率逐渐下降,而液态产物和不凝气体逐渐增加。固态产物中碳元素的含量可达到63.84%~88.69%,随热解温度的增加固态产物含碳逐渐降低,但碳氢和碳氮的比例逐渐增加。因3种热解材料中胶粘剂的种类和含量不同,热解液体呈弱酸性至弱碱性。掌握废弃人造板的热解产物得率和特性,可为废弃人造板的回收和利用提供更多研究方向。

木材热解特性和动力学研究

选取杉木、花梨木和水曲柳为样品 ,对其在不同升温速率下进行了 TG、DTG和 DSC分析。将木材的热解过程分为四个阶段 ,分析了每个阶段的化学物理变化以及热效应的变化 ,研究了不同升温速率对热解过程的影响 ,并建立试样的热解模型 ,求出了其动力学参数 ,有助于着火机理、火蔓延机理、阻燃机理的研究。

木材热分解动力学的研究

用ＴＧ－ＤＴＡ热分析联用技术测定了４种常用木材的ＴＧ－ＤＴＡ－Ｔ曲线，井用热动力学方法处理了ＴＧ曲线，获得了相应的热动力学参数。发现各种木材在于燥阶段和煅烧阶段的热性质大致相似，而炭化阶段的热性质则因木材的化学组成不同而有较大差异。

阴燃材料受热升温过程分析

阴燃材料在受热升温过程中会发生热解吸热反应和氧化放热反应。通过将实验过程与无反应固体受热模拟过程进行对比,来分析阴燃反应的特点。分析显示,材料中的水分蒸发在低于100℃时发生;温度达到约180℃时材料开始发生热解;温度达到约280℃时氧化反应超过热解反应开始放热;温度达到约305℃时材料内部的总放热量开始大于总吸热量。分析的结论同一些文献中的结果也是一致的。