Effect of pretreatment temperature of pine on bio-oil characteristics

通过螺旋反应器低温预处理除去松木中的半纤维素和水分,然后用预处理得到的固体残渣来快速热解制生物油.固体残渣的化学组成分析和红外光谱分析表明,由于木质素含量的增加和炭化反应的发生,生物油的产率降低、焦和不可冷凝气的产率增加.随着预处理温度的升高,生物油水分含量减少,高位热值增加,运动黏度增加,密度增加,pH值先升高后降低,固体颗粒物含量增加.核磁共振碳谱分析表明,生物油的脂肪碳含量减少,芳香碳含量增加,芳香度增加.     

松木预处理温度对生物油特性的影响

通过螺旋反应器低温预处理除去松木中的半纤维素和水分,然后用预处理得到的固体残渣来快速热解制生物油。固体残渣的化学组成分析和红外光谱分析表明,由于木质素含量的增加和炭化反应的发生,生物油的产率降低、焦和不可冷凝气的产率增加。随着预处理温度的升高,生物油水分含量减少,高位热值增加,运动黏度增加,密度增加,pH值先升高后降低,固体颗粒物含量增加。核磁共振碳谱分析表明,生物油的脂肪碳含量减少,芳香碳含量增加,芳香度增加。     

温度对稻草流化床快速热解液相产物影响的研究

研究了温度对稻草流化床快速热解中热解油产率的影响,利用GC/MS、FT-IR考察了不同热解温度(300℃~600℃)及冷凝温度(22℃、-4.4℃)下,稻草经过热解所获得的热解油组成。结果表明,稻草在400℃热解温度下可获得最高热解油产率43.1%;冷凝温度对热解油的品质有较大影响,降低冷凝温度能够增加热解油中有机物的含量,热解油中的水分含量随之降低,同时热解油的热值也随之得到提高。     

生物油中固体颗粒物的特性分析

利用电感耦合等离子体发射光谱、红外光谱分析和X射线衍射对不同固体颗粒物样品的特性进行了研究。结果表明,生物油中的固体颗粒物主要由焦炭颗粒、灰分和少量高分子有机物组成,其中,灰分主要包括多种金属元素和一定量SiO₂,有机物主要是具有木质素结构的低聚物。不同热解工艺的固体颗粒物样品特性也不同。循环流化床工艺制取的生物油中固体颗粒物含量较高。此外,固体颗粒物样品中的金属元素含量受到热解原料种类的影响。     

木质素热解生物油组成成分与分子尺寸分布特性分析

选用脱碱木质素作为原料,以热裂解气质联用技术(Py-GC/MS)研究木质素在350～600℃下热解产物成分和含量,并利用Joback法、 Lijie法和Tahami法3种基团贡献法计算了生物油各组成成分的临界参数和动力学直径,对木质素热解油产物的分子动力学直径分布特性进行计算.结果显示,愈创木基结构、紫丁香基结构、苯酚类、邻苯二酚类和芳烃类等5种芳香族化合物是350～600℃下木质素热解生物油的主要组成成分,其中愈创木基结构化合物的平均峰面积百分比达到70.7%.随着反应温度从350提高到600℃,分子动力学直径在0.560～0.610 nm区间内的木质素热解油组分含量从14.6%增加至31.3%.木质素热解生物油主要产物的动力学直径在0.560～0.710nm,表明一些孔径尺寸在此范围内的分子筛如SSZ-20、 ZSM-5和Beta可作为木质素裂解制备高品质芳烃燃料的催化剂.     

两种树皮热解微晶结构及生物油组分对比

以针叶材杉木树皮和阔叶材桉木树皮为原料,利用X射线衍射 (XRD) 对两种树皮热解前后固体颗粒微晶结构的变化进行了比较,利用气质联用 (GC-MS)、凝胶渗透色谱 (GPC) 等手段对两种树皮生物油组分进行了对比分析。结果表明,两种树皮中的纤维结构及脂肪链结构在热解过程中发生了分解,基本被破坏。杉木树皮和桉木树皮生物油主要组分相似,含有酸类、酮类、酚类、醇类、醛类、糖类、酯类等类物质,但相对含量存在差异;桉木树皮相对杉木树皮热解生成了较多的酸类、酮类物质,而酚类、醇类、糖类物质相对较少。两种树皮生物油中酚类物质占有较大的比例,以苯酚和邻苯二酚为主。两种树皮生物油主要物质分子量集中在300~500 g/mol,但桉木树皮生物油中分子量在300~500 g/mol的相对含量 (48.18%) 相比杉木树皮 (61.14%) 较少。     

离子液体作用下微波辐照生物质快速热解制备生物质油(英文)

以离子液体1-丁基-3-甲基咪唑氯([Bmim]Cl)和1-丁基-3甲基咪唑四氟化硼([Bmim]BF4)为催化剂,在微波加热作用下,研究了稻草和锯屑的热解。微波加热20 min,稻草和锯屑的生物油产率分别为38%和34%。考察了微波加热时间、微波功率和离子液体用量对生物质油产率的影响。当以相同的离子液体为催化剂时,稻草微波热解得到的生物质油产率大于锯屑的。生物油成分主要有糠醛、醋酸和1-羟基-2-丁酮等,其含量主要取决于生物质原料和加入的离子液体的类型。     

生物质热解过程中NO、NH3和HCN的释放特性

在氩气气氛下,利用固定床反应器对稻草（DC）、麦杆（MG）和锯末（JM）三种生物质进行热解实验,采用傅里叶变换红外光谱仪（FT-IR）在线检测热解气体产物中的含氮组分,分析各种气相含氮组分的释放规律。实验结果表明,由于锯末中木质素含量较高,锯末热解开始快速释放NO、NH₃和HCN的温度明显高于稻草和麦杆。稻草热解过程中生成的NH₃、HCN和NO量最大。低温下NH₃的生成至少部分与生物质中氨基结构的分解有关,HCN的生成温度较高。不同生物质热解过程中NO、NH₃和HCN释放特性的差异,是由生物质大分子结构不同、灰分含量及成分不同、N含量不同等决定的,以及氮在生物焦、焦油和气相间的分配差异造成的。     

Characterization and storage stability analysis of bio-oil

对松木和玉米芯快速热解制取的生物油进行储存稳定性实验,经过储存老化后的生物油黏度增大,水分含量和固体颗粒物含量增加,pH值、热值、密度无明显变化.通过GC-MS对储存前后生物油中主要组分进行定量分析表明,生物油经过储存后,羟基丙酮、乙酸、糠醛等主要组分的含量明显下降,而2-甲氧基苯酚、4-甲基-2-甲氧基-苯酚、4-甲基-苯酚的含量有所上升.核磁共振的碳谱分析表明,经过储存后生物油中甲氧基碳和双氧-烷基碳的含量降低,而芳基碳和不饱和碳的含量增大,生物油的芳香度有所提高.     

生物油储存稳定性实验研究

对松木和玉米芯快速热解制取的生物油进行储存稳定性实验,经过储存老化后的生物油黏度增大,水分含量和固体颗粒物含量增加,pH值、热值、密度无明显变化。通过GC-MS对储存前后生物油中主要组分进行定量分析表明,生物油经过储存后,羟基丙酮、乙酸、糠醛等主要组分的含量明显下降,而2-甲氧基苯酚、4-甲基-2-甲氧基-苯酚、4-甲基-苯酚的含量有所上升。核磁共振的碳谱分析表明,经过储存后生物油中甲氧基碳和双氧-烷基碳的含量降低,而芳基碳和不饱和碳的含量增大,生物油的芳香度有所提高。     

分级冷凝生物油组分富集与组分稳定性研究

利用GC-MS分别检测分级冷凝装置和常规冷凝装置制备的核桃壳生物油,对比常规冷凝生物油与分级冷凝多品级生物油有机组分的相对峰面积,发现分级冷凝对组分富集有较大影响,其中,乙酸在第四级生物油内相对峰面积从5.38%上升至9.44%;愈创木酚在第二级内从3.46%上升至6.23%;紫丁香醇在第一级内从1.48%上升至4.44%;异丁香酚在第一级内从5.52%上升至17.84%。经过75 d、15℃恒温恒湿储存后分级冷凝生物油水分增加,分别增加了1.58%、1.88%、1.80%、2.43%;脂肪类有机物峰面积减小;酚类有机物峰面积增大。第一、二级生物油内小分子有机物含量较少,老化反应强度较低;第三、四级生物油内小分子有机物含量较多,老化反应强度较高。根据GC-MS检测结果将有机物分类,统计各类有机物在储存前后的含量变化,分析储存过程中各类有机物发生的老化反应种类以及反应强度。     

Physical and chemical properties of bio-oils from microwave pyrolysis of corn stover

This study was aimed to understand the physical and chemical properties of pyrolytic bio-oils produced from microwave pyrolysis of corn stover regarding their potential use as gas turbine and home heating fuels. The ash content, solids content, pH, heating value, minerals, elemental ratio, moisture content, and viscosity of the bio-oils were determined. The water content was approx 15.2 wt%, solids content 0.22 wt%, alkali metal content 12 parts per million, dynamic viscosity 185 mPa.s at 40 degrees C, and gross high heating value 17.5 MJ/kg for a typical bio-oil produced. Our aging tests showed that the viscosity and water content increased and phase separation occurred during the storage at different temperatures. Adding methanol and/or ethanol to the bio-oils reduced the viscosity and slowed down the increase in viscosity and water content during the storage. Blending of methanol or ethanol with the bio-oils may be a simple and cost-effective approach to making the pyrolytic bio-oils into a stable gas turbine or home heating fuels.     

A Review of Characteristics of Bio-Oils and Their Utilization as Additives of Asphalts

Transforming waste biomass materials into bio-oils in order to partially substitute petroleum asphalt can reduce environmental pollution and fossil energy consumption and has economic benefits. The characteristics of bio-oils and their utilization as additives of asphalts are the focus of this review. First, physicochemical properties of various bio-oils are characterized. Then, conventional, rheological, and chemical properties of bio-oil modified asphalt binders are synthetically reviewed, as well as road performance of bio-oil modified asphalt mixtures. Finally, performance optimization is discussed for bio-asphalt binders and mixtures. This review indicates that bio-oils are highly complex materials that contain various compounds. Moreover, bio-oils are source-depending materials for which its properties vary with different sources. Most bio-oils have a favorable stimulus upon the low temperature performance of asphalt binders and mixtures but exhibit a negative impact on their high-temperature performance. Moreover, a large amount of oxygen element, oxygen-comprising functional groups, and light components in plant-based bio-oils result in higher sensitivity to ageing of bio-oil modified asphalts. In order to increase the performance of bio-asphalts, most research has been limited to adding additive agents to bio-asphalts; therefore, more reasonable optimization methods need to be proposed. Furthermore, upcoming exploration is also needed to identify reasonable evaluation indicators of bio-oils, modification mechanisms of bio-asphalts, and long-term performance tracking in field applications of bio-asphalts during pavement service life.     

Characterization of Fast Pyrolysis Bio-oils Produced from Pretreated Pine Wood

The pretreatment of biomass prior to the fast pyrolysis process has been shown to alter the structure and chemical composition of biomass feed stocks leading to a change in the mechanism of biomass thermal decomposition. Pretreatment of feed stocks prior to fast pyrolysis provides an opportunity to produce bio-oils with varied chemical composition and physical properties. This provides the potential to vary bio-oil chemical and physical properties for specific applications. To determine the influence of biomass pretreatments on bio-oil produced during fast pyrolysis, we applied six chemical pretreatments: dilute phosphoric acid, dilute sulfuric acid, sodium hydroxide, calcium hydroxide, ammonium hydroxide, and hydrogen peroxide. Bio-oils were produced from untreated and pretreated 10-year old pine wood feed stocks in an auger reactor at 450 °C. The bio-oils’ physical properties of pH, water content, acid value, density, viscosity, and heating value were measured. Mean molecular weights and polydispersity were determined by gel permeation chromatography. Chemical characteristics of the bio-oils were determined by gas chromatography–mass spectrometry and Fourier transform infrared techniques. Results showed that the physical and chemical characteristics of the bio-oils produced from pretreated pine wood feed stocks were influenced by the biomass pretreatments applied. These physical and chemical changes are compared and discussed in detail in the paper.     

Fast pyrolysis of rice straw,sugarcane bagasse and coconut shell in an induction-heating reactor

With the application of induction heating, a fast pyrolysis was used for producing valuable products from rice straw, sugarcane bagasse and coconut shell in an externally heated fixed-bed reactor. The effect of process parameters such as pyrolysis temperature, heating rate and holding time on the yields of pyrolysis products and their chemical compositions were investigated. The maximum yield of ca. 50% on the pyrolysis liquid product could be obtained at the proper process conditions. The chemical characterization by elemental (CHNO), calorific, Fourier transform infrared (FT-IR) spectroscopy and gas chromatography/mass spectrometry (GC–MS) showed that the pyrolysis liquid products contain large amounts of water (>65 wt.%), and fewer contents of oxygenated hydrocarbons composing of carbonyl groups, resulting in low pH and low heating values. The results were very similar to bio-oils obtained from other biomass materials. The residual solid (char or charcoal) was also characterized in the present study.     

Chemical composition of bio-oil produced by co-pyrolysis of biopolymer/polypropylene mixtures with K2CO3 and ZnCl2 addition

The chemical composition of liquid products of cellulose and lignin co-pyrolysis with polypropylene at 450 °C with and without the potassium carbonate or zinc chloride as an catalyst was investigated. The yield of liquid products of pyrolysis was in the range of 26–45 wt% and their form was liquid or semi-solid highly depending on the composition of sample and pyrolysis conditions. The potassium carbonate and zinc chloride addition to blends has also influenced the range of samples decomposition as well as the chemical composition of resulted bio-oils. All bio-oils from biopolymer and polypropylene mixtures were three-phase (water, oil and solid). While zinc chloride acted as catalyst, all bio-oils obtained from biopolymer and polypropylene mixtures were yellow liquids with well-separated water and oil phases. All analyses proved that the structure and quality of bio-oil strongly depends on both the composition of the blend and the presence of the additive. The FT-IR and GC–MS analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the composition of biomass/polypropylene mixture. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds, i.e. levoglucosan, 1,6-anhydro-β-d-glucofuranose and phenol derivatives due to the zinc chloride presence during pyrolysis process. All analyses showed that zinc chloride as catalyst was generally much more effective for removal of hydroxyl and methoxy groups than was potassium carbonate. It was demonstrated in this study that catalysts used in present work lead to the increased char yield and improved the fuel quality of bio-oil.     

Aromatics and phenols from catalytic pyrolysis of Douglas fir pellets in microwave with ZSM-5 as a catalyst

Microwave assisted catalytic pyrolysis was investigated to convert Douglas fir pellets to bio-oils by a ZSM-5 zeolite catalyst. A central composite experimental design (CCD) was used to optimize the catalytic pyrolysis process. The effects of reaction time, temperature and catalyst to biomass ratio on the bio-oil, syngas, and biochar yields were determined. GC/MS analysis results showed that the bio-oil contained a series of important and useful chemical compounds. Phenols, guaiacols, and aromatic hydrocarbons were the most abundant compounds which were about 50–82% in bio-oil depending on the pyrolysis conditions. Comparison between the bio-oils from microwave pyrolysis with and without catalyst showed that the catalyst increased the content of aromatic hydrocarbons and phenols. A reaction pathway was proposed for microwave assisted catalyst pyrolysis of Douglas fir pellets.     

酸性离子交换树脂催化酯化改质生物油的研究

以磺酸型离子交换树脂为催化剂, 在模型反应的基础上, 探讨了该催化剂在稻壳裂解油及其轻质馏分的催化酯化改质过程中的活性和效果, 并通过气-质联用仪对酯化前后的生物油进行了成分分析. 结果表明, 酯化过程中采用的催化剂可以方便地分离和循环使用; 生物油中的有机酸顺利地转化为相应的酯类(主要为乙酸乙酯). 通过催化酯化改质后, 两种生物油的理化特性均得到了有效改善, 热值分别由16.80和12.76 MJ/kg提高到20.08和18.33 MJ/kg, 相应提高了19.5%和43.6%; 黏度分别由11.83和1.42 mm2/s, 下降到3.77和1.12 mm2/s; 水分分别为23.7%和28.4%, 流动性明显增强, 理化特性得到了明显提高. 为生物油的精制加工提供了一种有效方法.     

Scale-up of microwave heating process for the production of bio-oil from sewage sludge

A pilot-scale microwave heating apparatus was constructed for the production of bio-oil from sewage sludge, and the effects of important microwave processing parameters and chemical additives on the quality and yield of bio-oils were investigated. It was found that bio-oil was mainly formed at the pyrolysis temperature range of 200–400 °C. A higher heating rate (faster pyrolysis) not only increased the yield of bio-oil, but also improved the quality of bio-oil according to the elemental composition and calorific values. The maximum bio-oil yield was 30.4% of organic fraction, obtained from the pyrolysis of original sewage sludge at microwave radiation power of 8.8 kW and final pyrolysis temperature of 500 °C. All of five simple additives (KOH, H₂SO₄, H₃BO₃, ZnCl₂, and FeSO₄) reduced the bio-oil yield, but the composition and property of bio-oil varied with the additive types greatly. KOH, H₂SO₄, H₃BO₃ and FeSO₄ were found to improve the quality of bio-oils remarkably according to the calorific value, density, viscosity and carbon content of bio-oils, but ZnCl₂ treatment went against that. GC–MS analysis of the bio-oils showed that, alkali treatment promoted the formation of alkanes and monoaromatics, while acid treatment favored the formation of heterocyclics, ketones, alcohols and nitriles. Compared with sulfate slat FeSO₄, chloride salt ZnCl₂ was a better catalyst for selective catalytic pyrolysis of sewage sludge. The addition of ZnCl₂ only promoted the formation reactions of a few kinds of nitriles and ketones remarkably. It is technologically feasible to produce bio-oil form microwave-induced pyrolysis of sewage sludge by optimizing pyrolysis conditions and selecting appropriate additives.