生物质热解焦油的性质与化学利用研究现状

介绍了生物质热解焦油的定义、性质及分析方法,简述了国内外生物质热解焦油的化学利用现状。生物质热解焦油是一种重要的化工材料,其单组分可用作重要的化学品,某些混合组分可用作抗氧化剂、抗聚合剂以及液体燃料等,并对未来生物质热解焦油的化学利用研究进行了展望。     

生物质碳基催化剂催化重整焦油

生物质热利用过程中产生的焦油极易造成管路腐蚀堵塞,是当前亟待解决的关键问题。焦油的催化重整制氢是一种有效的生物质高值化利用技术。以常压气化炉运行过程中产生的焦油为研究对象,利用杏壳制备催化剂炭载体,并负载催化金属以制备重整焦油用碳基催化剂;使用制备的碳基催化剂开展焦油水蒸气催化重整实验,并对比了不同负载金属的催化效果。结果表明：当采用单金属催化剂对焦油进行催化重整时,最佳工况为800℃、通入水蒸气与焦油质量比为3、焦油与催化剂质量比为2时,氢气产量高达91.52 g H₂ (每1 kg焦油),焦油转化率为93.30%。Ni-Co/C复合催化剂表现出比单金属催化剂更强的活性。     

石油焦对生物质气化中焦油裂解的影响

引言 生物质作为一种清洁可再生能源正在受到世界各国的重视.生物质气化是生物质高品位利用的一种主要技术,但在气化过程中产生的焦油对装置的长周期平稳运行有严重危害,一方面低温时焦油易凝结为黏稠的液体,与灰粒一起堵塞输气管道;另一方面焦油的存在还会降低气化效率[1-6],这在一定程度上影响了生物质气化技术的推广应用,因此有必要采取措施降低气化气中的焦油量.     

生物质气化燃气中焦油采样方法的研究进展

本文介绍了近年来国内、美国、欧盟等各地生物质气化燃气中的焦油采样方法的研究进展。分析了当前生物质燃气中焦油采样方法的原理,对各种采样方法进行了评价,指出了高效生物质燃气中焦油采样方法的设计关键和研究方向。     

基于回收理念的生物质燃气焦油脱除研究进展

生物质气化是重要的可再生能源方式。焦油是生物质气化过程大规模工业化的主要障碍之一。为了提高生物质燃气用于内燃机和燃气轮机发电以及甲醇合成的效率,燃气中的焦油必须深度脱除至低于20 mg/m3。本文简述了焦油污染和堵塞燃气下游设备的危害,介绍了焦油的特征和分类,分析了基于回收过程的焦油脱除方法优势,评述了回收法焦油脱除的研究进展,阐述了水洗和油洗回收脱焦的典型应用实例。指出了以油洗回收法为基础,将焦油和微孔材料的孔径进行匹配,高集成度的吸附和膜分离多级耦合焦油深度脱除工艺,将成为脱除生物质燃气焦油的主要发展方向。     

烘焙对生物质理化性质及气化特性的影响

生物质资源丰富廉价,因清洁可再生、碳中和等优点备受研究者的关注,但是其能量密度低、水分和氧含量高等缺点也限制了其规模化应用;另外,生物质直接气化产生的合成气热值较低,且会产生大量焦油。本文阐述了烘焙预处理对生物质燃料品质的提升以及对气化过程积极的调控作用。文章指出,生物质烘焙后,氧元素含量、H/C和O/C下降,固定碳含量和高位热值增加;可磨性和疏水性得以提高,在一定程度上弥补了烘焙过程的耗能。文中从微观角度对生物质燃料品质的提升进行了解释,并简述了微波烘焙的特点与优势。使用烘焙生物质气化,产生的合成气可燃成分高,且焦油产量有所下降。文章总结后续工作可以考虑从以下三个方面展开,即对“烘焙-利用”过程进行全生命周期评价、利用微波技术更准确地探索温度对烘焙效果的的影响机制、结合烘焙与焦油催化重整技术进一步降低焦油产量。     

烟煤与生物质固定床共热解实验研究

对烟煤与木质素类生物质松木屑、纤维素类生物质秸秆在固定床反应器中共热解行为进行了系统的实验研究,并对气体产物和焦油组成进行了分析.结果表明,烟煤与两种生物质共热解时存在明显的协同作用,挥发分产率的实验值较计算值有所增加,且使用松木屑时增幅较大.松木屑与烟煤共热解时焦油中愈创木酚类含量显著提高,在400℃松木屑配比为80%时,增量高达25.89%.焦油中酚类含量比计算值高,而PAH和烃类含量则明显降低,同时焦油产生了一定的轻质化.     

生物质焦油的特性及其去除方法的研究现状

生物质焦油是阻碍生物质热化学转化技术发展的瓶颈问题。只有全面正确的了解焦油的性质和特点,才能选择最合适的去除方法。介绍生物质焦油的特性,并将焦油的成分分类,最后介绍了目前国内外去除焦油的方法,为进一步研究提供参考。     

生物质气化中焦油特性及其处理

生物质气化过程中产生的焦油问题对整个气化系统的效率以及最终商业化发展有着重要的作用,焦油的危害在于其冷凝之后对反应设备有较大的腐蚀性而且对后续的反应也有影响。因此,生物质气化过程中去除焦油十分必要。本文综述了气化过程中温度、停滞时间、催化剂种类等因素对生物质气化过程中焦油产量的影响,并且详细介绍与对比了现实工业生产中去除焦油的几种常用方法。     

生物质炭在焦油裂解脱除领域的研究进展

基于生物质焦油的组成特性、危害及其处理方法,简单介绍了生物质焦油催化裂解脱除的机理及近年来的研究进展,重点阐述了生物质炭对焦油的催化转化机理(主要涉及裂解、重整和缩合3种反应)、生物质炭对焦油的吸附和重整作用,以及在催化转化过程中,生物质炭的催化性能受原料、裂解温度、加热速率和停留时间等因素的影响.通过分析生物质炭改性...     

杨木屑多元醇液化及聚氨酯泡沫材料的制备（摘要）

以杨木屑为研究对象,探索出一种转化率高、比较经济的多元醇液化工艺,并显著降低了液化反应温度和压力、减少了催化剂用量。对杨木屑液化油的性质和组分进行分析,利用此液化油部分取代聚醚多元醇制备聚氨酯发泡材料,并对液化油进行了分馏,考察了轻重组分的性质和成分。     

生物质灰硅资源高附加值利用的研究进展

生物质灰中含有具备化学活性的无定型硅，能用于合成高附加值产品。对生物质灰的组成、结构等方面进行了概述。在利用生物质灰合成凝胶方面，总结了近年利用生物质灰合成干凝胶、气凝胶、水凝胶的研究进展。综述了近年来利用生物质灰中的硅资源制备锂离子电池阳极材料、催化剂材料等方面的研究进展。通过对生物质灰硅资源的应用分析，提出生物质灰有望成为生产高附加值硅基材料的低成本前驱体来源，为生物质灰在工业上的资源化利用提供了重要的发展方向。     

生物油的特性及其应用研究进展

生物质是新型的可再生能源,将生物质热解生成生物油,不仅便于运输和储存,而且还可以作为生产化工产品的原料。本文讨论了生物油的物理化学性质及组成成分,概述了近年来生物油的利用和改性技术;提出了生物油研究的主要问题和未来发展方向;作者认为,反应机理的研究、催化剂的开发、能源利用与提取有价值的化工产品相结合是生物油改性技术研究的主要方向。     

浮法玻璃在线制备双层复合薄膜的性能

将离子渗透着色技术(IPC)和化学气相沉积技术(CVD)加以结合,在浮法玻璃生产线的锡槽内和A0区进行2次镀膜形成复合膜,克服了单一镀膜技术存在的不足.已经试制出了咖啡色、金黄色、桔红色、蓝色、绿色、灰色等5个系列的复合膜产品,对这种产品的薄膜显微硬度、耐酸碱性、耐磨性、光谱性能、热学性能进行了测定,结果表明:这种复合膜层既具有装饰性,又具有节能性,膜层均匀、平整、牢固,是性能优良的阳光控制镀膜玻璃产品.     

Structural investigation of asphalts produced from paraffinic-base crude oil by different methods

Four asphalts, produced by different methods, were separated into three fractions. The composition and chemical structure of these fractions were examined by means of molecular weight, elemental composition and ¹H n.m.r. and infrared spectroscopy methods. Correlation between the asphalt production method and its chemical structure was found.     

Development of a modeling approach to predict ash formation during co-firing of coal and biomass

The scope of this paper includes the development of a modelling approach to predict the ash release behaviour and chemical composition of inorganics during co-firing of coal and biomass. In the present work, an advanced analytical method was developed and introduced to determine the speciation of biomass using pH extraction analysis. Biomass samples considered for the study include wood chips, wood bark and straw. The speciation data was used as an input to the chemical speciation model to predict the behaviour and release of ash. It was found that the main gaseous species formed during the combustion of biomass are KCl, NaCl, K₂SO₄ and Na₂SO₄. Calculations of gas-to-particle formation were also carried out to determine the chemical composition of coal and biomass during cooling which takes place in the boiler. It was found that the heterogeneous condensation occurring on heat exchange surfaces of boilers is much more than homogeneous condensation. Preliminary studies of interaction between coal and biomass during ash formation process showed that Al, Si and S elements in coal may have a ‘buffering’ effect on biomass alkali metals, thus reducing the release of alkali–gases which act as precursors to ash deposition and corrosion during co-firing. The results obtained in this work are considered to be valuable and form the basis for accurately determining the ash deposition during co-firing.     

Performance assessment of drop tube reactor for biomass fast pyrolysis using process simulator

Biomass pyrolysis process from a drop tube reactor was modelled in a plug flow reactor using Aspen Plus process simulation software. A kinetic mechanism for pyrolysis was developed considering the recent improvements and updated kinetic schemes to account for different content of cellulose, hemicellulose, and lignin. In this regard, oak, beechwood, rice straw, and cassava stalk biomasses were analyzed. The main phenomena governing the pyrolysis process are identified in terms of the characteristic times. Pyrolysis process was found to be reaction rate controlled. Effects of pyrolysis temperature on bio-oil, gases, and char yields were evaluated. At optimum pyrolysis conditions (i.e., 500°C), a bio-oil yield of 67.3, 64, 43, and 52 wt.% were obtained from oak, beechwood, rice straw, and cassava stalk, respectively. Oak and beechwood were found to give high yields of bio-oil, while rice straw produced high gas and char yields compared to other biomasses. Although temperature is the main factor that plays a key role in the distribution of pyrolysis products, the composition of cellulose, hemicellulose, and lignin in the feedstock also determines the yield behaviour and composition of products. With the rise in pyrolysis temperature, further decomposition of intermediate components was initiated favouring the formation of lighter fractions. Comparably, species belonging to the aldehyde chemical family had the highest share of bio-oil components in all the investigated feedstocks. Overall, the present study shows a good agreement with the experimental study reported in the literature, confirming its validity as a predictive tool for the biomass pyrolysis process.     

变色缺陷海绵钛的形成机理研究

针对镁还原法生产的海绵钛中的变色缺陷产品,通过成分分析和XRD衍射分析,确定物相组成,并对其产生的原因进行了分析.     

Biomass as Feedstock in the Chemical Industry – An Examination from an Exergetic Point of View

Crude oil is the most important raw material for the chemical industry. Due to the continually rising price of crude oil, alternative carbon sources are becoming increasingly important. Biomass is basically the only available renewable carbon source. Because the chemical composition of biomass differs from fossil raw materials, the raw‐material change also offers many chances for new product properties and applications. At the same time, the chemical processes have to be redesigned if the feedstock changes to biomass. Here, the effects of a raw‐material change are examined on a rather generic level. The study is based on exergy balances and indicates that it is exergetically advisable to reconsider the previously established system of platform and basic chemicals. In general, exergy losses can be minimized if the synthesis pathways leading to the final products are adapted to the chemical structure of biomass.     

Cu-Ni composition gradient for the catalytic synthesis of vertically aligned carbon nanofibers

The influence of catalyst alloy composition on the growth of vertically aligned carbon nanofibers was studied using Cu-Ni thin films. Metals were co-sputtered onto a substrate to form a thin film alloy with a wide compositional gradient, as determined by Auger analysis. Carbon nanofibers were then grown from the gradient catalyst film by plasma enhanced chemical vapor deposition. The alloy composition produced substantial differences in the resulting nanofibers, which varied from branched structures at 81%Ni-19%Cu to high aspect ratio nanocones at 80%Cu-20%Ni. Electron microscopy and spectroscopy techniques also revealed segregation of the initial alloy catalyst particles at certain concentrations.