松木热解焦油的炭催化二次裂解特性

利用两段固定床反应器研究了木炭对松木热解焦油的催化二次裂解特性.焦油通过700 ℃木炭层与通过相同温度的空管相比,焦油产率(包括水分)从26.7% 降低至16.4 %(wt.), CH4 产率从3.7 降低至2.8 mmol/g 干基生物质,而CO 产率基本不变,H2 和CO2 的产率则分别从3.6、2.9 提高至11.8、6.6 mmol/g 干基生物质,表明木炭具有明显促进焦油二次裂解及甲烷分解的作用.并利用气质联用(GC-MS)和火焰离子检测气相色谱(FID-GC)对液体产物进行定性和定量分析,观察到下段松木热解焦油经过600℃的木炭层后,其组成中糖、醛、酮以及愈创木酚类等含氧化合物发生剧烈分解,液相成分主要为酚类;温度越高,芳香化程度越大.     

生物质合成气催化制取甲烷研究进展

天然气的供需矛盾促使人们去寻找新的天然气资源,其中利用生物质热化学催化制取生物质基天然气的技术受到了全世界的广泛关注。而生物质合成气催化制取甲烷是该工艺流程的核心步骤之一。分别从甲烷化反应器和甲烷化催化剂两个方面阐述了国际上生物质合成气催化制取甲烷的研究现状,并综述了关于甲烷化催化剂积碳现象的研究进展。同时分析了目前生物质合成气催化制取甲烷面临的主要问题,并指明了未来的发展方向。     

生物质气化制取代用天然气的模拟

介绍了生物质气化制取代用天然气的技术,并利用Aspen Plus软件建立了串行流化床生物质气化制取代用天然气的模型,并对整个流程进行模拟。着重研究了气化过程中操作参数(气化温度Tg、S/B)对甲烷化反应过程主要指标(包括甲烷产率、碳转化率等)的影响。研究结果表明提高气化温度和S/B有利于提高气化产物中生物质合成气的浓度,并得到较高氢碳比的合成气,从而可以提高甲烷的产率和整个系统的碳转化率;为获得较高的甲烷产率和碳转化率,适宜的气化温度为700～750℃,S/B值在0.4左右。     

生物质基平台分子5-羟甲基糠醛制备及其高值化转化

5-羟甲基糠醛是重要的生物质平台分子之一,可以由生物质糖类催化脱水重排直接制备,是实现生物质高值化转化的重要媒介。C—O键选择性地重构是5-羟甲基糠醛制备及催化转化过程中的核心科学问题。近年来,以5-羟甲基糠醛为原料制备生物质基燃料及材料单体的研究快速发展,各种新型催化剂和催化体系被不断用于5-羟甲基糠醛的相关转化过程的研究中。对5-羟甲基糠醛的制备及其下游生物质基燃料、材料单体制备的研究进行了概述和展望。     

生物质催化转化制备呋喃基化学品和酚类化合物

生物质转化制备精细化学品是解决石油能源危机的重要途径之一。其中,纤维素及半纤维素转化合成呋喃基化学品与木质素转化制酚类化合物是主要的反应路线,特别是借助催化技术加速生物质转化更是当今化学领域的研究重点;依据催化反应体系的不同,对近年来用于生物质催化转化的反应媒介以及催化剂研究进展进行了综述,并对未来生物质催化转化研究方向的发展前景进行了展望。     

多级孔分子筛在生物质催化热裂解制备芳烃中的研究进展

芳烃是石化工业的一种重要基础原料,目前主要来源于石油和煤焦油。随着化石能源的日益枯竭、全球环境问题的日益严重和芳烃需求量的不断增长,芳烃的传统生产工艺压力越来越大。生物质催化热解制备芳烃技术由于其绿色、原料来源广以及可持续等优点,近年来备受关注。微孔分子筛因其大比表面积、强酸性、微孔择形性和良好的水热稳定性等优点成为理想的催化热解催化剂,但是微孔分子筛扩散阻力大、易积碳致使催化剂寿命低,使其在生物质催化热解制备芳烃的应用方面受到很大限制。在微孔分子筛中引入介孔得到多级孔分子筛,可以有效解决分子传质问题,并且保留微孔的强酸性以及择形选择,提高催化反应活性的同时提高催化剂的使用寿命,因此,多级孔分子筛成为了近年来生物质催化热解的热点。本文中,笔者详细综述了近年来生物质催化热裂解制备芳烃过程中所需要的原料和反应机制,重点综述了多级孔分子筛的优势以及其在生物质催化热解制备芳烃方面的应用前景和研究进展,最后总结了该技术面临的挑战和发展方向。     

CN101629087 用松香生产及其深加工残渣制备生物质燃料油的方法

本发明提供了一种用松香生产及其深加工残渣制备生物质燃料油的方法,松香生产及其深加工利用过程中形成的固体残渣,其中虽然仍然含有少量松香树脂酸但含量很低,主要含有氧化松香树脂酸、聚合树脂酸、树脂酸酯、难于皂化甚至不能皂化的中性物质等,在活性白土、硅藻土、高岭土、分子筛等催化剂作用下进行催化裂解反应,从而制备得到生物质燃料油。     

生物质热裂解生产生物燃料的研究进展

生物质能源是一种绿色的可以替代化石能源的一种可再生的能源。尽管高温分解生物质处于发展阶段,但在目前水平,高温裂解因其可以在氧存在下热分解将生物材料直接转化为固态,液态和气态能源产品而受到广泛关注。本文介绍了生物质的热裂解,包括慢速热裂解、快速热裂解、闪解、催化热裂解等过程,重点讨论了在各种生物质材料的热裂解过程中各种操作参数如温度和生物粒子大小等对生物燃料收率的影响。     

木质素能源转化的研究进展

木质素具有较高的碳含量和热值,其最直接的利用方式是转化为各种能源产品,包括燃料和电能。因此,以来源丰富的木质素为原料转化制备生物质能源具有重要的意义。本文概述了近年来木质素转化为生物质能源的研究进展,包括木质素来源及提取、木质素热化学转化为生物燃料以及木质素发电技术,着重介绍了木质素的热解反应、气化反应、液化反应以及催化加氢脱氧反应,并总结了直接木质素燃料电池发电的最新研究成果。最后对木质素能源转化的研究前景进行了展望,提出实现工业化生产需根据目标产物需求开发新型催化剂、优化转化过程、建立低能耗且高效率的产物分离方法并加强木质素产电中电极材料、电池设计等研究,为木质素高值化、资源化和能源化利用提供参考。     

生物质生物预处理研究进展与展望

木质纤维素生物质分布广、产量大、可再生,用于制备生物基能源、生物基材料和生物基化学品。木质纤维素生物质组成复杂,包含纤维素、半纤维素和木质素等,木质素与半纤维素通过共价键、氢键交联形成独特的“包裹结构”,纤维素含有复杂的分子内与分子间氢键,上述因素制约着其资源化利用。生物预处理以其独特优越性成为生物质研究的重要方面。系统阐述了生物预处理过程中木质素降解和基团修饰对纤维素酶解的影响,纤维素含量及结晶区变化,半纤维素五碳糖利用,微观物理结构的改变。进一步提出了以生物预处理为核心的组合预处理、基于不同功能的多酶协同催化体系、木质纤维素组分分级利用和新型高效细菌预处理工艺是生物预处理未来发展的重要趋势。     

Two-stage steam gasification of waste biomass in fluidized bed at low temperature: parametric investigations and performance optimization

Steam gasification of waste biomass has been studied in a two-stage fluidized bed reactor, which has the primary pyrolysis fluidized bed using silica sand as bed material and the secondary reforming fixed bed with catalyst. The main objectives are parametric investigation and performance improvement especially at low temperature of around 600 °C using the wood chip and the pig manure compost as feedstock. Main operating variables studied are pyrolysis temperature, catalytic temperature, steam/biomass-C ratio, space velocity and different catalyst. Reaction temperatures and steam/C ratio have important role on the gasification process. About 60 vol.% H2 (dry and N2 free) and about 2.0 Nm3/kg biomass (dry and ash free basis) can be obtained under good conditions. Compared to Ni/Al2O3, Ni/BCC (Ni-loaded brown coal char) has a better ability and a hopeful prospect for the stability with coking resistance.     

Influence of supports on catalytic behavior of nickel catalysts in carbon dioxide reforming of toluene as a model compound of tar from biomass gasification

A series of supported Ni catalysts including Ni/MgO, Ni/γ-Al2O3, Ni/α-Al2O3, Ni/SiO2 and Ni/ZrO2 was tested in CO2 reforming of toluene as a model compound of tar from biomass gasification in a fluidized bed reactor, and characterized by the means of temperature programmed reduction with hydrogen (H2-TPR), XRD, TEM and temperature programmed oxidation (TPO). Combining the characterization results with the performance tests, the activity of catalyst greatly depended on Ni particles size, and the stability was affected by the coke composition. Both of them (Ni particle size and coke composition) were closely related to the interaction between nickel and support which would determine the chemical environment where Ni inhabited. The best catalytic performance was observed on Ni/MgO due to the strong interaction between NiO and MgO via the formation of Ni-Mg-O solid solution, and the highest dispersion of Ni particle in the basic environment.     

Development of a supported tri-metallic catalyst and evaluation of the catalytic activity in biomass steam gasification

A supported tri-metallic catalyst (nano-Ni–La–Fe/γ-Al₂O₃) was developed for tar reduction and enhanced hydrogen production in biomass steam gasification, with focuses on preventing coke deposition and sintering effects to lengthen the lifetime of developed catalysts. The catalyst was prepared by deposition–precipitation method and characterized by various analytical approaches. Following that, the activity of catalysts in biomass steam gasification was investigated in a bench-scale combined fixed bed reactor. With presence of the catalyst, the content of hydrogen in gas products was increased to over 10 vol.%, the tar removal efficiency reached 99% at 1073 K, and more importantly the coke deposition on the catalyst surfaces and sintering effects were avoided, leading to a long lifetime of catalysts.     

An experimental study on biomass air-steam gasification in a fluidized bed

The characteristics of biomass air-steam gasification in a fluidized bed are studied in this paper. A series of experiments have been performed to investigate the effects of reactor temperature, steam to biomass ratio (S/B), equivalence ratio (ER) and biomass particle size on gas composition, gas yield, steam decomposition, low heating value (LHV) and carbon conversion efficiency. Over the ranges of the experimental conditions used, the fuel gas yield varied between 1.43 and 2.57 Nm3/kg biomass and the LHV of the fuel gas was between 6741 and 9143 kJ/Nm3. The results showed that higher temperature contributed to more hydrogen production, but too high a temperature lowered gas heating value. The LHV of fuel gas decreased with ER. Compared with biomass air gasification, the introduction of steam improved gas quality. However, excessive steam would lower gasification temperature and so degrade fuel gas quality. It was also shown that a smaller particle was more favorable for higher gas LHV and yield.     

Operational characteristics of a 1.2-MW biomass gasification and power generation plant

In this study, we analyzed the operational characteristics of a 1.2-MW rice husk gasification and power generation plant located in Changxing, Zhejiang province, China. The influences of gasification temperature, equivalence ratio (ER), feeding rate and rice husk water content on the gasification characteristics in a fluidized bed gasifier were investigated. The axial temperature profile in the dense phase of the gasifier showed that inadequate fluidization occurred inside the bed, and that the temperature was closely related to changes in ER and feeding rate. The bed temperature increased linearly with increasing ER when the feeding rate was kept constant, while a higher feeding rate corresponded to a lower bed temperature at fixed ER. The gas heating value decreased with increasing temperature, while the feeding rate had little effect. When the gasification temperature was 700–800 °C, the gas heating value ranged from 5450–6400 kJ/Nm³. The water content of the rice husk had an obvious influence on the operation of the gasifier: increases in water content up to 15% resulted in increasing ER and gas yield, while water contents above 15% caused aberrant temperature fluctuations. The problems in this plant are discussed in the light of operational experience of MW-scale biomass gasification and power generation plants.     

Influence of operation conditions and additives on the development of producer gas and tar reduction in air gasification of construction woody wastes using a two-stage gasifier

Air gasification was conducted with fractions of construction woody wastes in a two-stage gasifier, consisting of a fluidized bed zone and a tar cracking zone. The aim of this work is to investigate the influence of reaction conditions and additives on the composition of producer gas and tar content in producer gas.A producer gas obtained with activated carbon of 540 g at an ER of 0.26 was mainly composed of H₂ (25 vol.%), CO (22 vol.%) and CH₄ (5 vol.%). Regarding tar removal efficiency, activated carbon was better than olivine. The tar removal rate with virgin activated carbon reached up to 80%. The reuse of spent activated carbon caused an efficiency loss in tar removal to some extent. Overall, it seems that the strong need for intensive downstream tar removal measurements can be removed with the use of a two-stage gasifier and the application of activated carbon.     

Assessment of black liquor gasification in supercritical water

Supercritical water gasification of black liquor (waste pulping chemicals) has been examined. The aim was to evaluate the feasibility of using this technique to convert such bio-based waste to value added fuel products, as well as recovery of pulping materials. Supercritical gasification may improve overall process efficiency by eliminating the energy intensive evaporation step necessary in conventional process and product gas obtained at high pressure may be ready for utilization without any compression requirement. Appropriate operating parameters, including pressure, temperature, feed concentration, and reaction time, which would yield the highest conversion and energy efficiency were determined. Reaction was performed in a quartz capillary heated in a fluidized bed reactor. Results indicated that pressure between 220 and 400 atm has insignificant influence on the gas products and extent of carbon conversion. Increasing temperature and residence time between 375-650 degrees C and 5-120 s resulted in greater gas production, overall carbon conversion, and energy efficiency. Maximum conversion to H(2), CO, CH(4), and C(2)H(X) was achieved at the highest temperature and longest residence time tested showing an overall carbon conversion of 84.8%, gas energy content of 9.4 MJ/m(3) and energy conversion ratio of 1.2. Though higher carbon conversion and energy conversion ratio were obtained with more dilute liquor, energy content was lower than for those with higher solid contents. Due to anticipated complex design and high initial investment cost of this operation, further studies on overall feasibility should be carried out in order to identify the optimum operating window for this novel process.     

Experimental study on air-stream gasification of biomass micron fuel (BMF) in a cyclone gasifier

Based on biomass micron fuel (BMF) with particle size of less than 250 microm, a cyclone gasifier concept has been considered in our laboratory for biomass gasification. The concept combines and integrates partial oxidation, fast pyrolysis, gasification, and tar cracking, as well as a shift reaction, with the purpose of producing a high quality of gas. In this paper, experiments of BMF air-stream gasification were carried out by the gasifier, with energy for BMF gasification produced by partial combustion of BMF within the gasifier using a hypostoichiometric amount of air. The effects of ER (0.22-0.37) and S/B (0.15-0.59) and biomass particle size on the performances of BMF gasification and the gasification temperature were studied. Under the experimental conditions, the temperature, gas yields, LHV of the gas fuel, carbon conversion efficiency, stream decomposition and gasification efficiency varied in the range of 586-845 degrees C, 1.42-2.21 N m(3)/kg biomass, 3806-4921 kJ/m(3), 54.44%-85.45%, 37.98%-70.72%, and 36.35%-56.55%, respectively. The experimental results showed that the gasification performance was best with ER being 3.7 and S/B being 0.31 and smaller particle, as well as H(2)-content. And the BMF gasification by air and low temperature stream in the cyclone gasifier with the energy self-sufficiency is reliable.     

Effects of gasifying conditions and bed materials on fluidized bed steam gasification of wood biomass

The effect of steam gasification conditions on products properties was investigated in a bubbling fluidized bed reactor, using larch wood as the starting material. For bed material effect, calcined limestone and calcined waste concrete gave high content of H(2) and CO(2), while silica sand provided the high content of CO. At 650 degrees C, calcined limestone proved to be most effective for tar adsorption and showed high ability to adsorb CO(2) in bed. At 750 degrees C it could not capture CO(2) but still gave the highest cold gas efficiency (% LHV) of 79.61%. Steam gasification gave higher amount of gas product and higher H(2)/CO ratio than those obtained with N(2) pyrolysis. The combined use of calcined limestone and calcined waste concrete with equal proportion contributed relatively the same gas composition, gas yield and cold gas efficiency as those of calcined limestone, but showed less attrition, sintering, and agglomeration propensities similar to the use of calcined waste concrete alone.