生物油水蒸气催化重整制氢研究进展

氢气作为一种环境友好的清洁能源,人们对它的关注度越来越高。生物油水蒸气催化重整制氢是未来制氢的一种可行性方案。本文综述了近年来生物油水蒸气重整制氢的研究进展。主要从重整制氢反应机理、热力学分析、催化重整催化剂、代表性的重整反应器方面进行讨论,指出催化重整中的主要问题是碳沉积导致催化剂失活。研制高活性、高稳定性、高选择性的催化剂是生物油催化重整制氢的关键。     

车载燃料重整技术的研究与展望

总结概述了目前的燃料重整技术,包括传统的重整制氢方法如水蒸汽重整、部分氧化重整、自热重整,以及逐渐成为研究热点的等离子体制氢技术.分析归纳了甲醇、乙醇、天然气、汽油和柴油的重整制氢研究,分析了反应机理和重整催化剂的研究进展,提出了各种燃料车载制氢的应用建议,尤其是汽油和柴油的车载应用.     

车载燃料重整制氢及其在发动机上的应用

综述了车载燃料重整制氢技术的现状,详细介绍了二甲醚水蒸气催化重整制氢的原理及其应用。跟踪了车载燃料重整制氢——燃料废气重整再循环(Reformed Exhaust Gas Recirculation,简写为REGR)技术在发动机上的应用状况,并分析了二甲醚水蒸气催化重整对二甲醚发动机性能和排放的影响。     

甲烷水蒸气重整制氢技术研究进展

甲烷水蒸气重整(SRM)是简单经济的制氢方法。对甲烷水蒸气重整工艺的反应过程机理进行归纳,分析了制约甲烷水蒸气重整发展的各个因素,重点从催化剂的研究制备及分离强化技术等方面进行归纳总结,简述重整反应器的结构及特性。研究表明,制备活性高、抗积碳能力强、稳定性好的催化剂和氢气的分离提纯是未来重要的研究方向。     

重整制氢技术及其研究进展

燃料电池技术的发展使得氢能利用也在快速发展，目前利用重整技术进行制氢是十分重要的一种手段。本文介绍了重整制氢技术的现状及其研究动态，指出了蒸汽重整是目前比较成熟的制氢方法，并正在由常规型设备向紧凑型、微通道型方向发展。另外介绍了部分氧化重整、催化部分氧化重整和自热重整技术的优缺点以及它们目前所遇到的技术困难。最后预测了今后重整制氢技术的研究重点是等离子体重整。     

Ni/KZSM-5催化剂的生物乙醇水蒸气重整制氢催化性能

采用浸渍法制备了Ni/γ-Al_2O_3,Ni/HZSM-5和Ni/KZSM-5 3种负载型催化剂,利用XRD,XPS,BET,NH3-TPD,CO2-TPD和H2-TPR等手段对催化剂的晶相、比表面积、酸/碱性等物化特性进行了表征,并通过固定床反应器对比考察了不同载体的Ni基负载型催化剂对乙醇水蒸气重整制氢的催化性能。实验结果表明:由于HZSM-5的酸性较强,Ni/HZSM-5催化剂不能有效催化乙醇水蒸气重整制氢,主要产物为乙烯;由于KZSM-5具有一定的碱性并有较高的比表面积,Ni/KZSM-5催化剂对乙醇水蒸气重整制氢表现出了较高的催化活性,当反应温度为450℃时,乙醇转化率为100%,氢气选择性达到65.0%,且反应积碳率仅为3.0%;由于载体的碱性较弱,导致产物中含有部分乙烯,降低了氢气选择性,从而Ni/γ-Al_2O_3催化剂的活性低于Ni/KZSM-5催化剂。     

HYDROGEN PRODUCTION RESERACH BY STEAM REFORMING OF ETHANOL OVER Ni-Cu/SrCeO3 CATALYST

利用固定床反应器对一系列自制催化剂Ni-Cu/SrCe03在乙醇水蒸气重整制氢反应中的催化性能进行考察,研究活性金属Ni的负载量、反应温度、水醇比对催化剂活性的影响.实验结果表明,Ni负载量为10％(质量分数)的催化剂Ni-Cu/SrCe03在乙醇重整制氢中表现出最佳催化活性,当反应温度为650℃,水醇比为8时,氢选择性达到最大值87.3％.     

柴油氧重整及部分氧化重整制氢

以复合氧化物为载体,稀土元素等为催化剂助剂,采用浸渍法制备了铂镧系列催化剂并探索了还原方法;通过柴油氧重整制氢及柴油部分氧化重整制氢试验,研究了催化剂的抗氧化性、活性及稳定性;研究了温度、水碳比、柴油液空速和氧碳比四因素对柴油部分氧化重整制氢的影响;研究了制氢过程的析碳及除碳方法.     

二甲醚水蒸气重整制氢的模型和数值模拟

为研究二甲醚的水蒸气重整制氢过程,设计了一种带有隔热套、瓦片式加热通道和催化反应床的重整反应器.建立了反应器的数学模型,并利用COMSOL软件对其仿真.试验研究了反应气体温度、水蒸气与二甲醚的物质的量比和反应器结构参数对二甲醚转化率、氢产率的影响.模拟结果显示了二甲醚水蒸气重整制氢过程中的各组分质量分布及不同温度、不同...     

甲醇重整制氢在燃烧电池中的应用

分别分析了甲醇重整制氢中的蒸气重整、氧化重整和自热重整技术的特点,介绍了近年来甲醇重整制氢在燃料电池中的应用现状及存在的主要问题.     

A review of biomass-derived fuel processors for fuel cell systems

Fuel cell coupled with biomass-derived fuel processor can convert renewable energy into a useful form in an environmental-friendly and CO₂-neutral manner. It is considered as one of the most promising energy supply systems in the future. Biomass-derived fuels, such as ethanol, methanol, biodiesel, glycerol, and biogas, can be fed to a fuel processor as a raw fuel for reforming by autothermal reforming, steam reforming, partial oxidation, or other reforming methods. Catalysts play an important role in the fuel processor to convert biomass fuels with high hydrogen selectivity. The processor configuration is another crucial factor determining the application and the performance of a biomass fuel processing system. The newly developed monolithic reactor, micro-reactor, and internal reforming technologies have demonstrated that they are robust in converting a wide range of biomass fuels with high efficiency. This paper provides a review of the biomass-derived fuel processing technologies from various perspectives including the feedstock, reforming mechanisms, catalysts, and processor configurations. The research challenges and future development of biomass fuel processor are also discussed.     

Design and performance of asymmetric supported membranes for oxygen and hydrogen separation

Producing syngas and hydrogen from biofuels is a promising technology in the modern energy. In this work results of authors’ research aimed at design of supported membranes for oxygen and hydrogen separation are reviewed. Nanocomposites were deposited as thin layers on Ni–Al foam substrates. Oxygen separation membranes were tested in CH₄ selective oxidation/oxi-dry reforming. The hydrogen separation membranes were tested in C₂H₅OH steam reforming. High oxygen/hydrogen fluxes were demonstrated. For oxygen separation membranes syngas yield and methane conversion increase with temperature and contact time. For reactor with hydrogen separation membrane a good performance in ethanol steam reforming was obtained. Hydrogen permeation increases with ethanol inlet concentration, then a slight decrease is observed. The results of tests demonstrated the oxygen/hydrogen permeability promising for the practical application, high catalytic performance and a good thermochemical stability.     

Thermodynamic analysis of hydrogen generation via oxidative steam reforming of glycerol

A thermodynamic analysis of the oxidative steam reforming of glycerol (OSRG) for hydrogen production has been carried out with Aspen plus ^TM. The reaction was investigated at ambient pressure within the carbon-to-oxygen (C/O) ratio of 0.5–3.0, steam-to-carbon (S/C) ratio of 0.5–8.0 and temperature of 400–850 °C. Higher C/O and S/C ratios favor the production of hydrogen from glycerol. The highest hydrogen selectivity is obtained at 600–700 °C. To predict the potential technical obstacles in the glycerol reforming process, the OSRG process was compared with oxidative steam reforming of ethanol (OSRE) in terms of hydrogen production, autothermal condition and carbon deposition. The selectivity to hydrogen via OSRG is lower than that via OSRE under identical conditions. To achieve autothermal reforming, higher S/C and C/O ratios are required for reforming of glycerol than for ethanol due to the higher oxygen content in a glycerol molecule. From the viewpoint of thermodynamics, the glycerol reforming is more resistant to the carbon deposition. On the basis of the thermodynamic analysis and the preliminary experimental study, suggestions were proposed to guide the development of the glycerol reforming technique.     

Simulation of a hydrogen production and purification system for a PEM fuel-cell using bioethanol as raw material

A process to produce “fuel-cell grade” hydrogen from ethanol steam reforming is analyzed from a thermodynamic point of view. The hydrogen purification process consists of WGS and COPROX reactors. Equations to evaluate the efficiency of the system, including the fuel cell, are presented. A heat exchange network is proposed in order to improve the exploitation of the available power. The effect of key variables such as the reformer temperature and the ethanol/water molar feed ratio on the fuel-cell efficiency is discussed. Results show that it is feasible to carry out the energy integration of the hydrogen catalytic production and purification—PEM fuel-cell system, using ethanol as raw material. The technology of “fuel-cell grade” hydrogen production using ethanol as raw material is a very attractive alternative to those technologies based in fossil fuels.     

Hydrogen from steam reforming of ethanol in low and middle temperature range for fuel cell application

The catalyst, Ni nano-particles supported on Y₂O₃, which was prepared by three methods, was studied. The structural properties of the catalysts were tested through X-ray diffraction and BET area. The catalyst of Ni/Y₂O₃ exhibits high activity for ethanol steam reforming with conversion of ethanol of 98% and selectivity of hydrogen of 38% at 300°C, conversion of ethanol of 98% and selectivity of hydrogen of 55% at 380°C. With temperature increasing to and above 500°C, the conversion of ethanol increased to 100%, but the selectivity of hydrogen did not increase so much, it was 58% at 600°C. The catalyst has long-term stability for steam reforming of ethanol and is a good choice for ethanol processors for fuel cell applications.     

Hydrogen production from ethanol steam reforming: energy efficiency analysis of traditional and membrane processes

The ethanol steam reforming reaction has been considered for producing pure hydrogen to be used for feeding a PEM fuel cell of power 4 kW. As an innovative technology, Pd–Ag thin wall membranes are proposed for building membrane reactors: accordingly, the energy efficiency analysis of the processes producing hydrogen from ethanol steam reforming has been carried out and, particularly, the comparison among a traditional process and different membrane processes is reported.     

Recent progress in thermochemical techniques to produce hydrogen gas from biomass: A state of the art review

The present work comprehensively covers the literature that describes the thermochemical techniques of hydrogen production from biomass. This survey highlights the current approaches, relevant methods, technologies and resources adopted for high yield hydrogen production. Prominent thermochemical methods i.e. pyrolysis, gasification, supercritical water gasification, hydrothermal upgrading followed by steam gasification, bio-oil reforming, and pyrolysis inline reforming have been discussed thoroughly in view of the current research trend and latest emerging technologies. Influences of important factors and parameters on hydrogen yield, such as biomass type, temperature, steam to biomass ratio, retention time, biomass particle size, heating rate, etc. have also been extensively studied. Catalyst is a vital integrant that has received enough attention due to its encouraging influence on hydrogen production. Literature confirms that hydrogen obtained from biomass has high-energy efficiency and potential to reduce greenhouse gases hence, it deserves versatile applications in the coming future. The study also reveals that hydrogen production through steam reforming, pyrolysis, and in-line reforming deliver a considerable amount of hydrogen from biomass with higher process efficiency. It has been identified that higher temperature, suitable steam to biomass ratio and catalyst type favor useful hydrogen yield. Nevertheless, hydrogen is not readily available in the sufficient amount and production cost is still high. Tar generation during thermochemical processing of biomass is also a concern and requires consistent efforts to minimize it.     

Thermochemical waste-heat recuperation as on-board hydrogen production technology

Thermochemical waste-heat recuperation (TCR) as an on-board hydrogen production technology is considered. To determine the effectiveness of using TCR systems as an on-board hydrogen production technology and to assess the possibility of hydrogen production in TCR systems, a thermodynamic analysis of various hydrocarbon reforming reactions was carried out. The thermodynamic analysis has been realized via Aspen HYSYS software. Three steam reforming reactions with methane, methanol, and ethanol were investigated. It was established that the composition of the initial reaction mixture and the process temperature has a significant effect on the efficiency of the thermochemical heat recuperation system. The maximum efficiency of thermochemical heat recuperation systems due to steam reforming is achieved at 600 K for methanol; 700 K for ethanol and 900 K for methane.