Biomass to hydrogen via catalytic steam reforming of bio-oil over Ni-supported alumina catalysts

Production of hydrogen (H₂) from catalytic steam reforming of bio-oil was investigated in a fixed bed tubular flow reactor over nickel/alumina (Ni/Al₂O₃) supported catalysts at different conditions. The features of the steam reforming of bio-oil, including the effects of metal content, reaction temperature, W_bHSV (defined as the mass flow rate of bio-oil per mass of catalyst) and S/C ratio (the molar ratio of steam to carbon fed) on the hydrogen yield were investigated. Carbon conversion (moles of carbon in the outlet gases to moles of the carbon feed) was also studied, and the outlet gas distributions were obtained. It was revealed that the Al₂O₃ with 14.1% Ni content gave the highest yield of hydrogen (73%) among the catalysts tested, and the best carbon conversion was 79% under the steam reforming conditions of S/C = 5, W_bHSV = 13 1/h and temperature = 950 °C. The H₂ yield increased with increasing temperature and decreasing W_bHSV; whereas the effect of the S/C ratio was less pronounced. In the S/C ratio range of 1 to 2, the hydrogen yield was slightly increased, but when the S/C ratio was increased further, it did not have an effect on the H₂ production yield.     

吸附强化焦油蒸汽重整制取氢气

分别采用固相反应法、溶胶凝胶法制备了Ni/Mg-Ca₁₂Al₁₄O₃₃催化剂、CaO-Ca₁₂Al₁₄O₃₃吸附剂,并将其作为重整催化剂、CO₂吸附剂应用在焦油蒸汽重整制取氢气的研究中,通过与普通蒸汽重整进行对比,系统地研究了重整温度、S/C比（反应体系中水蒸气与碳元素的摩尔比）、质量空速对焦油吸附强化蒸汽重整制氢特性的影响。结果表明,CO₂吸附剂的加入能够有效提升焦油重整效果,氢气产率、体积分数均得到显著提高,其中氢气体积分数达95%以上。随着S/C比的增加、质量空速的减小,普通蒸汽重整和吸附强化重整的制氢效果均是增强的,且均在S/C比、质量空速分别达到12：1、0.128 h⁻¹后增幅不再明显;尽管如此,相比普通重整,吸附强化重整降低了最佳重整制氢温度,在800℃时氢气产率能够达到87.35%。     

Hydrogen production via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system

Hydrogen production was prepared via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system. Low-cost catalyst dolomite was chosen for the primary steam reforming of bio-oil in consideration of the unavoidable deactivation caused by direct contact of metal catalyst and bio-oil itself. Nickel-based catalyst Ni/MgO was used in the second stage to increase the purity and the yield of desirable gas product further. Influential parameters such as temperature, steam to carbon ratio (S/C, S/CH₄), and material space velocity (W_BHSV, GHSV) both for the first and the second reaction stages on gas product yield, carbon selectivity of gas product, CH₄ conversion as well as purity of desirable gas product were investigated. High temperature (> 850 °C) and high S/C (> 12) are necessary for efficient conversion of bio-oil to desirable gas product in the first steam reforming stage. Low W_BHSV favors the increase of any gas product yield at any selected temperature and the overall conversion of bio-oil to gas product increases accordingly. Nickel-based catalyst Ni/MgO is effective in purification stage and 100% conversion of CH₄ can be obtained under the conditions of S/CH₄ no less than 2 and temperature no less than 800 °C. Low GHSV favors the CH₄ conversion and the maximum CH₄ conversion 100%, desirable gas product purity 100%, and potential hydrogen yield 81.1% can be obtained at 800 °C provided that GHSV is no more than 3600 h^− 1. Carbon deposition behaviors in one-stage reactor prove that the steam reforming of crude bio-oil in a two-stage fixed bed reaction system is necessary and significant.     

Au/La2O3/TiO2催化甲醇水蒸汽重整制氢

用沉积-沉淀法制备了Au/La2O3/TiO2催化剂,考察了制备条件和反应条件对催化剂活性的影响,并利用X射线衍射(XRD)、透射电子显微镜(TEM)等测试手段对催化剂进行了表征. 结果表明La2O3的加入可使催化剂催化甲醇水重整的催化活性明显提高,且明显降低产物气体中CO和CH4的含量,使氢气选择性明显增加. 当nH2O/nCH3OH=1.0、液体进料空速WHSV=3.42 h-1、反应温度为275℃时,Au/La2O3/TiO2催化剂催化甲醇水蒸汽重整制氢反应的效果最佳.     

High Efficient Production of Hydrogen from Bio-oil Using Low-temperature Electrochemical Catalytic Reforming Approach Over NiCuZn–Al2O3 Catalyst

High-efficient production of hydrogen from bio-oil was performed by a novel electrochemical catalytic reforming method over the NiCuZn–Al₂O₃ catalyst. The influences of current on the hydrogen yield, carbon conversion and products’ distribution were investigated. Both the hydrogen yield and carbon conversion were remarkably enhanced by the current through the catalyst, reaching nearly complete conversion with a hydrogen yield of 93.5% even at low reforming temperature of 400 °C. The thermal electrons would play important roles in promoting the reforming reactions of the oxygenated-organic compounds in bio-oil, molecular dissociation and the catalyst reduction.     

Pd/ZnO催化剂上甲醇水蒸气重整制氢

研究了并流共沉淀法制备的Pd/ZnO催化剂上的甲醇水蒸气重整制氢反应.考察了钯含量、还原温度、反应温度、重时空速（WHSV）和水-甲醇摩尔比（水醇比）对反应的影响.研究结果表明,当钯质量分数为15.9%,反应温度为523～573 K,还原温度为523～573 K,水醇比为1.0～1.2,WHSV=17.2 h^-1时,反应具有较好的CH3OH转化率、CO₂选择性、H₂产率及较低的出口CO摩尔分数.与铜基催化剂相比,Pd/ZnO催化剂表现出较好的稳定性.     

Steam reforming of the aqueous fraction of bio-oil over structured Ru/MgO/Al2O3 catalysts

A catalyst consisting of Ru (5%) dispersed on 15% MgO/Al₂O₃ carrier exhibits high activity and selectivity, as well as satisfactory stability with time on stream, under conditions of steam reforming of acetic acid, a model compound for pyrolysis oil. The presence of MgO in the catalyst formulation is shown to be related to oxygen and/or hydroxyl radical spillover from the carrier to the metal particles. A series of Ru/MgO/Al₂O₃ catalysts supported on cordierite monoliths, ceramic foams and γ-Al₂O₃ pellets were prepared and tested for the production of hydrogen by catalytic steam reforming of the aqueous fraction of bio-oil. All different structural forms of the catalyst exhibited satisfactory activity, converting completely the bio-oil, good selectivity toward hydrogen and satisfactory stability with time on stream. However, the catalyst supported on pellets exhibited the best catalytic performance, among all catalysts investigated. Reforming reactions, and thus hydrogen production, are favoured at high temperatures and low space velocities. Coking is one of the most significant problems encountered in these processes. It was found that only a small part of the incoming carbon is deposited on the catalyst surface, which is mainly present as CH_x. However, coke deposition is more intense on the reactor wall above the catalytic bed, due to homogeneous polymerization of unstable ingredients of bio-oil.     

A Comparison of Steam Reforming of Two Model Bio‐Oil Fractions

Two model bio‐oil fractions were chosen as two different major classes of components present in bio‐oil. Steam reforming of the two fractions was carried out to investigate the gas product distributions and carbon deposition behavior. Higher H₂ yield and carbon conversion to the gaseous phase can be obtained at relatively low temperature (650 °C) for steam reforming of the light fraction. For steam reforming of the heavy fraction, a higher temperature (800 °C) is necessary to obtain higher H₂ yield and carbon conversion to the gaseous phase. At 800 °C, the heavy fraction requires a higher steam to carbon ratio (10) than that for the light fraction (7) to achieve efficient steam reforming. Based on the same carbon space velocity, for 10 h stream time, the drop of H₂ yield and carbon conversion to the gaseous phase in the steam reforming of the heavy fraction is more rapid than that of the light fraction. Carbon deposition in the steam reforming of the heavy fraction is much more severe than that of the light fraction, as determined by carbon content analysis and SEM detection.     

Raney-Ni催化剂甘油蒸气重整制氢研究

采用管式固定床流动反应器,以Raney-Ni为催化剂,对甘油蒸气重整制氢进行了研究,考察了常压下不同温度、料液浓度和催化剂装载量对催化活性和氢气选择性的影响。结果表明:当进料浓度合适,催化剂Raney-Ni可在较低温度下呈现出对蒸气重整制氢反应较好的催化活性和选择性。当温度为280℃、料液浓度为5%(质量分数)、流量为0.5 mL/min时,碳转化率和H_2产率分别可达99.9%和93.21%,H_2和CO选择性分别为80.70%和0.20%。     

化学链耦合催化重整热解生物油制备合成气

生物油重整制合成气不仅能充分利用生物油中的成分,同时也展现了生物油转化为化学品的高值利用潜能。将载氧体NiFe₂O₄和Ni基催化剂耦合得到催化耦合化学链反应体系,为了比较催化剂的影响机制,分别构建了Ni/Si-NiFe和Ni/VR-NiFe催化耦合化学链反应体系,并以愈创木酚、乙酸和乙醇的纯物质及其混合液作为生物质热解液的模拟物,通过水蒸气重整实验考察了催化剂配比、反应温度、水碳比和反应时间对重整产物分布的影响。基于反应条件的筛选进一步通过寿命试验和BET、SEM表征,验证了反应体系的稳定性。最后,通过单组分及混合液体重整反应系统分析了化学链耦合催化反应体系的重整机制,为生物质热转化制备化学品提供了重要的理论支撑。     

Study of the performance of Mo2C for iso-octane steam reforming

In the present work, the performance of commercial molybdenum carbide (Mo₂C) for isooctane steam reforming has been investigated in order to determine the effects of major operating parameters (temperature, space velocity, and steam to carbon ratio) on the catalytic activity. While the results obtained indicate an onset reforming temperature of 850 °C, high concentrations of H₂ in the reforming environment were found to reduce the onset temperature to 750 °C. The catalytic activity at 850 °C was sufficient to produce hydrogen yields greater than 90% and carbon conversions close to 100%, with a low selectivity to CH₄ and CO₂. In addition, and consistent with thermodynamic predictions, a steam to carbon ratio of 1 appeared to optimize the reforming rates. Finally, based on experimental observations, a reaction mechanism was formulated and used to interpret the results obtained during catalytic activity measurements. This mechanism involves continuous oxidation and reduction of Mo metal, which can provide activity and stability to the catalyst when occurring at similar rates.     

生物油水蒸气催化重整制氢研究进展

生物油催化重整制氢是生物质转化为高品位能源的主要发展方向之一,引起了国内外的广泛关注。本文主要介绍了国内外生物油制取氢气的工艺、催化剂制备等技术。作者建议开发生物油流化床催化重整制氢技术和开发高效耐磨催化剂等,从而降低生物油制氢的成本。     

Mikrostrukturen für die katalytische Wasserstofferzeugung aus Ethanol

Hydrogen for fuel cell applications has been generated by catalytic steam reforming of ethanol in microstructures. The influence of reaction temperature, contact time and molar ratio steam to carbon (S/C) on the reaction has been investigated. The Co/ZnO catalyst coated on the microstructure showed high activity and selectivity. The hydrogen yield obtained was up to 5.2 mol mol^–1 ethanol. Ethanol has been completely converted at short contact time (W/F 25 g min mol^–1) and 600 °C at S/C ratio between 4.9 and 6.5.     

An Experimental Investigation of Hydrogen Production from Biomass

In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production from the raw gas of biomass steam gasification. In the present work, the characteristics of hydrogen production from biomass steam gasification were investigated in a small-scale fluidized bed. In these experiments, the gasifying agent (air) was supplied into the reactor from the bottom of the reactor and the steam was added into the reactor above biomass feeding location. The effects of reaction temperature, steam to biomass ratio, equivalence ratio (ER) and biomass particle size on hydrogen yield and hydrogen yield potential were investigated. The experimental results showed that higher reactor temperature, proper ER, proper steam to biomass ratio and smaller biomass particle size will contribute to more hydrogen and potential hydrogen yield.     

生物油水蒸气催化重整制氢研究进展

氢气作为重要的清洁能源和化工原料,目前主要来源于化石燃料,而生物质经快速热解制得生物油用于水蒸气催化重整制氢被认为是一种高效、环保、经济的可再生能源制氢途径。本文首先综述了近年来生物油水蒸气催化重整制氢相关反应原料;然后重点讨论了生物油水蒸气催化重整反应催化剂研究近况;总结了生物油水蒸气重整反应机理与动力学分析;最后列举了重整反应器等方面的研究进展。相比于生物油,生物油模型化合物因结构简单、转化率与氢气收率高,得到广泛研究;以Ni为代表的活性金属组分催化活性高,金属间协同作用强;不同类型的载体可增强催化剂的稳定性,碱性载体还可吸收CO₂、提高催化剂抗积炭、防烧结等方面的性能;不同结构的反应器在性能方面表现各异,主要以固定床反应器为主。研制高活性、稳定性强的催化剂,提高重整反应的循环稳定性,并总结最符合动力学规律的反应机理,以及研发高效的反应器是今后生物油水蒸气催化重整制氢研究的重点。     

Sustainable hydrogen production via reforming of ethylene glycol using a novel spouted bed reactor

Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil fuels and as a means for clean power generation via fuel cells. The aqueous fraction of bio-oil can be effectively reformed to hydrogen rich streams in the presence of active catalytic materials. In this paper we present the experimental work carried out in a novel spouted bed reactor for the reforming of bio-oil. The use of a specially designed injection nozzle in combination with the particular hydrodynamic characteristics of the spouted bed resulted in efficient processing of the organic feed. The known problem of coking was notably avoided regardless of the loading material of the reactor. The effect of reaction temperature and steam to carbon ratio in the feed was investigated in the presence of various catalytic and non-catalytic particles. Runs were conducted with ethylene glycol as a representative model compound of the aqueous phase of bio-oil. Olivine, when associated with nickel, proved to be a very suitable catalytic material for the process combining high activity in reforming, anti-coking characteristics combined with exceptional mechanical strength.     

水相生物油原位汽化-催化重整制氢工艺优化

为了“碳达峰,碳中和”的目标,开发以可再生能源为主体的绿色制氢技术势在必行。基于原位汽化策略,本文在自主研发的固定床/流化床催化重整一体式反应装置上开展水相生物油催化重整制氢对比实验。结果发现,在经原位汽化改进后的催化重整制氢工艺中,流化床内水相生物油转化效率（95%左右）明显高于固定床（80%左右）,两种反应体系中的H₂选择性均能100%保持较长时间稳定,但在反应进行到100min左右时,固定床反应体系中出现了明显的催化剂积炭失活现象,而流化床体系中催化剂始终保持较高活性,未发现积炭生成。从反应后液相产物分析可以发现,流化床反应体系中水相生物油各组分接近完全转化,而固定床反应体系中除有少量乙酸和苯酚残留外,还有少量酮类物质产生（丙酮等）。因此,原位汽化策略可以有效促进水相生物油催化重整制氢过程,结合流化床中催化剂的流化效果,将极大促进生物质-生物油-氢气的产业链推广进程。     

Recent advances in hydrogen production through catalytic steam reforming of ethanol: Advances in catalytic design

Catalytic reforming is a promising technology for producing renewable fuels; however, developing highly stable, efficient, green, and economical metallic catalysts that reduce metal sintering and carbon formation while improving catalyst activity, selectivity, and stability remains a major issue. In this regard, numerous studies have been documented in the past couple of decades evaluating the effects of various supports and promoters using ethanol as a co-reactant in the catalytic steam reforming to produce energy-efficient gaseous fuel, that is, hydrogen. This review article compiles research work focused on the catalytic reforming of ethanol reported in the last decade. Also, the outcomes of experimental studies have been presented and discussed for parametric analysis as case studies. The review shows that ethanol conversion, hydrogen selectivity, and catalyst stability are strongly influenced by the physicochemical properties of the catalyst, synthesis method, support choice, promoters, temperature, pressure, steam-to-ethanol ratio, and hourly space velocity. Noble metals (e.g., Pt, Rh, Ru, Pd, and Au), transition metals (e.g., Ni, Co, and Cu), and bimetallic composites were the most used catalysts in ethanol-steam reforming reactions. Also, proper selection of support and promoter plays a significant role in modifying catalyst morphology, surface area, and particle size, enhancing selectivity, and reducing catalyst carbon deposition.     

活性炭催化热解纤维素协同制备酚类和合成气

苯酚和合成气均为工业生产中重要的基础化工原料。以自制的活性炭为催化剂,以纤维素为原料实现了催化热解液相产物中苯酚和气相产物中CO的同时富集。实验发现,生物质灰分中的钾、热解过程中催化剂/纤维素质量比和热解温度均对气液相产物的品质有着不同程度的影响。研究表明：钾的存在不利于热解产物品质的提高。钾虽然提高了生物油中苯酚的富集度,但降低了实际产率。而热解气中CO的浓度和产率均下降。对催化热解条件的研究表明热解温度450℃,催化剂比例为1∶1时可获得最佳的热解产物。此时,生物油中酚类物质占可检测有机物相对含量的62.31%,其中苯酚为45.37%,产率为1.78%（质量）。热解气中CO的浓度和产率分别为69.21%（体积）和 169.95 ml/g,热值为12.93 MJ/m³。     

Ni-Mo/HM上偏三甲苯异构化性能研究

在加压固定床反应器上,研究了Ni-Mo/HM催化剂的偏三甲苯异构化性能。重点考察了反应温度、反应压力、质量空速和氢油比[n(氢气)/n(偏三甲苯),下同]等因素对反应的影响,得到了较适宜的反应工艺条件:反应温度260~270 ℃,反应压力1.2 ~1.4 MPa,质量空速0.9~1.1 h^-1,氢油比为5~6。在反应温度260 ℃,压力1.2 MPa,质量空速1.0 h^-1,氢油比为5的条件下,偏三甲苯的质量转化率为49.17%,均三甲苯的质量收率为23.10%,均三甲苯的选择性为46.98%。实验结果表明在该反应条件下,该催化剂具有良好的催化活性。