制氢加氢“子母站”建设规划浅析

通过简要介绍制氢加氢合建站规划设计的现实意义和国内外加氢站发展现状,提出制氢加氢“子母站”的概念。本文简要介绍了制氢加氢“子母站”的建设模式,即制氢加氢“子母站”采取分布式供氢模式,“母站”制氢加氢集成为一体,“子站”作为纯加氢站,“母站”与“子站”之间采用长管拖车运输,“母站”为制氢加氢一体站,“母站”总装置内的供氢单元主要考虑采用天然气制氢、甲醇制氢和电解水制氢3种模式。简要分析了天然气制氢、甲醇制氢、电解水制氢技术的优缺点,并从氢气的生产成本、氢气的储运成本、制氢加氢“子母站”中制氢站的建设成本、运营成本等几方面进行了较为详细的成本分析。通过供氢模式的特点和成本分析,提出以水电解制氢、甲醇制氢、天然气制氢装置作为氢源的制氢加氢“子母站”为适宜我国能源结构的新型氢能利用模式。     

Hydrogen production from liquid hydrocarbon fuels for PEMFC application

Lack of efficient hydrogen storage intermediate has boosted the development of fuel processor or economic onsite hydrogen production techniques for application to proton exchange membrane fuel cell promptly. Aiming to develop onsite hydrogen production techniques for proton exchange membrane fuel cell application using nickel-based reforming catalysts and stainless steel reactors, in this paper, a novel process for H₂ production from liquid hydrocarbon fuels was proposed and experimentally demonstrated on a lab scale. The main operations involved prereforming, autothermal reforming, high temperature water gas shift, low temperature water gas shift and H₂ enrichment by Pd membrane. The results indicated that prereforming introduction prior to autothermal reforming suppressed undesired gas phase reactions efficiently and made reforming reactions perform catalytically and smoothly, which was confirmed by a stable 500 h time-on-stream test of both prereforming and autothermal reforming catalysts. The air distributed feed applied in autothermal reforming reactor coupled the endothermic steam reforming and exothermic catalytic combustion reactions over the catalyst closely, maintaining an appropriate temperature distribution curve for autothermal reforming catalyst bed. During the process of H₂ enrichment by highly H₂ permeable Pd composite membrane, concentration polarization played an important role.     

液体碳氢燃料蒸汽重整制氢催化剂研究进展

液体碳氢燃料具有能量密度高、氢含量大及便于储存和运输的特点,以其为原料经重整制氢并应用到移动式的燃料电池/加氢站对民用设备及国防武器等具有现实意义。本文首先对液体碳氢燃料蒸汽重整机理进行概述,明确当前催化剂面临的积炭、硫中毒等主要问题,从而指导高性能催化剂的设计和开发;其次,总结了几种典型液体碳氢燃料（汽油、煤油、柴油、焦油、含硫碳氢燃料等）蒸汽重整催化剂的相关进展,对比了不同催化剂在相应工艺条件下的活性及稳定性;最后,归纳了几类蒸汽重整过程强化技术包括等离子体重整、化学链重整、吸附增强重整及反应与分离耦合重整,说明了各类强化技术的优点及存在的不足,提出通过构建高效催化剂与蒸汽重整强化技术耦合有望实现液体碳氢燃料的高效转化制氢。希望本综述能为进一步研究液体碳氢燃料重整制氢提供相关指导。     

天然气分散制氢的技术经济分析(英文)

It is well established that hydrogen has the potential to make a significant contribution to the world energy production.In U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centralized hydrogen production.However,there is a wide lack of agreement on the nascent stage of using hydrogen as fuel in vehicles industry because of the difficulty in delivery and storage.By performing technological and economic analysis,this work aims to establish the most feasible hydrogen production pathway for automotives in near future.From the evaluation,processes such as thermal cracking of ammonia and centralized hydrogen production followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible options.These two processes are further evaluated by comprehensive economic analysis.The results showed that the steam reforming(SR) of natural gas has a shorter payback time and a higher return on investment(ROI) and internal rate of return(IRR).Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price,capital of investment and operating capacity factor on the overall production cost of hydrogen.Based on this study,natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy,biomass and wind power.     

我国氢能产业发展和氢资源探讨

分析了我国氢能产业近期发展情况,我国氢能产业正步入快速发展机遇期。指出氢能是21世纪最具发展潜力的一种清洁二次能源,具有"清洁、高效、安全、可持续"四大特点,被誉为未来世界能源架构的核心。重点讨论了我国氢资源和绿色氢气制备问题,指出目前实际使用的氢气包括"灰氢""蓝氢"和"绿氢"三大类,显然"灰氢"不可取,"蓝氢"可以用,"废氢"可回收,"绿氢"是方向。讨论了加快氢能系统建设,建立发展氢气存储和运输系统及加氢站基础设施建设等问题。未来,我国氢能产业发展潜力巨大,但是在下决心大力发展氢能产业时,需要高度注意目前存在的实际情况和困难,要防范一系列的产业风险,做到有序发展,稳中有进,才能实施氢能产业的可持续发展。     

Combined pre-reforming-desulfurization of high-sulfur fuels for distributed hydrogen applications

A major challenge facing the future Hydrogen Economy is the issue of hydrogen fuel delivery and distribution. In the near term, it may be necessary to deliver high-density hydrocarbon fuels (e.g., diesel fuel) directly to the end-user (e.g., a fueling station) wherein it is reformed to hydrogen, on demand. This approach has the advantages of utilizing the existing fuel delivery infrastructure, and the fact that more energy can be delivered per trip when the tanker is filled with diesel instead of liquefied or compressed hydrogen gas. Reforming high-sulfur hydrocarbon fuels (e.g., diesel, JP-8, etc.) is particularly challenging due to rapid deactivation of conventional reforming catalysts by sulfurous compounds. A new on-demand hydrogen production technology for distributed hydrogen production is reported. In this process, first, the diesel fuel is catalytically pre-reformed to shorter chain hydrocarbons (C₁-C₆) before being fed to the steam reformer, where it is converted to syngas and further to high-purity hydrogen gas. In the pre-reformer, most sulfurous species present in the fuel are converted to H₂S. Desulfurization of the pre-reformate gas is carried out in a special regenerative redox system, which includes an iron-based scrubber coupled with an electrolyzer. The integrated pre-reformer and sulfur-scrubbing unit operated successfully for 100 h at desulfurization efficiency of greater than 95%.     

Metal-organic framework stabilizes Cu7S4-wrapped Cu2O heterostructure for photothermal-promoted methanol/water reforming into hydrogen

To realize highly efficient in situ release of hydrogen energy from methanol reforming at lower operation temperature, the introduction of solar energy can effectively activate the methanol and significantly reduce activation energy of reaction. Herein, the hierarchical integration of photoactive Cu₂O/Cu₇S₄ core-shell nanospheres stabilized by MIL-101(Cr) support for H₂ evolution from photothermal-driven aqueous phase reforming of methanol afforded nearly sixfold enhanced performance compared with thermocatalytic process. Impressively, the photothermal effect conferred the Cu₂O/Cu₇S₄@MIL-101(Cr) with unprecedented activity at low temperature subside to 100°C and accelerated the activation of water and methanol with distinctly decreased activation energy from 103.9 to 66.6 kJ·mol⁻¹. Meanwhile, the enhanced catalyst stability and facilitated charge separation between Cu₂O/Cu₇S₄ and MIL-101(Cr) also contribute to the extraordinary photothermal-enhanced H₂ evolution with an overall turnover number of up to 14,266 in 60 h (apparent quantum efficiency of 25.08% at 365 nm), almost 10,000 times higher than that of Cu₂O/Cu₇S₄.     

High vs. low temperature reforming for hydrogen production via microtechnology

Hydrogen production from a multifunctional microdevice consisting of thermally coupled catalytic plate combustion and reforming microreactors is simulated for methane and methanol reforming as representatives of a high and a low temperature process, respectively. Both reforming processes are feasible at microscales with high conversions over a wide combustible and reforming stream inlet velocity range, and can be tuned to provide variable power output. Interestingly, in low temperature reforming, the fraction of heat release that is wasted, as “excess enthalpy” in the products, is not significantly lower than in high temperature reforming at the breakthrough limit. Along the breakthrough line, more than 30% higher power efficiency to hydrogen is predicted for the methanol system due to the high CO₂:CO ratio. Finally, matching the reaction zones in the two channels via proper choice of catalyst loadings and channel gap sizes can alleviate hot spots and axial temperature gradients promoted by low conductivity materials.     

Slurry Phase Hydrogenation of CO2 to Methanol Using Supported In2O3 Catalysts as Promising Approach for Chemical Energy Storage

A promising approach for chemical energy storage from fluctuating renewable electricity is methanol synthesis from CO₂ and hydrogen in a slurry reactor concept, due to efficient heat storage and easy reactor control. In combination with a promising In₂O₃/ZrO₂ catalyst and mineral oil as carrier liquid, efficient methanol production under a wide range of changing process conditions is shown for the first time. A maximum methanol productivity of 2.1 g_MeOHg_In⁻¹h⁻¹ and multiple recycling stability of the catalyst and the carrier liquid was achieved, showing no significant decrease in methanol yields.     

甲醇制氢研究进展

介绍了制取氢气的常用原料。综述了用甲醇做原料制氢的研究进展,讨论了不同方式（裂化法、水蒸汽重整法、部分氧化法、自热重整法、等离子体法、电解法、超声波法）制氢技术的特点。目前甲醇气相重整技术较成熟,今后研究的重点是研制高效催化剂的制备、能量利用及氢气提纯方法。     

Characterization and oxidation states of Cu and Pd in Pd–CuO/ZnO/ZrO2 catalysts for hydrogen production by methanol partial oxidation

Copper and zinc oxide based catalysts prepared by coprecipitation were promoted with palladium and ZrO₂, and their activity and selectivity for methanol oxidative reforming was measured and characterized by N₂O decomposition, X-ray absorption spectroscopy, BET, X-ray photoelectron spectroscopy, X-ray diffraction, and temperature programmed reduction. Addition of ZrO₂ increased copper dispersion and surface area, with little effect on activity, while palladium promotion significantly enhanced activity with little change of the catalytic structure. A catalyst promoted with both ZrO₂ and palladium yielded hydrogen below 150 °C. EXAFS results under reaction conditions showed that the oxidation state of copper was influenced by palladium in the catalyst bulk. A palladium promoted catalyst contained 90% Cu⁰, while the copper in an unpromoted catalyst was 100% Cu¹⁺ at the same temperature. Palladium preferentially forms an unstable alloy with copper instead of zinc during reduction, which persists during reaction regardless of copper oxidation state. A 100-h time on stream activity measurement showed growth in copper crystallites and change in copper oxidation state resulting in decreasing activity and selectivity. A kinetic model of the reaction pathway showed that palladium and ZrO₂ promoters lower the activation energy of methanol combustion and steam reforming reactions.     

用于甲醇重整制氢的铜基催化剂研究进展

近年来,随着能源需求与日俱增,化石燃料的燃烧造成的温室效应使得地球气候变得更加恶劣,如何有效实现碳减排成为各国科学家的研究重点。将二氧化碳转化为绿色液体燃料(如甲醇)是一个重要方向。通过甲醇合成(MS)实现碳捕获,再在需要能量时进行甲醇水蒸气重整(MSR)制备氢气,实现二氧化碳的闭路循环和氢能的储存,因此MSR反应具有很高的研究价值。在众多应用于甲醇水蒸气重整的催化剂中,Cu基催化剂因其价格低廉和高活性等优点受到广泛关注。综述了Cu基催化剂在甲醇水蒸气重整中的研究进展,包括机理探索,催化剂优化及未来的发展方向,提出铜基催化剂中铜的高分散、价态调控和复合氧化物与铜的协同是性能优化的关键。     

Unlocking dynamics of compact methanol reformers during on-line catalyst activation using transient computational fluid dynamics simulation

On-board methanol reforming is a practical solution to supply hydrogen for fuel cell vehicles (FCVs). For commonly employed Cu-based reforming catalysts, activation has a profound influence on subsequent reaction performance. However, tailoring of this process at the reformer level has received little research attention. Herein, we present the dynamics of compact methanol reformers with Cu/ZnO/Al₂O₃ catalysts during in situ H₂/N₂ pre-activation as a preliminary step of online catalyst activation by computational fluid dynamics simulations. Raising inlet temperatures or hydrogen fractions is demonstrated to accelerate activation while generating a high-temperature band within the catalyst bed, which hampers effective activation. Increasing the reductant flow rates improves the homogeneity of activation thanks to enhanced convective heat and mass transfer. Notably, we revealed that inlet reductants exceeding 453 K trigger temperature runaway that may severely damage the reformer. These new insights will enlighten optimization of operation and control of on-board methanol reforming for FCVs.     

Steam reforming of ethanol over Pt/ceria with co-fed hydrogen

Metal/ceria catalysts are receiving great interest for reactions involving steam conversion, including CO for low-temperature water–gas shift, and the conversion of chemical carriers of hydrogen, among them methanol, and ethanol. The mechanism by which ROH model reagents are activated on the surface of the Pt/partially reduced ceria catalyst was explored using a combination of reaction testing and infrared spectroscopy. In this particular investigation, the activation and turnover of ethanol were explored and compared with previous investigations of methanol steam reforming and low-temperature water–gas shift under H₂-rich conditions, where the surface of ceria is in a partially reduced state. Under these conditions, activation of ethanol was found to proceed by dissociative adsorption at reduced defect sites on ceria (i.e., Ce surface atoms in the Ce³⁺ oxidation state), yielding an adsorbed type II ethoxy species and an adsorbed H species, the latter identified to be a type II bridging OH group. In the presence of steam, the ethoxy species rapidly undergoes molecular transformation to an adsorbed acetate intermediate by oxidative dehydrogenation. This is analogous to the conversion of type II methoxy species to formate observed in previous investigations of methanol steam reforming. In addition, although formate then decomposes in steam to CO₂ and H₂ during methanol steam reforming, in an analogous pathway for ethanol steam reforming, the acetate intermediate decomposes in steam to CO₂ and CH₄. Therefore, further H₂ production requires energy-intensive activation of CH₄, which is not required for methanol conversion over Pt/ceria.     

Adsorption of Off‐Gases from Steam Methane Reforming (H2, CO2, CH4, CO and N2) on Activated Carbon

Abstract

Hydrogen is the energy carrier of the future and could be employed in stationary sources for energy production. Commercial sources of hydrogen are actually operating employing the steam reforming of hydrocarbons, normally methane. Separation of hydrogen from other gases is performed by Pressure Swing Adsorption (PSA) units where recovery of high‐purity hydrogen does not exceed 80%.

In this work we report adsorption equilibrium and kinetics of five pure gases present in off‐gases from steam reforming of methane for hydrogen production (H₂, CO₂, CH₄, CO and N₂). Adsorption equilibrium data were collected in activated carbon at 303, 323, and 343 K between 0‐22 bar and was fitted to a Virial isotherm model. Carbon dioxide is the most adsorbed gas followed by methane, carbon monoxide, nitrogen, and hydrogen. This adsorbent is suitable for selective removal of CO₂ and CH₄. Diffusion of all the gases studied was controlled by micropore resistances. Binary (H₂‐CO₂) and ternary (H₂‐CO₂‐CH₄) breakthrough curves are also reported to describe the behavior of the mixtures in a fixed‐bed column. With the data reported it is possible to completely design a PSA unit for hydrogen purification from steam reforming natural gas in a wide range of pressures.     

Hydrogen production through chemical looping using NiO/NiAl2O4 as oxygen carrier

A new autothermal route to produce hydrogen from natural gas via chemical looping technology was investigated. Tests were conducted in a micro-fixed bed reactor loaded with 200 mg of NiO/NiAl₂O₄ as oxygen carrier. Methane reacts with a nickel oxide in the absence of molecular oxygen at 800 °C for a period of time as high as 10 min. The NiO is subsequently contacted with a synthetic air stream (21% O₂ in argon) to reconstitute the surface and combust carbon deposited on the surface. Methane conversion nears completion but to minimize combustion of the hydrogen produced, the oxidation state of the carrier was maintained below 30% (where 100% represents a fully oxidized surface). Co-feeding water together with methane resulted in stable hydrogen production. Although the carbon deposition increased with time during the reduction cycle, the production rate of hydrogen remained virtually constant. A new concept is also presented where hydrogen is obtained from methane with inherent CO₂ capture in an energy neutral 3-reactors CFB process. This process combines a methane combustion step where oxygen is provided via an oxygen carrier, a steam methane reforming step catalyzed by the reduced oxygen carrier and an oxidizing step where the O-carrier is reconstituted to its original state.     

Oxidative Reforming of Bio-Ethanol Over CuNiZnAl Mixed Oxide Catalysts for Hydrogen Production

Hydrogen (H₂) is expected to become an important fuel for the future to be used as an energy carrier in automobiles and electric power plants. A promising route for H₂ production involves catalytic reforming of a suitable primary fuel such as methanol or ethanol. Since ethanol is a renewable raw material and can be cheaply produced by the fermentation of biomass, the ethanol reforming for H₂ production is beneficial to the environment. In the present study, the steam reforming of ethanol in the presence of added O₂, which in the present study is referred to as oxidative steam reforming of ethanol (OSRE), was performed for the first time over a series of CuNiZnAl mixed oxide catalysts derived from layered double hydroxide (LDH) precursors. The effects of Cu/Ni ratio, temperature, O₂/ethanol ratio, contact time, CO co-feed and substitution of Cu/Ni by Co were investigated systematically in order to understand the influence of these parameters on the catalytic performance. An ethanol conversion close to 100% was noticed at 300 °C over all the catalysts. The Cu-rich catalysts favor the dehydrogenation of ethanol to acetaldehyde. The addition of Ni was found to favor the C–C bond rupture, producing CO, CO₂ and CH₄. Depending upon the reaction condition, a H₂ yield between 2.5 and 3.5 moles per mole of ethanol converted was obtained. A CoNi-based catalyst exhibited better catalytic performance with lower selectivity of undesirable byproducts, namely CH₃CHO, CH₄ and CO.     

Study on a multifunctional energy system producing coking heat, methanol and electricity

A multifunctional energy system (MES) capable of consuming coke oven gas (COG) and coal, and simultaneously producing coking heat, methanol and electricity, was subject to an exergy analyses based on Energy Utilization Diagrams (EUDs). In this system a coal-fired coke oven is adopted to produce coke and COG, where non-coking coal is burned to supply thermal energy to the coking process. The COG and coal gas gasified from coal in a gasifier, were mixed to produce syngas for methanol synthesis. Since COG rich in hydrogen and coal gas rich in CO, the mixture of COG and coal gas can easily adjust the mole ratio of CO to H₂ of syngas instead of the conversional reforming and shift processes. The active component of syngas is firstly converted into methanol and then the rest is introduced to a gas turbine for power generation. As a result, the overall efficiency of the MES system is about 62.3%, and its energy savings ratio is about 15% comparing with individual systems. The paper provides a new approach to use coal more efficiently and cleanly.     

Development of a Combined Plasma-Matrix Reformer for Solid Oxide Fuel Cell Application

A novel plasma-matrix reformer (PMR) was suggested for methane conversion into hydrogen-rich fuel. To demonstrate the possibility of reforming performance, characteristics of product gas and CH₄ conversion were identified according to O₂/C ratio, water vapor supply, reformed gas recirculation, and water feed in the recirculation gas affecting energy conversion and hydrogen production. When the reformed gas recirculation and water feed to the recirculation pipe were performed at the same time, hydrogen production and energy conversion efficiency were superior compared to the conventional reforming method. The optimal operating conditions of the PMR were determined. The obtained high energy conversion efficiency and hydrogen selectivity indicated the applicability to solid oxide fuel cell stacks for residential power generation.     

低温甲醇水重整制氢催化剂研究进展

甲醇具有结构简单、含氢量高、产能大等优点,利用甲醇与水蒸气进行重整是一种节能高效的现场制氢方式。甲醇水蒸气重整(MSR)与燃料电池联用能够实现多场景应用,但由于反应温度较高(250~300℃),存在启动速度较慢、副产CO含量较高和热效率较低等问题。低温甲醇水重整(LT-Methanol Water Reforming, LT-MWR)包括低温甲醇水蒸气重整(LT-MSR)与液相甲醇水重整(Aqueous-phase Reforming of Methanol, APRM),反应通常在200℃以下进行,同时保持较高的反应活性,进而能够减少预热时间、减弱副反应发生,且能与燃料电池实现更强的热耦合。本工作首先介绍了商用催化剂优异的性能与存在的缺陷,然后对低温甲醇水重整制氢催化剂,诸如Cu基催化剂、贵金属催化剂与光协同催化剂的研究进展进行了回顾。归纳了低温铜基催化剂的改性策略,包括合成方法、结构设计与元素掺杂。对国内外商用CuZnAlOx催化剂结构与性能的测试表明,其转化率高和稳定性好,存在的缺陷是价格较贵且在低温区催化活性急剧下降。Cu基催化剂活性受温度影响较大,在低温区活性很低,但通过适当的改性能够实现其应用价值,其改性策略包括合成方法、结构设计与元素掺杂。贵金属催化剂低温下活性较高,但存在价格昂贵、合成复杂等缺点。光协同催化剂则是在光照条件下进行催化重整,尚处于研究阶段。对于Cu基催化剂,合成方法的改进能够大大改善催化剂的微观混合程度与可重现性。适当的结构设计可提升催化剂的比表面积与热稳定性。元素掺杂则能够提升活性组分的分散度,修饰催化剂表面结构。三种改性策略能够有效提升Cu基催化剂低温下甲醇重整制氢的性能,在保持较高活性的同时,降低CO副产物的含量。展望了低温甲醇水重整制氢催化剂的发展前景和挑战,对催化剂的开发与应用有指导意义。