A review of recent researches on Bunsen reaction for hydrogen production via S–I water and H2S splitting cycles

The Bunsen reaction is the center reaction for both the sulfur–iodine water splitting cycle for hydrogen production and the novel hydrogen sulfide splitting cycle for hydrogen and sulfuric acid production from the sulfur-containing gases.This paper reviews the research progress of the Bunsen reaction in recent 10–15 years.Researches were initially focused on the optimization of the operating conditions of the conventional Bunsen reaction requiring excessive water and iodine to improve the products separation efficiency and to avoid the side reactions and iodine vapor deposition.Alternative methods including electrochemical methods,precipitation methods,and non-aqueous solvent methods had their respective advantages,but still faced challenges.In development of the technology of H2S splitting cycle,dissolving iodine in toluene solvent could render the Bunsen reaction to occur with the flowable I2 stream at ambient temperature such that the side reactions and iodine vaporization can be avoided and the corrosion hazard lessened.It also prevented the Bunsen reaction from using excessive iodine and water.The products from the Bunsen reaction including HI,H2SO4,H2O,and toluene could be directly electrolyzed.

Theoretical assessment of hydrogen production and multicycle energy conversion via solar thermochemical cycle based on nonvolatile SnO2

A kind of solar thermochemical cycle based on methanothermal reduction of SnO2 is proposed for H2 and CO production. We find that the oxygen release capacity and thermodynamic driven force for methanothermal reduction of SnO2 are large, and suggest CH4 :SnO2 = 2:1 as the feasible reduction condition for achieving high purities of syngas and avoiding vaporization of produced Sn. Subsequently, the amount of H2 and energetic upgrade factors under different oxidation conditions are compared, in which excess water vapor is found beneficial for hydrogen production and fuel energetic upgradation. Moreover, the effect of incom plete recovery of SnO2 on the subsequent cycle is underscored and explained. After accounting for factors such as isothermal operation and cycle stability, CH4 :SnO2 = 2:1 and H2O:Sn = 4:1 are suggested for highest solar-to-fuel efficiency of 46.1% at nonisothermal condition, where the reduction and oxidation temperature are 1400 and 600 K, respectively.

A New Industrial Hydrogen Production Process

This study was proposed to develop a new method for hydrogen production in significant amounts. It consisted in using sulfur dioxide (SO2), and discharged from the sulfuric acid (H2SO4) production unit. This process could be considered as an alternative to many classical processes for air quality treatment resulting in as afer environment. Furthermore, it was an innovative method for hydrogen production. In fact, SO2 was fed into a PEM electrolyzer stack. The dissolved SO2 was oxidized at the anode which led to the production of sulfuric acid;whereas, hydrogen (H2) was produced at the cathode. This new method was able to treat 3.7 t/day of SO22 in order to produce 0.116 t/day of hydrogen and recover 5.6 t/day of 35 wt.% H2SO4. Results showed that the studied procedure was more economical in terms of energy consumption than the Westinghouse hybrid process. Hence, 67% of the energy needed for the decomposition step was reduced by our proposed process. After the presentation of the principles of the new process design, each part of the process was sized. The calculations showed that the number of electrolyzers could be calculated using the same formula used for the number of electrolyzers for water electrolysis or flux cell.

Electricity Generation from Low Temperature Waste Heat with Application to Hydrogen Production from Water

This paper presents an extensive study of the heat pump cycle and associated working fluids to generate electricity from low temperature industrial waste heat. An Aspen Plus simulation has been developed to evaluate the effect of various working fluids on the net heat pump efficiency over a wide range of turbine inlet temperatures between 50℃ and 250℃. One hundred eight （108） refi＇igerants were investigated from the environmental classifications of Hydrochlorofluorocarbons （HCFC）, Hydrofluorocarbons （HFC）, Chlorofluorocarbons （CFC） and Hydrocarbons （HC） with boiling points between -88.65 ℃ and 110.65℃. Net efficiency, which ranged from 0.1% to 25.8% in this work tends to increases with the temperature of the waste heat. Results of the present study demonstrate that working fluid R41 （with source temperature of 44 ℃） provides the maximum efficiency among those evaluated. Refrigerants R13B1 and R32 provide the best efficiency for waste heat source temperatures ranges 60 - 67 ℃ and 68 - 78℃ respectively. Ammonia shows the highest efficiency from 79℃ to 132 ℃. Refrigerants R31, R21, 17,30 and benzene perform well in the temperature ranges 133-151 ℃, 152-178 ℃, 179-236℃ and 237-250 ℃respectively. The optimal heat pump systems are applied to the hybrid copper sulfate-copper oxide thermochemical cycle for hydrogen production from water. 100.8 MW of electrical energy is produced, which increased the efficiency from 24.1% to 25.9%.

Occurrence of the Bunsen side reaction in the sulfur-iodine thermochemical cycle for hydrogen production

This study aimed to establish a closed-cycle operation technology with high thermal efficiency in the thermochemical sulfur-iodine cycle for large-scale hydrogen production.A series of experimental studies were performed to investigate the occurrence of side reactions in both the H2SO4 and HI x phases from the H2SO4/HI/I2/H2O quaternary system within a constant temperature range of 323-363 K.The effects of iodine content,water content and reaction temperature on the side reactions were evaluated.The results showed that an increase in the reaction temperature promoted the side reactions.However,they were prevented as the iodine or water content increased.The occurrence of side reactions was faster in kinetics and more intense in the H2SO4 phase than in the HI x phase.The sulfur or hydrogen sulfide formation reaction or the reverse Bunsen reaction was validated under certain conditions.

Thermodynamic assessment of hydrogen production via solar thermochemical cycle based on MoO2/Mo by methane reduction

Inspired by the promising hydrogen production in the solar thermochemical(STC)cycle based on non-stoichiometric oxides and the operation temperature decreasing effect of methane reduction,a high-fuel-selectivity and CH4-introduced solar thermochemical cycle based on MoO2/Mo is studied.By performing HSC simulations,the energy upgradation and energy conversion potential under isothermal and non-isothermal operating conditions are compared.In the reduction step,MoO2:CH4=2 and 1020 K<Tred<1600 K are found to be most favorable for syngas selectivity and methane conversion.Compared to the STC cycle without CH4,the introduction of methane yields a much higher hydrogen production,especially at the lower temperature range and atmospheric pressure.In the oxidation step,a moderately excessive water is beneficial for energy conversion whether in isothermal or non-isothermal operations,especially at H2O:Mo=4.In the whole STC cycle,the maximum non-isothermal and isothermal efficiency can reach 0.417 and 0.391 respectively.In addition,the predicted efficiency of the second cycle is also as high as 0.454 at Tred=1200 K and Toxi=400 K,indicating that MoO2 could be a new and potential candidate for obtaining solar fuel by methane reduction.

计及微网余电制氢的加氢站设备容量优化配置

针对微网“弃风”、“弃光”、“弃水”现象和日益增长的氢负荷需求,考虑在异地加氢站配置一定容量的制/储氢设备集中消纳微网余电。通过研究含风电、光伏、小水电及电解槽、储氢罐、重整器的微网-加氢站系统(MHSS)的拓扑结构和数学模型,建立以加氢站全生命周期总净现值成本最低为目标的制/储氢设备容量优化配置模型,并提出余电制氢-绿氢先行(RETH-GHF)的电氢联合运营模式。算例中,结合实际场景,运用自适应模拟退火粒子群优化(ASAPSO)算法进行仿真。通过对比微网余电异地集中/就地分散制氢方案的配置结果和成本收益明细,说明算例场景下异地集中制氢方案经济性更好,并考虑工业电价、氢气及天然气价格波动对加氢站全生命周期总净现值成本的影响,比较两种制氢方案的经济性,最后以四季典型日系统运行情况验证了加氢站制/储氢设备容量优化配置模型的合理性。

热化学碘硫循环制氢中硫酸分解器结构设计与模拟研究

硫酸分解是影响热化学碘硫循环制氢效率的关键环节。通过数值模拟方法设计了一款满足1 m^(3)/h制氢量要求的中试规模的刺刀式硫酸分解器。首先开展实验测定了Fe_(2)O_(3)催化剂的反应动力学参数,其中指前因子和活化能分别为1.439×10^(7)s^(-1)和125.63 kJ/mol。然后对三种结构形式的硫酸分解器进行模拟对比。结果表明,刺刀式硫酸分解器中“半截面积”内管形式比“半直径”形式具有更强的传热效果,可将分解器预热段长度缩短43.27%,达到相同分解率时催化剂用量减少23%。而结构三在“半截面积”内管形式的基础上向预热段填充SiC小球,进一步优化了预热段传热效果,预热段长度可缩短70.51%,并且SiC小球所引起的压降和能耗增加相对较小。对比发现,当预热段长度为870 mm、催化分解段长度为333 mm时,结构三表现出最佳的经济性能,此时SO_(3)催化分解率达到73.73%,对应H_(2)的理论产率为1.2288 m^(3)/h。当分解器外壁面加热温度降低到860℃时,SO_(3)分解率降至60%,恰好对应H2的理论产率为1 m^(3)/h。该研究可为中试规模硫酸分解器的设计提供参考。

基于全生命周期评价的风光制氢综合系统容量配置优化研究

风光互补发电制氢是促进风光资源就地消纳、减少弃风弃光的重要技术途径。然而风光出力的波动性与系统设备复杂性也对风光制氢系统的容量优化配置决策提出了挑战。为此基于全生命周期评价方法,将平准化制氢成本、单位氢气碳排放强度与系统能量损失率作为优化目标,结合改进的NSGA-Ⅲ多目标优化算法,构建了年产2万t氢气的离网型风光制氢系统容量配置优化模型,并进一步分析了系统碳排放与经济性收益。研究结果表明,结合内蒙古某地区风光资源特征,经优化后系统平准化制氢成本为25.88元/kg,单位制氢碳排放量为0.59 kg/kg,同时全年风光利用率提升至91.09%,风光制氢系统的资源得到了高效利用。同时,结合全生命周期碳排放分析计算,系统碳排放总量为25.03万t,与典型煤制氢技术相比,单位制氢的碳减排量降低了97.05%。研究成果将为开展风光制氢综合利用提供了有益参考。

稠油油藏SAGD开发后腔体储氢潜力数值模拟

氢气作为一种清洁能源有望替代化石燃料成为主要能源载体,地下储氢是实现氢气大容量长期存储的有效途径,是近年来新兴研究领域。为此,在目前盐穴、枯竭油气藏及含水层3种传统地下储氢地质体外,探索了一种新的储氢方法,即利用稠油油藏蒸汽辅助重力泄油(SAGD)后形成的腔体进行储氢。首先对比了稠油油藏SAGD开发后储层储氢与常规地层储氢的优缺点,进而采用数值模拟方法对其建立地下储氢库的可能性进行论证,最后明确了不同注采方案的氢气储量及回收率,揭示了储层注采氢气阶段氢气与地层原有气体的流动特征。研究结果表明:①相较于常规枯竭油气藏储氢库,利用稠油油藏SAGD开发后的枯竭腔储氢具有储气量大、氢—油过渡带导致的氢损更低、无需注入或仅需注入少量的垫气、可降低氢脆风险、可提前监测闭圈盖层稳定性及气体密封性等优点;②典型单井组SAGD开发后的枯竭腔可储存约490 t氢气,回收率约为90%,且随着注采周期增多,采出的氢气纯度越高,第4个采氢周期后氢气采出纯度高达99%;③氢气存储方式的差异会导致甲烷在枯竭腔中的聚集位置发生变化,长期存储方式在氢气注入结束后,甲烷主要聚集在枯竭腔的底部,而短期存储方式下甲烷只会被氢气挤压到枯竭腔顶部的左右两侧,导致产氢过程中甲烷的产出规律不同。结论认为,利用稠油油藏SAGD开发后的储层进行高纯氢气的储存在储氢量、氢气回采纯度和建库成本方面都具有显著优势,是一种解决大规模储氢的高经济效益储氢技术,该研究成果能够为中国地下储氢技术的选址和建设运行提供指导和参考。

与核反应堆耦合的新型制绿氨模型

氨气是高效氢能载体,可有效解决氢能载运过程中安全性和经济性难题。核能-碘硫热化学循环制氢是实现无污染大规模工业制绿氢的可行途径。目前对核能-碘硫热化学循环制氢的研究集中于核热耦合问题,未考虑氢气产生后的载运问题。基于此,提出一种核-氨-氢新模型。此模型首先进行核能制氢,再通过核热将其转化为氨气,优化核热的梯级利用并解决氢储运问题。通过Aspen Plus软件模拟全流程,分析能耗、效率和成本。

基于掺氢燃气轮机的综合能源系统热经济学性能研究

为实现燃驱天然气场站的低碳高效运行,构建了一种新型综合能源系统架构,采用蒸汽循环回收燃气轮机的余热,电能用于驱动固体氧化物电解制氢技术产生氢气,进而将氢气通入燃气轮机中实现掺氢燃烧,同时利用压缩空气储能技术将可再生能源转化成稳定的电能输出。计算结果表明,系统在设计工况下的能量效率、(火用)效率和平准化单位能量成本分别为85.66%、41.37%和294.70元/(MW·h)。敏感性分析表明,燃气轮机压比和掺氢比例、蒸汽循环低压锅炉压力和抽汽系数、压缩空气储能技术释能功率对系统热力学性能影响显著,而燃气轮机压比和掺氢比例、蒸汽循环抽汽系数对系统经济学性能影响显著。多目标优化结果表明,系统的最优(火用)效率和平准化单位能量成本分别为42.31%和284.33元/(MW·h)。

Recent progress in synergistic electrocatalysis for generation of valuable products based on water cycle

Given the grim situation of global warming and energy crisis,replacing traditional energy conversions based on carbon cycle with water cycle is a sustainable development trend.The synergistic electrocatalysis for value-added chemical production through oxygen species(O_(ads):OH^(*),O^(*),and OOH^(*))and the active hydrogen species(H_(ads))derived from water splitting powered by“green”electricity from renewable energy resource(wind,solar,etc.)is a promising manner,because of its reduced energy consumption and emission and high Faradaic efficiency.The study and summarization of catalytic mechanism of synergistic electrocatalysis are particularly significant,but are rarely involved.In this review,recent progress of various synergistic electrocatalysis systems for generating valuable products based on water cycle is systematically summarized.Importantly,the catalytic mechanism of synergistic electrocatalysis and the positive effect of O_(ads) and H_(ads) species produced by water splitting during the synergistic electrocatalytsis are detailedly elucidated.Furthermore,the regulation of water-derived O_(ads) and H_(ads) species for achieving efficient matchability of synergistic electrocatalysis is emphatically discussed.Finally,we propose the limitations and future goals of this synergistic system based on water cycle.This review is guidance for design of synergistic electrocatalysis architectures for producing valuable substances based on water cycle.

核热制氢的路径及与钢铁产业耦合前景分析

研究了基于高温气冷堆的核热制氢路径及其与钢铁冶炼用氢耦合的前景。结论表明:核能对于钢铁行业减碳作用巨大,除了核电供应之外,核热制氢也是重要方面。国内基于高温气冷堆的核热制氢主流技术为S-I循环制氢和高温蒸汽电解制氢,但两者又存在与氢冶金大规模匹配的难题。建议现阶段核热制氢发展的重点应放在大规模热制氢技术攻关,同时依托建设中的氢冶金示范项目探索小型模块化反应堆与热解制氢方式的结合。钢铁企业应联合高温设备制造企业、核能企业、研究院校以规划建设为先,逐步落地联合示范项目并推广核热制氢方式。

基于Aspen Plus的制氢反应釜参数性能仿真研究

利用Aspen PlusTM化工过程模拟软件,通过建立模拟模型对Cu-Cl循环进行分析、设计和优化,分析五步循环过程的能量、火用和产率的有效性,根据氢气较低的热值计算出五步热化学过程的热效率为44%;通过分析其敏感性,得出各种操作参数对效率和产量的影响,并进行参数优化。该成果可用于开发利用Cu-Cl循环的新系统配置,提高Aspen Plus的制氢反应釜参数性能。

制氢项目全寿命周期成本研究

论述了全寿命周期成本的理论基础和研究现状,从建设成本、运行成本、弃置成本三方面分析了制氢项目全寿命周期成本,并进行建设期和运营期成本估算。

热化学硫碘循环水分解制氢研究进展

随着化石能源日益短缺和环境污染日益严重,寻求高效、清洁、可再生能源迫在眉睫。氢能作为现代能源体系新密码,因清洁、可再生、可存储、用途广泛等优点,近年来受到广泛关注。目前制氢方式众多,但大规模、高效、低成本、绿色的制氢方式才是未来氢能经济的基础。其中,热化学硫碘循环(也称碘硫循环)水分解制氢因具备上述优点被认为是最具发展潜力的制氢方法之一。从Bunsen反应、H2SO4分解和HI分解3方面综述了热化学硫碘循环水分解制氢的基础研究情况,对目前各国已建立的硫碘循环系统进行总结,着重介绍了核能耦合硫碘循环制氢流程的最新进展。从经济、环保和安全方面对目前核能耦合硫碘制氢进行分析讨论,以期为未来研究和发展提供新思路。针对Bunsen反应部分,寻找一种高效分离反应物的新方法至关重要;而对H2SO4分解和HI分解部分,现阶段主要研究仍集中在开发稳定、高效、低成本的催化剂。经过几十年研究,热化学硫碘循环水分解制氢技术已取得长足发展。在实际产氢中,苛刻的高温高腐蚀环境、复杂的耦合流程是限制其规模化、工业化的主要原因,开发由工业结构材料制成的耐腐蚀和耐热系统,继续对耦合流程进行优化和模拟是未来热化学硫碘循环水分解制氢技术的发展方向。

用于SO_(2)去极化电解制氢的铂基催化剂

综述了铂基SO_(2)去极化电解(SDE)阳极催化剂的研究进展。SDE阳极反应条件苛刻,铂基催化剂因具备良好的导电性、抗腐蚀性,并能够有效抵抗H_(2)S等硫物质的毒化,成为SDE阳极催化剂的首选。通过引入Al、Cr、Ni等非贵金属元素,可有效提高铂基催化剂性能并减少Pt的用量。在载体方面,综述和讨论了活性炭、石墨、炭黑、石墨烯以及SiC/TiC等对铂基催化剂性能的影响,此外分析了催化剂制备工艺对催化剂结构参数和性能的影响。尽管已经取得了很多研究成果,但当前对铂基SDE阳极催化剂的长期稳定性、多金属催化剂各金属元素间的相互作用等方面的研究尚较少,进一步优化催化剂设计、加强载体筛选及其改性,开发新的制备工艺,提高Pt利用率及催化剂的活性和稳定性,是未来相关研究的关键所在。

典型制氢工艺生命周期碳排放对比研究

氢能大规模发展需要解决“以何种方式制取氢气”的问题,在实现“双碳”目标的背景下,需要全面考察氢能产业链的碳排放情况。在相同的研究尺度下,建立统一的核算边界,采用统一的参数数据,定量测算典型制氢工艺的生命周期碳排放情况。结果显示,全生命周期视角下的CO_(2)排放量从大到小依次为甲醇制氢(煤炭为原料)、以火电为主的电解水制氢、煤制氢、甲醇制氢(天然气为原料)、天然气制氢、光伏发电电解水制氢、风电电解水制氢。煤制氢、天然气制氢的碳排放主要在氢气生产过程,甲醇制氢的碳排放主要在甲醇生产过程,电解水制氢过程虽清洁,但电力隐含的碳排放不容忽视。

硫碘循环制氢系统电解电渗析模块的模拟设计及关键参数对系统的影响

硫碘循环制氢是一种以二氧化硫和碘为中间介质使得水分解的制氢方法,由本生(Bunsen)反应、H2SO4相和HIx相3个工段组成。HIx相工段需使用电解电渗析法(Electro-electrodialysis, EED)提纯HI溶液。基于Aspen Plus建立了硫碘循环制氢模拟模型,并将其与基于MATLAB的EED数学模型耦合运行,分析EED阴阳极入口不同的物流配比时EED的参数设置、氢气和循环物料摩尔流率的变化规律;确定了反应工段(BUN工段)产物和HI精馏塔塔底物流流入EED阴极的最佳比例范围分别为0.6~0.7和0.5~0.7。研究结果可指导硫碘循环制氢系统的设计和优化。