甲醇水蒸气重整工艺的优化

甲醇在常温常压下为液态且具有极高的载氢密度，因而是一种较为理想的载氢介质。甲醇重整反应器的设计对于甲醇在线重整制氢燃料电池系统的设计具有重要意义。对于甲醇重整反应器，反应温度较高时重整气中CO浓度高，不利于后续的CO深度脱除；而反应温度较低时，甲醇转化率与液相空速低，会导致催化剂利用率低并且反应器体积较大。基于以上问题，本工作提出了一种由第一段300℃下等温重整和第二段300℃～220℃下绝热重整组成的两段变温重整工艺。基于Aspen Plus对该工艺进行了模拟研究，证明该工艺在理论上可以实现。然后通过固定床反应器进行实验研究，结果表明在甲醇完全转化的条件下，本变温工艺的甲醇液相空速为4.08h^-1，重整气中CO浓度为0.56%，重整制氢效率为108.98mL/(min·mL催化剂)。而220℃下等温重整工艺的液相空速为1.5h^-1，重整气中CO浓度为0.40%，重整制氢效率为44.89mL/(min·mL催化剂)。变温工艺可以在较大的液相空速下获得更高的重整制氢效率，降低催化剂用量，使重整器结构更加紧凑。同时，与300℃下等温重整工艺相比，...     

甲醇水蒸气重整制氢串联发电的性能研究

利用自组装的5 Nm~3/h制氢机串联5 kW燃料电池的热电联产系统,研究了某公司生产的工业优等品甲醇在重整制氢过程中温度、产品气流量和压力、CO浓度、甲醇转化率等指标的变化,及产生的氢在5 kW热电联产装置上运转7 h后输出电压、电流、功率等的变化。试验分析结果表明,使用该甲醇作为原料的制氢机在稳定运转过程中,产品气流量和压力分别在5Nm~3/h和0.55MPa左右波动,CO浓度始终低于0.03ppm,氢纯度达99.999%以上,甲醇转化率保持在99.3%以上,后续在热电联产系统上可连续发电7h以上,获得了预期的效果。该研究为甲醇生产企业合理布局甲醇燃料电池技术和规划产业发展战略提供了参考。     

二甲醚水蒸气重整制氢反应研究进展

质子交换膜燃料电池(PEMFC)是燃料电池汽车的首选动力源,其具有环境友好,比功率较高而使用温度较低等优点。但电池氢源是其能够实现商业化发展的瓶颈,因此本文主要介绍二甲醚水蒸气重整制氢反应的研究进展。     

甲醇氧化重整制氢过程(Ⅰ)反应条件对制氢过程的影响

通过对甲醇氧化重整 (POX)自热体系物料衡算、能量衡算 ,以及床层反应行为的研究 ,优化了POX过程操作条件 ,获得了理论产氢能量效率 η,分析了氢源与质子交换膜燃料电池 (PEMFC)衔接中的关键环节———合适的原料配比、反应压力、蒸发器和换热器中换热效率 ,以及适应PEMFC变载或电动汽车变速、爬坡的有效手段等     

甲醇氧化重整制氢过程(Ⅱ)反应器构型对制氢过程的影响

在质子交换膜燃料电池 (PEMFC)移动氢源———甲醇氧化重整制氢自热体系中 ,研究了反应器构型对产氢能量效率和床层内“热点”温度的影响 ,得到了反应器设计准则 ,提出了实际应用中可采用的反应器型式     

生物质合成气调变方式对其合成甲醇的影响

对生物质气、工业合成气、重整后生物质气及配氢后生物质气4种合成气进行了合成甲醇的研究. 发现甲醇产率顺序为工业合成气>重整生物质气>配氢生物质气>生物质气,生物质气合成甲醇产率较低主要是因为其为富CO2体系. 实验同时发现(H2-CO2)/(CO+CO2)比值在1.5~2之间时,(H2-CO2)/(CO+CO2)比值对液相产物中甲醇选择性没有明显影响. 液相产物中甲醇选择性随CO2含量上升而下降.     

高性能钯膜及其在氨分解制氢中的应用

引 言 液氨催化分解制氢工艺具有价格低廉、安全性好、附加值低、产物不含COx杂质等优点[1].此外,氨分解制氢体系的理论质量储氢量是17.6%,明显高于电解水(11.1%)、甲醇-水蒸气重整(12%)、汽油-水蒸气重整(12.4%)、氢化物水解(5.2%～8.6%)等制氢体系.但是,以纯氨为原料分解后只能得到含氢75%的混合气,而燃料电池只有在使用纯氢为原料气时才具有最高的工作效率,因此应当对氨分解产物中的氢进行提纯.     

Investigation of mini-reformer for hydrogen production

以解决小功率燃料电池氢源问题为目的,研制了集原料预热、甲醇水蒸气重整（MSR）、催化燃烧、水汽变换（WGS）于一体的自热式重整制氢反应器。通过条件实验考察了操作温度、甲醇气体空速、水醇比（W/M）等操作条件对重整反应的影响,并在苛刻条件下进行了稳定性研究。实验证明,反应器最大净产氢量可达90 L/h,可为百瓦级质子交换膜燃料电池提供氢源。     

微型套管式制氢反应器中物流分布的研究

创新研制了一种结构紧凑、性能高效的套管式微型制氢反应器;可在室温下自启动,甲醇重整制氢过程自热运行;考察了物流分布对反应器性能的影响,应用FLUENT软件对物流分布进行了数值计算,试验结果表明,重整物流分布均匀与否对反应器性能有很大影响;通过改善人口分布器的结构,可以显著提高反应器性能,甲醇转化率最高达到96.4%,产生重整气最大流量为125 L/h,反应器单位体积产氢率为0.61 m3/(h·L).     

CuO/CeO_2催化剂选择性氧化富氢气体中的CO

引言随着质子交换膜燃料电池技术的发展,甲醇在线重整制氢由于可以有效地解决氢能利用中存在的储存及配给等问题,成为当前研究的热点。然而甲醇重整气中少量的CO极易吸附在燃料电池阳极催化剂表面,使电池性能严重下降,必须对重整气中的CO进行去除,选择性氧化脱除重整气中的CO是成本较低、简单易行的方法,已见报道的用于CO选择性氧化反应的催化剂大多是Al_2O_3负载的Pt、Ru、Rh和Au等贵金属催化剂,它们能     

富氢合成气中杂质气体对质子交换膜燃料电池性能的影响

质子交换膜燃料电池以其高效、清洁的优点在微型热电联产中广泛应用。利用天然气重整反应制氢是燃料电池最经济的氢气来源之一。研究重整合成气中的杂质气体对燃料电池性能的影响至关重要。设计、搭建了测试合成气体中杂质气体成分对质子交换膜燃料电池性能影响的实验测试系统,研究、考察了含氢合成气中杂质气体CO2,CH4,N2对质子交换膜燃料电池性能的影响。测试结果表明：对于所采用的PEM燃料电池及试验所采用的杂质气体的浓度范围,这些气体对于燃料电池的性能都有影响。其中N2对燃料电池的影响是可逆的,CH4和CO2会对电池造成永久性的损坏。     

Performance of CO preferential oxidation reactor with noble-metal catalyst coated on ceramic monolith for on-board fuel processing applications

On-board fuel processors are being developed to provide hydrogen-rich gas to the polymer electrolyte fuel cell automotive propulsion systems. Whereas the anode catalyst in the fuel cell has low tolerance for carbon monoxide, 10–100 ppm, reforming of gasoline and other hydrocarbon fuels generally produces 1–2% of CO. Of the many methods of removing CO from the reformer gas, preferential oxidation (PrOx) of CO over noble-metal catalysts is practiced most frequently. In this paper, we present experimental data for CO conversion on a Pt-based catalyst that is active at room temperature and was coated on a ceramic monolith. The data is used to develop an empirical correlation for selectivity for CO oxidation as a function of CO concentration and oxygen stoichiometry at 30,000–80,000/h space velocity. The selectivity correlation is used in a model to analyze the performance of multi-stage, adiabatic PrOx reactors with heat exchange between the stages to cool the reformate to 100 °C. An optimization algorithm is used to determine the operating conditions that can reduce CO concentration to 10 ppm while minimizing parasitic loss of H₂ in the reformate stream. It is found that the 10 ppm constraint limits the maximum inlet CO concentration to 1.05% in a single-stage reactor and to 3.1% in a two-stage reactor. The results clearly show the incremental reduction in parasitic H₂ loss by addition of second and third stages.     

Electrochemical promotion of CO conversion to CO2 in PEM fuel cell PROX reactor

The possibility of electrochemically promoting the water–gas-shift reaction and the CO oxidation reaction in a PEM fuel cell reactor supplied with a methanol reformate mixture was investigated in PEM fuel cells with Pt or Au state-of-the-art E-TEK anodes, in order to explore the use of PEMFC units as preferential oxidation of CO (PROX) reactors. The electropromotion of CO removal was investigated both with air or H₂ fed to the cathode side and also by O₂ bleeding to the anode during normal PEMFC operation. It was found that the catalytic activity of the anode for CO conversion to CO₂ can be modified significantly by varying the catalyst potential. The magnitude of the electrochemical promotion depends strongly on the anodic electrocatalyst (Pt or Au), on the CO concentration of the fuel mixture, on the operating temperature and on the presence of oxygen. The electropromotion effect and the Faradaic efficiency were found to be much higher in CO-rich anode environments.     

用于PEMFC的天然气水蒸气制氢系统

针对质子交换膜燃料电池（PEMFC）的应用要求,开发了一个包括天然气水蒸气重整、CO变换和变压吸附净化的制氢工艺过程,并着重对重整反应和变压吸附的操作条件进行了实验研究。考察了温度、空速和水碳比对重整反应的影响,得到适宜的工艺操作条件,实验结果表明：温度650℃、水碳比6、空速42h^-1时,氢气含量为70.21%,甲烷转化率为77.41%;分析了温度、流速对变压吸附脱除CO效果的影响,结果表明：在0.2MPa、40℃和吸附、脱附时间120s的条件下,产品气中CO浓度接近于1×10^-6,经过多次循环后产品气质量稳定,可以连续获得满足80W质子交换膜燃料电池要求的高纯度氢气。     

杂质气体对质子交换膜燃料电池性能影响的研究进展

质子交换膜燃料电池（proton exchange membrane fuel cell,PEMFC）的商业化进程受到了其耐久性的严重制约。燃料气体中含有的微量CO、CO2、H2S和NH3等杂质以及空气中含有的NOx、SOx等污染物是影响PEMFC耐久性的最主要因素之一。本文综述了燃料气体杂质和空气污染物分别对PEMFC性能的影响及其机理,其中燃料中含的CO除了能影响PEMFC的阳极性能以外,还可能通过扩散传质过程对电池阴极性能造成影响;H2S不仅能对电池阳极性能造成严重的影响,也可能对电池阴极性能造成明显的破坏;而空气中的微量NOx会对PEMFC性能造成明显的影响,但NOx对电池性能的影响是一种可逆过程。最后指出对杂质气体影响PEMFC耐久性的研究需要将计算机模型和实际试验相结合,用模型数据指导实验的进行,同时有必要考虑杂质对PEMFC电堆性能的影响。     

SOFC内部重整反应与电化学反应耦合机理

以经过预重整反应的混合气为原料的固体氧化物燃料电池（SOFC）内部,甲烷蒸气重整反应与电化学反应同时发生在阳极多孔介质中,二者受到不同的操作与设计参数的影响,对电池总体性能起着决定性作用。编制了三维数值模拟程序,对由多孔阳极层、气体流动管道、固体支撑平板构成的单个复合管道进行了研究。结果显示：重整反应主要发生在多孔材料靠近流动管道的薄层内,只有靠近管道入口处才能在较深处进行;电化学反应发生在多孔层与电解质的交界面处;重整反应生成的H2、CO扩散到多孔材料底部参加电化学反应;电化学反应生成的热量供重整反应使用。说明研究范围内,SOFC阳极复合通道具有较好的传热、传质性能,化学/电化学反应存在较好的耦合关系。     

Start‐Up and Load‐Change Behavior of a Catalytic Burner for a Fuel‐Cell‐Based APU for Diesel Fuel

The catalytic burner CAB 4 was developed for a fuel‐cell‐based diesel‐APU (auxiliary power unit) with a capacity of 14.5 kW_th,APU. In order to operate a catalytic burner in such an APU, several requirements must be met. Normal operation involves combustion of anode off‐gas from the fuel cell. If the fuel cell malfunctions or if the gas quality is insufficient, the burner must also be able to fully convert the reformate while by‐passing the fuel cell. It must be possible to catalytically ignite the burner using a reformate with increased CO‐concentration. The burner must fully convert all combustible components in the fuel‐gas at all operating points. The energy contained in the fuel gas is utilized in the CAB to generate superheated steam with no oscillations and to supply this steam to the autothermal reformer. When the fuel processing system is being shut down, the burner should be able to continue providing steam for sweeping the downstream reactors for a limited period of time. Catalytic ignition of the CAB 4 was demonstrated with a reformate containing up to 5 mol.% CO. The behavior of the burner was characterized in steady‐state operation, during load changes, during transitions in the operating mode, and during shut‐down.     

Reforming methanol to electricity in a high temperature PEM fuel cell

In this paper we demonstrate for the first time a compact power unit, where a methanol reforming catalyst is incorporated into the anode of a PEMFC. The proposed internal reforming methanol fuel cell (IRMFC) mainly comprises: (i) a H₃PO₄-imbibed polymer electrolyte based on aromatic polyethers bearing pyridine units, able to operate at 200 °C and (ii) a 200 °C active and with zero CO emissions Cu–Mn–O methanol reforming catalyst supported on copper foam. Methanol is being reformed inside the anode compartment of the fuel cell at 200 °C producing H₂, which is readily oxidized at the anode to produce electricity. The IRMFC showed promising electrochemical behavior and no signs of performance degradation for more than 72 h.     

固定式质子交换膜燃料电池的天然气重整制氢

介绍了固定式质子交换膜燃料电池用氢气的各种天然气重整方法,其中包括水蒸气重整法、自热重整法和化学闭合燃烧法。同时简述了氢气进一步纯化的水煤气变换反应、选择氧化、变压吸附和气体膜分离脱一氧化碳的方法。通过上述重整和提纯的处理,最终能制备出满足固定式质子交换膜燃料电池要求的氢气。     

Low-level CO in hydrogen-rich gas supplied by a methanol processor for PEMFCs

The present study developed a low-CO methanol processor for the online supply of hydrogen to a proton exchange membrane fuel cell (PEMFC) composed of a steam reformer, a catalytic combustor and a reactor for the removal of CO. Commercial Cu/ZnO/Al₂O₃- and Pt/Al₂O₃-based catalysts were used in the methanol steam reforming and the preferential oxidation (PROX) reactor, respectively. The steam reformer was successfully heated with a catalytic combustor at room temperature without any additional electrical power supply. Hydrogen gas was obtained at a flow rate of 43.0 L h⁻¹ using a feed flow rate of 39.5 ml h⁻¹ (S/C=1.1) and an operation temperature of 250 °C, corresponding to a power output of 59 W_e. The CO concentration could be maintained at 4–5 ppm for stable operation.