CaO/MgO负载的钙钛矿型氧化物用于甲烷化学链蒸汽重整

甲烷化学链蒸汽重整(Chemical-looping steam methane reforming,CL-SMR)是基于化学链燃烧的概念而提出的一种新颖的技术。在重整反应器中,甲烷与载氧体中的晶格氧发生部分氧化反应生成合成气(H₂/CO物质的量比为2.0),还原后的载氧体进入到水蒸气反应器中,与水蒸气反应恢复晶格氧的同时生成H₂。以钙钛矿型氧化物LaFeO₃为载氧体用于甲烷化学链蒸气重整过程,同时通过碱金属CaO和MgO对LaFeO₃进行负载,以增大载氧体的比表面积、热稳定性和抗积炭能力。通过X射线衍射(XRD)、H₂程序升温还原(H₂-TPR)、BET比表面积分析(BET)和X光电子能谱(XPS)对载氧体进行表征。结果表明,三种载氧体均表现出较高的反应活性和合成气选择性,循环后仍能保持钙钛矿的结构。从反应性能、选择性和抗积炭能力等方面综合考虑,LaFeO₃-CaO的效果最好,五次循环后具有很好的再生性。     

面向氢能源、燃料电池和二氧化碳减排的制氢途径的选择

对氢气的多种制造途径加以探讨,也涉及到氢能的利用、燃料电池以及二氧化碳的减排。需要指出的是氢气并非能源,而只是能量的载体。 所以氢能的发展首先需要制造氢气。对于以化石燃料为基础的制氢过程,如煤的气化和天然气重整,需要开发更经济和环境友好的新过程,在这些新过程中要同时考虑二氧化碳的有效收集和利用问题。对于煤和生物质,在此提出了一种值得进一步深入研究的富一氧化碳气化制氢的概念。对于以氢为原料的质子交换膜燃料电池系统,必须严格控制制备的氢气中的一氧化碳和硫化氢;对于以烃类为原料的固体氧化物燃料电池,制备的合成气中的硫也需严格控制。然而,传统的脱硫方法并不适宜于这种用于燃料电池的极高深度的氢气和合成气的脱硫。氢能和燃料电池的发展是与控制二氧化碳排放紧密相关的。     

微型平板式反应器中甲醇水蒸气重整制氢的研究

研制了一种高效平板式微型制氢反应器,将甲醇重整和催化燃烧集于一体,吸热、放热合理耦合,实现快速启动和制氢过程自热运行;在反应器中进行甲醇水蒸气重整实验,考察了反应器腔内的温度分布,以及温度、空速和水醇比对制氢过程的影响。结果表明,当温度为270℃,空速为870h-1,水醇比为1.3时,甲醇转化率最高为94.85%,重整气组成为74.53%H2、1.76%CO、23.71%CO2;累计运行400h,重整最大产氢量接近6000mL/h,可为便携式燃料电池提供稳定氢源。     

化学循环重整甲烷制合成气LaBO3钙钛矿型氧载体研究

采用溶胶-凝胶法制备了不同B位可变价离子的La-B-O复合氧载体(B=Cr、Ni),采用XRD、BET、FT-IR、H2-TPR及CH4-TPSR等进行了表征,并用于化学循环重整(CLR)CH4反应中.结果表明,LaNiO3氧化物更易于与CH4发生深度氧化和选择氧化,LaCrO3氧化物则利于CH4裂解,其氧物种氧化CH4的能力较弱.在连续流动CLR反应中,LaNiO3具有较高的供氧量和持续供氧能力,能将CH4选择氧化为H2/CO=1.45的合成气,其CH4转化率和CO选择性分别达到23.4%和86.9%,且其结构保持了较高的稳定性.     

A MEMS methanol reformer heated by decomposition of hydrogen peroxide

This paper presents the design, fabrication and evaluation of a micro methanol reformer complete with a heat source. The micro system consists of the steam reforming reactor of methanol, the catalytic decomposition reactor of hydrogen peroxide, and a heat exchanger between the two reactors. In the present study, catalytic decomposition of hydrogen peroxide is used as a process to supply heat to the reforming reactor. The decomposition process of hydrogen peroxide produces water vapor and oxygen as a product that can be used efficiently to operate the reformer/PEMFC system. Cu/ZnO was selected as a catalyst for methanol steam reforming and Pt for the decomposition of hydrogen peroxide. Incipient wetness method was used to load catalysts on a porous support. Catalyst loaded supports were inserted in the cavity made on the glass wafer. The performance of the methanol steam reforming system was measured at various test conditions and the optimum operation condition was sought. At the optimum condition, the hydrogen selectivity was 86.4% and the thermal efficiency was 44.8%. The product gas included 74.1% H(2), 24.5% CO(2) and 1.4% CO and the total volume production rate was 23.5 ml min(-1). This amount of hydrogen can produce 1.5 W of power on a typical PEMFC.     

Kinetics of methanol steam reforming over COPZr-2 catalyst

The COPZr-2 catalyst, which was prepared in our prophase research, showed good catalytic performance in methanol steam reforming reaction. In this article, the best one was chosen as an example to study the reaction kinetics of methanol steam reforming over this type of catalyst. First, the effects of methanol conversion to outlet CO2 and methanol conversion to outlet CO on methanol pseudo contact time W/FMeOH were investigated. Then by applying the reaction route that methanol direct reforming （DR） and methanol decomposition （DE） were carried out in parallel, the reaction kinetic model with power function type was established. And the parameters for the model were estimated using a non-linear regression program which computed weighted least squares of the defined objects function. Finally, the kinetic model passed the correlation test and the F-test.     

Hydrogen and syngas production from two-step steam reforming of methane using CeO2 as oxygen carrier

CeO2 oxygen carrier was prepared by precipitation method and tested by two-step steam reforming of methane (SRM). Two-step SRM for hydrogen and syngas generation is investigated in a fixed-bed reactor. Methane is directly converted to syngas at a H2/CO ratio close to 2 : 1 at a high temperature (above 750 °C) by the lattice oxygen of CeO2; methane cracking is found when the reduction degree of CeO2 was above 5.0% at 850 °C in methane isothermal reaction. CeO2?δ obtained from methane isothermal reaction can split water to generate CO-free hydrogen and renew its lattice oxygen at 700 °C; simultaneously, deposited carbon is selectively oxidized to CO2 by steam following the reaction (C+2H2O→CO2+2H2). Slight deactivation in terms of amounts of desired products (syngas and hydrogen) is observed in ten repetitive two-step SRM process due to the carbon deposition on CeO2 surface as well as sintering of CeO2.     

K-La-Ni/Si-2催化低碳烷烃与二氧化碳重整制合成气(英文)

Ｎｉ／Ｓｉ２催化剂具有较好的低碳烷烃与二氧化碳重整制合成气的反应性能，添加Ｌａ２Ｏ３助剂和Ｋ２Ｏ助剂可提高催化剂活性和合成气收率，从而进一步改善催化剂的低碳烷烃与ＣＯ２重整制合成气的反应性能，研制的ＫＬａＮｉ／Ｓｉ２催化剂，用于天然气与ＣＯ２重整反应制合成气可达９７％的低碳烷烃转化率和９５％以上的合成气收率。     

Methanol Steam Reforming Reactions on CuZn（Zr）AlO Catalyst

The catalytic performances of methanol steam reforming reactions on CuZn(Zr)AlO catalysts were studied. When the ZrO2 promoter was added to a CuZnAlO catalyst, its methanol conversion, H2 production and H2 selectivity improved greatly. By using the (?)COPZr-2 catalyst as an example, which exhibited the best catalytic performance, the optimized reaction conditions were established to be:     

甲醇水蒸汽催化重整过程的研究进展

甲醇水蒸汽重整是车载燃料电池较为理想的氢源,其中选择合适的催化剂又是重整反应的一个关键问题.本文综述了应用于甲醇水蒸汽重整反应的常用催化剂,如含Cu、Ni、Cr、Pd等,包括这些催化剂的催化性能、反应条件、产物分析等,并对部分催化剂的催化机理和动力学分析进行了概述.另外,还简要地介绍了应用于氧化水蒸汽重整反应的催化剂。     

Synthesis Gas Production from Natural Gas on Supported Pt Catalysts

Auto-thermal reforming of methane, combining partial oxidation and reforming of methane with CO2 or steam, was carried out with Pt/Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts, in a temperature range of 300-900℃. The auto-thermal reforming occurs in two simultaneous stages, namely, total combustion of methane and reforming of the unconverted methane with steam and CO2, with the O2 conversion of 100% starting from 450 ℃. For combination with CO2 reforming, the Pt/CeO2 catalyst showed the lowest initial activity at 800 ℃, and the highest stability over 40 h on-stream. This catalyst also presented the best performance for the reaction with steam at 800 ℃. The higher resistance to coke formation of the catalyst supported on ceria is due to the metal-support interactions and the higher mobility of oxygen in the oxide lattice.     

Energy-efficient syngas production through catalytic oxy-methane reforming reactions

The considerable recent interest in the conversion of stranded methane into transportable liquids as well as fuel cell technology has provided a renewed impetus to the development of efficient processes for the generation of syngas. The production of syngas (CO/H2), a very versatile intermediate, can be the most expensive step in the conversion of methane to value-added liquid fuels. The catalytic oxy reforming of methane, which is an energy-efficient process that can produce syngas at extremely high space-time yields, is discussed in this Review. As long-term catalyst performance is crucial for the wide-scale commercialization of this process, catalyst-related studies are abundant. Correspondingly, herein, emphasis is placed on discussing the different issues related to the development of catalysts for oxy reforming. Important aspects of related processes such as catalytic oxy-steam, oxy-CO2, and oxy-steam-CO2 processes will also be discussed.     

生物质气化重整合成二甲醚

以松木粉为原料，采用空气 水蒸气气化制备了富氢气化气，通过添加甲烷重整富氢气化气，调整了合成气化学当量比，在260 ℃、4 MPa、12 000 h－1条件下，对生物质合成气一步法合成二甲醚进行了实验研究。结果表明：引入甲烷重整，活化了富氢气化气中过量的CO2，甲烷的最佳加入量为CH4/CO2=1，生物质碳转化率达到70%以上，尾气中二甲醚选择性达到69.6%。     

水蒸气对Ni/Ce-Zr-Al-Ox催化剂上CO2重整CH4瓜的影响

采用水热合成-负载法制备了Ni/Ce-Zr-Al-Ox催化剂,测试了该催化剂上CO2重整CH4反应的活性和稳定性,并考察了添加少量水蒸气对CO2重整CH4反应的影响.结果表明,在不含水蒸气的反应气中反应198 h后CH4和CO2的转化率分别为89%和98%,H2/CO摩尔比约为1.00,且没有任何失活.添加3.2%的水蒸气后,CH4转化率提高到94%,CO2转化率不变,H2/CO摩尔比约提高0.06,同时稳定性也很好.计算结果表明,添加少量水蒸气后,CO2重整CH4被促进,逆水煤气反应被抑制,而水蒸气重整CH4没有明显变化.     

Catalytic steam reforming of biomass over Ni-based catalysts: Conversion from poplar leaves to hydrogen-rich syngas

A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%–9.8 wt%have been prepared.The structure of the catalysts was characterized using X-ray diffraction(XRD),N2 adsorption-desorption,transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor.The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas.The ratio of H2:CO can reach ca 5:1 in the hydrogen-rich syngas.The yield of H2 can reach 273.30 mL/g(poplar leaves).In the CaO-Ni/SBA-15 catalyst,Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves,and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.     

Development of a Joint Hydrogen and Syngas Combustion Mechanism Based on an Optimization Approach

A comprehensive and hierarchical optimization of a joint hydrogen and syngas combustion mechanism has been carried out. The Kéromnès et al. (Combust Flame, 2013, 160, 995–1011) mechanism for syngas combustion was updated with our recently optimized hydrogen combustion mechanism (Varga et al., Proc Combust Inst, 2015, 35, 589–596) and optimized using a comprehensive set of direct and indirect experimental data relevant to hydrogen and syngas combustion. The collection of experimental data consisted of ignition measurements in shock tubes and rapid compression machines, burning velocity measurements, and species profiles measured using shock tubes, flow reactors, and jet‐stirred reactors. The experimental conditions covered wide ranges of temperatures (800–2500 K), pressures (0.5–50 bar), equivalence ratios (? = 0.3–5.0), and C/H ratios (0–3). In total, 48 Arrhenius parameters and 5 third‐body collision efficiency parameters of 18 elementary reactions were optimized using these experimental data. A large number of directly measured rate coefficient values belonging to 15 of the reaction steps were also utilized. The optimization has resulted in a H₂/CO combustion mechanism, which is applicable to a wide range of conditions. Moreover, new recommended rate parameters with their covariance matrix and temperature‐dependent uncertainty ranges of the optimized rate coefficients are provided. The optimized mechanism was compared to 19 recent hydrogen and syngas combustion mechanisms and is shown to provide the best reproduction of the experimental data.     

Effect of O2 and H2O on the tri-reforming of the simulated biogas to syngas over Ni-based SBA-15 catalysts

A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method. The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor. The stability of the catalyst was tested at 800 ℃. The results indicated that 10 wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas. Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6, GHSV = 24000 ml•g{cat}-1\cdoth-1 and the reaction temperatureT = 800 ℃, the conversions of CH4 and CO2 were 92.8% and 76.3%, respectively, and the yields of CO and H2 were 99.0% and 82.0%, respectively. The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.     

两种甲醇水蒸气重整制氢催化剂的研究

对采用共沉淀法制备的CuZnAlO类铜系催化剂和采用水滑石类层柱材料（LDHs）前驱体制备的催化剂在甲醇水蒸气重整制氢反应中的性能进行了研究。对共沉淀法制备的CuZnAlO类铜系催化剂考察了ZrO2助剂的加入对催化剂反应性能的影响，发现Zr的质量分数为10％的催化剂显著提高CuZnAlO催化剂的反应性能。该催化剂的最佳反应条件：0.1 MPa、250 ℃、H2O/MeOH摩尔比1.0～1.3、3.56 h－1。在此反应条件下进行了COPZr2催化剂150 h稳定性实验。结果表明，该催化剂具有很好的反应稳定性。甲醇转化率和氢产率分别约为88％和83％，产物湿基组成中H2和CO的质量分数分别为>63％和0.20％～0.31％。对LDHs前驱体制备的催化剂，进行了70 h反应稳定性实验，结果表明，催化剂虽具有较高的起始活性，但随反应进行，活性有所下降，30?h后基本保持稳定，甲醇转化率和产氢率分别为73％和66％，产物湿基组成中H2和CO的质量分数分别为>55％和0.07%～0.08%。该类催化剂的反应稳定性虽较差，但却可以显著降低产物湿基组成中CO的摩尔分数。对LDHs前驱体制备的催化剂进行XRD和SEM表征结果表明，ZrO2的加入使催化剂中CuO晶粒分散更为均匀，颗粒更细。     

Effect of O_2 and H_2O on the tri-reforming of the simulated biogas to syngas over Ni-based SBA-15 catalysts

A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method.The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor.The stability of the catalyst was tested at 800 ?C.The results indicated that 10wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas.Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6,GHSV = 24000 ml gc?a1t h?1 and the reaction temperature T = 800 ?C,the conversions of CH4 and CO2 were 92.8% and 76.3%,respectively,and the yields of CO and H2 were 99.0% and 82.0%,respectively.The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.     

甲醇水蒸气重整制氢的高效碳纳米管改性Cu/ZnO/Al2O3催化剂

以碳纳米管为助剂,制备用于甲醇水蒸气重整制氢的新型高效Cu/ZnO/Al₂O₃催化剂,并与传统Cu/ZnO/Al₂O₃催化剂在相同条件下的催化性能进行了比较.结果表明,添加适量碳纳米管可显著提高催化剂的低温催化活性和选择性,在大幅度提高产氢速率的同时有效降低了重整产气中CO的含量.SEM和XRD分析证实适量碳纳米管的添加有效促进了Cu/ZnO/Al₂O₃催化剂结构特性的改善,有利于活性铜物种的分散,从而显著提高了催化剂的低温催化性能.