Ni基催化剂上乙酸水蒸汽重整研究

为降低生物质裂解过程中副产物乙酸含量,避免对设备的高腐蚀性,通过湿法浸渍制备Ni基催化剂,在此催化剂上进行乙酸水蒸汽重整反应,考察了原料比例和反应温度对乙酸转化率的影响,结果表明,在乙酸与水体积比为1:12、反应温度为600℃下,获得了100%的乙酸转化率。Mg助剂的加入能够有效提高催化剂的抗积炭性能,在长达600min的寿命实验中活性一直维持在100%乙酸转化率。     

甘油水蒸汽重整制氢Ni、Co、Fe催化剂的研究

采用等体积浸渍法制备了催化剂,研究了Ni/Al2O3,Fe/Al2O3,CoMo/Al2O3和NiCo/Al2O3催化剂对甘油水蒸汽重整制氢反应的催化效果,对催化剂进行BET、TPR、XRD表征,以氢产率为实验指标对催化剂进行了评价。研究结果表明,CoMo/Al2O3催化剂在温度650℃氢产率6.02。NiCo/Al2O3催化剂在温度600℃、水醇比16、液空速0.12 h-1条件下的氢产率为6.08。催化剂活性次序为NiCo/Al2O3Co-Mo/Al2O3Ni/Al2O3Fe/Al2O3。     

乙醇水蒸汽重整制氢负载型镍基催化剂研究进展

负载型镍基催化剂是一种良好的乙醇水蒸汽重整制氢催化荆,但反应中存在氢气选择性较差和反应温度高的缺点.介绍乙醇水蒸汽重整制氢的反应机理,在此基础上,探讨通过载体改性和添加助剂提高负载型镍基催化剂的氢气选择性以及降低反应温度,并对研究进展进行综述.     

甘油在改性Ni/γ-Al2O3催化剂上水蒸气重整制氢的研究

通过催化剂性能评价,考察了助剂CeO2、CaO和La2O3对催化剂Ni/γ-Al2 O3催化性能的影响,发现Ni/γ-Al2O3经3种助剂修饰后催化剂活性都明显提高,其中La2O3修饰后的催化剂活性最高,甘油转化率在450～650℃内一直保持100％;氢气选择性在450℃时即达到85％,而且随着温度升高逐渐变大并趋于平稳,最高时可达到92.37％.同时考察了温度、甘油溶液浓度、空速对甘油水蒸气重整制氢反应的影响.运用NH3-TPD和TPR对催化剂进行了表征,发现助剂的添加降低了催化剂的酸性,经改性后催化剂中NiAl2 O4相含量明显降低;催化剂中加入La2O3降低了Ni与Al2O3载体之间的相互作用,因此有利于甘油水蒸气重整制氢反应.     

水热法合成Ce0.9Gd0.1O1.95及其光催化性质研究

采用水热法合成了花状Ce0.9Gd0.1O1.95纳米粉,通过X射线衍射、红外光谱、场发射扫描电子显微镜测试手段对产物进行了表征,探讨了其生长机制,以亚甲基蓝的光降解为模型反应,研究其光催化性能。结果表明,以甲酸为介质,110℃的水热条件下合成的纳米Ce0.9Gd0.1O1.95颗粒经800℃煅烧后具有萤石结构,平均晶粒尺寸为21.6 nm,花状形貌;由于Gd3+的掺杂,纳米Ce0.9Gd0.1O1.95对亚甲基蓝紫外光催化性能强于未掺杂的CeO2。该合成方法简单易行,对纳米Ce0.9Gd0.1O1.95的形貌控制起到了启示作用,所得的花状纳米Ce0.9Gd0.1O1.95在光催化领域有着重要应用价值。     

不同方法制备的MgO负载金属Ni催化水蒸汽重整乙酸制氢

应用浸渍法,在两种不同MgO载体上浸渍N(iNO3)2,经焙烧后得到NiO/MgO固溶体,再经H2还原得到Ni/NixMg1-xO催化剂。对比研究了两种方法所制备催化剂,催化水蒸汽重整乙酸制氢反应的活性和稳定性。结果表明,介孔MgO作载体所得催化剂催化水蒸汽重整乙酸制氢反应中,乙酸的转化率可达97.5%、H2的产率为2.1mol·mol-1,并且反应20h后无明显失活现象,明显高于普通方法制备的MgO作载体所得催化剂的稳定性和活性。结合N2吸附表征可知,介孔MgO具有较高的比表面积和较大的孔径,故其有利于活性组分Ni分散,以及有利于反应物和产物在催化剂孔道中的扩散。因此,介孔MgO作载体所得Ni/NixMg1-xO催化剂,具有更高的催化活性和稳定性。     

甲醇水蒸汽重整制氢催化剂制备的研究

针对燃料电池用氢制备用于甲醇水蒸汽重整制氢的Cu/Zn/Al系列催化剂,研究催化剂组成、制备方法对催化剂性能的影响。利用热分析和X射线衍射等分析手段对催化剂前驱体和焙烧后催化剂样品进行分析和表征。结果表明,铜基催化剂对甲醇水蒸汽重整制氢反应有较好的活性和选择性,合适的组成是Cu、Zn和Al的原子质量百分比为45∶45∶10和47.5∶47.5∶5,210 ℃反应转化率达到100%;并流共沉淀法和热分解法制备的催化剂都具有较好的催化性能。     

甲醇水蒸汽重整制氢Au/TiO2催化剂

采用沉积-沉淀法制备了一系列Au/TiO2催化剂,考察了Au负载量、焙烧温度以及助剂等因素对甲醇水蒸汽重整制氢反应催化性能的影响;并利用XRD, TEM对催化剂进行了表征. 结果表明,制备条件对催化性能有明显影响;Au负载量为5%(w)时所得催化剂活性较好;助剂NiO可使催化剂催化甲醇水重整的催化活性明显提高;100℃烘干未焙烧制得的催化剂活性最好;TEM结果显示,NiO的加入使载体TiO2颗粒分散度提高,Au粒粒度变小.     

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%。     

甘油水蒸汽重整制氢Ni/Ce_(0.9)Gd_(0.1)O_(1.95)催化剂的研究

采用浸渍法和共沉淀法制备了Ni质量分数10%的10%Ni/Ce_(0.9)Gd_(0.1)O_(1.95)催化剂,通过X射线衍射、N_2物理吸附与H_2脉冲化学吸附、H_2程序升温还原等技术表征了催化剂的结构和性质,并考察了其催化甘油水蒸汽重整制氢反应性能。结果表明,浸渍法制备的10%Ni/Ce_(0.9)Gd_(0.1)O_(1.95)-S催化剂的活性最佳,该催化剂上Ni晶粒小、分散度高,形成氧空穴使得催化剂抗积炭能力大大提高,所以活性、氢气选择性较高,稳定性也较好。同时考察了水与甘油物质的量比和泵流速对甘油重整反应性能的影响,发现在水与甘油物质的量比为24∶1,泵流速为0.06 mL·min~(-1)的条件下,甘油几乎完全转化,氢气选择性也非常高,而且反应10 h没有失活。     

甲醇水蒸气重整制氢研究进展

氢气需求的持续增长,带动制氢技术的不断进步。煤制氢技术投资较高,天然气制氢原料来源受到限制,电解水制氢成本较高。甲醇制氢投资适中,适合各种规模的制氢装置,铜基催化剂反应温度低,低温活性和氢气选择性好,价格低廉,因而甲醇制氢技术得到广泛应用。催化剂载体和助剂的改进研究,对工业催化剂的改进具有重要的指导意义。综述甲醇水蒸气重整制氢工艺、反应机理和催化剂,介绍了催化剂载体和助剂等方面的研究进展情况。     

催化剂制备方法对甘油液相重整制氢反应的影响

能源紧缺和环境问题已成为全世界关注的话题,开发利用可再生的清洁能源备受关注,甘油水溶液催化重整制氢是一条资源利用生态化的工艺路线。分别采用共沉淀法和浸渍法制备了NiCoAl复合氧化物催化剂,并采用XRD、比表面积及热分析等对催化剂进行结构表征,结合甘油液相重整制氢中催化剂活性测试结果表明,共沉淀法制得的NiCoAl复合氧化物催化剂的活性较好,较适宜的焙烧温度为550 ℃。     

热解油模型化合物甲醇的蒸汽转化制氢研究

研究了Ce促进的Ni基镁橄榄石催化剂上热解油模型化合物甲醇的水蒸汽转化制氢反应过程，得到活性和稳定性较好的催化剂。浸渍法制备了添加Ce的Ni基镁橄榄石催化剂，Ce的添加改善了催化剂的活性和稳定性。催化剂活性受镍铈原子比的影响，选择合适的镍铈原子比可以得到性能较好的催化剂。在750 ℃、水与甲醇物质的量比为1.5和气体体积空速11 200 h^－1条件下，6%Ni－3%Ce/Olivine催化剂有最好的催化效果，此条件下，甲醇转化率达到85.72%，氢气收率为55.31％。     

Sustainable H2 production from ethanol steam reforming over a macro-mesoporous Ni/Mg-Al-O catalytic monolith

A macro-meso-porous monolithic Ni-based catalyst was prepared via an impregnation route using polystyrene foam as the template and then used in the steam reforming of ethanol to produce a H₂-rich gas. The Ni/Mg-Al catalyst has a hierarchically macro-meso-porous structure as indicated by photographs and scanning electron microscopy (SEM). The surface area of the catalyst was 230 m²?g^-1 and the Ni dispersion was 5.62%. Compared to the pelletized sample that was prepared without a template, the macro-meso-porous Ni/Mg-Al monolith exhibited superior reactivity in terms of H₂ production and also had lower CH₄ yields at 700oC and 800oC. Furthermore, the monolithic catalyst maintained excellent activity and H₂ selectivity after 100-h on-stream at 700^oC, as well as good resistance to coking and metal sintering.     

Yolk-shell structured Pt-CeO2@Ni-SiO2 as an efficient catalyst for enhanced hydrogen production from ethanol steam reforming

A novel Pt-CeO₂@Ni-SiO₂ yolk-shell catalyst was fabricated through modified Stöber method and was applied to the ethanol steam reforming reaction. The catalyst structure was characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy. Compared with the mechanically mixed catalyst, the yolk-shell catalyst exhibited excellent catalytic performance and stability in ethanol steam reforming. The selection of hydrogen reached as high as 66%, and the conversion reached nearly 100% at 400 °C for 28 h.     

Characterization of Ce0.9Gd0.1O1.95 powders synthesized by spray drying

Ce_0.9Gd_0.1O_1.95 powders were synthesized by spray drying and successive calcinations. The phase purity, BET surface area, and particle morphology of as-sprayed and calcined powders were characterized. After calcination above 300 °C, the powders were single phase and showed a BET surface area of 68 m²/g when calcined at 300 °C. The conductivity, in air, of sintered pellets was measured by electrochemical impedance spectroscopy (EIS) and it was found to be comparable with literature values. The activation energy for the total conductivity was around 0.83 eV. The powder calcined at lower temperature showed better sinterability and higher total conductivity due to an increased bulk conductivity.     

Mesoporous high surface area Ce0.9Gd0.1O1.95 synthesized by spray drying

Mesoporous gadolinium doped cerium dioxide with high surface area was produced by spray drying using Pluronic 123 as surfactant. The powder, when calcined at 400 °C, had a BET surface area of 136 m² g⁻¹ and was polycrystalline as confirmed by XRD and TEM. XEDS confirmed Ce, Gd and O, as the only elements present in the powders. Nitrogen adsorption measurements showed that the material was mesoporous with pore diameters of approximately 10 nm, which was later confirmed by TEM studies. TEM-EELS were used to confirm that Ce was in the +4 oxidation state. SEM studies showed particles of 10 nm diameter, corresponding to the crystallite size calculated from XRD data. The similar size range of the mesopores and the observed crystallite size indicates that the porosity is partly formed from intergranular mesoporosity. Using the spray drying method of a surfactant assisted liquid precursor solution it can be possible to manufacture mesoporous gadolinium doped ceria in large quantities in a continuous production.     

国内外蒸汽转化制氢催化剂及工艺进展

本文分别对烃类蒸汽转化制氢技术中涉及的原料、工艺、设备及催化剂等方面的国内外进展进行了讨论，评述了烃类蒸汽转化制氢技术的发展趋势并提出有关建议。     

FeCrAl金属壁载PdZn/Al2O3催化剂上甲醇水蒸汽重整制氢

采用等体积浸渍法制备了不同Pd负载量和不同Pd与Zn物质的量比的PdZn/Al<,2>O<,3>甲醇水蒸汽重整颗粒催化剂,结果表明,Pd负载质量分数9.25%和n(Pd):n(Zn)=0.24的催化剂表现出较佳的催化性能.XRD表征表明,由于生成了较大的Pd-Zn合金粒子,从而有利于甲醇重整反应的进行.制备了金属壁载型...