镍基催化剂上乙醇水蒸气重整反应的研究

考察了载体对Ni催化剂乙醇水蒸气重整制氢反应性能的影响。结果表明,Ni/CeO2催化剂具有较好的低温活性和氢气选择性。对Ni担载量和焙烧温度考察发现,400℃焙烧的15%NiCeO2催化剂具有较好的催化性能;继续升高焙烧温度引起NiO和CeO2粒子的显著增大,导致对氢气选择性的降低。较小的Ni和CeO2粒子有利于乙醇水汽重整反应的进行,而大的粒子倾向于乙醇的分解反应。 350℃时,在反应过程中分别添加CO、CO2和CH4的结果表明没有发生CO和CO2甲烷化反应,而发生了一定程度的CH4水汽重整反应。     

流化床中高分散镍基催化剂上甲烷的自热重整和部分氧化

Highly dispersed Ni catalysts on spherical SiO2 were prepared by simple impregnation of Ni（acac）2, [Ni-（NH3）6-n（H2O）n]^2＋, [Ni（en）3]^2＋ and [Ni（EDTA）]^2-. Pulse adsorption of H2 and TEM analysis results confirmed that Ni was dispersed very well on the surface of SiO2 even after calcination （4 h） and reduction （1 h） at high temperature of 800 ℃. These highly dispersed and uniquely sized Ni crystallites were more stable and more reactive for both autothermal reforming and partial oxidation of methane in fluidized reactor.     

镍基催化剂上稻草水蒸气重整制富氢合成气

采用浸渍法制备了SiO₂, γ-Al₂O₃, CaO和TiO₂负载的Ni催化剂, 以及不同MgO含量的MgO-7.5%Ni/γ-Al₂O₃催化剂,利用X射线衍射和N₂吸附-脱附技术表征了催化剂的结构,在固定床反应器上评价了它们在稻草水蒸气催化重整制合成气反应中的催化性能,考察了反应条件对催化剂性能的影响.结果表明, 以γ-Al₂O₃为载体时Ni催化剂活性最高,其中7.5%Ni/γ-Al₂O₃催化剂的H₂收率可达1071.3ml/g,H₂:CO的体积比为1.4:1;同时,MgO的添加进一步提高了该催化剂的性能,当MgO含量为1.0%时,H₂收率可达1194.6ml/g,H₂:CO体积比可达3.9:1.可见MgO的加入促进了Ni基催化剂上稻草水蒸气催化重整制合成气反应的进行,同时使得合成气中CO发生水-汽转换反应,从而大大提高了合成气中H₂含量.     

液化石油气水蒸气重整镍催化剂新型载体研究

以共沉淀法合成了硅铝系载体（AS和SA），并采用改性天然高铝石为原料合成了矿物质载体（MC-1和MC-2）,采用浸渍法合成了镍负载型催化剂。用常压固定床管式反应器，考察了液化石油气水蒸气重整反应活性，通过XRD、物理吸附等手段对催化剂进行了表征。结果表明，以MC-1、MC-2和SA、AS为载体的催化剂的水蒸气重整活性明显高于目前普遍使用的Ni/α-Al2O3催化剂。以SA为载体，负载5%镍的催化剂具有最好的水蒸气重整活性。在750 ℃，水碳比为2.0的条件下转化率达100％，C1选择性达94.46％。XRD分析结果表明1 300 ℃焙烧后的SA载体中存在α-Al2O3晶型和莫来石结构。硅、铝添加次序对水蒸气重整活性影响较大，硅-铝添加次序的催化剂样品的活性高于铝-硅添加次序的样品，C1选择性提高12.7％。     

载体对镍催化剂催化乙醇水蒸气重整制氢反应性能的影响

 采用等量浸渍法制备了不同载体负载的镍催化剂,考察了载体对催化剂催化乙醇水蒸气重整制氢反应性能的影响. 结果表明,在650 ℃和101.3 kPa下,不同载体负载的催化剂上乙醇的转化率都接近100%,但选择性相差很大,选择性大小顺序为: ZnO≈La2O3＞CeO2＞MgO＞γ-Al2O3＞TiO2＞ZrO2＞硅胶＞硅藻土. TPR和XRD结果表明,除TiO2外,各载体负载的催化剂的主要物相中都包括NiO相,其对催化剂的活性起重要作用,而Ni与载体的相互作用程度影响催化剂的选择性. 当相互作用较弱,活性组分基本以NiO相存在时,催化剂的选择性较低;当相互作用太强,不存在NiO相时,催化剂的活性和选择性都很低; 当相互作用较强,部分Ni与载体作用生成新物相且与NiO相共存时,催化剂的活性和选择性最高.     

镍负载量对乙醇水蒸气重整制氢催化性能和催化剂的影响

采用稳态实验对镍负载量对Ni/MgO催化剂在乙醇水蒸气重整反应的影响进行了研究。结果表明,在101.3kPa下,镍负载量越高,催化剂的活性越高。对于催化剂的选择性,存在一个最佳镍负载量为10%Ni/MgO。按选择性从大到小排序,不同镍负载量的催化剂为：10Ni/MgO>15Ni/MgO>12.5Ni/MgO>7.5Ni/MgO≈5Ni/MgO。热分析表明,焙烧过程中不同镍负载量的催化剂镍前体与载体前体之间发生的相互作用不同。XRD和TPR 表征结果显示,催化剂的晶体结构和还原特性也与催化剂上镍的负载量有关。焙烧过程中样品10Ni/MgO上镍前体与载体前体发生了两种相互作用, 并且其氧化态与其他催化剂相比具有特殊的结构和还原性。说明催化剂的选择性不仅受活性相Ni的影响而且受Ni活性相周围环境的影响。     

Ni-Cu/CeO2催化剂上乙醇水蒸气重整反应

 研究了Ni-Cu/CeO2催化剂在乙醇水蒸气重整反应中的催化性能. 以具有高比表面积的CeO2为载体,用沉积沉淀法制备了一系列不同担载量的Ni, Cu双组分催化剂,采用X射线衍射、程序升温还原和透射电子显微镜对催化剂的晶相组成、还原性能和形貌进行了表征. 结果表明, CuO, NiO和CeO2的相互作用明显改善了NiO的分散. 适量CuO的加入使NiO分散度增大,颗粒明显变小,从而使催化剂具有更好的催化性能,但过多CuO的加入反而降低了催化剂的活性. Ni和Cu的催化性能差异较大, Ni具有优异的断裂C-C键性能,在低温下即可实现乙醇的完全转化,而在高温区则具有很好的甲烷重整性能,可获得很高的氢气产率; Cu在低温区倾向于使乙醇脱氢生成乙醛以及进一步脱羰基生成丙酮,在高温区也具有一定的乙醇裂解性能.     

碳纳米管负载镍基催化剂对甘油水蒸气重整的性能研究

以硝酸盐为前驱体，CNTs为载体，采用简单浸渍法制备了一系列不同NiO含量的催化剂3Ni-CNTs、 5Ni-CNTs、 10Ni-CNTs和15Ni-CNTs（NiO含量分别为3.0%、 5.0%、 10.0%和15.0%），通过X-射线衍射（XRD）、氢气程序升温还原（H₂TPR）、氢气程序升温脱附（H₂TPD）、 X-射线光电子能谱（XPS）和透射电镜（TEM）对其物理化学性质进行了分析，并考察其对甘油水蒸气重整反应的影响。结果表明：15Ni-CNTs的催化性能最好，在375 ℃条件下，甘油转化率和氢气选择性分别为100%和72.9%。     

Pd/ZnO催化剂的还原及其催化甲醇水蒸气重整制氢

考察了共沉淀法制备的15.9%Pd/ZnO催化剂的还原对甲醇水蒸气重整制氢反应的影响.结果显示,当催化剂的还原温度为523~573K时,523K下反应的甲醇转化率达到了41.6%,CO2选择性为94.6%,出口CO浓度为1.26%.X射线衍射结果显示,当催化剂的还原温度为523K时PdZn合金开始形成.还原温度为523~573K范围内催化剂活性的提高归因于5~14nmPdZn合金粒子的存在.用程序升温还原及X射线衍射表征手段探究了还原过程中Pd与ZnO之间的相互作用.结果表明,Pd/ZnO可能经历了PdO/ZnO→Pd/ZnO→PdZnO1-x/ZnO→PdZn合金/ZnO的还原过程,而部分PdZn合金在反应过程中可重新被氧化成PdZnO1-x.对反应的活性物种进行了初步探讨.     

金属壁载PdZn/Al2O3/FeCrAl催化剂上甲醇水蒸气重整制氢

研究了金属壁载PdZn/Al2O3/FeCrAl催化剂在不锈钢平板式微型制氢反应器中对甲醇水蒸气重整制氢的催化性能.结果表明,在反应温度为350℃,甲醇GHSV=1·6L/(g·h),水/醇摩尔比为1·2时,甲醇转化率可达100%,H2选择性达99%以上,出口CO含量低于0·5%,同时催化剂具有很好的稳定性.     

乙醇水汽重整制氢反应中钯铜合金膜的透氢性能

 采用真空化学镀技术制备了厚度较薄的具有 fcc 结构的 Pd0.9Cu0.1/Al2O3 合金复合膜, 在 250~500 °C, 160~310 kPa 的乙醇水汽重整制氢模拟反应条件下, 考察了不同醇/水比的 H2-Ar-C2H5OH-H2O 混合气体系中该膜的透氢性能. 结果表明, 乙醇和水的存在均相同程度地降低了膜的透氢性能, 但测试条件下 Pd-Cu 合金膜仍保持完整的膜致密性和稳定的相结构. 在 500 °C, 310 kPa, H2-Ar-C2H5OH-H2O (H2:Ar:(C2H5OH+H2O) 体积比为 60:30:10) 混合气中, 膜的最大透氢量为 11.3 m3/(m2?h), H2 回收率大于 62.5%. Pd-Cu 合金膜在乙醇水汽重整制氢反应中具有潜在的应用前景.     

Studies of the Methane Steam Reforming Reaction at High Pressure in a Ceramic Membrane Reactor

The effects of temperature and pressure on the steam reforming of methane 3H2+CO) were investigated in a membrane reactor (MR) with a hydrogen permeable membrane. The studies used a novel silica-based membrane prepared by using the chemical vapor deposition (CVD) technique with a permeance for H2 of 6.0×l0-8 mol·m-2·s-1·Pa-1 at 923 K. The results in a packed-bed reactor (PBR) were compared to those of the membrane reactor at various temperatures (773-923 K) and pressures (1-20 atm, 101.3-2026.5 kPa) using a commercial Ni/MgAl2O4 catalyst. The conversion of methane was improved significantly in the MR by the countercurrent removal of hydrogen at all temperatures and allowed product yields higher than the equilibrium to be obtained. Pressure had a positive effect on the hydrogen yield because of the increase in driving force for the permeance of hydrogen. The yield of hydrogen increased with pressure and reached a value of 73×10-6 mol·g-1·s-1 at 2026.5 kPa and 923 K which was higher by 108% than the value of 35×10-6 mol·g-1·s-1 obtained for the equilibrium yield. The results obtained with the silica-based membrane were similar to those obtained with various other membranes as reported in the literature.     

Study of a Catalyst for Energy—Saving Natural Gas Steam Reforming

The DS-1 catalyst for energy-saving natural gas steam reforming was prepared by using potash as a carbon-resistant additive and adding rare earth oxide. The catalyst demonstrated good reducibility,carbon resistance, activity and stability in aging tests and 500 h stability tests at low water/carbon ratios.     

复合催化剂及稀土助催的甲醇水蒸汽重整制氢的研究

采用并流共沉淀法制备了不同配比的CuZnAl复合氧化物催化剂,通过X-衍射(XRD)和程序升温还原(TPR)等表征技术考察了焙烧温度对催化剂催化活性的影响,且考察了La助剂对催化剂催化活性的影响。结果表明,La的含量为15%时的的催化剂具有最高的催化活性。当反应温度为250℃,水醇摩尔比为1:1,焙烧温度为550℃时,甲醇转化率可高达95%左右。     

Maximum Hydrogen Production by Autothermal Steam Reforming of Bio-oil With NiCuZnAl Catalyst

Autothermal steam reforming (ATR) of bio-oil, which couples the endothermic steam reform-ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600 oC, the ratio of steam to carbon fed (S/C) of 3 and the oxygen to carbon ratio (O/C) of 0.34. The reaction con-ditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.     

Highly Active Steam Reforming Catalyst for Hydrogen and Syngas Production

Toyo Engineering Corporation developed a steam reforming catalyst, which is four times as active as conventional catalysts, for hydrogen and syngas production from light natural gas. The catalyst has over three years experience in 1500 t/d class NH₃ plant. Benefits, such as fuel saving, etc., by the developed catalyst are discussed.     

直接内重整熔融碳酸盐燃料电池中甲烷蒸汽重整催化剂探索性研究

选择甲烷蒸汽重整催化剂用于直接内重整熔融碳酸盐燃料电池(DIR-MCFC)中,并考察了DIR-MCFC的性能,讨论了电池放电量、气体压力、燃料气进料水/碳比(S/C)等因素对该催化剂性能的影响.结果表明,重整催化剂能够满足电池放电需求;放电量大小影响电池内的H2含量,但对CH4含量影响不大;当气体压力为0.36MPa时...     

Thermodynamic Assessment of a Solar-Driven Integrated Membrane Reactor for Ethanol Steam Reforming

To efficiently convert and utilize intermittent solar energy, a novel solar-driven ethanol steam reforming (ESR) system integrated with a membrane reactor is proposed. It has the potential to convert low-grade solar thermal energy into high energy level chemical energy. Driven by chemical potential, hydrogen permeation membranes (HPM) can separate the generated hydrogen and shift the ESR equilibrium forward to increase conversion and thermodynamic efficiency. The thermodynamic and environmental performances are analyzed via numerical simulation under a reaction temperature range of 100–400 °C with permeate pressures of 0.01–0.75 bar. The highest theoretical conversion rate is 98.3% at 100 °C and 0.01 bar, while the highest first-law efficiency, solar-to-fuel efficiency, and exergy efficiency are 82.3%, 45.3%, and 70.4% at 215 °C and 0.20 bar. The standard coal saving rate (SCSR) and carbon dioxide reduction rate (CDRR) are maximums of 101 g·m⁻²·h⁻¹ and 247 g·m⁻²·h⁻¹ at 200 °C and 0.20 bar with a hydrogen generation rate of 22.4 mol·m⁻²·h⁻¹. This study illustrates the feasibility of solar-driven ESR integrated with a membrane reactor and distinguishes a novel approach for distributed hydrogen generation and solar energy utilization and upgradation.