共查询到20条相似文献,搜索用时 15 毫秒
1.
Josef-Christian Buhl 《Reaction Kinetics and Catalysis Letters》2005,84(2):375-382
Summary The activity of Pt/Ce1-xGdxO2-y samples in steam and dry reforming of methane at short contact times correlates with the lattice oxygen mobility. For the partial oxidation of methane (POM), the oxygen mobility should be optimized to prevent methane combustion. 相似文献
2.
Sergio L. González-Cortés Tian-Cun Xiao Andrew P. E. York Ding Ma Hamid Al-Megren Malcolm L.H. Green 《Reaction Kinetics and Catalysis Letters》2005,84(1):21-28
Summary For Pr-doped ceria Ce1-xPrxO2-y prepared by the Pechini route and promoted with Pt, the mobility and reactivity of lattice oxygen were found to depend on the Pr content, which seems to determine the density of surface and bulk anion vacancies and domain boundaries. 相似文献
3.
《Mendeleev Communications》2022,32(1):129-131
Ceria-based solid solutions have been proposed as catalytic supports for the conversion of methane to syngas. Control of oxygen vacancies in vacancy-rich oxides represents a promising way to stable catalysts with improved activity. 相似文献
4.
V.A. Sadykov L.A. Isupova I.S. Yakovleva G.M. Alikina A.I. Lukashevich S. Neophytides 《Reaction Kinetics and Catalysis Letters》2004,81(2):393-398
The reactivity and mobility of the surface and lattice oxygen in a La1-xCaxFeO3-y system prepared via a ceramic route were studied by using CH4-TPR. While the middle-temperature (400-700oC) oxygen lattice mobility reaches maximum for samples with disordered anion vacancies, the high-temperature lattice oxygen
flux appears to be controlled by a rapid transfer along disordered domain walls. In the high-temperature range, a high selectivity
to syngas of methane oxidation by the lattice oxygen was achieved both for pure lanthanum ferrite and for samples with a microdomain
structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
不同CuO/CeO2催化剂上CO低温氧化反应 总被引:10,自引:0,他引:10
分别用热解硝酸铈法和浸渍法制备了不同物性的CeO2粉体和相应的CuO/CeO2催化剂,并用XRD, HRTEM和TPR等对样品进行了表征,利用微反-色谱装置考察了其催化CO低温氧化的活性. 结果表明,热解温度影响CeO2的物性(形貌、粒度大小及分布等). 相同条件下,不同物性的CeO2载体上CuO的负载情况不同, 500 ℃热解获得的CeO2载体上非晶态CuO负载量最高,相应的CuO/CeO2催化剂活性也较高. 非晶态CuO一部分进入CeO2晶格,另一部分高度分散于CeO2表面上. 焙烧温度较低时(≤ 600 ℃), 催化剂活性受焙烧温度的影响较小,而高温(800 ℃)焙烧后,催化剂则因载体粒度增大和CuO烧结团聚等因素导致催化活性明显降低. 相似文献
6.
采用沉淀法和浸渍法制备了具有氧空位的CeO2纳米材料和甲醇水蒸气重整制氢CuO/CeO2催化剂,探索不同焙烧气氛对CeO2纳米材料结构、性质和甲醇水蒸气重整制氢性能的影响。采用SEM、XRD、BET、H2-TPR、N2O滴定和XPS等手段对催化剂进行了表征。结果表明,CuO/CeO2催化剂的催化活性与催化剂的Cu比表面积大小、Cu-Ce的相互作用强弱、表面缺陷和表面氧空位的多少有关。其中,在氢气气氛下焙烧所得的CeO2负载CuO后的CuO/CeO2-H催化剂催化活性最佳。在反应温度为250℃,水醇物质的量比为1.2时,甲醇气体空速为800 h-1,甲醇转化率达到了100%,重整尾气中CO含量为0.87%。 相似文献
7.
Huijun Wan Xiujin Li Shengfu Ji Bingyao Huang Kai Wang Chengyue Li 《天然气化学杂志》2007,16(2):139-147
A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt?xZn-xO2/SBA-15 (z=0, 0.5, 1) were prepared. The structures of the catalysts were characterized using XRD, TPR, TEM and BET techniques. The catalytic activities of the catalysts for steam reforming of methane were evaluated in a continuous flow microreactor. The results indicated that both the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts had good catalytic activities at atmospheric pressure. The 10wt%Ni/SBA-15 catalyst exhibited excellent stability at 800癈 for time on stream of 740 h. After the reaction, carbon deposits were not formed on the surface of the catalyst. There existed a regular hexagonal mesoporous structure in the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts. The nickel species and the CexZr1-xO2 component were all confined in the SBA-15 mesopores. The CexZr1-xO2 could promote dispersion of the nickel species in the Ni/CexZr1-xO2/SBA-15 catalysts. 相似文献
8.
The effects of CeO2 and CaO composite promoters on the properties of eggshell Ni/MgO-Al2O3 catalysts of 1.5 mm diameter for the partial oxidation of methane to syngas were investigated. The addition of 1wt.% promoters could enhance the catalytic performance of the Ni/MgO-Al2O3 catalyst, while further increasing the promoter content to 4wt.% results in the decrease of reactivity. The catalytic property is related to the oxidizability of surface nickel species. 相似文献
9.
Ali Nakhaei Pour Yahya Zamani Kheirolah Jafari Jozani Jafar Yeganeh Mehr 《Reaction Kinetics and Catalysis Letters》2005,86(1):157-162
Summary The effect of La2O3 and TiO2 on product selectivity, methane conversion and coke formation over NiO/MgO/ α -Al2O3 catalyst were studied in a simultaneous steam and CO2 reforming of methane to syngas. La2O3 and TiO2 were added to the catalyst via incipient wetness impregnation and bulk precipitation techniques and catalyst activity was tested in a fixed bed quartz reactor. Results reveal that although the addition of these oxides has no effect on the product selectivity and methane conversion, but can reduce coke formation on the surface of the catalysts as it can enhance the mobility of lattice oxygen anions. The results further show that the catalysts prepared by bulk precipitation technique decrease the coke formation more effectively. 相似文献
10.
Xiu-cheng Zheng Xiang-yu Wang Xiao-li Zhang Shu-rong Wang Shi-hua Wu 《Reaction Kinetics and Catalysis Letters》2006,88(1):57-63
Summary CeO2 nanoparticles were prepared by thermal decomposition of cerous nitrate and then used as supports for CuO/CeO2 catalysts prepared via the impregnation method. The samples were characterized by XRD, HRTEM, H2-TPR and XPS. The catalytic properties of the catalysts for low-temperature CO oxidation were studied by using a microreactor-GC
system. 相似文献
11.
甲烷部分氧化制合成气:载体及助剂对Ni系催化剂活性的影响 总被引:22,自引:1,他引:22
采用浸渍法制备了Ni系催化剂,并用程序升温还原和X射线衍射技术对催化剂进行了表征,用固定床微反装置考察了催化剂的催化活性.活性考察结果表明,在Ni担载量为8%的Ni/γ-Al2O3,Ni/δ-Al2O3,Ni/θ-Al2O3和Ni/α-Al2O3四种催化剂上,甲烷部分氧化制合成气反应的活性及产物选择性存在着明显的差异.在770℃下,甲烷转化率及CO和H2的选择性按Ni/γ-Al2O3<Ni/δ-Al2O3<Ni/θ-Al2O3≈Ni/α-Al2O3顺序排列.在相同的条件下,加入适量的CeO2助剂后,Ni/γ-Al2O3和Ni/δ-Al2O3上的反应活性和选择性显著提高,而Ni/θ-Al2O3和Ni/α-Al2O3上的活性和选择性却变化不大.同时,表征结果显示,Ni易与γ-Al2O3形成镍铝尖晶石NiAl2O4,加入CeO2助剂能有效地抑制该组分的生成,而Ni/α-Al2O3样品中未发现NiAl2O4.因此,不同Ni/Al2O3催化剂体系上的反应活性及选择性的差异可归结为不同结构Al2O3载体的性质不同,及CeO2对抑制镍铝尖晶石生成的效果不同. 相似文献
12.
Low-temperature utilization of CO2 and CH4 by combining partial oxidation with reforming of methane over Ru-based catalysts
下载免费PDF全文
![点击此处可从《天然气化学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Combination of partial oxidation of methane (POM) with carbon dioxide reforming of methane (CRM) has been studied over Ru-based catalysts at 550 ℃. POM, CRM and combined reaction were performed over 8wt%Ru/γ-Al2O3 and the results show that both POM and CRM contribute to the combined reaction, between which POM plays a more important role. Moreover, the addition of Ce to Ru-based catalyst results in an improvement in the activity and CO selectivity under the adopted reaction conditions. The Ce-doped catalyst was characterized by N2 adsorption-desorption, SEM, XRD, TPR, XPS and in situ DRIFTS. The mechanism has been studied by in situ DRIFTS together with the temperature distribution of catalyst bed. The mechanism of the combined reaction is more complicated and it is the combination of POM and CRM mechanisms in nature. The present paper provides a new catalytic system to activate CH4 and CO2 at a rather low temperature. 相似文献
13.
三维有序大孔钙钛矿型氧化物LaFe.Co.O的合成及甲烷化学链水蒸气重整性能 《燃料化学学报》2016,44(10):1168-1176
采用无皂乳液聚合法制备聚苯乙烯(PS)微球,通过自组装得到排列均匀有序的聚苯乙烯(PS)胶晶模板,然后经过浸渍和煅烧得到三维有序大孔(3DOM)钙钛矿型氧化物LaFe_(0.7)Co_(0.3)O_3。通过扫描电镜、透射电镜和X射线衍射等手段对制备的3DOM钙钛矿型氧化物LaFe_(0.7)Co_(0.3)O_3的物理化学性能进行表征。在固定床反应器上考察3DOM LaFe_(0.7)Co_(0.3)O_3的甲烷化学链水蒸气重整性能。结果表明,聚苯乙烯(PS)微球粒径受苯乙烯单体使用量的影响,随着苯乙烯单体使用量的增加聚苯乙烯(PS)微球粒径呈增大的趋势;煅烧温度对三维有序大孔结构有显著影响,浸渍后模板在500℃煅烧下即能形成三维有序大孔结构比表面积达到19.820 m2/g,随着煅烧温度的升高三维有序大孔结构遭到部分破坏,在900℃煅烧下三维有序大孔结构遭到完全破坏。在氧载体与甲烷的反应前期,气体产物中CO2含量较高,是表面吸附氧将甲烷完全氧化所致,在表面吸附氧消耗完后体相晶格氧将甲烷部分氧化生成H2与CO。在水蒸气氧化阶段,水蒸气与还原态的氧载体发生反应生成氢气,产氢率为4.0-5.0 mmol/g。同时水蒸气氧化阶段气相产物中CO和CO2含量很低,说明3DOM LaFe_(0.7)Co_(0.3)O_3具有优秀的抗积炭性能。 相似文献
14.
助剂对甲烷部分氧化制合成气镍基催化剂性能的影响 总被引:4,自引:4,他引:4
考察了添加助剂铈、镧和钙对镍基催化剂反应性能的影响,发现助剂对以α-Al2O3为载体的镍基催化剂的调变作用比以γ-Al2O3为载体的镍基催化剂好,且助剂铈对催化剂的性能改善最好。在此基础上,研究了不同载量的铈对催化剂性能的影响。结果表明,铈的质量分数为1%时对催化剂的性能改善最好。同时采用XRD、XPS、TG等技术,研究了助剂铈对10%Ni/γ-Al2O3催化剂的改性作用。XRD分析表明,铈负载量较低时,催化剂中的CeO2高度分散在催化剂表面,铈负载量较高时,CeO2形成微晶颗粒,降低了催化活性。 相似文献
15.
高稳定性Ni/SBA-15催化剂的结构特征及其对二氧化碳重整甲烷反应的催化性能 总被引:4,自引:3,他引:4
采用浸渍法制备了Ni含量为2.5%~20%的系列Ni/SBA-15催化剂,在常压连续流动固定床反应器上考察了催化剂对二氧化碳重整甲烷制合成气的催化性能,并用X射线衍射和N2吸附法研究了Ni/SBA-15催化剂的结构特征. 结果表明, Ni/SBA-15催化剂具有很高的CH4和CO2转化率, 12.5%Ni/SBA-15催化剂在800 ℃反应600 h后活性没有明显下降,但反应710 h后CH4的转化率下降了约50%, CO2的转化率下降了约25%. 其活性下降的主要原因是催化剂积炭. 在高温条件下反应时, SBA-15的介孔结构也没有遭到破坏,分子筛的孔壁能有效阻止活性组分Ni的团聚. SBA-15孔中组装一定量的Ni活性组分后,除了SBA-15的介孔外,还会形成另外一种较小的孔,但这不影响SBA-15的有序介孔结构,只是其孔径、孔容和BET比表面积降低. 相似文献
16.
采用水热法制备了一系列不同Ce/Ni物质的量比的纳米棒CeO_2(x)-NiO催化剂。运用低温N_2吸附-脱附、XRD、TEM、拉曼光谱、H_2-TPR及XPS等技术对催化剂的形貌、结构进行了表征。考察了Ce/Ni物质的量比对CeO_2(x)-NiO催化剂形貌及富氢气氛下CO选择性氧化(CO PROX)反应性能的影响。TEM测试结果表明,调变Ce/Ni物质的量比可制得不同粒径的CeO_2(x)-NiO纳米棒催化剂。H_2-TPR测试结果表明,将NiO掺入CeO_2可提升Ce O_2(x)-NiO催化剂的氧化还原能力。拉曼光谱及XPS测试结果表明,镍含量较低时,CeO_2(x)-NiO催化剂表面活性氧物种及氧空位含量均较多,利于提升其催化性能。CO PROX催化性能测试结果显示,镍含量较低的CeO_2(0.89)-NiO纳米棒催化剂的活性和选择性最好,在170-220℃的反应条件下,CO转化率为100%,CO_2选择性为52%。 相似文献
17.
Rosa Fenoglio Pablo Rolandi Paola Massa Jorge Gonzalez Patricia Haure 《Reaction Kinetics and Catalysis Letters》2004,81(1):83-90
Two CuO/Al2O3 catalysts were synthesized at different calcination temperatures and used for the oxidation of phenol solutions. Deactivation is due to leaching of the active phase and deposition of carbonaceous material.This revised version was published online in December 2005 with corrections to the Cover Date. 相似文献
18.
Ni/ZrO2催化剂上甲烷水蒸气重整反应的研究 总被引:4,自引:2,他引:4
研究了Ni/ZrO2催化剂对甲烷水蒸气重整制合成气的反应性能。考察了催化剂的还原温度、载体焙烧温度以及反应温度、原料配比和空速等对催化剂性能的影响。利用XRD、TEM、XPS等手段对催化剂的织构形貌进行了表征。研究表明,Ni/ZrO2催化剂用于甲烷水蒸气重整制合成气不仅具有较高的活性,也具有较好的稳定性。水蒸气比增加,CH4转化率增大、CO选择性下降。CH4转化率及CO选择性均随空速增大而下降。使用10%Ni/ZrO2催化剂,在650 ℃、空速1.984×104 h-1、原料气配比H2O∶CH4∶N2=2∶1∶2.67的条件下,获得CH4转化率85%、CO选择性70%的结果。 相似文献
19.
乙醇水蒸气重整Co/CeO2催化剂 总被引:5,自引:0,他引:5
采用共沉淀法制备了Co/CeO2催化剂并将其应用于乙醇水蒸气重整制氢反应,考察了活性组分含量和焙烧温度对催化剂性能的影响. 结果表明,在原料气水∶乙醇∶N2摩尔比为3∶1∶16, 空速为40 L/(g·h)和反应温度为350~600 ℃的条件下, 经650 ℃焙烧的10%Co/CeO2催化剂对乙醇水蒸气重整制氢反应具有高活性和高选择性. 在500 ℃下进行的40 h稳定性测试中,该催化剂上的乙醇转化率始终接近100%, 反应后气体中的H2含量保持在65%左右. X射线衍射表征结果显示,焙烧后催化剂的主要物相组成为Co3O4和CeO2, 二者之间存在相互作用. Co/CeO2催化剂中钴的主要存在形式包括小晶粒的钴氧化物、大晶粒Co3O4和进入CeO2晶格的钴,Co3O4含量和焙烧温度的改变可影响催化剂中钴的存在形式. 由催化剂中高分散小晶粒的钴氧化物还原所得的金属钴是关键的活性组分. 相似文献
20.
Jafar Yeganeh Mehr Kheirolah Jafari Jozani Ali Nakhaei Pour Yahya Zamani 《Reaction Kinetics and Catalysis Letters》2002,75(2):267-273
Simultaneous steam and CO2 reforming of methane to syngas (H2and CO) over NiO/MgO/a-Al2O3 catalyst have been investigated at different MgO wt.%. The catalyst has been characterized by temperature-programmed reduction and XRD techniques. Addition of MgO reduced the carbon deposition and energy consumption. The stability and less coking on MgO-promoted catalysts are attributed to the lewis basicity of MgO. 相似文献