Ce0.5Zr0.5O2修饰的Ni/SiC、Fe/SiC和Co/SiC催化燃烧甲烷性能

以铈锆固溶体(Ce0.5Zr0.5O2)修饰的高比表面积SiC为载体,采用两步浸渍法制备了Ni、Fe和Co基催化剂,研究了其在煤层气催化燃烧脱氧中的催化活性和稳定性.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、电感耦合等离子体质谱(ICP-MS)、高分辨透射电子显微镜(HRTEM)、比表面积(BET)、热重分析(TGA)和H2程序升温还原(H2-TPR)对催化剂进行了表征.分析结果表明,Ni、Fe和Co部分进入Ce0.5Zr0.5O2固溶体晶格内部,导致催化剂体相形成更多的缺陷;同时Ce0.5Zr0.5O2固溶体有助于加速金属氧化物和金属之间氧化还原过程的进行,促进了氧吸附、传输和对甲烷的活化.另外,SiC和Ce0.5Zr0.5O2固熔体良好的抗积碳性能,有效避免了催化剂在富甲烷反应气氛中因积碳而失活,从而使三种催化剂均具有优良的催化燃烧脱氧活性和稳定性.其中,Co/Ce0.5Zr0.5O2/SiC活性最高,可在320℃活化催化甲烷,并在410℃实现完全脱氧.     

Ce0.5Zr0.5O2修饰的Ni/SiC、Fe/SiC和Co/SiC催化燃烧甲烷性能

以铈锆固溶体(Ce0.5Zr0.5O2)修饰的高比表面积SiC为载体,采用两步浸渍法制备了Ni、Fe和Co基催化剂,研究了其在煤层气催化燃烧脱氧中的催化活性和稳定性.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、电感耦合等离子体质谱(ICP-MS)、高分辨透射电子显微镜(HRTEM)、比表面积(BET)、热重分析(TGA)和H2程序升温还原(H2-TPR)对催化剂进行了表征.分析结果表明,Ni、Fe和Co部分进入Ce0.5Zr05O2固溶体晶格内部,导致催化剂体相形成更多的缺陷;同时Ce0.5Zr0.5O2固溶体有助于加速金属氧化物和金属之间氧化还原过程的进行,促进了氧吸附、传输和对甲烷的活化.另外,SiC和Ce0.5Zr0.5O2固熔体良好的抗积碳性能,有效避免了催化剂在富甲烷反应气氛中因积碳而失活,从而使三种催化剂均具有优良的催化燃烧脱氧活性和稳定性.其中,Co/Ce0.5zr0.5O2/SiC活性最高,可在320 ℃活化催化甲烷,并在410 ℃实现完全脱氧.     

Ni-La/CexZr1-xO2对甲烷部分氧化/CH4-CO2重整耦合制合成气的催化剂制备及反应性能

通过共沉淀法制备铈锆固溶体作为载体,采用等体积、分步浸渍的方法制备了一系列10% Ni-3% La/CexZr1-xO2（X=0、0.16、0.5、0.75、1）催化剂,并将其应用到甲烷部分氧化和甲烷二氧化碳重整耦合制合成气的反应中。对不同Ce/Zr比的催化剂性能展开研究,采用XRD、H2-TPR、SEM手段对载体及催化剂进行了表征。结果表明,铈锆固溶体的形成不仅提高了催化剂表面活性组分的分散度,使催化剂表面NiO晶粒尺寸从26.5 nm减到13.7 nm;而且能够加强活性组分与载体之间的相互作用,提高催化剂的热稳定性能;随着Ce/Zr比的增加,催化剂的转化率、选择性及稳定性随之增强,其关系为：Ni-La/Ce0.75Zr0.25O2 > Ni-La/Ce0.5Zr0.5O2 > Ni-La/Ce0.16Zr0.84O2。     

一锅法合成Ce_xZr_(1-x)O_2固溶体催化剂用于热化学循环分解CO_2制CO

采用一锅蒸发诱导自组装法(EISA)制备了一系列不同铈锆物质的量比的铈锆固溶体催化剂,用TGA研究了其热化学循环分解CO_2制CO的催化性能,并采用XRD、Raman光谱、H2-TPR、XPS、SEM和N_2吸附-脱附等手段对催化剂的物相结构、还原性能和表面化学性质进行了表征分析,用热重分析(TGA)研究了铈锆固溶体对热化学循环分解CO_2制CO的催化性能。结果表明,随着Ce/Zr物质的量比增加,铈锆固溶体催化剂的CO_2高温分解活性先增大后减小。Ce/Zr物质的量比为1的Ce_(0.5)Zr_(0.5)O_2催化剂由于具有较多的晶格缺陷和氧空穴,氧迁移能力强,催化活性高,而Ce/Zr物质的量比为3的Ce_(0.75)Zr_(0.25)O_2催化剂具有相对稳定的氧空穴数,循环稳定性好。循环反应后,所有的催化剂均出现了一定程度的烧结,且富锆固溶体发生了相分离,这可能会影响催化剂的性能。     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n(Ce)/n(Zr)比为0.67/0.33,用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体.采用这些固溶体作载体,以Fe2O3为活性组分,用浸渍法制备了一系列催化剂.BET结果显示,将适量Ce0.67Zr0.33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积.TPR结果显示,载体中引入适量的Ce0.67Zr0.33O2可以改善催化剂的氧化还原性能.XRD结果表明,Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况,老化前后催化剂的晶相结构基本无明显变化.特别是当载体中m(Ce0.67Zr0.33O2)∶m(Al2O3)的值为1∶2时,Fe2O3/CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能.     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n(Ce)/n(Zr)比为0.67/0.33, 用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体. 采用这些固溶体作载体, 以Fe2O3为活性组分, 用浸渍法制备了一系列催化剂. BET结果显示, 将适量Ce0.67Zr0.33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积. TPR结果显示, 载体中引入适量的Ce0.67Zr0.33O2可以改善催化剂的氧化还原性能. XRD结果表明, Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况, 老化前后催化剂的晶相结构基本无明显变化. 特别是当载体中m(Ce0.67Zr0.33O2)∶m(Al2O3)的值为1∶2时, Fe2O3/CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能.     

CexZr1-xO2/Co/C-N催化CO2加氢性能研究

将不同比例的铈锆前驱体负载到ZIF-67,氮气气氛焙烧制备CexZr1-xO2/Co/C-N催化剂,对催化剂进行了XRD,H2-TPR、XPS表征,并在固定床反应器评价其CO2加氢制甲醇性能。XRD结果表明,在铈中加入适量锆形成铈锆固溶体,铈锆固溶体与钴物种较强的相互作用力可以阻止表明金属Co的氧化。但过量加入的锆又会削弱这一作用力,部分金属Co被氧化为Co3O4。H2-TPR结果表明适量的锆的加入改善催化剂的还原性能,催化剂还原温度降低。XPS证实了25%Ce0.67Zr0.33O2/Co/C-N催化剂中含有更多的氧空穴及氮含量,氧空穴和碱性氮都有利于CO2的解离吸附。优化后的25%Ce0.67Zr0.33O2/Co/C-N 催化剂在225 oC,2 MPa,GHSV = 6 L/gcat/h反应条件下取得最高甲醇时空收率,为3.0 mmol/gcat/h。     

Pt/γ-Al2O3/CexZr1-xO2催化剂低温催化燃烧去除饮食油烟

以CexZr1-xO2固溶体做载体,制备了系列Pt/γ-Al2O3/CexZr1-xO2催化剂(x=1,0.75,0.5,0.25,0).应用Brunauer-Emmet-Teller(BET)比表面积分析、X射线衍射(XRD)和H2程序升温还原(H2-TPR)等手段对催化剂进行相关表征,并系统研究了催化剂在饮食油烟催化燃烧中的催化活性.BET结果表叫催化剂的比表面积随Ce/Zr摩尔比的减小而减小.XRD结果表明贵金属Pt很好地分散在氧化铝和CexZr1-xO2固溶体上.H2-TPR结果发现催化剂Pt/γ-Al2O3/Ce0.5Zr0.5O2的还原峰面积最大且氧离子的流动性最好.催化活性研究结果表明Pt负载在CexZr1-xO2固溶体上有利于油烟的催化燃烧,降低了反应温度.随着CexZr1-xO2固溶体中Ce/Zr摩尔比的变化,催化剂的活性顺序为Pt/γ-Al2O3/Ce0.5Zr0.5O2＞Pt/γ-Al2O3/Ce0.25Zr0.75O2＞Pt/γ-Al2O3/Ce0.75Zr0.25O2＞Pt/γ-Al2O3/CeO2＞Pt/γ-Al2O3/ZrO2.     

微波辅助法制备铈锆固溶体在CO低温氧化反应中的应用

采用共沉淀法并分别结合室温老化、常规加热回流和微波辅助加热回流三种不同的处理方法制备了铈锆固溶体Co0.6Zr0.4O2,并以其为载体制备了CuO/Ce0.6Zr0.4O2催化剂.采用N2吸附、X射线衍射和H2程序升温还原等技术对Ce0.6Zr0.4O2载体和CuO/Ce0.6zr0.4O2催化剂的织构特性和可还原性进行了表征,另外还考察了CuO/Ce0.6zr0.4O2催化剂对CO低温氧化反应的催化活性.结果表明,采用微波辅助加热回流处理方法制备的CuO/Ce0.6zr0.4O2载体具有最大的比表面积(170.8 m2/g)和孔容(0.408 cm3/g),以其为载体所制备的CuO/Ce0.6zr0.4O2催化剂,其CuO具有良好的分散性和低温可还原性,在CO低温氧化反应中表现出最好的催化活性.     

Pt/γ-Al2O3/CexZr1-xO2催化剂低温催化燃烧去除饮食油烟

以CexZr1-xO2固溶体做载体, 制备了系列Pt/γ-Al2O3/CexZr1-xO2催化剂(x=1, 0.75, 0.5, 0.25, 0). 应用Brunauer-Emmet-Teller (BET)比表面积分析、X射线衍射(XRD)和H2程序升温还原(H2-TPR)等手段对催化剂进行相关表征, 并系统研究了催化剂在饮食油烟催化燃烧中的催化活性. BET结果表明催化剂的比表面积随Ce/Zr摩尔比的减小而减小. XRD结果表明贵金属Pt很好地分散在氧化铝和CexZr1-xO2固溶体上. H2-TPR结果发现催化剂Pt/γ-Al2O3/Ce0.5Zr0.5O2的还原峰面积最大且氧离子的流动性最好. 催化活性研究结果表明Pt负载在CexZr1-xO2固溶体上有利于油烟的催化燃烧, 降低了反应温度. 随着CexZr1-xO2固溶体中Ce/Zr摩尔比的变化, 催化剂的活性顺序为Pt/γ-Al2O3/Ce0.5Zr0.5O2>Pt/γ-Al2O3/Ce0.25Zr0.75O2>Pt/γ-Al2O3/Ce0.75Zr0.25O2>Pt/γ-Al2O3/CeO2>Pt/γ-Al2O3/ZrO2.     

Effect of Transition Metals (Cu, Co and Fe) on the Autothermal Reforming of Methane over Ni/Ce0.2Zr0.1Al0.7Oδ Catalyst

The transition metals (Cu, Co, and Fe) were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst.The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS.Tests in autothermal reforming of methane to hydrogen showed that the addition of transition metals (Cu and Co) significantly increased the activity of catalyst under the conditions of lower reaction temperature,and Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ was found to have the highest conversion of CH4 among all catalysts in the operation temperatures ranging from 923 K to 1023 K. TPR, XRD and XPS measurements indicated that the cubic phases of CexZr1-xO2 solid solution were formed in the preparation process of catalysts.Strong interaction was found to exist between NiO and CexZr1-xO2 solid solution. The addition of Cu improved the dispersion of NiO, inhibited the formation of NiAl2O4, and thus significantly promoted the activity of the catalyst Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ.     

Pd/CexZr1-xO2/SiO2催化剂的制备及其甲烷催化燃烧性能的研究

采用浸渍法制备了Pd质量分数为0.1%~1.0%的Pd/SiO2和Pd/5%CexZr1-xO2/SiO2（x0.0~1.0）系列催化剂，在微型固定床反应器上对催化剂的甲烷催化燃烧性能进行了评价，用XRD、H2-TPR等分析测试技术对催化剂的结构进行了表征。结果表明，Pd/SiO2和Pd/CexZr1-xO2/SiO2催化剂都具有较好的甲烷催化燃烧活性，CexZr1-xO2可以明显提高催化剂的催化活性，并且Ce和Zr的比值对催化剂催化活性也有显著的影响。XRD和TPR显示，Pd/CexZr1-xO2/SiO2催化剂中的CexZr1-xO2对PdO的分散性和还原性有较好的促进作用。     

Effect of Ni Loading and CexZr1-xO2 Promoter on Ni-Based SBA-15 Catalysts for Steam Reforming of Methane

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.     

Preparation and Characterization of Modified-ZrO2 Catalysts for the Reaction of Co Hydrogenation

ZrO2 in different structures and CexZr4-xO8 solid solutions have been prepared by a sol-gel related method with propionic acid as the solvent.The results of their characterization and CO hydrogenation performance eveluation show that ｔ-ZrO2 has better catalytic performance for CO hydrogenation to hydrocarbon than ｍ-ZrO2.Cerium(Ⅲ）acetate and zirconium (Ⅵ）acetylacetonate have been chosen as the most suitable starting materials for CexZr4-xO8 solid solution preparation.Ce-Zr reducibility properties are increased by the incorporation of zirconium oxide in the ceria structure.Ce2Zr2O8 exhibits a higher activity,lower methane selectivity and higher iso-C4 selectivity than tetragonal ZrO2.This implies that the formation mechanism of C4 hydrocarbons,especially that for the iso-C4 fraction is different over Ce2Zr2O8 and t-ZrO2.     

Doping of Ceria-Zirconia Solid Solution with Rare-earth Elements

The increasingly restrictive regulations on car exhaust emissions will necessitate the development of a new generation of three way catalysts (TWC) with better performance1. Ceria (CeO2) is the main component of the current TWC: its key role is to compensate the fluctuations in the exhaust stream composition, therefore, allowing to expand the air/fuel(A/F) operating window of catalytic converters2. This property is related to its oxygen storage capacity (OSC), associated to the redox couple Ce4+/Ce3+. However, CeO2 alone is easy to sinter to lost OSC at high temperature3.Ceria-zirconia (CexZr1-xO2) solid solutions by incorporation of Zr4+ in the CeO2 lattice have enhanced OSC and greater thermal stability, which are becoming the key materials for the new generation of TWC4. OSC of ceria-zirconia solid solutions can be further improved by the addition of M3+ dopants5. Besides Ce, other rare-earth elements such as Pr and Tb can vary their oxidation state. Pr and Tb are particularly suitable for making solid solutions with cerium because the known structure of PrO2 and TbO2 is of the cubic fluorite type, and the ionic radii of Pr4+ and Tb4+ are close to that of Ce4+6.In this paper, Ce0.6Zr0.3M0.1O2 (M=Y, La, Pr, Tb) were prepared by co-precipitation technique and characterized by a series of methods. Meanwhile, palladium-only TWCs were prepared by slurry coating and their catalytic activity was evaluated under the condition of simulated exhaust in the lab.XRD and FT-Raman spectra results show Ce0.6Zr0.3M0.1O2 have cubic fluorite structure which keep unchanging at high temperature. The different dopant ion radii brought different effect on the cell parameter of Ce0.6Zr0.3M0.1O2. The X-ray photoelectron spectroscopy (XPS) results show that the binding energy of Ce3d, Zr3d and O1s for Ce0.6Zr0.3M0.1O2 rose compared with that for Ce0.6Zr0.4O2, indicating dopant elements changed chemistry environment of solid solutions which was available to improve redox performance From TPR results, doping La can not change redox performance of solid solution, but doping Y decreased reduction temperature. Doping Pr and Tb notably improved redox performance of solid solutions due to appearance of low-temperature reduction peak in TPR profile which come from mobility of bulk oxygen.Compared with Pd/Ce0.6Zr0.4O2, doping Y and La unchanged A/F characteristic of TWCs, but doping Pr and Tb widen A/ F operating window and make HC, CO and NO have higher conversion.The light-off temperature of Pd/Ce0.6Zr0.3La0.1O2 was corresponded to that of Pd/Ce0.6Zr0.4O2.However, the light-off temperatures of Pd/Ce0.6Zr0.3M0.1O2 (M=Y, Pr, Tb) were lower than that of Pd/Ce0.6Zr0.4O2, which kept much lower after high temperature treatments. Among Pd/Ce0.6Zr0.3M0.1O2 (M=Y, La, Pr, Tb), Pd/Ce0.6Zr0.3Tb0.1O2 showed wider A/F operating window,higher conversion, lower light-off temperature and better high-temperature resistance     

The Active Phase of Nickel/Ordered Ce(2) Zr(2) O(x) Catalysts with a Discontinuity (x=7-8) in Methane Steam Reforming

Breaking news: A unique discontinuous property and an active phase of Ni/ordered Ce(2) Zr(2) O(x) (x=7-8) solid-solution catalysts were observed during methane steam reforming. The catalytic performance of Ni/Ce(2) Zr(2) O(x) strongly depended on the phase and oxygen content of the Ce(2) Zr(2) O(x) support.     

掺杂助剂Ce和Zr的Ni/Al2O3催化剂的X光电子能谱分析

以Na2CO3为沉淀剂,在pH 9.0的沉淀条件下,采用并流沉淀法制备了Ni/Al2O3、Ni/CeO2-Al2O3、Ni/ZrO2-Al2O3和Ni/ZrO2-CeO2-Al2O34种催化剂,催化剂中Ni负载量(质量分数)为10%。采用XPS表征手段及常压固定床反应器对催化剂进行活性评价,考察了助剂Ce和Zr及二者的协同作用对Ni基催化剂表面物种结合能的影响以及对甲烷自热重整制氢反应性能的影响。结果表明,助剂Ce和Zr的添加及二者的协同作用对Ni基催化剂表面各物种的结合能均有一定的影响,结合评价结果可知,Ce和Zr二者的协同作用对Ni基催化剂的催化性能提高最大。