共查询到18条相似文献,搜索用时 187 毫秒
1.
采用固相浸渍法制备了一系列NiO/CeO2催化剂,并通过与常规湿浸渍法比较,考察了制备方法对催化剂和CO氧化反应性能的影响.同时结合X射线衍射(XRD),N2吸附-脱附(BET),透射电镜(TEM),氢气-程序升温还原(H2-TPR),拉曼(Raman)光谱,X射线光电子能谱(XPS)等手段对催化剂的结构和表面物种分散状态进行了表征.CO氧化活性测试结果表明,当镍负载量相同时,固相浸渍法制备的催化剂相比于湿浸渍法表现出更好的催化性能.TEM、XPS、H2-TPR结果表明,固相浸渍法更有利于加强镍铈间的相互作用和得到高分散的镍物种,从而促进镍物种的还原.Raman结果表明固相浸渍法相比于湿浸渍法能产生更多氧空位,这有利于氧气在催化剂表面的活化,使得CO氧化反应更容易进行. 相似文献
2.
采用浸渍和共沉淀两种方法分别制备了BaO改性的Pd/CeO2-ZrO2-La2O3-Al2O3催化剂.运用N2吸附-脱附,X射线衍射(XRD),H2程序升温还原(H2-TPR),NH3程序升温脱附(NH3-TPD),透射电子显微镜(TEM)和X射线光电子能谱(XPS)对催化剂进行表征,并考察其对甲醇,CO, C3H8 和 NO的催化性能.活性测试结果表明,BaO的引入可明显改善Pd催化剂对甲醇,CO, C3H8和NO的催化活性,且浸渍法最佳,起燃温度(T50)分别降低了43,31,45和35 ℃.XRD,H2-TPR及XPS结果表明,浸渍法引入BaO主要通过表面改性方式,强化Pd-Ce界面间的相互作用,改善催化剂的还原性能,进而提高催化剂的低温活性;而共沉淀法则是通过结构改性方式增加CeO2晶格缺陷,加速活性氧物种的流动,Ce3+浓度的增加是促使CO氧化活性显著提高的主要原因. 相似文献
3.
采用不同方法制备了铈锆复合氧化物催化剂用于催化HCl氧化反应。自发沉积策略制备的CeO2@ZrO2催化剂中,超细CeO2纳米粒子均匀的镶嵌于非晶态ZrO2中。CeO2粒子显著的“尺寸效应”使得该催化剂具有更高的Ce3+和氧空位浓度,而较高的Ce3+和氧空位浓度使得催化剂具有优异的低温氧化还原性能和储释氧能力。催化性能测试表明,CeO2@ZrO2催化剂展现出最好的催化活性(1.90 gCl2·gcat-1·h-1),同时CeO2粒子周围非晶态的ZrO2阻碍CeO2的高温烧结,提高了该催化剂的稳定性。 相似文献
4.
钌基催化剂因其在低温低压下具有比常规的铁基催化剂更具活性的特点成为合成氨催化剂的理想选择.我们研究了CeO2载体表面碱性对Ru基合成氨催化剂的影响.通过调节KOH沉淀剂的量来制备具有不同碱性位点的CeO2载体(pH=10/11/12),证明了催化剂适当碱性位点密度提高了合成氨催化活性.催化性能测试结果表明,1.25% Ru/CeO2-11催化剂在3.8 MPa,450℃,H2/N2=3(60 mL·min-1)下表现出优异的氨合成活性(7040 μmol·g-1·h-1).CeO2-11的碱性位点增强了载体的电子给予能力,这有利于电子向活性金属Ru转移,从而促进了N2的活化.碱金属和碱土金属的引入提高了活性金属Ru的还原能力.4% Cs-1.25% Ru/CeO2-11(12 000 μmol·g-1·h-1)催化剂具有更多的氧空位,这增加了Ru周围的电子密度并促进了N≡N的裂解.通过XRD,BET,SEM,CO2-TPD,H2-TPR和XPS分析了不同碱性CeO2载体对合成氨催化反应的影响. 相似文献
5.
通过在Cu/AC催化剂中添加稀土助剂Ce,考察不同的浸渍顺序对CuCe/AC(活性炭)催化剂表面结构及其催化甲醇气相氧化羰基化合成碳酸二甲酯性能的影响,并采用XRD、XPS、H2-TPR、AAS和HR-TEM等表征了催化剂活性组分含量、分散状态和价态等性质。发现共浸渍法制备的催化剂,Ce对活性组分Cu在活性炭表面的分散起到一定的促进作用;先浸渍Cu后浸渍Ce制备的催化剂,后浸渍的Ce覆盖部分Cu组分,使这些Cu组分难以还原并无法与反应物分子接触,导致其催化性能有所降低;而先浸渍Ce后浸渍Cu制备的催化剂,Ce组分和Cu组分产生相互作用,使表面存在较多分散均匀的Cu(0)和Cu(Ⅰ)物种,其催化性能最佳,碳酸二甲酯的时空收率及选择性分别达到了142 mg·g-1·h-1和85%。 相似文献
6.
通过在Cu/AC催化剂中添加稀土助剂Ce,考察不同的浸渍顺序对CuCe/AC(活性炭)催化剂表面结构及其催化甲醇气相氧化羰基化合成碳酸二甲酯性能的影响,并采用XRD、XPS、H2-TPR、AAS和HR-TEM等表征了催化剂活性组分含量、分散状态和价态等性质。发现共浸渍法制备的催化剂,Ce对活性组分Cu在活性炭表面的分散起到一定的促进作用;先浸渍Cu后浸渍Ce制备的催化剂,后浸渍的Ce覆盖部分Cu组分,使这些Cu组分难以还原并无法与反应物分子接触,导致其催化性能有所降低;而先浸渍Ce后浸渍Cu制备的催化剂,Ce组分和Cu组分产生相互作用,使表面存在较多分散均匀的Cu(0)和Cu(Ⅰ)物种,其化性能最佳,碳酸二甲酯的时空收率及选择性分别达到了142 mg·g-1·h-1和85%。 相似文献
7.
采用不同沉淀剂制备CeO2-Co3O4复合金属氧化物载体,通过浸渍负载不同含量Ag获得Ag/CeO2-Co3O4催化剂.借助氮气物理吸附、XRD、Raman和H2-TPR等手段研究了催化剂的物理化学性质.结果表明:当WHSV=30 000 mL·g-1·h-1时,催化剂能表现出良好的催化氧化甲醛性能,在≤ 90℃时实现甲醛的完全转化.草酸沉淀能有效降低Ce-Co氧化物的结晶度,使得Co2+含量增加,提供更多的氧空位,促进了氧分子的活化与迁移,从而提高了催化活性.随着Ag含量增加,使得由草酸沉淀制备的Ag/CeO2-Co3O4催化剂的活性增强,且金属与载体间的相互作用也增强,当Ag负载量为1%(重量百分比)时活性最佳. 相似文献
8.
介孔氧化铝负载Ni-Co氧化物催化剂上丙烷氧化脱氢制丙烯 总被引:1,自引:0,他引:1
以非离子型三嵌段共聚物作为模板剂, 异丙醇铝为氧化铝的前驱物, 采用一锅法合成了一系列介孔氧化铝负载镍氧化物、钴氧化物以及镍-钴双金属氧化物催化剂, 并以介孔氧化铝为载体, 采用浸渍法制备了负载Ni-Co 氧化物催化剂. 采用N2吸附-脱附、高分辨透射电镜(HRTEM)、X射线粉末衍射(XRD)、H2程序升温还原(H2-TPR)以及激光拉曼光谱(LRS)等技术对催化剂的结构与性质进行表征, 并考察了催化剂的丙烷氧化脱氢反应性能. 结果表明: 一锅法制备的各催化剂均有大的比表面积和规整的孔道结构, 且负载的金属氧化物高度分散; 而浸渍法制备的催化剂, 其载体的介孔结构被破坏并有Co3O4晶相生成. 在考察的催化剂中, 一锅法合成的介孔氧化铝负载Ni-Co 氧化物催化剂表现出最佳的丙烷氧化脱氢性能. 在450 °C、C3H8:O2:N2的摩尔比为1:1:4和空速(GHSV)为10000 mL·g-1·h-1条件下, 该催化剂上丙烯产率为10.3%, 远高于浸渍法制备的催化剂上所获得的丙烯产率(2.4%). 关联催化剂表征和反应结果, 讨论了催化剂结构与性能之间的关系. 相似文献
9.
以99.995% Ce(NO3)3和强碱性阴离子交换树脂为原料,采用离子交换-双氧水氧化法合成制备出纳米CeO2晶体。并就离子交换反应中的Ce3+浓度、树脂加入速度和离子交换温度及H2O2加入速度等条件对CeO2粒径的影响进行了探讨,得出了离子交换-双氧水氧化法制备纳米CeO2晶体的最佳工艺条件。FTIR、TEM分析表明,离子交换法无需对合成的Ce(OH)3溶胶进行洗涤即可去除NO3-、CO32-等阴离子杂质,并用H2O2将该溶胶氧化,经真空干燥可制得粒径分布均匀,平均晶粒尺寸约3 nm,高纯度的CeO2粉体。 相似文献
10.
11.
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
12.
Xiu-cheng Zheng Xiao-li Zhang Xiang-yu Wang Shi-hua Wu 《Reaction Kinetics and Catalysis Letters》2007,92(2):195-203
Ceria were prepared by various processes. The prepared samples and commercial ceria were used as supports to prepare the CuO/CeO2 catalysts via an impregnation method. The samples were characterized by using TEM, XRD, H2-TPR, and their catalytic activities in low-temperature CO oxidation were also investigated. 相似文献
13.
采用微波加热分解法(一步法)和微波加热处理共沉淀+浸渍法(两步法)制备了CuO/CeO2-ZrO2催化剂,并对其进行了X射线衍射、低温氮气吸附/脱附和程序升温还原等表征,采用色谱流动法考察了催化剂的催化CO低温氧化性能.结果表明,一步法比两步法更有利于使催化剂表面CuO高度分散,CuO与CeO2-ZrO2间的相互作用更强,CuO更容易被还原,从而具有更高的催化CO氧化活性.与CeO2-ZrO2有相互作用的高分散和小颗粒CuO有利于催化剂活性的提高,与CeO2-ZrO2无相互作用的大颗粒CuO对催化剂的活性有抑制作用. 相似文献
14.
Shu-Ping Wang Xiao-Ying Wang Xiu-Cheng Zheng Shu-Rong Wang Shou-Min Zhang Wei-Ping Huang Shi-Hua Wu 《Reaction Kinetics and Catalysis Letters》2006,89(1):37-44
Summary Copper oxide catalysts supported on Ce0.8Zr0.2O2 were prepared via an impregnation method and characterized by XRD and H2-TPR techniques. The catalytic activity of the samples for low-temperature CO oxidation was investigated by means of a microreactor-GC
system. The influence of calcination temperature, calcination time and different CuO content on the catalytic activity was
studied. TPR analysis indicated that well-dispersed CuO was responsible for the low-temperature CO oxidation. The results
of the investigation showed that the calcination temperature and CuO loadings had larger influence than the calcination time. 相似文献
15.
《Journal of Energy Chemistry》2014,23(1):35-42
The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method and characterized by N2-adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and laser Raman spectroscopy (LRS). The conversions of CO for Mo-Co/Al, Co-Mo/Al and CoMo/Al catalysts were 59.7%, 54.3% and 53.9%, respectively. Among these catalysts, the Mo-Co/Al catalyst prepared stepwisely by impregnating Mo precursor firstly showed the best catalytic performance. Meanwhile, the conversions of CO were 48.9% for Mo/Al catalyst and 10.5% for Co/Al catalyst. The addition of cobalt species could improve the catalytic activity of Mo/Al catalyst. The N2-adsorption results showed that Co-Mo/Al catalyst had the smallest specific surface area among these catalysts. CoMoO4 species in CoMo/Al catalyst were detected with XRD, TPR and LRS. Moreover, crystal MoS2 which was reported to be less active than amorphous MoS2 was found in both Co-Mo/Al and CoMo/Al catalysts. Mo-Co/Al catalyst showed the best catalytic performance as it had an appropriate surface structure, i.e., no crystal MoS2 and very little CoMoO4 species. 相似文献
16.
High-surface area mesoporous 20 mol% CuO/ZrO2 catalyst was prepared by a surfactant-assisted method of nanocrystalline particle assembly, and characterized by x-ray powder diffraction (XRD), N2 adsorption, transmission electron microscopy (TEM), H2-TPR, TG-DTA, and x-ray photoelectron spectra (XPS) techniques. The catalytic properties of the CuO/ZrO2 nanocatalysts calcined at different temperature were evaluated by low-temperature carbon monoxide oxidation using a CATLAB system. The results showed that these mesoporous nanostructured CuO/ZrO2 catalysts were very active for low-temperature CO oxidation and the CuO/ZrO2 catalyst calcined at 400°C exhibited the highest catalytic activity. 相似文献
17.
利用具有高比表面积和介孔结构的改性铝土矿为载体,采用并流共沉淀法制备不同Fe2O3含量的Cu-Fe/铝土矿催化剂。以水煤气变换反应为探针反应,考察了催化剂性能。利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、H2程序升温还原(H2-TPR)、CO程序升温脱附(CO-TPD)和X射线光电子能谱(XPS)等对催化剂进行了表征。结果表明:负载的Fe2O3能显著提高CuO/改性铝土矿催化剂的水煤气变换活性特别是热稳定性能,且随负载的Fe2O3含量增加而提高,当负载量为20%时达到最佳。其原因是负载的Fe2O3和CuO之间发生了相互作用,形成了类似于CuFe2O4复合氧化物,且随负载的Fe2O3含量的增加而增强,这种相互作用同时促进了CuO和Fe2O3的还原,抑制了CuO的烧结,进而提高了催化剂的性能。 相似文献
18.
Xian-Zhi Guo Jing Huang Shu-Rong Wang Yan-Mei Wang Bao-Long Zhang 《Journal of Dispersion Science and Technology》2013,34(7):1114-1119
The porous TiO2 microspheres were prepared by the reversed-phase suspension polymerization and sol-gel method using reversed-phase suspension droplets as the templates. The CO oxidation catalytic properties of the CuO/TiO2 catalysts prepared by hydrothermal method and impregnation method were extensively investigated. The structure of CuO/TiO2 catalysts was determined by TG-DTA, XRD, TEM, and XPS. The results indicated that the redox capacity of CuO/TiO2 was greatly depended on the aqueous solution concentration of Cu(NO3)2 used in the preparation of CuO/TiO2 and the calcination temperature of the CuO/TiO2 catalysts. 相似文献