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采用镍、铜、镧和铁为活性组分制备单一活性组分催化剂和混合活性组分催化剂,利用反应评价装置,在常压条件下对各催化剂催化性能进行考察,结果表明,单活性组分和混合组分催化剂的转化率和选择性均达到加压冷氢化法水平,混合组分催化剂的稳定性优于单一活性组分催化剂。 相似文献
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以氮化碳(g-C3N4)为载体,采用液相还原法制备了一系列Pd-P/g-C3N4催化剂用于甲酸分解制氢,通过优化还原温度和活性组分负载量可以显著提高催化剂性能。采用X射线衍射仪、透射电子显微镜和X射线光电子能谱仪对催化剂的晶相结构、微观形貌、活性组分分布以及价态进行分析,并通过甲酸分解制氢实验测试了催化剂的甲酸分解制氢活性。结果表明:使用次磷酸钠还原剂需要在较高还原温度(90℃)才能实现Pd-P活性组分在g-C3N4载体表面的高度分散,获得较小的纳米粒子,过高或过低的还原温度都不利于制备高性能催化剂。当Pd负载量为8.0%(质量分数)时,2-Pd-P/g-C3N4催化剂表现出最佳催化性能,通过动力学研究和Arrhenius方程计算得到该催化剂的甲酸分解活化能为33.83kJ/mol。 相似文献
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利用Ce和锰盐复配对单组分锰盐活性组分进行掺杂改性,并采用分步共混法制备一系列催化剂。催化剂活性测试显示锰盐复配及Ce的掺杂均能提高锰基催化剂低温活性,且锰盐复配形式的掺杂对催化剂低温活性提高更多。通过对比各催化剂强度状况发现活性组分的掺杂使催化剂的机械强度得到很大提高,而BET结果显示掺杂改性后的锰基催化剂其表面织构得到较大改善。催化剂的XRD结果表明500℃焙烧的锰基催化剂活性组分均以无定形态存在。通过对改性后的催化剂进行NH3-TPD和H2-TPR分析,发现相比于Ce对单组分锰盐的掺杂改性,锰盐复配形式的掺杂改性对催化剂表面酸量和氧化还原性能的提高更加显著。 相似文献
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采用浸渍法制备了RuO2/γ-A12O3和RuO2/CeO2/γ-A12O3催化剂,并利用XRD、SEM和XPS对催化剂进行了表征,研究了Ce的加入对RuO2/γ-A12O3催化剂表面分散性和催化剂表面元素Ru,O和Ce化学态的影响,同时考察了RuO2/γ-A12O3和RuO2/CeO2/γ-A12O3催化剂湿式氧化降解苯酚的活性,并深入探讨了Ce对RuO2/γ-A12O3催化剂的助催化作用。结果表明:Ce掺杂改性后,使催化剂表面Ru的化学态降低、表面氧空位增加,并且活性组分Ru的分散性增加,从而使RuO2/CeO2/γ-A12O3催化剂的活性提高,因此Ce起到了显著的助催化作用。 相似文献
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用乙二醇法和浸渍法制备两种负载在堇青石上的钴基负载催化剂,并用XRD、XPS、TPR和TPD对制备的催化剂进行表征,比较两种催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,与浸渍法制备的Co/cord催化剂相比,乙二醇法制备的催化剂Co/cord-EG对甲苯催化燃烧活性明显提高。应用乙二醇法制备Co/cord-EG负载型催化剂,Co元素主要以Co2+存在于载体表面;而传统浸渍法制备的Co/cord催化剂,Co元素是以Co2+与Co3+的两种化学状态存在于载体表面。应用乙二醇法制备Co/cord-EG负载型催化剂,有助于在载体表面形成比较均匀的吸附活性位。应用乙二醇法制备的Co/cord-EG催化剂,催化活性组分能在载体表面上以更小颗粒而且更高的分散度存在,从而能明显提高其催化活性。 相似文献
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Pt/Fe_2O_3/TiO_2的制备、表征及其光催化活性研究 总被引:1,自引:0,他引:1
报道了担载不同贵金属或过渡金属氧化物的TiO2 催化剂对空气中微量甲醛的光催化氧化的研究结果。实验发现 ,TiO2 上担载Fe2 O3 或Pt时对甲醛均有较高的光催化氧化活性。同时担载双组分的光催化剂Pt Fe2 O3 TiO2 ,由于 2种组分的协同作用 ,具有更高的光催化活性。研究了催化剂制备因素、催化剂的结构及表面特性对催化活性的影响 相似文献
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首次用Sol—gel法合成了纳米KF/A12O3复合超强碱催化剂,克服了传统浸渍法的易团聚及负载物分布不均匀等缺点。用Knoevenagel反应对所制备的KF/A1203复合催化剂的催化性能进行了研究,用均匀设计软件对催化剂的制备过程进行了优化,用SEM、XRD、XPS对催化剂进行了表征。 相似文献
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报道了担载不同贵金属或过渡金属氧化物的TiO2催化剂对空气中微量甲醛的光催化氧化的研究结果,实验发现,TiO2上担载Fe2O3或Pt时对甲醛均有较高的光催化氧化活性,同时担载双组分的光催化剂Pt/Fe2O3/TiO2,由于2种组分的协同作用,上仍更高的光催化活性,研究了催化剂制备因素,催化剂的结构及表面特性对催化活性的影响。 相似文献
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综述了Pd-Ni双金属催化剂的制备及应用研究进展,分析Pd-Ni双金属催化剂制备过程对催化剂结构和性能的影响及其应用研究现状,展望研究方向和趋势。浸渍法虽然操作简单、活性组分利用率较高,但存在颗粒分布不均匀、催化活性低的局限性;与浸渍法相比,化学沉淀法和置换法具有更高的分散度、催化活性及稳定性,是PdNi双金属催化剂制备的可行方法。电沉积法具有可以控制颗粒分布和晶核生长等优点,能大大提高催化剂的活性,是极具发展前景的研究方向。在传统制备方法中引入超声、微波辐照等手段的耦合法制备Pd-Ni双金属催化剂,能有效提高活性组分的分散度,是Pd-Ni双金属催化剂制备的趋势。 相似文献
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采用等体积浸渍法分别制备了不同稀土元素@阑或铈)添加量的VOx/TiO催化剂,通过XRD、EDS和TPR对样品进行表征,考察了它们催化燃烧氯苯的活性,结果表明,不同镧或铈添加量的催化剂样品仍保持TiO2税钛矿晶相。当LaOx与VOx的摩尔比为1:5时,会出现镧钒氧物种或镧钛氧物种的晶相;当CeOx与VOx的摩尔比为1.5时,会出现CeOx方铈矿萤石结构的晶相;镧和铈的添加会提高活性物种VOx在催化剂表面的含量和分数}生。当CeOx与VOx的摩尔比为1:13.7时,活性组分VOx绝大部分分布在载体表面;镧对于催化剂的氧化性能没有影响,而铈能提高催化剂的氧化性;适量镧或铈的添加对于VO/TiO2催化剂催化降解氯苯有促进作用。锏的添加对于催化剂催化活性的促进作用与催化剂表面活性物VOx含量有关,而铈的添加对催化剂催化活性的提高作用除此原因外,还与催化剂氧化洼的提高有关。 相似文献
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采用超临界干燥法制备了活性高、比表面大的Fe/Mo/Al2O3催化剂.通过超临界干燥,催化剂的比表面由294m2/g提高到401m2/g.在1000℃下用该催化剂催化裂解甲烷, 合成了大产量、高质量的单壁纳米碳管(SWNTs).利用SEM、TEM、HRTEM、TGA 和Raman等手段对所制备的SWNTs进行了表征.结果表明:超临界法制备催化剂合成的粗产品中SWNTs含量在30%以上,大大高于同一配方催化剂采用常规干燥法的产率(约2%); SWNTs的管径分布在0.8-1.0nm之间,其形态以束状为主. 相似文献
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E. V. Ishchenko S. V. Gaidai A. G. Dyachenko E. V. Prilutskiy A. A. Beda T. M. Zakharova 《Journal of Superhard Materials》2014,36(2):82-88
The paper addresses the catalytic activity of oxygen-containing Cu-Co-Fe catalysts applied onto carbon nanotubes in the CO oxidation reaction. The carbon nanotubes were synthesized on an Fe2O3catalyst. The activity of oxide-containing Cu-Co-Fe catalysts is shown to depend on the treatment of metal-carbon precursor material, amount of the active component and method of its application. According to the X-ray phase analysis, thermal desorption mass spectroscopy, and transmission electron microscopy, the active component is a mixture of Cu2(OH)3NO3 and CuO phases whose ratio and distribution depend on the catalyst optimal synthesis conditions, which provide the structural formation of active sites in the CO oxidation reaction. The presence of an active Cu-Co-Fe oxide component in the surface layer, which is produced by a single application of the active component to carbon nanotubes, results in a higher activity of the catalysts in the CO oxidation in comparison to the catalysts prepared by a step-wise application of the active component. 相似文献
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采用挤出成型法制备系列Ti-Al-Si-Ox脱硝催化剂载体, 评价其NH3选择性催化还原NO的活性。通过正交实验优化Ti-Al-Si-Ox配方, 采用液N2-BET、ESEM及XRD分别表征载体的比表面积、孔容孔径分布、微观形貌和固相结构; 采用阿基米德法测试载体的吸水率、开气孔率和体积密度。结果表明, 当Ti/Al/Si摩尔比为1:0.2:0.1时, TiAl0.2Si0.1Ox载体NH3-SCR脱除NO活性及轴向抗压碎强度匹配最好。当空速为7200 h-1, 载体在450~550℃内NH3-SCR脱除NO效率均>80%, 494℃脱除NO效率达到最大值85.8%; 载体抗压碎强度为6.17 MPa, 比表面积为89.1 m2/g, 开气孔率达63.0%, 吸水率达48.3%, 介孔最可几分布为8.1 nm, 次可几分布为3.7 nm。TiAl0.2Si0.1Ox脱硝催化剂载体具备优异的性能。 相似文献
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Carbon-supported Pd electrocatalyst is prepared by an improved aqueous impregnation method applying a reducing agent of HCHO and an acidic sedimentation promoter of HCl. We investigate the effect of a solution pH on the zeta potential of both Pd particles and carbon support. The opposite sign of zeta potential results in uniform dispersion of Pd on carbon surface without aggregation problem. TEM analysis shows that optimal solution pH of 4.27 adjusted by NaOH provides a mean particle diameter of 3.2 nm with narrow size distribution. Cyclic voltammograms indicate that home-made Pd/C catalyst exhibits significantly higher electrochemical active surface area and better stability compared with commercial 40 wt.% Pd/C in a formic acid oxidation. 相似文献
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Qilin Wei Kiersten G.Guzman Xinyan Dai Nuwan H.Attanayake Daniel R.Strongin Yugang Sun 《纳微快报(英文)》2020,(3):169-178
Photothermal catalysis represents a promising strategy to utilize the renewable energy source(e.g.,solar energy)to drive chemical reactions more efficiently.Successful and efficient photothermal catalysis relies on the availability of ideal photothermal catalysts,which can provide both large areas of catalytically active surface and strong light absorption power simultaneously.Such duplex requirements of a photothermal catalyst exhibit opposing dependence on the size of the catalyst nanoparticles,i.e.,smaller size is beneficial for achieving higher surface area and more active surface,whereas larger size favors the light absorption in the nanoparticles.In this article,we report the synthesis of ultrafine RuOOH nanoparticles with a size of 2–3 nm uniformly dispersed on the surfaces of silica(SiOx)nanospheres of hundreds of nanometers in size to tackle this challenge of forming an ideal photothermal catalyst.The ultrasmall RuOOH nanoparticles exhibit a large surface area as well as the ability to activate adsorbed molecular oxygen.The SiOx nanospheres exhibit strong surface light scattering resonances to enhance the light absorption power of the small RuOOH nanoparticles anchored on the SiOx surface.Therefore,the RuOOH/SiOx composite particles represent a new class of efficient photothermal catalysts with a photothermal energy conversion efficiency of 92.5%for selective aerobic oxidation of benzyl alcohol to benzylaldehyde under ambient conditions. 相似文献
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Ying Tao Rong Li Ai-Bin Huang Yi-Ning Ma Shi-Dong Ji Ping Jin Hong-Jie Luo 《先进制造进展(英文版)》2020,8(4):429-439
Among the transition metal oxide catalysts, manganese oxides have great potential for formaldehyde (HCHO) oxidation at ambient temperature because of their high activity, nontoxicity, low cost, and polybasic morphologies. In this work, a MnO2-based catalyst (M-MnO2) with an interconnected network structure was successfully synthesized by a one-step hydrothermal method. The M-MnO2 catalyst was composed of the main catalytic agent, δ-MnO2 nanosheets, dispersed in a nonactive framework material of γ-MnOOH nanowires. The catalytic activity of M-MnO2 for HCHO oxidation at room temperature was much higher than that of the pure δ-MnO2 nanosheets. This is attributed to the special interconnected network structure. The special interconnected network structure has high dispersion and specific surface area, which can provide more surface active oxygen species and higher surface hydroxyl groups to realize rapid decomposition of HCHO.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00321-2 相似文献