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以三氧化二铝为载体,以钯、铜及锰等为活性组份,用浸轩的Pa/AL2O3、CuO/Al2O3及CuO-MnO/Al2O3催化剂,放于民用蜂窝煤炉对烟气中一氧化碳及有机物的催化氧化性能,结果表明:烟道上不仅使烟气中C煌排放量明显减少,同时也使其中低碳烃、酚类及多环芳烃的量减少,催化氧化性能同大到小的顺序为:Pa/Al2O3Cu-MnO/Al2O3CuO/Al2O3。 相似文献
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汽车尾气净化剂的发展,现状及前景 总被引:4,自引:0,他引:4
催化净化是控制汽车尾气污染的主要手段。文章介绍了汽车尾气催化剂的发展过程:描了了当今普遍使用的三效转化催化剂“提出了未来尾气净化催化剂的发展趋势及需要解决的问题,TWC催化剂是以贵金属Pt,Pd和Rh为适性组元,引入Ce,La,Ba和Zr等为助剂,担载在高比表面物质上制备面成一的类性能优虹的催化剂,它能对尾气中的3种主要有害物质NOx,CO和HC同时进行转化。 相似文献
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分别采用沉积沉淀、直接混合和传统的浸渍法制备1% Pd/Ce0.5Zr0.5O2 催化剂, 研究了Pd负载方法对催化剂活性影响.运用H2-TPR和原位漫反射红外(DRIFTS)研究了Pd-铈锆载体间的相互作用及Pd/Ce0.5Zr0.5O2催化剂上的三效反应机理.结果表明沉积沉淀法制备的Pd/Ce0.5Zr0.5O2催化剂(Pd-DP)表现出最强的Pd-载体作用及最优活性,原位红外实验发现Pd-DP上存在与传统的浸渍法制备的Pd-IMP催化剂不同的NO催化还原途径,推测Pd-载体间相互作用引起NO还原机理差异,进而导致活性差异. 相似文献
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Pd/CZ/Al2O3催化剂的制备、表征与三效催化性能 总被引:6,自引:0,他引:6
以共浸渍法制得的氧化铝负载铈锆固溶体为载体,并浸渍贵金属Pd得到了Pd/CZ/Al2O3催化剂.实验结果表明,该催化剂在老化前后都表现出良好的三效催化活性,新鲜样品Pd/CZ/Al2O3活性与Pd/CZ相当,老化后样品前者优于后者.结合XRD,BET,TPR等表征手段,讨论了Pd/CZ/Al2O3的催化活性特别是高温老化后活性与其组成结构之间的内在关系,揭示了其老化后仍具有较高活性的主要原因在于保持了Pd与CZ/Al2O3复合载体之间的强相互作用(SMSI). 相似文献
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Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), temperatureprogrammed desorption of NH3(NH3-TPD), H2temperature-programmed reduction(H2-TPR), and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM). The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al2O3catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al2O3catalyst,benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al2O3catalyst. Moreover, the 1.0% Pd-5% Mo/Al2O3catalyst was more active than the 2.0% Pd/Al2O3catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion. 相似文献
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铂、钯蜂窝催化剂高温老化对甲醇深度氧化的影响 总被引:1,自引:0,他引:1
本研究对铂、钯蜂窝催化剂及分别添加助化剂CeO_2或WO_3,并于500℃、700℃、900℃或1100℃下经受热老化4h后,考察催化剂比表面、晶相结构及其对甲醇深度氧化活性、产物分布及反应动力学网络变化的情况。实验证明,添加CeO_2后,降低了铂催化剂的耐高温性能,但对钯催化剂无明显影响。添加WO_3,降低了钯催化剂对甲醇的氧化活性。经X-线衍射分析证明,在1100℃高温下,WO_3与堇青石载体中的氧化镁和氧化钙发生强相互作用,生成了相应的钨酸盐。甲醇氧化反应动力学研究表明,甲醇在新鲜和高温热老化的铂催化剂上,反应动力学网络表示式是有区别的。 相似文献
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A series of oxygen-deficient perovskite-supported palladium catalysts were prepared by the “solid phase crystallization“(spc) ethod and investigated with XRD, TPR, TPD, TEM, XPS, BET analysis and CO oxidation. It was found that Pd/perovskite catalysts ynthesized by the spc method were more active for CO oxidation than the calcined LaCoo.95 Pdo.05 03, where Pd dispersed in the solid olution. H2-reducing treatment in the spc method could yield not only high-dispersed fine Pd particles on the perovskite surface but also xygen-deficient structure. In these perovskite-supported Pd catalysts, oxygen vacancies adsorbed, activated and supplied oxygen to the ctive Pd sites, where the oxidation occurred with adsorbed CO. The high activities were due to the cooperative action of Pd and oxygen acancies. 相似文献
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为了在极短的时间内制备具有超低贵金属含量的结构化催化剂,并将其应用于邻二甲苯的催化燃烧体系,在阴极极化技术的基础上采用电解法制备具有不同载体的Pd基结构化催化剂,通过SEM(扫描电子显微镜)、EDS(能谱仪)、XRD(X射线衍射)、CO-Pulse(一氧化碳脉冲化学吸附)等表征手段分析不同催化剂上Pd的分散行为对催化活性的影响,并利用交流阻抗试验解释Pd在不同载体上的负载机理.结果表明:①阴极极化技术有效地减薄了AAO/Al(CP-AAO/Al、CP-AlOOH/Al和CP-γ-Al2O3/Al 3种载体的前驱体)的阻挡层,从而提高了载体的导电性,2.5 min内AAO/Al的表面电阻从7.23×108 Ω降至1.21×108 Ω.②当w(Pd)为0.1%时,采用电解法在3种载体上负载Pd的时间在5 min以内.③3种载体中CP-γ-Al2O3/Al(阴极极化后的γ-Al2O3载体)的阻抗最小,其电荷转移能力最好,更有利于Pd的负载及分散.④Pd/CP-AAO/Al、Pd/CP-AlOOH/Al和Pd/CP-γ-Al2O3/Al催化剂上Pd的分散度分别为11.24%、10.90%、17.42%,对应的T50(转化率为50%时的温度)分别为170、172、160℃.研究显示,电解法可有效地将催化剂制备时间由传统的数十小时缩短为数分钟,同时邻二甲苯催化活性结果表明,催化剂活性与Pd的分散度呈正相关,即Pd的分散度越高,催化剂的催化活性越好. 相似文献
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The 0.7 wt% Pt + 0.3 wt% Rh/Ce0.6Zr0.4O2 catalysts were fabricated via different methods, including ultrasonic-assisted membrane reduction(UAMR) co-precipitation, UAMR separation precipitation, co-impregnation, and sequential impregnation. The catalysts were physico-chemically characterized by N2 adsorption, XRD, TEM, and H2-TPR techniques, and evaluated for three-way catalytic activities with simulated automobile exhaust. UAMR co-precipitation- and UAMR separation precipitationprepared catalysts exhibited a high surface area and metal dispersion, wide λ window and excellent conversion for NOx reduction under lean conditions. Both fresh and aged catalysts from UAMRprecipitation showed the high surface areas of ca. 60–67 m2/g and 18–22 m2/g, respectively, high metal dispersion of 41%–55%, and small active particle diameters of 2.1–2.7 nm. When these catalysts were aged, the catalysts prepared by the UAMR method exhibited a wider working window(Δλ = 0.284–0.287) than impregnated ones(Δλ = 0.065–0.115) as well as excellent three-way catalytic performance, and showed lower T50(169.C) and T90(195.C) for NO reduction than the aged catalysts from impregnation processes, which were at 265 and 309.C, respectively. This implied that the UAMR-separation precipitation has important potential for industrial applications to improve catalytic performance and thermal stability. The fresh and aged 0.7 wt% Pt + 0.3 wt% Rh/Ce0:6Zr0:4O2 catalysts prepared by the UAMR-separation precipitation method exhibited better catalytic performance than the corresponding catalysts prepared by conventional impregnation routes. 相似文献