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工业堇青石打磨成适当大小的长方体,用草酸溶液沸煮预处理后作为整体式催化剂的载体,利用自动物理吸附仪和电子压力机分别考查了酸预处理条件对堇青石载体的比表面积、失重率以及机械强度的影响。实验结果表明用20%的草酸沸煮处理2 h时堇青石载体的失重率有所增加,可以在保证较强的机械强度前提下获得较为理想的比表面积。 相似文献
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采用不同浓度硝酸和草酸溶液,对堇青石蜂窝陶瓷载体进行预处理,考察了酸处理对载体失重率、吸水率及压缩强度的影响。采用催化剂粉体浆料涂覆法,制备了堇青石蜂窝陶瓷负载锰酸锶镧基La0.8Sr0.2Mn0.4Al0.4Zn0.2O3-δ(LSMAZ)整体式催化剂,运用X射线衍射(XRD)、扫描电镜(SEM)等手段对催化剂进行表征,并在管式反应器上进行甲烷催化燃烧活性测试。结果表明,酸处理能增大载体比表面积和吸水率;相同条件下草酸对载体的侵蚀效果优于硝酸;提高草酸浓度能增强侵蚀效果,但过高浓度的酸处理会使载体压缩强度过小而无法应用。经1050℃煅烧5 h后,所制备的整体式催化剂具有适宜的脱落率,无明显载体-LSAMZ界面反应,并具有最高的甲烷燃烧催化活性。 相似文献
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整体式催化剂性能及应用的研究进展 总被引:9,自引:0,他引:9
由整体式催化剂的结构特点出发.系统地阐述了整体式催化剂具有的一系列超越传统颗粒状催化剂的独特优越性,提出了其在三相反应中有待解决的几个关键性问题。同时概述了整体式催化剂在环保领域和化工产品合成领域的应用、研究现状和展望。 相似文献
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以硅溶胶为黏结剂,采用浆液浸涂法对堇青石蜂窝陶瓷基体进行涂覆,制备整体式脱硝催化剂的TiO2涂层。考察固含量、pH和不同添加剂等对TiO2浆液及涂层性质的影响,结合超声振荡、比表面积、扫描电镜和X射线衍射等手段对TiO2涂层进行表征。结果表明,随着固含量的增加,浆液黏度的增加速率逐渐加快,固含量超过22.82%时,浆液发生团聚,不可进行涂覆;随着pH的增大,浆液黏度先降低后增加,在pH为1.05时,浆液黏度最低;浆液中加入适量的聚乙烯醇、六次甲基四胺和铝溶胶均可提高涂层负载量,降低涂层脱落率。其中,在浆液中添加质量分数5%的铝溶胶可以使涂层负载质量分数增至8.58%,比表面积达10.22 m2·g-1,而涂层脱落率仅为12.84%,该涂层可作脱硝催化剂的良好载体。 相似文献
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Iron-ruthenium catalysts prepared by impregnation of calcination products of -, , -and -iron oxide-hydroxides with either ruthenium chloride or ruthenium red were tested for the activity for the water-gas shift reaction. The effect of support, ruthenium containing impregnation agent and thermal treatment on catalyst performance was discussed. 相似文献
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铜含量对Cu/CeO2水煤气变换催化剂性能的影响 总被引:2,自引:0,他引:2
采用共沉淀法制备了不同铜含量的Cu/CeO2水煤气变换催化剂,考察了铜含量对催化活性的影响。结果表明,Cu/CeO2催化剂呈现出良好的水煤气变换活性。铜含量对催化活性有显著影响,铜摩尔分数为50%时,催化剂的低温活性最高,在200 ℃时CO转化率达到66.1%。Cu/CeO2与FBD型铁基高温变换催化剂相比,具有低温活性好、活性温区宽的特点。用XRD、N2吸附法、H2-TPR和CO-TPD对催化剂进行了表征,结果表明,无定形CuO、纳米颗粒CuO等可能是催化反应的活性物种,晶粒CuO对催化活性影响不大。铜含量的催化剂在不同温度下呈现出不同的活性。 相似文献
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负载型铁基高温变换催化剂的制备和性能研究 总被引:4,自引:1,他引:4
分别以镁铝尖晶石和活性炭作为载体制备了负载型铁基高温变换催化剂,通过XRD、TEM和活性评价测试,考察了催化剂的结构和催化反应性能。以镁铝尖晶石负载γ-Fe2O3制得的催化剂,其催化活性明显高于负载α-Fe2O3催化剂,当催化剂组成为:Fe2O3 26%,K2O 2%,MgO 0.05%,Cr2O3 0.7%时,400℃下CO转化率为92%,350℃为84%(汽/气=1, 空速=2000 h-1);经氧化处理的活性炭作为催化剂载体时,低铬条件下也具有较好的催化活性,当负载量为40%时,相同变换反应条件下CO的转化率在400℃和350℃下分别为88%和80%。两种催化剂在低Cr2O3含量时都保持了与传统铁铬系变换催化剂(B117型)相当的催化活性,对于改善环境具有很大意义。 相似文献
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James T. Richardson James D. Ortego Jr. Nicolas Coute Martyn V. Twigg 《Catalysis Letters》1996,41(1-2):17-20
This Letter reports preliminary findings on the role of chloride poisoning during steam reforming of chlorocarbons over nickel catalysts. When conversions of chlorocarbon are very high and thermal pyrolysis absent, the principal effect of chloride is to decrease water-gas shift and CH4-steam reforming activity. Product carbon dioxide/carbon monoxide ratios are then far from equilibrium and methane remains unconverted when introduced into the feed. These results are linked to previously published surface science studies. 相似文献
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分别制备了以Mn、Ce、Cu、Zn、K等为助剂的Cr/SiO2催化剂,考察了助剂在逆水煤气变换耦合乙烷脱氢制乙烯反应中对Cr/SiO2催化剂反应性能的影响。结果表明,高温下Mn的加入有利于催化活性的提高,Cr-Mn/SiO2催化剂显示了较好的催化活性。在740℃、n(CO2)/n(C2H6)=7的条件下,乙烷转化率为47%,乙烯选择性为99%。XRD、XPS、UV-DRS和TPR技术的表征表明催化剂表面存在Cr3+、Cr6+、Mn4+物种,Mn的加入使得催化剂还原性能增强,有助于反应过程中氧化还原循环的进行,提高了反应活性。 相似文献
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Nina Hammer Ingvar Kvande Wouter van Beek De Chen Magnus Rønning 《Topics in Catalysis》2007,45(1-4):25-29
In situ X-ray absorption spectroscopy (XAS) has been performed to investigate the active site on Au-based catalysts in the water-gas
shift (WGS) reaction. The surface area and hence the WGS activity is higher for AuTiO2 catalysts supported on carbon nanofibres (CNF) than TiO2. The WGS reaction rate depends on the Au coordination number with an apparent maximum close to eight which corresponds to
a particle size of approximately 2.5–3.0 nm. A likely cause for the changes in the electronic structure of Au is the adsorption
of CO on the surface, which also creates a small positive charge in the Au atoms. The catalytic activity significantly improves
when titania is present compared to Au deposited directly on CNF. 相似文献
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Weiling Deng Colin Carpenter Nan Yi Maria Flytzani-Stephanopoulos 《Topics in Catalysis》2007,44(1-2):199-208
We compare the activity and relevant gold species of nanostructured gold–cerium oxide and gold–iron oxide catalysts for the
CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO
oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze
the water-gas shift reaction. Gold species weakly bound to ceria (doped with lanthana) or iron oxide can be removed by sodium
cyanide at pH ≥12. Both parent and leached catalysts were investigated. The activity of the leached gold–iron oxide catalyst
in CO oxidation is approximately two orders of magnitude lower than that of the parent material. However, after exposure to
H2 up to 400 °C gold diffuses out and is in reduced form on the surface, a process accompanied by a dramatic enhancement of
the CO oxidation activity. Similar results were found with the gold–ceria catalysts. On the other hand, pre-reduction of the
calcined leached catalyst samples did not promote their water-gas shift activity. UV–Vis, XANES and XPS were used to probe
the oxidation state of the catalysts after various treatments. 相似文献