TiO2 Supported Nano—Au Catalysts Prepared via Solvated Metal Atom Impregnation for Low-Temperature CO Oxidation

TiO₂ supported nano-Au catalysts were prepared by solvated metal atom impregnation (SMAI) method. The catalysts were characterized by means of AAS, TPD, H₂ reduction desorption (H₂-RD), XRD, TEM, XPS and tested for low-temperature CO oxidation. XRD and TEM results showed that the pretreatment temperature had an influence on the particle size of Au/TiO₂catalysts. The average particle size increased with the increase in pretreatment temperature. XPS indicated that gold in the catalysts was presented in the form of metallic state clusters. Catalytic studies showed these catalysts were very active and stable in low-temperature CO oxidation. The CO oxidation activity of the catalysts increased as the Au particle size decreased. The measurement results of AAS, TPD and H₂-RD revealed that there were some organic fragments on the surface of Au particles which might be responsible for the high stability of the Au/TiO₂ catalysts.     

TiO2 Supported Nano-Au Catalysts Prepared Via Solvated Metal Atom Impregnation for Low–Temperature CO Oxidation

The Ce _x Ti_1?x O₂ mixed oxides at different mole ratios (x=0.1–1.0) were prepared by co-precipitation of TiCl₄ and Ce(NO₃)₃. The structural and reductive properties of the Ce _x Ti_{1? x} O₂ were affected by calcination temperature. At x=0.1–0.3, CeTi₂O₆ phase was formed and mainly as amorphous after calcination at 650°C. At x=0.3, only CeTi₂O₆ was formed after calcination at 750°C and CeTi₂O₆ crystallized completely after calcination at 800°C. TPR analyses showed that the amount of H₂ consumption by Ce _x Ti_1?xO₂ (650°C) (except x=0.1) was greater than that by single CeO₂, and the valence of CeO₂was the lowest (+3.18) at x=0.3. CuO/Ce_0.3Ti_0.7O₂ was prepared by the impregnation method and catalytic properties were examined by means of a GC micro-reactor NO+CO reaction system, BET, TPR, XRD, XPS and NO-TPD. It was found that CuO/Ce_0.3Ti_0.7O₂ calcined at 650°C had the highest activity in NO+CO reaction with 100% NO conversion at reaction temperature of 300°C, and at 650°C Ce_0.3Ti_0.7O₂just began to crystallize. The catalytic activities were largely affected by the pre-treatment conditions. At low reduction temperature (100°C), CuO species was difficult to reduce. When high degree of reductions took place, both CuO species and Ce_0.3Ti_0.7O₂ reduced and thus a part of CuO species on the support surface would be covered. The XPS and NO-TPD analyses showed that CuO/Ce_0.3Ti_0.7O₂ had four NO absorption centers (Cu⁺, Cu²⁺(I), Cu²⁺(II) and Ce³⁺). The CuO species involving in NO+CO reaction included Cu²⁺(I) and Cu⁺, and CeO₂ species (Ce³⁺ and Ce⁴⁺).     

Electrochemical reduction of NO and O2 on Cu/CuO

The electrochemical reduction of NO and O₂ on a Cu-point electrode covered with a surface layer of CuO is investigated in an electrochemical cell with a gadolinium doped cerium oxide oxygen ion conducting electrolyte in the temperature interval 300–500 C. It is shown that the reduction of NO on CuO is possible at a lower overvoltage than it is in the case of the reduction of O₂. The results indicate that the reduction of NO on CuO is not inhibited in the presence of O₂ and that the reduction of NO can be selectively performed on a CuO-electrode.     

用溶剂化金属原子浸渍法制备的高分散负载型催化剂Pd－Cu／C的结构与性质

应用溶剂化金属原子浸渍（ＳＭＡＩ）法制备了三种金属含量比不同的Ｐｄ－Ｃｕ／Ｃ双金属催化剂。经ＸＲＤ和ＴＥＭ测定结果表明，催化剂中Ｐｄ和Ｃｕ已形成合金，合金颗粒平均直径小于５ｎｍ。ＸＰＳ和Ａｕｇｅｒ谱说明Ｐｄ和Ｃｕ均以零价态存在。在亚异丙基丙酮（ＣＨ＿３）＿２Ｃ＝ＣＨＣＯＣＨ＿３加氢反应中，随着催化剂中Ｃｕ比例增加，催化活性增大，而生成六碳酮的选择性基本不变。     

Adsorption and reaction of CO on CuO–CeO2 catalysts prepared by the combustion method

Temperature-programmed techniques were employed to investigate the interaction of CO with CuO–CeO₂ prepared by the urea-nitrates combustion method. These catalysts exhibited high and stable CO oxidation activity at relatively low reaction temperatures (< 150 °C). The CO adsorption capacity and catalytic activity of the catalysts was analogous to the concentration of easily-reduced copper oxide surface species. TPD and TPSR results can be explained by a dual scheme of CO adsorption: (i) on oxidized sites, which get reduced with simultaneous formation of surface CO₂ and (ii) on reduced sites created by the former interaction. 10–20% of adsorbed CO desorbs molecularly in the absence of gas-phase O₂, but reacts totally towards CO₂ in the presence of gas-phase O₂. Inhibition by CO₂ observed under steady-state CO oxidation conditions is due to CO₂ adsorption as found by CO₂-TPD.     

CuO/ZrO_2催化剂的催化性能研究

研究了粉体性能、Cu O负载量及灼烧温度对 Cu O/Zr O2 催化剂 CO氧化性能的影响 .结果表明 ,催化剂的活性随氧化铜的负载量的增加而增加 ,较低比表面积的 Zr O2 载体更容易制备高活性的催化剂 .实验还发现 ,Cu O/Zr O2 催化剂的活性与载体单位表面 Cu O的负载量相关 ,Cu O的负载量超过载体分散容量为 75% ,是制备高活性催化剂的重要条件 .     

船形氧化铈的制备及其在CO催化中的应用

近年来,氧化铈（CeO₂）形貌控制合成的研究已成为稀土研究的重要组成部分。采用溶菌酶为模板,硝酸铈作为铈源,碳酸钾为沉淀剂,使用简单的水热反应和热处理制备了具有三维船形形貌的CeO₂材料。对制备的CeO₂材料进行XRD、SEM、 TEM和N2吸附等的结构表征,结果表明,船形氧化铈为椭圆结构,整个三维结构由许多CeO₂晶粒组装堆积而成,晶粒尺寸为（8～10） nm,比表面积为32.2 m²·g^-1。并在CeO₂上进行CO催化氧化模型反应研究,考察了该材料在CO催化氧化中的应用,发现船形CeO₂的CO催化氧化起燃温度T₅₀和完全转化温度T100分别为230 ℃和250 ℃,具有较高的CO催化氧化活性。     

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

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.     

Comparison of CuO/Ce0.8Zr0.2O2 and CuO/CeO2 Catalysts for Low-temperature CO Oxidation

CuO/Ce_0.8Zr_0.2O₂ and CuO/CeO₂ catalysts were prepared via a impregnation method characterized by using FT-Raman, XRD, XPS and H₂-TPR technologies. The catalytic activity of the samples for low-temperature CO oxidation was investigated by means of a microreactor-GC system. The influence of the calcination temperature and different supports on the catalytic activity was studied.     

ZrO_2负载Cu催化剂对CO低温催化氧化研究

用溶胶-凝胶-超临界干燥法制备了纳米氧化锆。采用沉淀法制备氧化锆负载铜催化剂。制备的催化剂用X-ray射线衍射(XRD),透射电镜(TEM),比表面积(BET)和H2-TPR等进行了表征。研究了催化剂的焙烧温度和负载比例对CO转化效率的影响,其最佳焙烧温度为650℃,Zr与Cu的最佳物质的量比是10:8。获得催化剂在温度为68℃具有催化活性,176℃时CO的转化率达到50%,较好地实现了ZrO2负载Cu在较低温度下对CO的催化。     

SnO2对CuO-CeO2/γ-Al2O3催化剂湿式氧化降解苯酚活性的影响

从电子助剂的角度考虑,以SnO2为添加剂,以γ Al2O3为载体,CuO为活性组分,CeO2为助剂,采用分层浸渍与混合浸渍相结合的方式制备出CuO SnO2 CeO2/γ Al2O3负载型湿式氧化催化剂。利用XPS对催化剂进行表征,研究Sn的掺杂对催化剂表面微观结构的影响,进而研究对其催化剂活性的影响。研究证明了Sn的掺杂可以提高催化剂表面Cu 的含量,从而提高催化剂表面晶格氧空位的数量。通过对苯酚的湿式氧化降解,得出催化剂表面晶格氧空位的数量是影响催化剂活性的主要因素。     

二氧化铈载金催化剂催化CO氧化的研究进展

将金纳米颗粒负载在二氧化铈上,形成负载型催化剂,能应用于多种反应体系,表现出良好的催化活性,有着广阔的发展前景。综述了二氧化铈载金催化剂在一氧化碳催化氧化中的应用研究进展,介绍了二氧化铈载金催化剂中金的结构、价态和纳米尺寸,载体二氧化铈的形貌、结构、尺寸和氧空位以及金和载体二氧化铈两者之间的相互作用对一氧化碳催化氧化性能的影响。     

ZrO2负载铜镍双金属对CO低温催化活化研究

用两种方法合成载体ZrO2,分别负载镍单金属和铜镍双金属制备催化剂,对其做CO催化,确定载体最佳制备方法。用最佳方法制备的载体负载铜镍金属做催化剂,考察催化剂焙烧温度和负载比例不同对CO催化影响。实验结果表明,用溶胶凝胶超临界干燥法制备的ZrO2为载体负载铜镍制备的催化剂其最佳焙烧温度为250℃,Zr与Cu和Ni的最佳物质的量比是10：8：4时,获得催化剂起始催化活性温度为22℃,169℃时C0的转化率达到50％,较好地实现了ZrO2负载铜镍在较低温度下对CO的催化。     

金属氧化物催化剂上H_2S选择性催化氧化研究进展

选择性催化氧化法作为一种新型的脱除H_2S尾气技术,重点是开发具有高活性和多种性能特点的催化剂形成系列产品。总结了金属氧化物催化剂上H_2S选择性催化氧化反应的研究进展。重点介绍了不同载体、活性组分和助剂对催化剂活性的影响;阐述了H_2S选择性催化氧化的反应机理和失活机理,并对金属氧化物催化剂的未来发展方向上进行了展望。     

Preparation, Characterization and Catalytic Activity for CO Oxidation of SiO2 Hollow Spheres Supporting CuO Catalysts

Silica hollow spheres were synthesized by sol–gel process using carbon microspheres as templates, and used as supports for CuO/SiO₂ catalysts. The samples were characterized by TEM, nitrogen adsorption–desorption, XRD and TPR, and furthermore, the catalytic performance for CO oxidation was approached. The results indicated that the catalytic activity of CuO supported on SiO₂ hollow spheres exhibited much higher as compared to that supported on commercial SiO₂. Enhancement of the catalytic activity may be attributed to the fact that the unique hollow spherical texture should facilitate the formation of main active species and gas diffusion in catalysts.     

焙烧温度对CuO/Co_3O_4-CeO_2催化剂CO优先氧化性能的影响

采用浸渍法制备了Cu O/Co3O4-Ce O2(Cu Co Ce10)催化剂,考察了在不同温度(250、300、350、400和450℃)焙烧后的样品在富氢气氛中对CO优先氧化反应的催化性能。应用BET、XRD、H2-TPR及XAFS技术详细表征了催化剂的结构与性能。结果表明,不同温度焙烧的催化剂中,铜物种均主要以Cu O相存在;350℃焙烧的Cu Co Ce10催化剂具有最大的比表面积和最好的氧化还原性能,在98~173℃的温度范围内能够将CO完全转化为CO2,呈现出最宽的CO优先氧化可操作温度窗口,以及良好的催化活性稳定性。     

石墨烯负载铜在富氢条件下催化CO氧化的研究

石墨烯具有许多优良性质,在燃料电池和催化领域应用前景广阔。以石墨烯为载体负载不同含量的Cu在富氢条件下催化CO氧化的影响。     

Oxidation Reactions over Multi-Component Catalysts: Low-Temperature CO Oxidation and the Total Oxidation of CH4

A series of NM/MO _x /Al₂O₃ (NM = Pd, Ag, Pt, and Au) catalysts were prepared and tested in the oxidation of CO and CH₄. The catalysts were characterized with X-ray diffraction and transmission electron microscopy. Where addition of MO _x generally does not seem to affect the catalyst activity in CH₄ oxidation, a large enhancement in CO oxidation was observed. Fourier transform infrared spectroscopy has been used to identify the role of MO _x as a promoter for low-temperature CO oxidation. The results were found to support a Mars and van Krevelen type model.     

Fe-promoted CuO/CeO2 catalyst: Structural characterization and CO oxidation activity

In the present paper, effect of iron on activity of catalyst CuO/CeO₂ in selective CO oxidation in H₂-containing gases mixture was investigated. Catalysts were prepared by wet impregnation and calcination at 400 °C, characterized by ICP, BET, H₂-TPR, XRD and TEM. The addition of iron to Cu/CeO₂ catalyst improved the catalytic activity and selectivity for CO oxidation. Discussion of the results showed that the synergistic effect is correlated to better reducibility and dispersion of copper in the presence of the iron metal additive.     

超临界CO_2萃取与浸渍法提取白刺果油化学成分的分析与比较

为了促进白刺属植物在医药和精细化工等领域中的应用,该研究采用超临界CO2萃取法和溶剂浸渍法提取唐古特白刺果油,并用气相色谱-质谱联用技术对其化学成分进行了分析,从超临界CO2萃取出的白刺果油中分离鉴定出51种化学成分;从浸渍法提取出的白刺果油中鉴定出22种成分;两种方法提取的果油共有14种相同化学成分,含量较高的主要有:二十九烷、二十七烷、亚油酸乙酯、γ-生育酚、VE(α-生育酚)、γ-谷甾醇、菜油甾醇、等。该研究工作的新颖性,已为新疆维吾尔自治区科委石河子大学图书馆2007年1月15日出具的第20070000000005号《科技查新报告》所证实。