Effect of metal doping into Ce0.5Zr0.5O2 on catalytic activity of MnOx/Ce0.5–xZr0.5–xM0.2xOy/Al2O3 for benzene combustion

The research investigated the effect of doping two metals separately or together into Ce0.5Zr0.5O2 on the catalytic activity of MnOx/Ce0.5-xZr0.5-xM0.2xOy/Al2O3 （M=Y, Mn, Y and Mn） for catalytic combustion of benzene. The prepared catalysts were characterized by X-ray diffraction （XRD）, surface area analysis, oxygen storage capacity （OSC）, and H2-temperature programmed reduction （H2-TPR）. Catalytic test was performed on a conventional fixed bed flow reactor. The characterization results revealed that Y and Mn ions entered into the ceria-zirconia mixed oxides framework, which improved the textural properties and greatly promoted the MnOx dispersion on the support surface. The complete conversion temperature of benzene on MnOx/Ce0.4Zr0.4Y0.1Mn0.1Oy/Al2O3 was 563 K, and the selectivity of carbon dioxides was 99%. This catalyst could be applied in a wide range of GHSV and wide concentration condition, showing great potential for application.     

Pt/MoO3/ZrO2催化剂的制备及三效催化性能的研究

采用浸渍法制备了MoOz/ZrO2,用低温氮吸附-脱附法和NH3-程序升温脱附法(TPD)分别对其比表面积和酸碱性进行了表征.结果表明,MoO3/ZrO2具有106.8m2/g的比表面积和超强酸的性能.用等体积浸渍法制备了Pt/MoO3/ZrO2催化剂,在汽车尾气模拟气中考察了其对C3H8、CO和NO的催化活性.与传统三效催化剂Pt/La2O3/Al2O3相比较,Pt/MoO3/ZrO2具有更好的低温起燃性能和更宽的空燃比窗口,并显著地改善了C3H8在富氧状态下的转化效率.通过XRD、H2-TPR对催化剂进行了表征,结果表明,Pt在催化剂载体上具有高度的分散性和优异的氧化还原性能.     

焙烧温度对Ce0.65Zr0.35O2储氧材料性能的影响

用共沉淀法制备了Ce0.65Zr0.35O2氧化物,对不同温度处理后的样品进行了XRD、Raman、BET和储氧量(OSC)的表征.并考察了不同温度焙烧后的氧化物对单钯催化剂三效性能的影响.结果表明,焙烧温度的不同,样品具有不同的织构性能,但该样品的晶相结构稳定,老化前后均为立方相的铈锆固溶体,经1000℃焙烧后未出现相分离,说明该氧化物具有良好的热稳定性能;活性测试结果表明,不同焙烧温度的载体对催化活性影响较大,并以700℃焙烧后的氧化物为载体的催化剂具有最好的三效性能.     

BaO对单Pd催化剂净化甲醇燃料车尾气性能的影响

利用FIB/SEM切片、XRD、TEM和EDX、EELS等先进分析技术对微球模板法所制备的Au/Ag泡沫材料的微观结构、形貌、成分及成分分布等进行了细致的研究.结果表明:由微球状Au/Ag球壳堆积而成的泡沫材料中微球直径约8 μm,微球壁厚200～1200 nm; Au/Ag泡沫材料的球壳可细分为3层,内层和外层为Au/Ag合金的微粒,中间主要是非晶碳层,夹杂有少量的Au/Ag微粒;Au/Ag泡沫材料的骨架由单个空心球壳组成,球壳之间通过接触点的金属镀层连接在一起;球壳上有小孔状结构,是在热分解法去除聚苯乙烯微球模板对形成的;球壳壁厚分布不均匀,少数球壳有塌陷、变形、破裂等现象.这些详细的分析有助于改进工艺,提高Au/Ag泡沫材料的制备质量.     

陈化体系中醇对Ce0.65Zr0.35O2及其负载的单Pd催化剂性能的影响

采用共沉淀法制备了Ce_0.65Zr_0.35O₂(CZ)储氧材料, 分别以乙醇-水、丙醇-水、乙二醇-水、丙三醇-水体系对沉淀物进行陈化, 研究了醇的种类对CZ及其负载的单Pd催化剂性能的影响。对CZ进行了扫描电镜(SEM), N₂-吸脱附分析, 对Pd/CZ进行了粉末X射线衍射(XRD)、X射线光电子能谱(XPS)、储氧量 (OSC)和程序升温还原( H₂-TPR)的表征, 并考察了三效催化性能。结果表明, 醇的种类对CZ及Pd/CZ的性能有显著影响。在乙醇-水和丙醇-水陈化体系中制备的CZ分散性高, 颗粒堆积松散, 比表面积和孔径大, 孔容高, 且具有优异的热稳定性, 其中丙醇-水陈化体系中制备的CZ老化后比表面积和孔容分别可达28 m²/g和0.1 mL/g, 具有最高的热稳定性, 其负载的单Pd催化剂在老化后对C₃H₈、CO和NO转化显著优于乙二醇-水和丙三醇-水陈化体系中制备的CZ所制备的催化剂。     

Synergetic effect of thermo-photocatalytic oxidation of benzene on Pt-TiOe/Ce-MnOx

Pt-TiO2/Ce-MnOx catalysts were obtained by depositing TiO2 and platinum, respectively,on the Ce-Mn oxides prepared by co-precipitation method. The phases of CeO2 and anatase TiO2 were observed in the catalysts from X-ray diffraction (XRD) patterns. X-ray photoelectron spectroscopy (XPS) revealed that lattice oxygen and surface active oxygen were found to be the major components of O1s. The experiment results showed that the kinetic constant of thermo-photocatalysis was 7.6 times of the kinetic constant of single photocatalysis, and was 2.29 times of the kinetic constant sum of photocatalytic and thermal catalytic reaction.     

Synthesis of neodymium modified CeO2-ZrO2-Al2O3 support materials and their application in Pd-only three-way catalysts

Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffraction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperature pro-grammed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd2O3 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox prop-erty. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified sam-ples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.     

Rh－Co／Al_2O_3双金属催化剂上CO加氢反应

用非传统方法制备了Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３、Ｃｏ２／Ａｌ２Ｏ３、Ｒｈ４／Ａｌ２Ｏ３和用传统方法制备了（Ｒｈ＋Ｃｏ）／Ａｌ２Ｏ３催化剂。用连续流动微反装置研究了上述催化剂的ＣＯ加氢活性及选择性，并系统地研究了Ｈ２／ＣＯ比值和温度对反应活性及选择性的影响。结果表明，Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３的活性不仅高于Ｒｈ４／Ａｌ２Ｏ３和Ｃｏ２／Ａｌ２Ｏ３，而且也高于（Ｒｈ＋Ｃｏ）／Ａｌ２Ｏ３，在选择性方面与上述样品也有明显差异。当Ｈ２／ＣＯ比值从６：１变到１：１时，其它催化剂的反应活性大为降低，而Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３仍保持高活性。     

Effects of ceria/zirconia ratio on properties of mixed CeO_2-ZrO_2-Al_2O_3 compound

A series of CexZr0.50-xAl0.50O1.75(0.05≤x≤0.45) mixed oxides with different Ce/Zr ratio were prepared by co-precipitation method and characterized by means of X-ray diffraction(XRD),Brunauer-Emmet Teller method(BET),temperature-programmed reduction(H2-TPR) and oxygen pulsing technique.The XRD results showed that all samples kept the single CeO2 cubic fluorite structure after calcination at 600 and 1000 oC for 5 h.The results of BET revealed that CexZr0.50-xAl0.50O1.75 with Ce/Zr molar ratio 1/1 exhibited higher specific surface area(212 m2/g) and larger pore volume(0.40 ml/g).For all aged samples,CZA with Ce/Zr molar ratio 3/7 presented the highest specific surface area(104 m2/g) and pore volume(0.34 ml/g).The compounds could still keep prominent structural and textural stability with excellent redox properties even calcined at 1000 oC.