钛基LaxCe1-xTiyM1-yO3/γ-Al2O3催化剂的制备及催化燃烧性能

为提高钙钛矿型催化剂的活性,以γ-Al2O3为载体,采用等体积浸渍法制备负载型钙钛矿LaxCe1-xTiyM1-yO3/γ-Al2O3催化剂,考察了活性组分负载量、焙烧温度、A位元素配比和B位元素掺杂对催化剂催化燃烧甲苯性能的影响,并对催化剂进行XRD和BET表征。结果表明:催化剂的最佳制备条件是活性组分负载量为12%,焙烧温度为750℃,催化剂的最佳形式为La0.8Ce0.2 Ti0.8 Mn0.2 O3/γ-Al2 O3,在该催化剂的作用下,甲苯的起燃温度T50和完全转化温度T90分别为292℃和338℃;负载型钙钛矿催化剂保持了完整的钙钛矿结构,活性组分均匀分布在载体的孔道中,虽然会导致载体的比表面积有所降低,但催化剂可以更最大程度地分散,更有利于提高催化剂的催化活性。     

催化剂MnCe（y）Ox/TiO2的制备及其催化燃烧甲苯的活性

以TiO2为载体,采用浸渍法制备了不同配比的MnCe复合型催化剂,并采用X射线衍射(XRD)、氧气的程序升温脱附(O2-TPD)和氢气的程序升温还原(H2-TPR)对制备的催化剂进行表征,比较了催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,所制备的催化剂MnCe(y)Ox/TiO2对甲苯有明显的催化活性。当Ce/(Mn+Ce)的摩尔比为0.1时,催化剂MnCe(0.1)Ox/TiO2的催化活性最高,甲苯的转化率达到90%时的温度为254℃。在催化剂MnOx/TiO2中掺杂少量的Ce元素,有利于活性组分Mn物种在载体表面上以更小颗粒而且更高的分散度存在,从而提高催化剂的催化活性。     

H_2还原预处理CuO/γ-Al_2O_3催化剂对其催化燃烧甲苯活性的影响

用浸渍法和H2还原预处理法制备两种CuO/γ-Al2O3催化剂,并用N2吸附脱附、XRD、TPR和CO化学吸附对经H2还原处理前后的催化剂进行表征,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CuO/γ-Al2O3催化剂相比,经H2还原预处理,再次焙烧后得到的CuO/γ-Al2O3/HR催化剂对甲苯催化燃烧活性明显提高。XRD和TPR分析表明,H2还原预处理提高了催化剂表面活性组分CuO的分散度、还原能力,同时,还降低了CuO的晶体尺寸,从而提高了催化剂催化氧化甲苯的活性。     

Ce改性Fe2O3/γ-Al2O3催化剂的表征及催化活性研究

采用浸渍焙烧法分别制备了Fe2O3/γ-Al2O3和Ce改性的Fe2O3/γ-Al2O3催化剂,采用BET、XRD、XPS和XRF对其结构进行了表征,并用于常温常压CWPO工艺中,考察了Ce的掺杂对Fe2O3/γ-Al2O3催化剂催化活性和稳定性的影响.结果表明,Ce的掺杂提高了活性组分在载体表面的分散度,在相同的CWPO工艺条件下,Ce的掺杂使得Fe2O3/γ-Al2O3催化剂处理偶氮染料废水的催化活性提高了10%左右.     

Fe2O3/γ-Al2O3催化剂的制备表征及其催化活性的研究

采用浸渍法制备用于常温常压下催化湿式过氧化氢氧化工艺(CWPO)的负载型Fe2O3/γ-Al2O3催化剂,采用BET,SEM,XRD,XPS和XRF对其进行了表征,并以偶氮染料酸性橙为特征污染物,考察了Fe2O3/γ-Al2O3催化剂的催化活性和稳定性.研究表明,Fe2O3/γ-Al2O3催化剂中的活性组分Fe是以α-Fe2O3的形式存在,且Fe的负载量为1.907%(质量分数).对于初始浓度为500mg/L的酸性橙模拟废水,当Fe2O3/γ-Al2O3催化剂和H2O2氧化剂的投加量分别为30g/L和330mg/L时,处理3h时染料的脱色率、COD去除率和TOC去除率可分别达到82.10%,80.14%和74.2%.与传统Fenton试剂法相比,以Fe2O3/γ-Al2O3为催化剂的CWPO工艺具有矿化程度高和催化剂易回收再用的优点.     

制备方法对Ru/γ-Al2O3与等离子体共活化CO2甲烷化反应的影响

等离子体与催化材料协同作用CO2甲烷化反应为CO2再利用提供了可能,但催化材料的制备方法对其结构和性能有重要影响。本研究以等体积浸渍法制备的Ru/γ-Al2O3为催化材料前驱体,分别采取H2大气压冷等离子体还原和H2热还原方法制备Ru/γ-Al2O3-P和Ru/γ-Al2O3-T催化材料。考察两种方法制备Ru/γ-Al2O3催化材料与大气压冷等离子体共同作用下CO2甲烷化反应中的催化活性,并采用不同测试方法研究制备方法对Ru/γ-Al2O3结构的影响,分析影响Ru/γ-Al2O3催化活性的结构因素,进而探究了Ru/γ-Al2O3-P和Ru/γ-Al2O3-T催化材料的制备机理。研究结果表明:载体γ-Al2O3与大气压等离子体共同作用下CO2转化率为24.8%,主要产物是CO;Ru/γ-Al2O3与大气压等离子体共同作用下的主要产物是甲烷。Ru/γ-Al2O3-T和Ru/γ-Al2O3-P催化材料的CO2转化率分别为66.9%和77.3%。Ru/γ-Al2O3-P较高的催化活性源于其表面Ru还原程度高、Ru/Al原子比高以及Ru单质在载体γ-Al2O3上分散性较好且粒径较小,说明采用大气压H2冷等离子体技术可制备高活性的负载型金属催化材料。     

焙烧温度对Cu-Mn/γ-Al_2O_3催化剂催化氧化甲苯性能的影响

采用浸渍法合成了Cu-Mn/γ-Al2O3催化剂,通过XRD、BET、H2-TPR和XPS等方法对经不同温度(300~600℃)焙烧的催化剂进行表征,采用固定床管式反应装置考察了焙烧温度对催化剂催化氧化甲苯的影响,并讨论活性组分、表面Cu+/(Cu++Cu2+)和Mn4+/(Mn4++Mn3+)摩尔比值与催化剂活性的关系。结果发现,550℃焙烧温度的催化剂活性最好,氧化能力最强,其转化率为95%时对应的反应温度T95(286℃)最低,CO2的选择性达100%。在550℃焙烧时生成的Cu1.4Mn1.6O4新相以及催化剂表面中相对含量更高的Cu+和Mn4+是催化剂具有高活性的主要原因。     

CeO2对RuO2/γ-Al2O3催化剂湿式氧化降解苯酚性能的影响

采用浸渍法制备了RuO2/γ-Al2O3和RuO2/CeO2/γ-Al2O3催化剂,并利用XRD、sEM和XPS对催化剂进行了表征,研究了Ce的加人对RuO2/γ-Al2O3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-Al2O3和RuO2/CeO2/γ-Al2O3催化剂湿式氧化降解苯酚的活性,并深入探讨了Ce对RuO2/γ-Al2O3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-Al2O3催化剂的活性提高,因此Ce起到了显著的助催化作用.     

Cum-Fen/Ti1-xSnxO2复合催化剂的脱硝性能及抗硫活性

采用共沉淀法制备Ti1-x Snx O2复合氧化物,浸渍负载质量分数10％的CuOx和FeOy活性组分,制备一系列Cum-Fen/Ti1-x Snx O2催化剂.探究不同Ti/Sn和Cu/Fe(物质的量比)对Cum-Fen/Ti1-x Snx O2催化剂的NH3-SCR反应活性的影响.研究结果表明,Ti0.67 Sn0.33 O2载体可促进活性组分CuOx和FeOy的相互作用.当Cu/Fe为3:1时,在300℃ 下NOx的转化率达到91.3％;向反应体系通入286 mg/m3 SO2反应3 h后,NOx的转化率仅下降2.6％.X射线光电子能谱(XPS)、程序升温还原(H2-TPR)、程序升温脱附(NH3-TPD和NOx-TPD)的表征表明,CuOx和FeOy之间存在相互作用,与单一的Cu/Ti0.67 Sn0.33 O2和Fe/Ti0.67 Sn0.33 O2对比,复合催化剂表面吸附氧浓度相对增加15％ ～33％,总酸量增大56％,从而提高了催化剂脱硝活性.     

负载型Fe2O3/γ-Al2O3催化剂的制备及其对煤微波热解的催化活性

为实现低变质煤资源化的目标,在低变质煤微波热解的基础上采用超声浸渍-焙烧法制备负载型Fe2O3/γ-Al2O3催化剂,采用场发射扫描电镜(SEM)及X射线能谱(EDS)对催化剂进行表征,研究了其对煤微波热解过程中的催化效果及机理,考察焙烧时间、焙烧温度等因素对催化剂催化活性的影响,通过气-质联用(GC-MS)及煤气分析仪对焦油及气体组分和含量进行测定。结果表明,Fe2O3/γ-Al2O3催化剂的加入提高了煤微波热解制氢气及焦油产率,超声浸渍条件下400℃焙烧4h制备的产品催化活性最佳。     

Effect of nanosized gold particle addition to supported metal oxide catalyst in methanol oxidation

Gold has rarely been utilized as a catalytic component because of its poor affinity to chemical species. It is however known that nanosized gold particles promote the dissociation of oxygen or hydrogen. In this study, alumina-supported metal oxide catalysts were prepared by impregnation method and applied to methanol oxidation. The dispersion form and size of the gold particles were observed by transmission electron microscopy (TEM). In the results, the maximum catalytic activity was obtained over the ZnO/Al2O3 catalyst, and the optimum loading was 4 wt%. Furthermore, nano-sized gold particles at various loadings were added to ZnO/Al2O3 catalyst by deposition method. The gold particles on Au/ZnO/Al2O3 catalyst were well dispersed and the catalyst activity was remarkably increased compared to ZnO/Al2O3 catalyst. The role of gold particles in the increased catalytic activity is discussed and a possible mechanism is presented.     

Effect of Mn precursors on benzene oxidation with ozone over MnOx/MCM-41 at low temperature

Low temperature benzene oxidation in the presence of ozone on MnOx/MCM-41 catalysts has been studied. MnOx/MCM-41 catalysts were prepared from two different precursors, Mn(NO3)2 and Mn(CH3COO)2, and these samples were characterized by N2 sorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction. The characterization results showed that the MnOx/MCM-41 prepared from Mn(CH3COO)2 had higher oxygen mobility and dispersion than the MnOx/MCM-41 from Mn(NO3)2. As a result, the MnOx/MCM-41 obtained from Mn(CH3COO)2 showed higher catalytic activity for the oxidation of benzene using ozone; however, without ozone, the catalytic activity was negligible.     

Ni／CNTs及钙改性Ni／CNTs催化剂在二氧化碳甲烷化反应中性能

分别以碳纳米管（CNTs）和活性氧化铝（Al2O3）为载体,通过浸渍法制备了负载型镍基催化剂和钙改性的镍基催化剂,用二氧化碳甲炕化反应评价其催化性能,通过X射线衍射（XRD）、程序升温还原（H2-TPR）、程序升温脱附（H2-TPD）和氮气等温吸附脱附等手段对催化剂进行表征,结果表明,Ni／CNTs催化剂中的镍物种比Ni／Al2O3中的镍物种容易还原,同时钙改性Ni／CNTs催化剂更能促进镍物种的还原,添加钙可以促进CNTs载体催化剂的分散度,这些特性能提高钙改性Ni／CNTs催化剂的催化活性和稳定性。     

Complete oxidation of ethylene over supported gold nanoparticle catalysts

Complete oxidation of ethylene was performed over supported noble metals or transition metals oxide catalysts and on monoliths under atmospheric pressure. Gold nanoparticles on Al2O3 or MxOy(M = Mo, Fe, Mn) were prepared by impregnation, coprecipitation, deposition, and dispersion methods. Nanoparticles prepared by impregnation method were irregular and very large above 25 nm, but those by coprecipitation and deposition method were uniformly nanosized at 4-5 nm. The gold nanoparticle were outstandingly active in catalyzing oxidation of ethylene. The activity order of these catalysts with preparation methods was deposition > coprecipitation > impregnation, and Au/Co3O4 prepared by deposition method showed the best performance in ethylene oxidation. The addition of gold particles to MxOy/Al2O3 catalyst enhanced the ethylene oxidation activity significantly. The main role of the gold nanoparticles apparently was to promote dissociative adsorption of oxygen and to enhance the reoxidation of the catalyst.     

Influence of catalyst pretreatments on the catalytic oxidation of toluene over nanostructured platinum based spent catalyst

In this study, we regenerated a nano-structured platinum based spent catalyst by applying thermal gas and acid pretreatment and examined the influence of treatment on the catalytic oxidation of toluene. The spent catalysts were pretreated with air, hydrogen and six different acid aqueous solutions (HCl, H2SO4, HNO3, H3PO4, CH3COOH and C2H2O4). The physicochemical properties of the parent and its modified catalysts were characterized by XRD, BET, TEM, and ICP. The results of light-off curves showed that air and hydrogen treated catalysts were more active than the parent catalyst. In addition, the catalytic activities of toluene oxidation for acid aqueous treated samples were identical with the order of Pt/Al ratio.     

Effect of pretreatment conditions on particle size of bimetallic pt-au catalysts supported on ZnO/Al2O3 and its activity for toluene oxidation

Bimetallic Pt-Au catalysts supported on ZnO/Al2O3 were prepared by incipient wetness impregnation (IW-IMP) method with different pretreatment conditions such as flow velocity, calcination temperature, and heating rate under H2 during the calcination procedure, and characterized by X-ray diffraction (XRD), CO chemisorption, and scanning transmission electron microscopy (STEM) equipped energy dispersive spectroscopy (EDS). Furthermore, catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. Finally, relationship between the particle sizes with pretreatment conditions and catalytic activity for toluene on the bimetallic Pt-Au catalysts was discussed. In these results, nanosized bimetallic Pt-Au particles on ZnO/Al2O3 could be prepared by IW-IMP method. Relationship between the Pt and Au particle size and activity for toluene oxidation was clearly observed.     

Transmitted-light microscopy - a new method for surface structure analysis of cleanable non-woven dust filter media

A series of CeO(2)-ZrO(2) mixed oxides were prepared using coprecipitation method and characterized by BET, oxygen storage capacity (OSC), X-ray diffraction (XRD) and H(2)-temperature-programmed reduction (H(2)-TPR). The catalytic activities toward toluene combustion were investigated in a micro-reactor. The results demonstrate that the catalytic activity of Pt/gamma-Al(2)O(3)/Ce(0.50)Zr(0.50)O(2) monolithic catalyst can be greatly improved by doping metal into Ce(0.50)Zr(0.50)O(2). When doping Y and Mn into Ce(0.50)Zr(0.50)O(2) simultaneously, the catalyst Pt/gamma-Al(2)O(3)/Ce(0.40)Zr(0.40)Y(0.10)Mn(0.10)O(X) shows the highest activity. The T(10) (the temperature of 10% toluene conversion) and the complete conversion temperature (the temperature of 90% toluene conversion) of toluene are 443 and 489K, respectively. Gas hourly space velocity (GHSV) results show that the prepared catalyst can be applied in a wide range of GHSV (from 12,000 to 20,000h(-1)). The catalyst prepared shows great potential for practical application.     

The catalytic oxidation of aromatic hydrocarbons over supported metal oxide

The catalytic activity of metals (Cu, Mn, Fe, V, Mo, Co, Ni, Zn)/gamma-Al2O3 was investigated to bring about the complete oxidation of benzene, toluene and xylene (BTX). Among them, Cu/gamma-Al2O3 was found to be the most promising catalyst based on activity. X-ray diffraction (XRD), Brunauer Emmett Teller method (BET), electron probe X-ray micro analysis (EPMA) and temperature programmed reduction (TPR) by H2 were used to characterize a series of supported copper catalysts. Increasing the calcination temperature resulted in decreasing the specific surface areas of catalysts and, subsequently, the catalytic activity. Copper loadings on gamma-Al2O3 had a great effect on catalytic activity, and 5 wt.% Cu/gamma-Al2O3 catalyst was observed to be the most active, which might be contributed to the well-dispersed copper surface phase. Using TiO2 (anatase), TiO2 (rutile), SiO2 (I) and SiO2 (II) as support instead of gamma-Al2O3, the activity sequence of 5 wt.% Cu with respect to the support was gamma-Al2O3 > TiO2 (rutile) > TiO2 (anatase)>SiO2 (I) > SiO2 (II), and this appeared to be correlated with the distribution of copper on support rather than with the specific surface area of the catalyst. The smaller particle size of copper, due to its high dispersion on support, had a positive effect on catalytic activity. The activity of 5 wt.% Cu/gamma-Al2O3 with respect to the VOC molecule was observed to follow this sequence: toluene > xylene > benzene. Increasing the reactant concentration exerted an inhibiting effect on the catalytic activity.     

Preparation of nanosized Pt-Au alloy catalyst and its activity in methanol oxidation

The alloy catalyst has been widely used because it will be able to improve the activity and selectivity of the single metal catalyst in a given chemical reaction. In this study, the preparation and characteristics of nanosized Pt and Au particles on alumina and their catalytic activity were described. Nanosized Pt-Au catalysts were prepared by impregnation (IMP) method and deposition (DP) method using alumina or ZnO/Al2O3 as support. The size of Pt and Au particles were observed by transmission electron microscopy (TEM), energy dispersive spectroscope (EDS), and X-ray diffraction (XRD). Catalytic activity for oxidation of methanol was measured using a flow reactor. It could be seen that the Pt particle size and dispersion in the alloy catalysts was rarely influenced by preparation methods and Au particles coated by deposition method were well dispersed. TEM images showed that Au particles were well dispersed in the Pt/Au/ZnO/Al2O3 catalyst of which Au particles was supported by deposition method. The catalytic activity for methanol are given in the order of Pt-Au[IMP]/ZnO/Al2O3 > Pt[IMP]/Au[DP]/ZnO/Al2O3 > Au[DP]/Pt[IMP]/ZnO/Al2O3 > Pt-Au[DP]/ZnO/Al2O3. Therefore, Au particle size was doing not play an important role in increasing the oxidation activity, but the Au particles may promote the methanol oxidation.