CuO/CeO_(2)/γ-Al_(2)O_(3)工业球型催化剂的制备及其脱除石灰窑尾气CO的性能

采用分步浸渍法制备了CuO/CeO_(2)/γ-Al_(2)O_(3)工业球型催化剂。通过XRD,SEM,TEM,Raman,H_(2)-TPR等方法对催化剂的结构进行表征,并将CuO/CeO_(2)/γ-Al_(2)O_(3)应用于石灰窑尾气处理中,考察了CuO/CeO_(2)/γ-Al_(2)O_(3)的CO催化氧化效果及使用寿命。实验结果表明,在气体流量为1 m^(3)/h,150℃条件下,CuO/CeO_(2)/γ-Al_(2)O_(3)脱除石灰窑尾气(2%(φ)CO,2%(φ)O_(2),35%(φ)CO_(2)及N2)时,可实现超350 h的稳定运行,且稳定运行后催化剂的结构并未被破坏。

Cl掺杂CuO在Cu^(+)和O空位协同作用下高效电催化还原CO_(2)为C_(2)H_(4)

通过简单的一步水热合成法合成具有富集Cu^(+)和氧空位活性位点的氯掺杂氧化铜催化剂(Cl-CuO),并通过调节氯元素的掺杂量使得Cu基催化剂对乙烯(C_(2)H_(4))拥有较高的选择性和法拉第效率(FE)。结果表明,在-1.2 V[针对可逆氢电极(RHE)]下,C_(2)H_(4)的最大法拉第效率为46.8%;并且在经过15 h电解后,法拉第效率和电流密度无明显下降。Cl-CuO中C_(2)H_(4)的生成归因于Cu^(+)与氧空位的协同作用。

Effect of CeO_(2)on Activity of Catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)for Synthesis of Methanol

The size of the nanoparticles and the number of oxygen vacancies have a significant effect on the catalytic activity of copper-based catalysts used for the synthesis of methanol from syngas.In this study,the authors prepared a series of catalysts CuO/ZnO/Al_(2)O_(3)/CeO_(2)(CZAC)with CuO particles of different sizes and varying number of oxygen vacancies on the surface by changing the added volume of CeO2 by using the co-precipitation method.The properties of the catalysts were characterized and their activity was evaluated by using high-pressure fixed-bed reaction equipment.The results showed that the addition of CeO_(2)to CuO/ZnO/Al_(2)O_(3)not only influenced the size of the CuO particles and metal-metal interactions,but also had an effect on the concentrations of oxygen vacancies and strongly basic sites.The presence of CuO particles of small sizes and a large numbers of oxygen vacancies on the surface of the catalyst were beneficial to its activity for the synthesis of methanol.The catalyst CZAC,when modified by 5%of CeO_(2),recorded CuO particles of the smallest size(8.9 nm),strong intermetallic interactions,and the highest concentrations of oxygen vacancies and strongly basic sites.It also exhibited the highest catalytic activity,with a space-time yield of methanol of 0.315 g/(h·g)that was higher than that of the enterprise RK-5 catalyst[0.215 g/(h·g)].

Fe_2O_3-MnO_2-CuO-Co_2O_3体系红外辐射材料的微波合成与表征

采用微波合成法制备了Fe2 O3 MnO2 CuO Co2 O3 体系红外辐射材料 ,测量了微波合成粉料的红外辐射性能 ,运用XRD ,IR ,SEM和图像分析等测试方法研究了合成粉料的结构和颗粒形态。结果表明 ,采用微波加热在 10 0 0℃保温 10min和在 90 0℃保温 30min ,均得到立方尖晶石结构的合成产物。与常规固相合成法相比 ,微波合成温度减低 ,反应时间缩短。合成粉料的颗粒细小均匀 ,平均粒度分别为 1.175 μm和 1.814 μm。微波合成粉料的红外辐射性能与采用常规固相合成法制备粉料的红外辐射率基本相当 ,其法向全辐射率均达到 0 .84。

MnO_2-CuO-CeO_2复合催化剂的制备及处理化工集装罐清洗废水的应用

针对非均相贵重金属催化剂成本高,非均相过渡金属催化剂性能良好、成本低,但使用寿命短、易流失的特点,研制高效复合MnO2-Cu O-CeO2非均相过渡金属催化剂.采用正交实验对催化剂制备过程中的n(Cu)∶n(Mn)、Ce的摩尔分数、焙烧温度、焙烧时间进行探讨,确定最佳制备条件,并对其结构和组成通过扫描电镜分析、X射线衍射分析及热重分析进行表征.用该催化剂催化氧化模拟苯酚废水,对催化剂用量、氧化剂H2O2用量、反应温度、反应时间进行优化,确定最佳反应条件并利用其进行降解化工集装罐清洗废水的应用研究.研究表明催化剂MnO2-Cu O-CeO2的最佳制备条件为:n(Cu)∶n(Mn)=4∶6、Ce的摩尔分数为10%、焙烧温度为600,℃、焙烧时间为4,h.催化氧化法处理苯酚废水的最佳工艺参数:催化剂用量0.8,g/L、H2O2用量与COD比值为3、反应温度170,℃、反应时间1,h.化工集装罐清洗废水COD去除效果显著,COD去除率达到95%左右.

Local structural evolutions of CuO/ZnO/Al2O3 catalyst for methanol synthesis under operando conditions studied by in situ quick X-ray absorption spectroscopy

In situ quick X-ray absorption spectroscopy(QXAFS) at the Cu and Zn K-edge under operando conditions has been used to unravel the Cu/Zn interaction and identify possible active site of CuO/ZnO/Al_2O_3 catalyst for methanol synthesis. In this work, the catalyst, whose activity increases with the reaction temperature and pressure, was studied at calcined, reduced, and reacted conditions. TEM and EDX images for the calcined and reduced catalysts showed that copper was distributed uniformly at both conditions. TPR profile revealed two reduction peaks at 165 and 195 °C for copper species in the calcined catalyst. QXAFS results demonstrated that the calcined form consisted mainly of a mixed Cu O and Zn O, and it was progressively transformed into Cu metal particles and dispersed Zn O species as the reduction treatment. It was demonstrated that activation of the catalyst precursor occurred via a Cu^+intermediate, and the active catalyst predominantly consisted of metallic Cu and Zn O evenunder higher pressures. Structure of the active catalyst did not change with the temperature or pressure, indicating that the role of the Zn was mainly to improve Cu dispersion.This indicates the potential of QXAFS method in studying the structure evolutions of catalysts in methanol synthesis.

Preparation, Characterization of CuO/CeO_2 and Cu/CeO_2 Catalysts and Their Applications in Low-Temperature CO Oxidation

CeO2 was synthesized via sol-gel process and used as supporter to prepare CuO/CeO2, Cu/CeO2 catalysts by impregnation method. The catalytic properties and characterization of CeO2, CuO/CeO2 and Cu/CeO2 catalysts were examined by means of a microreactor-GC system, HRTEM, XRD, TPR and XPS techniques. The results show that CuO has not catalytic activity and the activity of CeO2 is quite low for CO oxidation. However, the catalytic activity of CuO/CeO2 and Cu/ CeO2 catalysts increases significantly. Furthermore, the activity of CuO/CeO2 is higher than that of Cu/CeO2 catalysts.

A comparative study of CuO/TiO_2-SnO_2,CuO/TiO_2 and CuO/SnO_2 catalysts for low-temperature CO oxidation

Nanometer SnO2 particles were synthesized by sol-gel dialytic processes and used as a support to prepare CuO supported catalysts via a deposition-precipitation method. The samples were characterized by means of TG-DTA, XRD, H2-TPR and XPS. The catalytic activity of the CuO/TiO2-SnO2 catalysts was markedly depended on the loading of CuO, and the optimum CuO loading was 8 wt.% （Tloo = 80 ℃）. The CuO/TiO2-SnO2 catalysts exhibited much higher catalytic activity than the CuO/TiO2 and CuO/SnO2 catalysts. H2-TPR result indicated that a large amount of CuO formed the active site for CO oxidation in 8 wt.% CuO/TiO2-SnO2 catalyst.

Experimental and Kinetic Study of Selective Catalytic Reduction of NO with NH_3 over CuO/Al_2O_3/Cordierite Catalyst

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy Eá of 94.01 kJ·mol-1 and the corresponding p re-exponential factor A′ of 3.39×108 cm3·g-1·s-1 when NH3 is excessive. However, when NH3 is not enough, an E ley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ·mol-1, the corresponding A of 2 .94×109 cm3·g-1·s-1, heat of adsorption-Hads of 87.90 kJ·mol-1 and the corresponding Aads of 9.24 cm3·mol-1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reac-tor design and engineering scale-up.

Preferential oxidation of CO in excess H_2 over the CeO_2/CuO catalyst: Effect of initial support

Three series of CeO2/CuO samples were prepared by impregnation method and characterized by XRD, N2 adsorption-desorption, temperatureprogrammed reduction （TPR）, XPS and TEM techniques. In comparison with the samples prepared with CuO as initial support, the samples with Cu（OH）2 as initial support have higher reducibilities and smaller relative TPR peak areas, and also larger specific surface areas at calcina- tion temperatures of 400 ℃--600 ℃. As a result, Cu（OH）2 is better than CuO as initial support for preferential oxidation of CO in excess H2 （CO-PROX）. The best catalytic performance was achieved on the sample calcined at 600 ℃ and with an atomic ratio of Ce/Cu at 40%. XPS analyses indicate that more interface linkages Ce-O-Cu could be formed when it was calcined at 600 ℃. And the atomic ratio of Ce/Cu at 40% led to a proper reducibility for the sample as illustrated by the TPR measurements.

Catalytic Oxidative Properties and Characterization of CuO/CeO_2 Catalysts

The oxidative properties and characterization of CuO, CeO 2 and CuO/CeO 2 cata lysts were examined by means of a CO micro-reactor GC system, TPR, XPS and X-r ay diffraction Rietveld methods. The results show that either CuO or CeO 2 ac tivity is quite low for CO oxidation. However, when CuO and CeO 2 are mixed, the oxidative activity of the catalyst increases significantly, probably owing to the valency status of copper species (Cu 2+ and Cu+) on the CeO 2 surfa ce, the dispersion and reducibility. XPS surface analysis shows that CuO loading is very important in forming of either Cu 2+ or Cu+. Rietveld analysis s hows that some CuO, which has smaller ion radius than Ce 4+, enters the Ce O 2 lattice after CuO and CeO 2 are mixed. When the CuO loading reaches 5.0%, the size of CuO crystals is a minimum (6.1 nm) and the micro-strain value i s a maximum (2.86×10 -3), resulting in high surface energy and the best ac tivity for CO oxidation.

Ce_xTi_(1-x)O_2 Mixed Oxides Supported CuO Catalyst for NO Reduction by CO

Ce x Ti 1- x O 2 mixed oxides of different mole ratios ( x =0, 0.1, 0.2～0.9, 1.0) were prepared by co precipitation of TiCl 4 with Ce(NO 3) 3 and then loaded with different amounts of CuO. The effects of CuO on NO+CO reaction were investigated, and the structure and reductive properties of various CuO/Ce x Ti 1- x O 2 were characterized by the methodologies of BET, TPR and XRD. The results show that different Ce/Ti mole ratios and calcination temperatures induce changes of structure and reductive properties of the Ce x Ti 1- x O 2 mixed oxides. When x =0.1～0.5, amorphous CeTi 2O 6 phase mainly forms at 650 ℃ compared to the formation of CeTi 2O 6 which crystallizes at 800 ℃. When x >0.6, some TiO 2 enters the CeO 2 lattice and a CeO 2 TiO 2 solid solution is formed. The activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 650 ℃ is largely affected by the x values, which is the highest when x =0.3, 0.4 and 0.9. The NO conversion reaches 70% at a reaction temperature of 150 ℃. By comparison, the x values have little effect on the activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 800 ℃ . There are strong interactions between CuO and CeTi 2O 6, i.e., formation of the CeTi 2O 6 phase shifts the CuO reduction peak temperature from 380 to 200 ℃, and CuO, in turn, shifts the CeTi 2O 6 reduction peak temperature from 600 to 300 ℃.

Effect of Addition of Base on Ceria and Reactivity of CuO/CeO_2 Catalysts for Low-Temperature CO Oxidation

In this work, we have reported the influence of the addition of base （KOH） on the physicochemical property of ceria synthesized by alcohothermal process, and the alcohothermal mechanism was also put forward. Furthermore, the prepared CeO2 was used as the support to prepare CuO/CeO2 catalysts via the wet impregnation method. The samples were characterized by N2 adsorption-desorption, X-ray powder diffraction （XRD）, high resolution transmission electron microscopy （HRTEM）, and temperatureprogrammed reduction by H2 （H2-TPR）. The catalytic properties of the CuO/CeO2 catalysts for lowtemperature CO oxidation were studied using a microreactor-GC system. The crystal size of CeO2-A was much smaller than that of CeO2-B, and the corresponding copper oxide catalysts exhibited higher catalytic activity than that of the CeO2-B-supported catalysts under the same reaction conditions. The alcohothermal mechanism indicated that KOH plays a key role in determining the physicochemical and catalytic properties of ceria-based materials.

Stable CuO/La_(2)Sn_(2)O_(7) catalysts for soot combustion:Study on the monolayer dispersion behavior of CuO over a La_(2)Sn_(2)O_(7) pyrochlore support

To understand the dispersion behavior of metal oxides on composite oxide supports and with the expectation of developing more feasible catalysts for soot oxidation,CuO/La_(2)Sn_(2)O_(7)samples containing varied CuO loadings were fabricated and characterized by different techniques and density functional theory calculations.In these catalysts,a spontaneous dispersion of CuO on the La_(2)Sn_(2)O_(7)pyrochlore support formed,having a monolayer dispersion capacity of 1.90 mmol CuO/100 m^(2) La_(2)Sn_(2)O_(7)surface.When loaded below this capacity,CuO exists in a sub-monolayer or monolayer state.X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,and Bader charge and density of states analyses indicate that there are strong interactions between the sub-monolayer/monolayer CuO and the La_(2)Sn_(2)O_(7)support,mainly through the donation of electrons from Cu to Sn at the B-sites of the structure.In contrast,Cu has negligible interactions with La at the A-sites.This suggests that,in composite oxide supports containing multiple metals,the supported metal oxide interacts preferentially with one kind of metal cation in the support.The Raman,in situ diffuse reflectance infrared Fourier transform spectroscopy,and XPS results confirmed the formation of both O2^(-)and O2^(2-)as the active sites on the surfaces of the CuO/La_(2)Sn_(2)O_(7)catalysts,and the concentration of these active species determines the soot combustion activity.The number of active oxygen anions increased with increase in CuO loading until the monolayer dispersion capacity was reached.Above the monolayer dispersion capacity,microsized CuO crystallites formed,and these had a negative effect on the generation of active surface oxygen sites.In summary,a highly active catalyst can be prepared by covering the surface of the La_(2)Sn_(2)O_(7)support with a CuO monolayer.

Synthesis and study of λ-MnO_2 supported Pt nanocatalyst for methanol electro-oxidation

A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, and energy disperse spectroscopy（EDS） were used for catalyst structure and morphology characterization, which showed that the metallic Pt particles were attached on a λ-MnO2 surface through the interaction between Pt and λ-MnO2.Cyclic voltammetry（CV） was used to test the catalytic activity of Pt/λ-MnO2 toward methanol oxidation, which showed that Pt/λ-MnO2 catalyst has much higher catalytic activity than baseline Pt/C catalyst.

Effects of Carrier on CuO/TiO_2 and CuO/Ti_(0.5)Zr_(0.5)O_2 Catalysts in the NO+CO Reaction

Using TiO2 and Ti0.5Zr0.5O2 as carriers, the CuO/TiO2 and CuO/Ti0.5Zr0.5O2 catalystswere prepared by the impregnation method with Cu(NO3)2 as active component. The catalyticactivities in NO+CO reaction were investigated using a microreactor-GC system, and structure andreducibility of catalysts were characterized by means of physical adsorption, TPR, XRD, NO-TPDtechnologies. It was found that the activity of CuO/Ti0.5Zr0.5O2 catalyst was higher than that ofCuO/TiO2, probably due to the large specific surface area of Ti0.5Zr0.5O2 that played an importantrole in NO+CO reaction.

高活性CuO/Al_(2)O_(3)催化剂的制备及加氢性能研究

负载型催化剂中表面活性组分的分散度影响催化剂的性能,因此,合理调控合成条件提高活性组分分散度是高效催化剂开发的有效策略。通过控制焙烧条件(氛围、温度、时长)制备了多种负载型铜基催化剂(CuO/Al_(2)O_(3)),利用SEM和XRD研究了合成条件对催化剂结构和表面组成的影响,考察了所制备催化剂在对硝基苯酚(4-NP)催化加氢反应中的性能。研究结果表明,在250℃、N_(2)氛围中热处理6 h所制备的催化剂在3 min内即可实现4-NP及其他芳香族硝基化合物90.5%的催化加氢效率。此外,该催化剂循环利用5次仍有较高的活性,在实际工业生产中具有巨大的应用潜力。

Effect of yttrium addition on water-gas shift reaction over CuO/CeO_2 catalysts

This paper presented a study on the role of yttrium addition to CuO/CeO2 catalyst for water-gas shift reaction. A single-step co-precipitation method was used for preparation of a series of yttrium doped CuO/CeO2 catalysts with yttrium content in the range of 0-5wt.%. Properties of the obtained samples were characterized and analyzed by X-ray diffraction （XRD）, Raman spectroscopy, H2-TPR, cyclic voltammetry （CV） and the BET method. The results revealed that catalytic activity was increased with the yttrium content at first, but then decreased with the further increase of yttrium content. Herein, CuO/CeO2 catalyst doped with 2wt.% of yttrium showed the highest catalytic activity （CO conversion reaches 93.4% at 250 ℃） and thermal stability for WGS reaction. The catalytic activity was correlated with the surface area, the area of peak γ of H2-TPR profile （i.e., the reduction of surface copper oxide （crystalline forms） interacted with surface oxygen vacancies on ceria）, and the area of peak C2 and A1 （Cu^0→←Cu^2＋ in cyclic voltammetry process）, respectively. Besides, Raman spectra provided evidences for a synergistic Cu-Ovacancy interaction, and it was indicated that doping yttrium may facilitate the formation of oxygen vacancies on ceria.

Effect of Addition of Sm_2O_3 on Property of CuO-γ-Al_2O_3 Catalyst

Effect of the addition of Sm 2O 3 on CuO γ Al 2O 3 catalyst for CO oxidation reaction was investigated. The result shows that the right amount of Sm 2O 3 can promote the adsorption of the surface oxygen and recovery of CuO γ Al 2O 3 catalyst. Sm 2O 3 plays an important role in change of γ Al 2O 3 phase into θ Al 2O 3 phase. In addition, the right amount of Sm 2O 3(5%) can improve the oxidation activity of the CuO γ Al 2O 3 catalyst. Whereas an excess of Sm 2O 3(10%) makes the CuO crystal in CuO γ Al 2O 3 catalyst become bigger and restrain the oxidation activity of the CuO γ Al 2O 3 catalyst.

CuO/活性炭催化湿式氧化甲基橙废水的研究

基于以硝酸铜为活性组分的前驱物,采取浸渍焙烧法制备了CuO/活性炭催化剂,并以H_(2)O_(2)为氧化剂,对比了在常压条件下催化湿式氧化工艺中处理质量浓度500 mg·L^(-1)甲基橙模拟废水的效果,分别考察了不同CuO/活性炭催化剂加入量、质量分数30%的H_(2)O_(2)氧化剂用量、脱色反应时间、脱色反应温度对甲基橙废水脱色率的影响。结果表明:随着CuO/活性炭催化剂加入量、30%H_(2)O_(2)氧化剂用量、反应温度的不断增加,甲基橙废水的脱色率明显增大;而增加反应时间对甲基橙废水脱色率增加幅度较小。当CuO/活性炭催化剂加入量为0.1 g、质量分数30%H_(2)O_(2)氧化剂加入量为6 mL、催化反应时间为2 h、催化反应温度为35℃时,其对甲基橙废水的脱色率可达到82.44%。