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3D printing of poly(ethyleneimine)-functionalized Mg-Al mixed metal oxide monoliths for direct air capture of CO_(2)
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作者 Qingyang Shao Zhuozhen Gan +4 位作者 Bingyao Ge Xuyi Liu Chunping Chen Dermot O’Hare Xuancan Zhu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第9期491-500,共10页
Direct air capture(DAC)of CO_(2)plays an indispensable role in achieving carbon-neutral goals as one of the key negative emission technologies.Since large air flows are required to capture the ultradilute CO_(2)from t... Direct air capture(DAC)of CO_(2)plays an indispensable role in achieving carbon-neutral goals as one of the key negative emission technologies.Since large air flows are required to capture the ultradilute CO_(2)from the air,lab-synthesized adsorbents in powder form may cause unacceptable gas pressure drops and poor heat and mass transfer efficiencies.A structured adsorbent is essential for the implementation of gas-solid contactors for cost-and energy-efficient DAC systems.In this study,efficient adsorbent poly(ethyleneimine)(PEI)-functionalized Mg-Al-CO_(3)layered double hydroxide(LDH)-derived mixed metal oxides(MMOs)are three-dimensional(3D)printed into monoliths for the first time with more than 90%adsorbent loadings.The printing process has been optimized by initially printing the LDH powder into monoliths followed by calcination into MMO monoliths.This structure exhibits a 32.7%higher specific surface area and a 46.1%higher pore volume,as compared to the direct printing of the MMO powder into a monolith.After impregnation of PEI,the monolith demonstrates a large adsorption capacity(1.82 mmol/g)and fast kinetics(0.7 mmol/g/h)using a CO_(2)feed gas at 400 ppm at 25℃,one of the highest values among the shaped DAC adsorbents.Smearing of the amino-polymers during the post-printing process affects the diffusion of CO_(2),resulting in slower adsorption kinetics of pre-impregnation monoliths compared to post-impregnation monoliths.The optimal PEI/MeOH ratio for the post-impregnation solution prevents pores clogging that would affect both adsorption capacity and kinetics. 展开更多
关键词 3D printing mixed metal oxides Amine functionalization Structured adsorbent Direct air capture
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Highly dispersed MgInCe-mixed metal oxides catalyzed direct carbonylation of glycerol and CO_(2)into glycerol carbonate
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作者 Xufang Chen Xin Shu +5 位作者 Yanru Zhu Jian Zhang Zhigang Chai Hongyan Song Zhe An Jing He 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第8期153-163,共11页
Glycerol carbonate,an important glycerol value-added product,has been widely used as an active intermediate and inert solvent in the synthesis of cosmetics,detergents,chemical intermediates,polymers,and so on.The dire... Glycerol carbonate,an important glycerol value-added product,has been widely used as an active intermediate and inert solvent in the synthesis of cosmetics,detergents,chemical intermediates,polymers,and so on.The direct carbonylation from glycerol with CO_(2)is considered a promising route,but still tough work due to the thermodynamic stability and the kinetic inertness of CO_(2).In this work,highlyselective direct carbonylation of glycerol and CO_(2)into glycerol carbonate has been achieved over highly dispersed MgInCe-mixed metal oxides(MgInCe-MMO),which were prepared through the topological transformation derived from the MgInCe-layered double hydroxides(MgInCe-LDHs).By precisely modulating the surface basic-acidic properties and the oxygen vacancies,an efficient carbonylation of glycerol with CO_(2)has been achieved with a selectivity of up to>99%to glycerol carbonate.Deep investigation into the synergistic catalysis of base-acid sites and oxygen vacancies has been clarified. 展开更多
关键词 Catalytic reaction engineering Glycerol carbonate Direct carbonylation from glycerol Carbon dioxide mixed metal oxides Synergistic catalysis
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Cooperative structure of Li/Ni mixing and stacking faults for achieving high-capacity Co-free Li-rich oxides
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作者 Zhen Wu Yu-Han Zhang +9 位作者 Hao Wang Zewen Liu Xudong Zhang Xin Dai Kunyang Zou Xiaoming Lou Xuechen Hu Lijing Ma Yan Liu Yongning Liu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第8期315-324,I0007,共11页
Co-free Li-rich layered oxides(LLOs)are emerging as promising cathode materials for Li-ion batteries due to their low cost and high capacity.However,they commonly face severe structural instability and poor electroche... Co-free Li-rich layered oxides(LLOs)are emerging as promising cathode materials for Li-ion batteries due to their low cost and high capacity.However,they commonly face severe structural instability and poor electrochemical activity,leading to diminished capacity and voltage performance.Herein,we introduce a Co-free LLO,Li_(1.167)Ni_(0.222)Mn_(0.611)O_(2)(Cf-L1),which features a cooperative structure of Li/Ni mixing and stacking faults.This structure regulates the crystal and electronic structures,resulting in a higher discharge capacity of 300.6 mA h g^(-1)and enhanced rate capability compared to the typical Co-free LLO,Li_(1.2)Ni_(0.2)Mn_(0.6)O_(2)(Cf-Ls).Density functional theory(DFT)indicates that Li/Ni mixing in LLOs leads to increased Li-O-Li configurations and higher anionic redox activities,while stacking faults further optimize the electronic interactions of transition metal(TM)3d and non-bonding O 2p orbitals.Moreover,stacking faults accommodate lattice strain,improving electrochemical reversibility during charge/discharge cycles,as demonstrated by the in situ XRD of Cf-L1 showing less lattice evolution than Cf-Ls.This study offers a structured approach to developing Co-free LLOs with enhanced capacity,voltage,rate capability,and cyclability,significantly impacting the advancement of the next-generation Li-ion batteries. 展开更多
关键词 Co-free Li-rich oxides Li/Ni mixing Stacking faults Electronic structure
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Accurate estimation of Li/Ni mixing degree of lithium nickel oxide cathode materials
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作者 陈鹏浩 徐磊 +1 位作者 禹习谦 李泓 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期631-635,共5页
Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials.However,accurately measuring the Li/Ni mixing degree is difficult due to the preferred orient... Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials.However,accurately measuring the Li/Ni mixing degree is difficult due to the preferred orientation of labbased XRD measurements using Bragg–Brentano geometry.Here,we find that employing spherical harmonics in Rietveld refinement to eliminate the preferred orientation can significantly decrease the measurement error of the Li/Ni mixing ratio.The Li/Ni mixing ratio obtained from Rietveld refinement with spherical harmonics shows a strong correlation with discharge capacity,which means the electrochemical capacity of lithium nickel oxide and high-nickel ternary cathode can be estimated by the Li/Ni mixing degree.Our findings provide a simple and accurate method to estimate the Li/Ni mixing degree,which is valuable to the structural analysis and screening of the synthesis conditions of lithium nickel oxide and high-nickel ternary cathode materials. 展开更多
关键词 lithium nickel oxide high-nickel ternary cathode Li/Ni mixing spherical harmonics function discharge capacity
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Comparative structural and electrochemical properties of mixed P2/O′3-layered sodium nickel manganese oxide prepared by sol-gel and electrospinning methods:Effect of Na-excess content 被引量:1
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作者 Thongsuk Sichumsaeng Atchara Chinnakorn +3 位作者 Ornuma Kalawa Jintara Padchasri Pinit Kidkhunthod Santi Maensiri 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第10期1887-1896,共10页
The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X... The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors. 展开更多
关键词 sodium nickel manganese oxide mixed P2/O′3-type Na-excess content sol-gel method electrospinning method electrochemical properties
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Sub-2 nm mixed metal oxide for electrochemical reduction of carbon dioxide to carbon monoxide
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作者 Devina Thasia Wijaya Andi Haryanto +2 位作者 Hyun Woo Lim Kyoungsuk Jin Chan Woo Lee 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第9期303-310,共8页
Mixed metal oxide(MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components:reduced metal and its metal oxide counterpart during an electrocatalytic reaction... Mixed metal oxide(MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components:reduced metal and its metal oxide counterpart during an electrocatalytic reaction.Here,a synthetic method utilizing a MOF-derived micro/mesoporous carbon as a template to prepare sub-2 nm MMO catalysts for CO_(2) electro reduction is reported.Starting from the zeolite imidazolate framework(ZIF-8),the pyrolyzed derivatives were used to synthesize sub-2 nm Pd-Ni MMO with different compositions.The Ni-rich(Pd_(20)-Ni_(80)/ZC) catalyst exhibits unexpectedly superior performance for CO production with an improved Faradaic efficiency(FE) of 95.3% at the current density of 200 mA cm^(-2) at-0.56 V vs.reversible hydrogen electrode(RHE) compared to other Pd-Ni compositions.X-ray photoelectron spectroscopy(XPS) analysis confirms the presence of Ni^(2+) and Pd^(2+) in all compositions,demonstrating the presence of MMO.Density functional theory(DFT) calculation reveals that the lower CO binding energy on the surface of the Pd_(20)-Ni_(80) cluster eases CO desorption,thus increasing its production.This work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface. 展开更多
关键词 Carbon dioxide reduction mixed metal oxide NANOALLOY Carbon monoxide Metal-organic framework
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Synthesis and highly efficient photocatalytic activity of mixed oxides derived from ZnNiAl layered double hydroxides 被引量:6
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作者 张丽 戴超华 +2 位作者 张秀秀 刘又年 阎建辉 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第9期2380-2389,共10页
ZnO/NiO/ZnAl2O4 mixed-metal oxides were successfully synthesized through a hydrotalcite-like precursor route, in which appropriate amounts of metal salts solutions were mixed to obtain a new series of ZnNiAl layered d... ZnO/NiO/ZnAl2O4 mixed-metal oxides were successfully synthesized through a hydrotalcite-like precursor route, in which appropriate amounts of metal salts solutions were mixed to obtain a new series of ZnNiAl layered double hydroxides(LDHs) as precursors, followed by calcination under different temperatures. The as-obtained samples were characterized by SEM, HRTEM, TEM, XRD, BET, TG-DTA, and UV-Vis spectra techniques. The photocatalytic activities of the samples were evaluated by degradation of methyl orange(MO) under the simulated sunlight irradiation. The effects of Zn/Ni/Al mole ratio and calcination temperature on the composition, morphology and photocatalytic activity of the samples were investigated in detail. The results indicated that compared with ZnNiAl-LDHs, the mixed-metal oxide showed superior photocatalytic performance for the degradation of MO. A maximum of 97.3% photocatalytic decoloration rate within 60 min was achieved from the LDH with the Zn/Ni/Al mole ratio of 2:1:1 and the calcination temperature of 500 ℃, which much exceeded that of Degussa P25 under the same conditions. The possible mechanism of photocatalytic degradation over ZnO/NiO/ZnAl2O4 was discussed. 展开更多
关键词 ZnNiAl layered double hydroxide mixed oxide photocatalytic degradation phototatalytic activity
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Catalytic reduction of SO_2 by CO over CeO_2-TiO_2 mixed oxides 被引量:5
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作者 张丽 秦毅红 +3 位作者 陈白珍 彭亚光 何汉兵 袁依 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第11期2960-2965,共6页
The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and catalytic activity tests. Acco... The structure and catalytic desulfurization characteristics of CeO2-TiO2 mixed oxides were investigated by means ofX-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and catalytic activity tests. According to the results, a CeO2-TiO2solid solution is formed when the mole ratio of cerium to titanium n(Ce):n(Ti) is 5:5 or greater, and the most suitable n(Ce):n(Ti) isdetermined as 7:3, over which the conversion rate of SO2 and the yield of sulfur at 500℃ reach 93% and 99%, respectively.According to the activity testing curve, Ce0.7Ti0.3O2 (n(Ce):n(Ti)=7:3) without any pretreatment can be gradually activated by reagentgas after about 10 min, and reaches a steady activation status 60 min later. The XPS results of Ce0.7Ti0.3O2 after different time ofSO2+CO reaction show that CeO2 is the active component that offers the redox couple Ce4+/Ce3+ and the labile oxygen vacancies, andTiO2 only functions as a catalyst structure stabilizer during the catalytic reaction process. After 48 h of catalytic reaction at 500℃,Ce0.7Ti0.3O2 still maintains a stable structure without being vulcanized, demonstrating its good anti-sulfur poisoning performance. 展开更多
关键词 CeO2-TiO2 mixed oxides solid solution catalytic reduction carbon monoxide sulfur dioxide
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Cycling performance of layered oxide cathode materials for sodium-ion batteries
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作者 Jinpin Wu Junhang Tian +1 位作者 Xueyi Sun Weidong Zhuang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第7期1720-1744,共25页
Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the applicat... Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials. 展开更多
关键词 sodium-ion battery layered oxide materials cycling performance bulking doping surface coating concentration gradient mixed structure high-entropy
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A rationale for the development of thermally stable nanostructured CeO_2-ZrO_2-containing mixed oxides 被引量:10
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作者 Roberta Di Monte Jan Kapar +1 位作者 Heather Bradshaw Colin Norman 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第2期136-140,共5页
CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for... CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides. 展开更多
关键词 CeO2-ZrO2 mixed oxides CeO2-ZrO2 solid solution CeO2-ZrO2 mixed oxides thermal stability of three-way catalysts oxygen storage capacity rare earths
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Catalytic performance for methane combustion of supported Mn-Ce mixed oxides 被引量:7
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作者 士丽敏 储伟 +2 位作者 瞿芬芬 胡金燕 李民敏 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第6期836-840,共5页
A series of supported Mn-Ce mixed oxide catalysts were prepared by the impregnation method and used for the oxidation of methane. The catalysts were characterized by N2 adsorption (BET), X-ray diffraction (XRD), l... A series of supported Mn-Ce mixed oxide catalysts were prepared by the impregnation method and used for the oxidation of methane. The catalysts were characterized by N2 adsorption (BET), X-ray diffraction (XRD), laser Raman spectrum (LRS), and temperature programmed reduction (TPR) techniques. The XRD and LRS results confirmed the high dispersion of active components or formation of solid solution between manganese and cerium oxides in the bulk and on the surface of mixed oxide catalysts. The reducibility was remarkably promoted by the stronger synergistic interaction between the two oxides from H2-TPR measurements. As expected, all the experimental mixed oxide catalysts showed excellent activity for methane combustion at low temperature. Especially, for the catalyst with Mn-Ce ratio 3:7, methane conversion reached 92% at a temperature as low as 470 ℃. 展开更多
关键词 Mn-Ce mixed oxides solid solution methane combustion rare earths
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Effect of Manganese Doping on Oxygen Storage Capacity of Ceria-Zirconia Mixed Oxides 被引量:7
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作者 吴晓东 梁清 翁端 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第5期549-553,共5页
CeO2-ZrO2-MnOx mixed oxide series were prepared by sol-gel method. CO pulse and CO-O2 cycle measurements were carried out to examine the oxygen storage complete capacity (OSCC) and dynamic oxygen storage capacity (... CeO2-ZrO2-MnOx mixed oxide series were prepared by sol-gel method. CO pulse and CO-O2 cycle measurements were carried out to examine the oxygen storage complete capacity (OSCC) and dynamic oxygen storage capacity (OSC) of the samples. The doping method brought about strong interactions between manganese oxide and ceria, both in the bulk and on the surface. Only a small part of Mn cations are incorporated into the ceria lattice to form solid solutions and the remaining are left on the surface as finely dispersed Mn3O4. The OSC behaviors of the materials are influenced by the doping amount of Mn and the solubility of Mn in the CeO2 lattice. The OSC is more easily affected by available contents of oxygen storage components when the measurement frequency is low. Comparatively, the concentration of lattice defects, which affects the mobility of bulk oxygen, is the determining factor under high frequency. 展开更多
关键词 CeO2-ZrO2 mixed oxides Mn doping OSCC dynamic OSC rare earths
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Recent advance on VOCs oxidation over layered double hydroxides derived mixed metal oxides 被引量:9
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作者 Shuangde Li Dongdong Wang +1 位作者 Xiaofeng Wu Yunfa Chen 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第4期550-560,共11页
Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)a... Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)as precursors,are extensively used as catalysts for VOCs oxidation due to their uniformity advantage.This review summarizes the developments in the LDH-derived VOCs heterogeneous catalytic oxidation over the last 10 years.Particularly,it addresses the VOCs abatement performance over MMO,noble metal/MMO,core-shell structured MMO,and integral MMO film catalysts originating from LDHs.Moreover,it highlights the water vapor effect and oxidation mechanism.This review indicates that LDH-based catalysts are a category of important VOCs oxidation materials. 展开更多
关键词 Volatile organic compounds oxidation Layered double hydroxides mixed metal oxides Water vapor oxidation mechanism
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Enhanced selective catalytic reduction of NO with NH3 via porous micro-spherical aggregates of Mn–Ce–Fe–Ti mixed oxide nanoparticles 被引量:4
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作者 Junqi Tian Ke Zhang +6 位作者 Wei Wang Fu Wang Jianming Dan Shengchao Yang Jinli Zhang Bin Dai Feng Yu 《Green Energy & Environment》 SCIE CSCD 2019年第3期311-321,共11页
We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitatio... We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst. 展开更多
关键词 Mn-Ce-Fe-Ti mixed oxide POROUS MICROSPHERES Spray drying Selective catalytic reduction DENITRATION
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Properties of TiO_2-SiO_2 Mixed Oxides and Photocatalytic Oxidation of Heptane and Sulfur Dioxide 被引量:3
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作者 XIEChao XUZi-li YANGQiu-jing LINa WANGDe-bao DUYao-guo 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2005年第1期48-52,共5页
A series of TiO 2-XSiO 2[X denotes the molar fraction(%) of silica in the mixed oxides] with different \{n(Ti)\}/n(Si) ratios was prepared with ammonia water as a hydrolysis catalyst. The photocatalysts prepared wer... A series of TiO 2-XSiO 2[X denotes the molar fraction(%) of silica in the mixed oxides] with different \{n(Ti)\}/n(Si) ratios was prepared with ammonia water as a hydrolysis catalyst. The photocatalysts prepared were characterized by XRD, thermal analysis, FTIR, UV-Vis and SPS. The characterization results of FTIR and UV-Vis spectra show that Ti atoms were gradually changed from octahedral coordination to tetrahedral coordination with the addition of silica, which is not beneficial for obtaining strong Brnsted acidity and higher photocatalytic activity. The photocatalytic activity experiments, which were conducted by using heptane(or SO 2) as the model reactant, showed that TiO 2-SiO 2 containing a suitable amount of silica can exhibit much higher photocatalytic activity than pure TiO 2. The enhanced photocatalytic activity can be attributed to three following factors: (1) smaller crystalline size; (2) higher thermal stability; (3) the new strong Brnsted acidity. 展开更多
关键词 TiO 2-SiO 2 mixed oxide Basic hydrolysis Photocatalytic oxidation
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Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O_2 Mixed Oxide by Mechanochemical Processing 被引量:2
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作者 程昌明 李永绣 +1 位作者 周雪珍 陈伟凡 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第6期775-779,共5页
Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the cryst... Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains. 展开更多
关键词 ceria-zirconia mixed oxide ultra-fine powders mechanochemical process rare earths
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Co–Cr–O mixed oxides for low–temperature total oxidation of propane: Structural effects, kinetics, and spectroscopic investigation 被引量:4
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作者 Wen-Min Liao Pei-Pei Zhao +3 位作者 Bing-Heng Cen Ai-Ping Jia Ji-Qing Lu Meng-Fei Luo 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第3期442-453,共12页
A series of Co–Cr–O mixed oxides with different Co/Cr molar ratios are synthesized and tested for the total oxidation of propane.The reaction behaviors are closely related to the structural features of the mixed oxi... A series of Co–Cr–O mixed oxides with different Co/Cr molar ratios are synthesized and tested for the total oxidation of propane.The reaction behaviors are closely related to the structural features of the mixed oxides.The catalyst with a Co/Cr molar ratio of 1:2(1 Co2 Cr)and a spinel structure has the best activity(with a reaction rate of 1.38μmol g^–1 s^–1 at 250℃),which is attributed to the synergistic roles of its high surface acidity and good low-temperature reducibility,as evidenced by the temperature-programmed desorption of ammonia,reduction of hydrogen,and surface reaction of propane.Kinetic study shows that the reaction orders of propane and oxygen on the 1 Co2 Cr catalyst(0.58±0.03 and 0.34±0.05,respectively)are lower than those on the 2 Co1 Cr catalyst(0.77±0.02 and 0.98±0.16,respectively)and 1 Co5 Cr(0.66±0.05 and 1.30±0.11,respectively),indicating that the coverages of propane and oxygen on 1 Co2 Cr are higher than those on the other catalysts due to its higher surface acidity and higher reducibility.In addition,in-situ diffuse reflectance infrared spectroscopic investigation reveals that the main surface species on 1 Co2 Cr during the reaction are polydentate carbonate species,which accumulate on the surface at low temperatures(<250℃)but decompose at relatively high temperatures. 展开更多
关键词 Propane combustion Co-Cr mixed oxides REDUCIBILITY Surface acidity KINETICS
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Ethylbenzene to styrene over ZrO_2-based mixed metal oxide catalysts with CO_2 as soft oxidant 被引量:3
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作者 NanzheJiang Abhishek Burri Sang-Eon Park 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第1期3-15,共13页
ZrO2-based mixed metal oxide catalysts for the industrially important dehydrogenation process of ethylbenzene to styrene monomer have been explored by our group for the past 20 years.These efforts were subjected to th... ZrO2-based mixed metal oxide catalysts for the industrially important dehydrogenation process of ethylbenzene to styrene monomer have been explored by our group for the past 20 years.These efforts were subjected to the activation of CO2 over mixed metal oxide catalysts and resulted in several promising benefits to the dehydrogenation processes,such as stabilized conversion and selectivity,suppressed coke formation and commercially-acceptable longevity.In this review,we summarize the most recent developments on ZrO2-based mixed metal oxide catalysts,including the further optimization of sol-gel process in the synthesis of catalysts,rationalizing acid-base properties by doping,co-operative properties between redox and acid-base active sites and additional promoters towards the effective improvement of the longevity of catalysts. 展开更多
关键词 oxidative dehydrogenation Carbon dioxide activation Zirconia-based mixed oxide Acid-base properties Redox properties
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Preparation and characterization of Cu-Ce-La mixed oxide as water-gas shift catalyst for fuel cells application 被引量:2
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作者 智科端 刘全生 +2 位作者 赵瑞岗 何润霞 张利峰 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第4期538-543,共6页
Cu-Ce-La mixed oxides were prepared by three precipitation methods (coprecipitation, homogeneous precipitation, and deposition precipitation) with variable precipitators and characterized using X-ray diffraction, BE... Cu-Ce-La mixed oxides were prepared by three precipitation methods (coprecipitation, homogeneous precipitation, and deposition precipitation) with variable precipitators and characterized using X-ray diffraction, BET, temperature-programmed reduction, and catalytic reaction for the water-gas shift. The Cu-Ce-La mixed oxide prepared by coprecipitation method with NaOH as precipitator presented the highest activity and thermal stability. Copper ion substituted quadrevalent ceria entered CeO2 (111) framework was in favor of activity and thermal stability of catalyst. The crystallinity of fresh catalysts increased with the reduction process. La^3+ or Ce^4+ substituted copper ion entered the CeO2 framework during reduction process. The coexistence of surface copper oxide (crystalline) and pure bulk crystalline copper oxide both contributed to the high activity and thermal stability of Cu-Ce-La mixes oxide catalyst. 展开更多
关键词 Cu-Ce-La mixed oxide water-gas shift reaction PRECIPITATION precipitator rare earths
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Structure and Catalytic Behavior of CuO-ZrO-CeO_2 Mixed Oxides 被引量:1
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作者 王恩过 陈诵英 《Journal of Rare Earths》 SCIE EI CAS CSCD 2002年第5期533-537,共5页
The effect of doping CuO on the structure and properties of zirconia ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structu... The effect of doping CuO on the structure and properties of zirconia ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO ZrO CeO 2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability. 展开更多
关键词 rare earths mixed oxide CO oxidation copper oxide
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