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Effects of impregnation sequence on the NH_(3)-SCR activity and Hydrothermal stability of a Ce-Nb/SnO_(2) catalyst

Journal of Environmental Sciences 2024年第4期138卷 450-457页

作者： Ying Zhu Wenpo Shan Zhihua Lian Jingjing Liu Yan Zhang Hong He Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control Ningbo Urban Environment Observation and Research StationInstitute of Urban EnvironmentChinese Academy of SciencesNingbo 315800China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Hydrothermal stability is crucial for the practical application of deNO_(x)catalyst on diesel vehicles,for the selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).SnO_(2)-based materials possess superior Hydrothermal stability,which is attractive for the development of NH_(3)-SCR catalyst.In this work,a series of Ce-Nb/SnO_(2)catalysts,with Ce and Nb loading on SnO_(2)support,were prepared by impregnation method.It was found that,the NH_(3)-SCR activities and hydrothermal stabilities of the Ce-Nb/SnO_(2)catalysts significantly varied with the impregnation sequences,and the Ce-Nb(f)/SnO_(2) catalyst that firstly impregnated Nb and then impregnated Ce exhibited the best performance.The characterization results revealed that CeNb(f)/SnO_(2)possessed appropriate acidity and redox capability.Furthermore,the strong synergistic effect between Nb and Sn species stabilized the structure and maintained the dispersion of acid sites.This study may provide a new understanding for the effect of impregnation sequence on activity and Hydrothermal stability and a new environmental-friendly NH_(3)-SCR catalyst with potential applications for NO_(x)removal from diesel and hydrogenfueled engines.

关键词： NO_(x)emission control NH_(3)-SCR Hydrothermal stability Ce-Nb/SnO_(2)catalyst Impregnation sequence

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Possible negative influences of increasing content of cerium on activity and Hydrothermal stability of Rh/ceria-zirconia three-way catalysts

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Journal of Rare Earths 2021年第7期39卷 797-804,I0002页

作者： Tianming Huang Meiqing Shen Guanghao Cheng Yunhao Wang Jianqiang Wang Wei Li Se HOh Gongshin Qi Ming Yang Jun Wang Key Laboratory for Green Chemical Technology of State Education Ministry School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300350China State Key Laboratory of Engines Tianjin UniversityTianjin 300350China Chemical and Materials Systems Laboratory General Motors Global Research and Development30470 Harley Earl BlvdWarrenMl 48092USA

The activity and Hydrothermal stability of the Rh/Ce_(x)Zr_(1-x)O_(2)(x=0,0.05,0.3,0.5) model three-way catalysts for gasoline vehicle emissions control were investigated in this work.Among the Rh/Ce_(x)Zr_(1-x)O_(2) samples with different Ce/Zr ratios,the Rh/ZrO_(2) sample exhibits a significantly better activity and Hydrothermal stability than the rest of the samples.The impacts of having more Ce components in the Rh/Ce_(x)Zr_(1-x)O_(2) catalysts are associated with the strong Rh-O-Ce interaction that tends to over stabilize the rhodium species.A significant amount of such rhodium atoms can be found in the bulk of the support oxides after a hydrothermal aging at 1050℃ with 10% H_(2)O in air for 12 h.Differently,the sintering of rhodium on the surface of Rh/ZrO_(2) catalysts is the main reason for the catalyst deactivation during the hydrothermal aging.These findings provide an example where high dispersion of supported metal induced by strong metal-support interactions does not necessarily lead to high catalytic activity.

关键词： Rh catalysts CeO_(2)-ZrO_(2) Emission control reactions Activity Hydrothermal stability Rare earths

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Hydrothermal stability of MO_x-Ce_(0.75)Zr_(0.25)O_2 catalysts for NO_x reduction by ammonia

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Journal of Rare Earths 2013年第12期31卷 1148-1156页

作者：王敏司知蠢陈磊吴晓东於俊 Department of Applied Physics Tsinghua University Graduate School at Shenzhen Tsinghua University State Key Laboratory of New Ceramics & Fine Process School of Materials Science and EngineeringTsinghua University

Various acidic components（MOx：phosphate,sulfate,tungstate and niobate） were loaded on Ce0.75 Zr0.25 O2 powders by an impregnation method.The as-prepared catalysts were hydrothermally treated at 760 oC for 48 h in air containing 10 vol.% H2 O to obtain the aged catalysts.The catalysts were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,H2 programmed-reduction,NH3 adsorption and deNOx activity measurements.The results showed that,among the catalysts investigated,the phosphated Ce0.75 Zr0.25 O2 catalyst showed the highest Hydrothermal stability.The remained high acidity of the phosphated catalyst with moderate redox property helped to maintain the excellent NH3-SCR activity of hydrothermally aged catalyst.Cerium tungstate led to the poor redox property of the tungstated catalyst although the acidity of catalyst was still high.The decomposition of sulfates at temperatures higher than 600 °C restrained the usage of sulfated catalysts in high temperature conditions.The overall dehydration of niobate to niobium oxides led to the low acidity of hydrothermally aged Nb2 O5-Ce0.75 Zr0.25 O2 catalyst.

关键词： Ce0.75Zr0.25O2 NH3-SCR acidic additives Hydrothermal stability rare earths

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Synthesis of Ordered Cubic Periodic Mesoporous Silica with High Hydrothermal stability

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Chemical Research in Chinese Universities 2009年第5期25卷 773-774页

作者： LAI Xiao-yong TU Jin-chun WANG Hong DU Jiang YANG Mei MAO Dan XING Chao-jian WANG Dan LI Xiao-tian College of Materials Science and Engineering Jilin University Changchun 130012 P. R. China State Key Laboratory of Multi-phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 P. R. China

1 Introduction Since its first discovery in 1992, ordered mesoporous silica material with large pore size, high surface area, and high pore volume has attracted great attention for the potentially wide application in catalysis, adsorption, separation, and ion exchange, etc. However, the poor Hydrothermal stability of mesoporous silica has limited its wide application in industry. Therefore, in the last 10 years, many studies have been dedicated to improving the Hydrothermal stability of mesoporous silica. Xiao et al.

关键词： Mesoporous silica Hydrothermal stability Nanocasting Ia3d cubic structure

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Nano-sized alumina supported palladium catalysts for methane combustion with excellent thermal stability

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Journal of Environmental Sciences 2023年第4期126卷 333-347页

作者： Wei Shi Guangyan Xu Xuewang Han Yingjie Wang Zhi Liu Sen Xue Nannan Sun Xiaoyan Shi Yunbo Yu Hong He State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Weichai Power Co. Ltd.Weifang 261061China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

Pd/Al_(2)O_(3)catalysts supported on Al_(2)O_(3)of different particle sizes were synthesized and applied in methane combustion.These catalysts were systematically characterized by Brunauer-Emmett-Teller (BET),X-ray diffraction (XRD),high resolution-transmission electron microscopy (HR-TEM),high-angle annular dark?eld-scanning transmission electron microscopy (HAADF-STEM),H_(2)-temperature-programmed reduction (H_(2)-TPR),O_(2)-temperature-programmed oxidation (O_(2)-TPO),X-ray photoelectron spectroscopy (XPS),and X-ray absorption?ne structure (XAFS).The characterization results indicated that nanosized Al_(2)O_(3)enabled the uniform dispersion of palladium nanoparticles,thus contributing to the excellent catalytic performance of these nano-sized Pd/Al_(2)O_(3)catalysts.Among them,Pd/Al_(2)O_(3)-nano-10 (Pd/Al_(2)O_(3)supported by alumina with an average particle size of 10 nm)showed superior catalytic activity and stability for methane oxidation under harsh practical conditions.It maintained excellent catalytic performance for methane oxidation for50 hr and remained stable even after harsh hydrothermal aging in 10 vol.%steam at 800℃ for 16 hr.Characterization results revealed that the strong metal-support interactions and physical barriers provided by Al_(2)O_(3)-nano-10 suppressed the coalescence ripening of palladium species,and thus contributed to the superior sintering resistance of the Pd/Al_(2)O_(3)-nano-10 catalyst.

关键词： Methane combustion Pd/Al_(2)O_(3) Hydrothermal stability Metal-support interaction Physical barriers

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A highly hydrothermal stable copper-based catalyst for catalytic wet air oxidation of m-cresol in coal chemical wastewater

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Chinese Journal of Chemical Engineering 2023年第5期57卷 338-348页

作者： Bingxiao Feng Lining Hao Chaoting Deng Jiaqiang Wang Hongbing Song Meng Xiao Tingting Huang Quanhong Zhu Hengjun Gai College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042China

Catalytic wet air oxidation(CWAO) can degrade some refractory pollutants at a low cost to improve the biodegradability of wastewater. However, in the presence of high temperature and high pressure and strong oxidizing free radicals, the stability of catalysts is often insufficient, which has become a bottleneck in the application of CWAO. In this paper, a copper-based catalyst with excellent Hydrothermal stability was designed and prepared. TiO_(2) with excellent stability was used as the carrier to ensure the longterm anchoring of copper and reduce the leaching of the catalyst. The one pot sol–gel method was used to ensure the super dispersion and uniform distribution of copper nanoparticles on the carrier, so as to ensure that more active centers could be retained in a longer period. Experiments show that the catalyst prepared by this method has good stability and catalytic activity, and the catalytic effect is not significantly reduced after 10 cycles of use. The oxidation degradation experiment of m-cresol with the strongest biological toxicity and the most difficult to degrade in coal chemical wastewater was carried out with this catalyst. The results showed that under the conditions of 140℃, 2 MPa and 2 h, m-cresol with a concentration of up to 1000 mg·L^(-1) could be completely degraded, and the COD removal rate could reach 79.15%. The biological toxicity of wastewater was significantly reduced. The development of the catalyst system has greatly improved the feasibility of CWAO in the treatment of refractory wastewater such as coal chemical wastewater.

关键词： Hydrothermal stability Ultra-dispersed copper-based catalyst Catalytic wet air oxidation m-Cresol Biological toxicity

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Highly Durable MIL-96 Membranes via a One-step Active γ-Alumina Conversion Strategy for Gas Separation

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Chemical Research in Chinese Universities 2023年第6期39卷 1084-1091页

作者： GAO Zhuangzhuang LI Baoju OU Shuxian LI Dongsheng FANG Qianrong QIU Shilun XUE Ming State Key Laboratory of Inorganic Synthesis&Preparative Chemistry Jilin UniversityChangchun 130012P.R.China School of Chemical Engineering and Technology Sun Yat-sen UniversityZhuhai 519082P.R.China

Metal-organic frameworks(MOFs)are attractive in membrane separation due to their special pore structure and suitable aperture size.The fabrication of defect-free and robust MOF membranes with excellent durability is highly demanded but remains challenging.In this work,we report a one-step activeγ-alumina conversion strategy for the facile and reliable fabrication of an MIL-96 membrane.In this case,theγ-Al_(2)O_(3) sol was dip-coated and sintered on theα-Al_(2)O_(3) disc as the active aluminum source and substrate for the nucleation and growth of MOF.A continuous and well-intergrown MIL-96 membrane was generated with exceptional stability due to the strong adhesion to the substrate.The resultant MIL-96 membrane yielded a satisfactory H_(2)/CO_(2) permselectivity and high-temperature resistance,delivering a selectivity of 12.35 with H_(2) permeance of 6.20×10^(−7) mol·m^(−2)·s^(−1)·Pa^(−1) at 150℃.Moreover,the probe membrane presented remarkable durability and recyclability under harsh hydrothermal conditions.This method paves the way for constructing highly stable and selective MOF membranes and could accelerate the development of advanced membrane separation technologies for gas purification and recycling in addressing the severe energy and environmental problems.

关键词： Metal-organic framework Membrane Activeγ-alumina Gas separation Hydrothermal stability

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The role of Si coordination structures in the catalytic properties and durability of Cu-SAPO-34 as NH_(3)-SCR catalyst for NO_(x) reduction

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Chinese Chemical Letters 2022年第2期33卷 893-897页

作者： Zhen Chen Ce Bian Chi Fan Tao Li Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Material Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Si coordination structures have been proven to greatly influence the ammonia-selective catalytic reduc-tion(NH_(3)-SCR)catalytic properties and the Hydrothermal stability of Cu-based silicoaluminophosphate-form catalysts.However,the role of various Si coordination structures in the NH_(3)-SCR reaction over Cu-SAPO-34 catalyst remains unknown.Herein,a batch of Cu-SAPO-34 samples with various Si contents was synthesized via a one-pot method to study the role of Si coordination structures in the NH_(3)-SCR catalytic properties and Hydrothermal stability.Cu/34-2 with the highest proportion of Si(xOAl)(x=1~3)struc-tures exhibits remarkable durability with 90%NO reduction efficiency within 200~450℃ even after a hydrothermal aging treatment at 850℃.In contrast,Cu/34-1 and Cu/34-4 with the highest proportions of Si(4OAl)and Si(0OAl)structures,respectively,are significantly deactivated by the same hydrothermal treatment.To better understand this phenomenon,the relationship between the Si coordination struc-tures and SCR performance is established using characterization techniques and kinetics measurements.Results reveal that a high content of Si(4OAl)and Si(0OAl)is detrimental to the Hydrothermal stability of Cu-SAPO-34 catalyst.However,Si(x OAl)(x=1~3)structures are conducive to the stabilization of isolated Cu^(2+),thus enhancing the stability to severe hydrothermal treatment.

关键词： NO_(x) NH_(3)-SCR Cu-SAPO-34 Si coordination structure Hydrothermal stability

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Synergetic catalytic removal of chlorobenzene and NOχfrom waste incineration exhaust over MnNb0.4Ce0.2Oχcatalysts:Performance and mechanism study

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Journal of Rare Earths 2020年第11期38卷 1178-1189,I0002页

作者： Bo Yang Qijie Jin Qiong Huang Mindong Chen Leilei Xu Yuesong Shen Haitao Xu Shemin Zhu Xiujun Li Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET) Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlSchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites College of Materials Science and EngineeringNanjing TechUniversityNanjing 210009China Department of Chemistry and Biochemistry Environmental Science&Engineeringand Biomedical EngineeringUniversity of Texas at EL PasoEL PasoTX 79968USA

Nb doped MnCe0.2Ox complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NOx and chlorobenzene(CB)at low temperatures.The MnNb0.4Ce0.2Ox catalyst with a molar ratio of Nb/Mn=0.4 exhibits excellent activity and the NOx and CB removal efficiency reaches 94.5%and 96%at 220℃,respectively.Furthermore,the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox still remains above 80%after injecting 300 ppm SO2 and 7 vol%H2 O for 36 h.In addition,the presence of CB and NOx+NH3 can improve the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox,respectively.The analysis results from N2-BET,Py-IR,H2-TPR and NH3-TPD reveal that the introduction of Nb increases the average pore size,pore volume and surface area,promoted the growth of Lewis acid amount obviously,and enhances redox ability of MnCe0.2Ox at 100-250℃.Moreover,the molecular migration process of NOx,NH3,CB and SO2 in NH3-SCR and CB oxidation reaction over MnNb0.4Ce0.2Ox catalysts were systematically studied.In situ DRIFTS,FT-IR and XPS also confirm that the adsorption of sulfate species and SO2 on the surface of MnNb0.4Ce0.2Ox is inhibited effectively by the introduction of Nb in the presence of SO2 and H2 O.Moreover,Nb additives also enhance the structural stability of MnNb0.4Ce0.2Ox,due to the interactions among Mn,Nb and Ce.The NH3-TPD,H2-TPR and in situ DRIFTS results also confirm that the MnNb0.4Ce0.2Ox still retains abundant acid sites and high redox ability in the presence of SO2 and H2O.In summary,MnNb0.4Ce0.2Ox catalysts represent a promising and effective candidate for controlling NOx and CB at low temperatures.

关键词： Synergistic catalytic removal Nitrogen oxides(NOx) Chlorobenzene(CB) Hydrothermal stability Removal mechanism Rare earths

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Effect of LaPO_(4) Introduction as a Vanadium Trap for Preventing USY Zeolite Destruction

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China Petroleum Processing & Petrochemical Technology 2021年第1期23卷 53-57页

作者： Du Xiaohui Gao Xionghou Liu Pusheng Lanzhou Petrochemical Research Center Petrochemical Research InstitutePetroChinaLanzhou 730060 Petrochemical Research Institute PetroChinaBeijing 102206

The use of lanthanum phosphate as a vanadium trap for preventing destruction of USY zeolite was studied.The effect of deposited vanadium on the hydrothermal destruction of zeolite was investigated by the solid-state NMR technique.LaPO4 species can inhibit the zeolite framework structure from being collapsed by vanadium after steaming treatment.The EPR results show the oxidation-reduction reaction in LaPO4 and V2O5 system and inhibition of zeolite destruction by V5+.The catalysts prepared from USY and LaPO-USY zeolites were also tested in the catalytic reactions of heavy oil.The assessment results indicated that the USY modified with LaPO4 could bring about remarkably high dehydrogenation ability.

关键词： FCC USY zeolite vanadium lanthanum phosphate Hydrothermal stability

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