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Probing crystalline phase effect of rare earth metal oxides(REO)on Cu/REO(RE=Gd,Eu,Sm)catalysts for methanol steam reforming(MSR)to produce H_(2)

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Journal of Rare Earths 2023年第6期41卷 820-829,I0002页

作者： Xiaofei Liu Jiamei Ma Chengxin Lu Junwei xu xianglan xu Xiuzhong Fang Xiang Wang Key Laboratory of Jiangxi Province for Environment and Energy Catalysis School of Chemistry and Chemical EngineeringNanchang UniversityNanchang 330031China

In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-*** the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic *** the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of *** with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic ***,the contents of Cu^(+) on the catalysts follow the same *** reaction performance is positively related to the amount of these three types of surface *** metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox *** rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the ***/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the *** conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.

关键词： Methanol steam reforming H_(2)production Supported Cu catalysts Rare earth metal oxide supports Phase structure effect Cut and Cu^(0)sites

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On the monolayer dispersion behavior of Co_(3)O_(4)on HZSM-5 support:designing applicable catalysts for selective catalytic reduction of nitrogen oxides by ammonia

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Frontiers of Chemical Science and Engineering 2023年第11期17卷 1741-1754页

作者： Yufeng Yang Lihong Zhang Tao Song Yixing Huang xianglan xu Junwei xu Xiuzhong Fang Qing Wang Haiming Liu Xiang Wang Key Laboratory of Jiangxi Province for Environment and Energy Catalysis School of Chemistry and Chemical EngineeringNanchang UniversityNanchang 330031China Shanghai Tech University School of Physical Science&TechnologyShanghai 201210China

Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ***_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants *** the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen ***,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the *** is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.

关键词： Co_(3)O_(4)/ZSM-5 NO_(x)-SCR by NH_(3) monolayer dispersion threshold effect surface acid sites surface active O_(2)^(-)anions

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Changes in albedo and its radiative forcing of grasslands in East Asia drylands

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Ecological Processes 2024年第1期13卷 237-251页

作者： Qingsong Zhu Jiquan Chen Liangxu Wu Yuting Huang Changliang Shao Gang Dong Zhe xu xianglan Li State Key Laboratory of Remote Sensing Science College of Global Change and Earth System Science Faculty of Geographical ScienceBeijing Normal University Department of Geography Environment and Spatial Sciences Michigan State University State Key Laboratory of Efficient Utilization of Arid and Semi-Arid Arable Land in Northern China National Hulunber Grassland Ecosystem Observation and Research Station Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences School of Life Science Shanxi University

Background Grasslands in drylands are increasingly influenced by human activities and climate change, leading to alterations in albedo and radiative energy balance among others. Surface biophysical properties and their interactions change greatly following disturbances. However, our understanding of these processes and their climatic impacts remains limited. In this study, we used multi-year observations from satellites and eddy-covariance towers to investigate the response of albedo to variables closely associated with human disturbances, including vegetation greenness（EVI） and surface soil volumetric water content（VWC）, as well as snow cover and clearness index（Ta） for their potential *** EVI and VWC during the growing season were the primary factors influencing albedo. EVI and VWC were negatively correlated with albedo, with VWC's total direct and indirect impacts being slightly smaller than those of EVI. During the non-growing season, snow cover was the most influential factor on albedo. VWC and Ta negatively affected albedo throughout the year. We estimated the impact of variations in EVI and VWC on climate to be in the range of 0.004 to 0.113 kg CO2m-2yr-1in *** This study indicates the significant impacts of climate change and human disturbances on vulnerable grassland ecosystems from the perspective of altered albedo. Changes in vegetation greenness and soil properties induced by climate change and human activities may have a substantial impact on albedo, which in turn feedback on climate change, indicating that future climate policies should take this factor into consideration.

关键词： Albedo Global warming potential Grassland Disturbance

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A2B2O7 pyrochlore compounds:A category of potential materials for clean energy and environment protection catalysis

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Journal of Rare Earths 2020年第8期38卷 840-849,I0001页

作者： Junwei xu Rong Xi xianglan xu Yan Zhang Xiaohui Feng Xiuzhong Fang Xiang Wang Key Laboratory of Jiangxi Province for Environment and Energy Catalysis College of ChemistryNanchang UniversityNanchang 330031China

A2B2O7 pyrochlore is a kind of important functional materials for different purposes,which has been investigated extensively by crystallographers and material ***,the catalytic chemistry of this type of special compounds has rarely been documented,though a few researchers have tried to synthesize some pyrochlore compounds with different chemical compositions for a variety of green energy production and air pollution control reactions in the *** the expectation to help catalysis scientists to get better acquaintance with,and gain deeper understanding on this type of compounds as heterogeneous catalysts,the major publications over the past several decades have been screened and reviewed in this paper,based also on our own experience of studying on this type of catalytic *** crystalline phase transformations of the compounds with the change of the A and B site cations,the phase change’s influences on the surface and bulk properties,and their subsequent impact on the catalytic performance for different reactions have been ***,the future work which needs to be performed to perceive in depth this kind of important materials as catalysts has been proposed and *** trust that this short review contains valuable information,which will provide great help for people to get better cognition for A2 B2 O7 pyrochlore compounds,and assist them to develop better catalysts for various reactions.

关键词： A2B2O7 pyrochlore compounds Crystalline phase change Lattice and surface oxygen vacancies Value-added CH4 transformation Air pollution control reactions Rare earths

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Ln2Zr2O7 compounds（Ln=La,Pr, Sm, Y） with varied rare earth A sites for low temperature oxidative coupling of methane

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Chinese Chemical Letters 2019年第6期30卷 1141-1146页

作者： Xiuzhong Fang Lianghui Xia Liang Peng Yuan Luo Junwei xu Luoji xu xianglan xu Wenming Liu Renyang Zheng Xiang Wang Key Laboratory of Jiangxi Province for Environment and Energy Catalysis College of Chemistry Nanchang University Nanchang 330031 China Research Institute of Processing (RIIP) SINOPEC Beijing 100083 China

With the objective to develop catalysts having application potential for oxidative coupling of methane (OCM) at relatively lower temperature. A series of Ln2Zr2O7 compounds with varied rare earth A sites have been prepared by a co-precipitation method. XRD and Raman have proved that pure Ln2Zr2O7 compounds have been successfully prepared for all the catalysts. By decreasing the rA/rB ratio, their crystalline structure transform from an ordered pyrochlore (La2Zr2O7) to a less ordered pyrochlore (Pr2Zr2O7 and Sm2Zr2O7) and eventually to a defective cubic fluorite phase (Y2Zr2O7). H2-TPR, O2-TPD and XPS have testified that the amount of surface active O2-species follows the order of La2Zr2O7>Pr2Zr2O7>Sm2Zr2O7 > Y2Zr2O7, which is well consistent with the reaction performance, indicating that the abundance of surface O2- sites is a critical factor influencing the reaction performance. CO2-TPD has demonstrated that a better catalyst generally possesses a larger amount of surface moderate alkaline sites, which is another factor to affect the reaction performance. It is concluded that the concerted interaction between the two types of surface active sites controls the reaction performance of the Ln2Zr2O7 catalysts. In comparison with the state-of-the art Mn/Na2WO4/SiO2, La2Zr2O7, the best catalyst, exhibits much improved reaction performance below 750 ℃.

关键词： Pyrochlore compounds Low temperature OCM A site substitution effects Surface superoxide sites Surface alkaline sites

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Dry reforming of methane on active and coke resistant Ni/Y_2Zr_2O_7 catalysts treated by dielectric barrier discharge plasma

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Journal of Energy Chemistry 2016年第5期25卷 825-831页

作者： Xiuzhong Fang Jie Lian Kaiwen Nie Xianhua Zhang Yanfeng Dai xianglan xu Xiang Wang Wenming Liu Changqing Li Wufeng Zhou College of Chemistry Nanchang University Jiangxi Golden Century Advanced Materials Co. Ltd Nanchang

In this study, Ni/YZrOcatalysts prepared with impregnation method and treated by dielectric barrier discharge plasma(DBD) in different atmospheres have been investigated for methane dry reforming. It is revealed by H-TPR that plasma treatment can enhance the interaction between Ni O/Ni particles and the YZrOpyrochlore support. Therefore, catalysts with smaller Ni O and Ni grains sizes, higher metallic Ni active surface areas can be achieved, as evidenced by XRD, TEM and Hadsorption-desorption measurements. As a consequence, the plasma-treated catalysts show significantly improved activity, stability and coke resistance, as testified by the TEM and TGA-DSC results. Plasma treatment in H/Ar gas mixture is found to be the best condition to prepare Ni/YZrO, which can be used to obtain a catalyst with the highest activity, stability and most potent coke resistance. It is believed that the smaller Ni grain size and higher metallic Ni active surface area induced by plasma treatment are the inherent reasons accounting for the promoted reaction performance of the Ni/YZrOpyrochlore catalysts.

关键词： Plasma treatment Y2Zr2O7 pyrochlore support Supported Ni catalysts Methane dry reforming Coke resistance

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Methane dry reforming on Ni/La_2Zr_2O_7 treated by plasma in different atmospheres

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Journal of Energy Chemistry 2015年第4期24卷 416-424页

作者： Honggen Peng Youhe Ma Wenming Liu xianglan xu Xiuzhong Fang Jie Lian Xiang Wang Changqing Li Wufeng Zhou Ping Yuan College of Chemistry Nanchang University Jiangxi Golden Century Advanced Materials Co. Ltd.

A series of Ni/La2Zr2O7 pyrochlore catalysts prepared by impregnation method and treated by dielectric barrier discharge（DBD） plasma in different atmospheres and varied sequences were prepared and applied for dry reforming of methane（DRM）. It is found that all of the plasma treated catalysts show evidently improved activity and coke resistance in comparison with the non-plasma treated one. The best performance is achieved on Ni/La2Zr2O7–H2P–C,a catalyst treated in H2 plasma before calcination. TGA-DSC and SEM demonstrate that carbon deposition is significantly suppressed on all of the plasma treated samples. Moreover,XRD and TEM results testify that both Ni O and Ni sizes on the calcined and reduced samples treated by plasma are also decreased,which results in higher Ni metal dispersion on the reduced and used catalysts and enhances the interactions between Ni sites and the support. It is believed that these are the inherent reasons accounting for the promotional effects of plasma treatment on the reaction performance of the Ni/La2Zr2O7 pyrochlore catalysts.

关键词： Methane dry reforming Ni-based catalysts Pyrochlore support DBD plasma Coke resistance

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Study on ceria-modified SnO_2 for CO and CH_4 oxidation

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Journal of Rare Earths 2012年第10期30卷 1013-1019页

作者：曾宪荣张荣斌徐香兰王翔 Department of Chemistry Nanchang University Institute of Applied Chemistry Nanchang University

Sn-Ce-O binary catalysts with different Sn/Ce molar ratios were prepared with co-precipitation method and applied for CO and CH4 oxidation. The catalysts were characterized by means of Nz-BET, XRD and H2-TPR techniques. It was found that for those Sn rich sam- pies such as SnCe91 and SnCe73, Ce cations were doped into the matrix of tetragonal rutile SnO2 to form SnO2-based solid solution. As a consequence, the oxidation activity as well as the thermal stability was significantly improved compared with pure SnO2. In contrast, for Ce rich samples such as SnCel9, SnCe37 and SnCe55, though the thermal stability was improved, the activity was worse than SnO2, due to the presence of much less amount of active oxygen species. Co-precipitation was found to be the best method to prepare Sn-Ce binary catalysts among all of the methods tried in this study.

关键词： Sn-Ce mixed oxide catalysts solid solution CH4 combustion CO oxidation rare earths

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Debt,sleep deprivation and psychological distress among online ride-hailing drivers:evidence from China

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General Psychiatry 2024年第2期37卷 319-323页

作者： Wanjie Tang Jingyue Chen Simiao Wang xianglan Jiang Yi Lu Siqi Wu Luyu Yang Meng Tian Han Zhang Yinan Zhang Jiuping xu Zeyuan Sun Mental Health Centre Sichuan UniversityChengduSichuanChina Department of Child&Adolescent Psychiatry King's College London Institute of Psychiatry Psychology&NeuroscienceLondonUK Sichuan University Business School ChengduSichuanChina Department of Psychology King's College London Institute of Psychiatry Psychology&NeuroscienceLondonUK Sichuan University West China School of Medicine ChengduSichuanChina The University of Edinburgh School of Health in Social Science EdinburghEdinburghUK Department of Psychology University of WarwickCoventryUK Division of Psychiatry University College London Faculty of Brain SciencesLondonUK Wuxi Mental Health Center Nanjing Medical UniversityWuxiJiangsuChina King's College London Centre for the Developing Brain LondonUK

An online ride-hailing driver(ORHD)refers to a driver who takes orders and provides rental car services to passengers via an online service platform.1 ORHD plays a significant role in the urban transport system worldwide,operating through many *** to official data from the Chinese Ministry of Transport,a total of 1.6 million vehicle transport permits were issued by the end of March 2022.

关键词： services service official

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二十辊轧机辊系耦合振动特性及振动控制

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振动与冲击 2024年第7期43卷 278-289页

作者：孔祥岚和东平徐慧东王涛黄庆学太原理工大学机械与运载工程学院太原030024 先进金属复合材料成形技术与装备教育部工程研究中心太原030024

精密极薄带因具备高精度、耐腐蚀、优异表面光洁度等性能,被广泛应用于微制造、微电子等高技术领域。二十辊轧机辊系的耦合振动对极薄带的生产有着重要的影响。考虑到轧制工艺和润滑状态等变化形成非线性轧制界面,建立了一种二十辊轧机... 详细信息

精密极薄带因具备高精度、耐腐蚀、优异表面光洁度等性能,被广泛应用于微制造、微电子等高技术领域。二十辊轧机辊系的耦合振动对极薄带的生产有着重要的影响。考虑到轧制工艺和润滑状态等变化形成非线性轧制界面,建立了一种二十辊轧机辊系耦合动力学模型。应用多尺度法求解主共振和内共振的幅频特性方程,分析了不同参数对幅频特性曲线的影响。基于奇异性理论探究了不同参数与系统分岔的关系。同时,根据李雅普诺夫一次近似稳定性判据,结合系统动相平面相轨迹图,对系统稳定性进行判断分析。然后,基于Washout filter控制器原理设计了一种状态反馈控制器,通过对系统进行状态空间表达式变换,分析了控制增益对幅频特性的影响。利用时域图、相位图、频谱图以及Poincaré截面图进行仿真对比,验证了所设计控制器的可行性和有效性,为二十辊轧机振动及其控制的研究提供了一定的理论指导。

关键词：二十辊轧机非线性轧制界面多尺度法幅频特性稳定性 Washout filter控制器

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