Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods ...Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result could be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate could reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as concentration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm could be prepared when the concentration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was controlled at 25 ml/min. Compared with commercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of commercial polishing powder.展开更多
Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different ...Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.展开更多
The granule shape and crystal structure of the the ceria-based rare earth oxide which were roasted at 600～1050 ℃ for 2～6 h and then cooled in furnace, cooled out of furnace or cooled in water were studied by means ...The granule shape and crystal structure of the the ceria-based rare earth oxide which were roasted at 600～1050 ℃ for 2～6 h and then cooled in furnace, cooled out of furnace or cooled in water were studied by means of XRD and SEM. The results revealed that the rich cerium rare earth carbonate could be changed into the rare earth oxide which was a kind of sandwich made of globose granule whose diameter was between 0.5～3.0 μm after being roasted in 900 ℃ for 2 h. This kind of crystal lattice in rare earth oxide belonged to face-centered cubic lattice and its space between crystal surface {111} and {200} (viz. L111 and L200) would enlarge as the roasting temperature increasing. With increasing roasting temperature, L111 would rise straightly upward, and L200 would rise straightly upward when roasting time was 2～4 h but changed little when roasting time was 4～6 h. The glass-polishing experiments found that the polishing ability of the ceria-based rare earth oxide was the best as L111 was 43～53 nm and the L200 was 43～56 nm.展开更多
Dynamic oxygen storage and release capability （OSC） measurement apparatus was designed to evaluate the OSC performance of ceria-based oxygen storage material. The optimum measurement condition was at a frequency of ...Dynamic oxygen storage and release capability （OSC） measurement apparatus was designed to evaluate the OSC performance of ceria-based oxygen storage material. The optimum measurement condition was at a frequency of 0.1 Hz with the inlet gas-flow sequence CO （5S）→O2（5S）→CO→O2 and a flow rate of 300 ml·min^-1. Under this condition, similar regular square wave in the inlet and outlet of the reactor was obtained to guarantee the reliability of the dynamic OSC results. The dynamic OSC performance of the CeO2 and Ce0.67Zr0.33O2 mixed oxide prepared using the citric sol-gel method was studied at the optimum measurement condition with focus on both quantitative and qualitative analyses, The results reveal distinctly that Ce0.67Zr0.33O2 had better dynamic OSC performance because of its higher oxygen migration rate than CeO2. Under dynamic conditions, two CO2 production peaks occurred corresponding to the CO pulse and the O2 pulse, respectively, during the entire cycle. The intensity and ratio between the two CO2 productions were highly influenced by temperature and frequency indicating complex surface phenomena during the oxygen storage/release process, As a result, this set-up can be applied to the evaluation of ceria-based material on the OSC performance.展开更多
Solid oxide cells(SOCs),including solid oxide fuel cells(SOFCs)and solid oxide electrolysis cells(SOECs),hold great potential for commercial viability because of their high heat utilization,reduced carbon emissions,hi...Solid oxide cells(SOCs),including solid oxide fuel cells(SOFCs)and solid oxide electrolysis cells(SOECs),hold great potential for commercial viability because of their high heat utilization,reduced carbon emissions,high efficiency,and fuel flexibility.A key component in enhancing cell performance and extending lifetime is the thin and dense ceria-based barrier layer at the electrolyte and air electrode interface to avoid cell degradation during manufacturing.The barrier layer needs to be densified at low temperatures(ideally less than 1000℃),which remains a significant challenge.This review focuses on a typical low-cost ceramic powder-based route for the preparation of a barrier layer and explores various approaches to achieve low-temperature densification.It covers techniques such as synthesizing finer powders,optimizing deposition methods for the green-body layer,using sintering aids,and employing post-sintering processes to increase density.Recent advancements in these areas are highlighted to provide insights into future development directions.Finally,the review discusses new opportunities and emerging techniques that could further improve the barrier layer performance.展开更多
A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorpo...A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorporation of Al3＋ into CeO2‐MnOx mixed oxides. CeO2‐MnOx, CeO2‐Al2O3, and MnOx‐Al2O3 mixed oxides, and CeO2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N2 physisorption, H2‐TPR, XPS, and in situ DRIFTS. The catalytic re‐duction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al3＋into CeO2‐MnOx mixed oxides resulted in a decrease of crys‐tallite size, with the increase of the BET specific surface area and pore volume, as well as the in‐crease of Ce3＋and Mn4＋. The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO＋CO model reaction. A reaction mecha‐nism was proposed to explain the excellent catalytic performance of CeO2‐MnOx‐Al2O3 catalysts for NO reduction by CO.展开更多
Ceria-based heterostructure composite(CHC)has become a new stream to develop advanced low-temperature(300–600°C)solid oxide fuel cells(LTSOFCs)with excellent power outputs at 1000 mW cm−2 level.The state-ofthe-a...Ceria-based heterostructure composite(CHC)has become a new stream to develop advanced low-temperature(300–600°C)solid oxide fuel cells(LTSOFCs)with excellent power outputs at 1000 mW cm−2 level.The state-ofthe-art ceria–carbonate or ceria–semiconductor heterostructure composites have made the CHC systems significantly contribute to both fundamental and applied science researches of LTSOFCs;however,a deep scientific understanding to achieve excellent fuel cell performance and high superionic conduction is still missing,which may hinder its wide application and commercialization.This review aims to establish a new fundamental strategy for superionic conduction of the CHC materials and relevant LTSOFCs.This involves energy band and built-in-field assisting superionic conduction,highlighting coupling effect among the ionic transfer,band structure and alignment impact.Furthermore,theories of ceria–carbonate,e.g.,space charge and multi-ion conduction,as well as new scientific understanding are discussed and presented for functional CHC materials.展开更多
While the electrochemical nitrogen reduction reaction(NRR) represents a prospective blueprint for environmentally renewable ammonia generation,it has yet to overcome the limitations of weak activity and inferior selec...While the electrochemical nitrogen reduction reaction(NRR) represents a prospective blueprint for environmentally renewable ammonia generation,it has yet to overcome the limitations of weak activity and inferior selectivity.In this regard,surface modification tactic was constructed to markedly enhance the activity and selectivity via introducing Sn atoms into the surface of defective cerium oxide(denoted as Sn-CeO_(2-x)) as the active and robust electrocatalyst for NRR under benign environment.The introduction of Sn atoms in CeO_(2-x)can not only inhibit the HER activity of the catalyst but also modulate the electronic structure of ceria and optimize N-Ce interaction,thus enhancing NRR activity and selectivity.Outperforming all previous CeO_(2)-based NRR catalysts,this catalyst has demonstrated an ammonia yield rate of 41.1 μg mg_(cat)^(-1) h^(-1) and an exceptional Faradic efficiency of 35.3%.This work presents a viable approach for the development of advanced NRR electrocatalysts.展开更多
Solid oxide fuel cells （SOFCs） offer high energy conversion, low noise, low pollutant emission, and low processing cost. Despite many advantages, SOFCs face a major challenge in competing with other types of fuel ce...Solid oxide fuel cells （SOFCs） offer high energy conversion, low noise, low pollutant emission, and low processing cost. Despite many advantages, SOFCs face a major challenge in competing with other types of fuel cells because of their high operating temperature. The necessity to reduce the operational temperature of SOFCs has led to the development of research into the materials and fabrication technology of fuel cells. The use of composite cathodes significantly reduces the cathode polarization resistance and expands the triple phase boundary area available for oxygen reduction. Powder preparation and composite cathode fabrication also affect the overall performance of composite cathodes and fuel cells. Among many types of cathode materials, lanthanum-based materials such as lanthanum strontium cobalt ferrite （Lal_xSrxCOl_yFey03_~） have recently been discovered to offer great compatibility with ceria-based electrolytes in performing as composite cathode materials for intermediate- to low-temperature SOFCs （IT-LTSOFCs）. This paper reviews various ceria-based composite cathodes for IT-LTSOFCs and focuses on the aspects of progress and challenges in materials technology.展开更多
As the promising catalysts for the water-gas shift(WGS)reaction,the activity of Au-CeO_(2) composites is susceptible to the aggregation size and electronic state of Au species.Previous reports were extensively focused...As the promising catalysts for the water-gas shift(WGS)reaction,the activity of Au-CeO_(2) composites is susceptible to the aggregation size and electronic state of Au species.Previous reports were extensively focused on the discrepancy between nonmetallic Au and metallic Au nanoparticles,whereas the understanding of the authentic role of the isolated Au atoms was limited.Herein,we investigated the catalytic behavior and structural information over two types of Au/CeO_(2) catalysts,in which the predominant conjunctions were isolated Au1-CeO_(2) and Aun-CeO_(2),respectively.Based on comprehensive characterizations,particularly by in-situ Raman and in-situ DRIFTS,we found that the isolated Au atoms were responsible for enhancing the reducibility of the CeO_(2) matrix.The CO adsorption ability on the isolated Au sites was significantly inferior to clustered Au atoms,especially at relatively high temperatures(>200°C).As a result,the boosted O vacancy on the isolated Au1-CeO_(2) conjunctions could improve the H2O activation ability for the Au-CeO_(2) catalysts and demonstrate a comparable activity to the clustered Aun-CeO_(2) sites.This work might deepen understanding of the catalytic function for the isolated Au1 site within Au/CeO_(2) systems while catalyzing the WGS reaction.展开更多
基金Project supported by The National High Technology Research and Development Program of China(863Program:2010AA03A405)Twelfth Five-Year National Science and Technology Pillar Program(2012BAE01B02)
文摘Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result could be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate could reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as concentration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm could be prepared when the concentration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was controlled at 25 ml/min. Compared with commercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of commercial polishing powder.
文摘Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.
文摘The granule shape and crystal structure of the the ceria-based rare earth oxide which were roasted at 600～1050 ℃ for 2～6 h and then cooled in furnace, cooled out of furnace or cooled in water were studied by means of XRD and SEM. The results revealed that the rich cerium rare earth carbonate could be changed into the rare earth oxide which was a kind of sandwich made of globose granule whose diameter was between 0.5～3.0 μm after being roasted in 900 ℃ for 2 h. This kind of crystal lattice in rare earth oxide belonged to face-centered cubic lattice and its space between crystal surface {111} and {200} (viz. L111 and L200) would enlarge as the roasting temperature increasing. With increasing roasting temperature, L111 would rise straightly upward, and L200 would rise straightly upward when roasting time was 2～4 h but changed little when roasting time was 4～6 h. The glass-polishing experiments found that the polishing ability of the ceria-based rare earth oxide was the best as L111 was 43～53 nm and the L200 was 43～56 nm.
基金Project supported by the National"973"Project (2004CB719503) and the Programfor New Century Excellent Talents in University
文摘Dynamic oxygen storage and release capability （OSC） measurement apparatus was designed to evaluate the OSC performance of ceria-based oxygen storage material. The optimum measurement condition was at a frequency of 0.1 Hz with the inlet gas-flow sequence CO （5S）→O2（5S）→CO→O2 and a flow rate of 300 ml·min^-1. Under this condition, similar regular square wave in the inlet and outlet of the reactor was obtained to guarantee the reliability of the dynamic OSC results. The dynamic OSC performance of the CeO2 and Ce0.67Zr0.33O2 mixed oxide prepared using the citric sol-gel method was studied at the optimum measurement condition with focus on both quantitative and qualitative analyses, The results reveal distinctly that Ce0.67Zr0.33O2 had better dynamic OSC performance because of its higher oxygen migration rate than CeO2. Under dynamic conditions, two CO2 production peaks occurred corresponding to the CO pulse and the O2 pulse, respectively, during the entire cycle. The intensity and ratio between the two CO2 productions were highly influenced by temperature and frequency indicating complex surface phenomena during the oxygen storage/release process, As a result, this set-up can be applied to the evaluation of ceria-based material on the OSC performance.
基金supported by the Shanghai Municipal Science and Technology Major Project,the Shanghai Pilot Program for Basic Research(No.21TQ1400207)the ShanghaiScienceandTechnology InnovationProgram(No.21DZ1206400)Na Ni acknowledges the funding received from the National Natural Science Foundation of China(No.52072238).
文摘Solid oxide cells(SOCs),including solid oxide fuel cells(SOFCs)and solid oxide electrolysis cells(SOECs),hold great potential for commercial viability because of their high heat utilization,reduced carbon emissions,high efficiency,and fuel flexibility.A key component in enhancing cell performance and extending lifetime is the thin and dense ceria-based barrier layer at the electrolyte and air electrode interface to avoid cell degradation during manufacturing.The barrier layer needs to be densified at low temperatures(ideally less than 1000℃),which remains a significant challenge.This review focuses on a typical low-cost ceramic powder-based route for the preparation of a barrier layer and explores various approaches to achieve low-temperature densification.It covers techniques such as synthesizing finer powders,optimizing deposition methods for the green-body layer,using sintering aids,and employing post-sintering processes to increase density.Recent advancements in these areas are highlighted to provide insights into future development directions.Finally,the review discusses new opportunities and emerging techniques that could further improve the barrier layer performance.
基金supported by the National Natural Science Foundation of China (21507130)the Open Project Program of Chongqing Key Laboratory of Environmental Materials and Remediation Technology from Chongqing University of Arts and Sciences (CEK1405)+3 种基金the Open Project Program of Beijing National Laboratory for Molecular Sciences (20140142)the Open Project Program of Jiangsu Key Laboratory of Vehicle Emissions Control (OVEC001)the Open Project Program of Chongqing Key Laboratory of Catalysis and Functional Organic Molecules from Chongqing Technology and Business University (1456029)the Chongqing Science & Technology Commission (cstc2014pt-gc20002)~~
文摘A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorporation of Al3＋ into CeO2‐MnOx mixed oxides. CeO2‐MnOx, CeO2‐Al2O3, and MnOx‐Al2O3 mixed oxides, and CeO2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N2 physisorption, H2‐TPR, XPS, and in situ DRIFTS. The catalytic re‐duction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al3＋into CeO2‐MnOx mixed oxides resulted in a decrease of crys‐tallite size, with the increase of the BET specific surface area and pore volume, as well as the in‐crease of Ce3＋and Mn4＋. The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO＋CO model reaction. A reaction mecha‐nism was proposed to explain the excellent catalytic performance of CeO2‐MnOx‐Al2O3 catalysts for NO reduction by CO.
文摘Ceria-based heterostructure composite(CHC)has become a new stream to develop advanced low-temperature(300–600°C)solid oxide fuel cells(LTSOFCs)with excellent power outputs at 1000 mW cm−2 level.The state-ofthe-art ceria–carbonate or ceria–semiconductor heterostructure composites have made the CHC systems significantly contribute to both fundamental and applied science researches of LTSOFCs;however,a deep scientific understanding to achieve excellent fuel cell performance and high superionic conduction is still missing,which may hinder its wide application and commercialization.This review aims to establish a new fundamental strategy for superionic conduction of the CHC materials and relevant LTSOFCs.This involves energy band and built-in-field assisting superionic conduction,highlighting coupling effect among the ionic transfer,band structure and alignment impact.Furthermore,theories of ceria–carbonate,e.g.,space charge and multi-ion conduction,as well as new scientific understanding are discussed and presented for functional CHC materials.
基金financially supported by the National Natural Science Foundation of China (51972349 and 91963210)the Natural Science Foundation of Guangdong Province (2022A1515011596)the Key Research and Development Program of Guangdong Province (2020B0101690001)。
文摘While the electrochemical nitrogen reduction reaction(NRR) represents a prospective blueprint for environmentally renewable ammonia generation,it has yet to overcome the limitations of weak activity and inferior selectivity.In this regard,surface modification tactic was constructed to markedly enhance the activity and selectivity via introducing Sn atoms into the surface of defective cerium oxide(denoted as Sn-CeO_(2-x)) as the active and robust electrocatalyst for NRR under benign environment.The introduction of Sn atoms in CeO_(2-x)can not only inhibit the HER activity of the catalyst but also modulate the electronic structure of ceria and optimize N-Ce interaction,thus enhancing NRR activity and selectivity.Outperforming all previous CeO_(2)-based NRR catalysts,this catalyst has demonstrated an ammonia yield rate of 41.1 μg mg_(cat)^(-1) h^(-1) and an exceptional Faradic efficiency of 35.3%.This work presents a viable approach for the development of advanced NRR electrocatalysts.
基金Project supported by the Universiti Kebangsaan Malaysia (No. UKM-RF-07-FRGS0260-2010)the Malaysia Government for Research Sponsorship (No. OUP-2012-075)
文摘Solid oxide fuel cells （SOFCs） offer high energy conversion, low noise, low pollutant emission, and low processing cost. Despite many advantages, SOFCs face a major challenge in competing with other types of fuel cells because of their high operating temperature. The necessity to reduce the operational temperature of SOFCs has led to the development of research into the materials and fabrication technology of fuel cells. The use of composite cathodes significantly reduces the cathode polarization resistance and expands the triple phase boundary area available for oxygen reduction. Powder preparation and composite cathode fabrication also affect the overall performance of composite cathodes and fuel cells. Among many types of cathode materials, lanthanum-based materials such as lanthanum strontium cobalt ferrite （Lal_xSrxCOl_yFey03_~） have recently been discovered to offer great compatibility with ceria-based electrolytes in performing as composite cathode materials for intermediate- to low-temperature SOFCs （IT-LTSOFCs）. This paper reviews various ceria-based composite cathodes for IT-LTSOFCs and focuses on the aspects of progress and challenges in materials technology.
基金funded by the National Key Research and Development Program of China(2021YFA1501103)the National Science Fund for Distinguished Young Scholars of China(22225110)+1 种基金the National Science Foundation of China(22075166,22271177)the Young Scholars Program of Shandong University.
文摘As the promising catalysts for the water-gas shift(WGS)reaction,the activity of Au-CeO_(2) composites is susceptible to the aggregation size and electronic state of Au species.Previous reports were extensively focused on the discrepancy between nonmetallic Au and metallic Au nanoparticles,whereas the understanding of the authentic role of the isolated Au atoms was limited.Herein,we investigated the catalytic behavior and structural information over two types of Au/CeO_(2) catalysts,in which the predominant conjunctions were isolated Au1-CeO_(2) and Aun-CeO_(2),respectively.Based on comprehensive characterizations,particularly by in-situ Raman and in-situ DRIFTS,we found that the isolated Au atoms were responsible for enhancing the reducibility of the CeO_(2) matrix.The CO adsorption ability on the isolated Au sites was significantly inferior to clustered Au atoms,especially at relatively high temperatures(>200°C).As a result,the boosted O vacancy on the isolated Au1-CeO_(2) conjunctions could improve the H2O activation ability for the Au-CeO_(2) catalysts and demonstrate a comparable activity to the clustered Aun-CeO_(2) sites.This work might deepen understanding of the catalytic function for the isolated Au1 site within Au/CeO_(2) systems while catalyzing the WGS reaction.
