Chemical looping technology holds great potential on efficient CO2 splitting with much higher CO production and CO2 splitting rate than photocatalytic processes.Conventional oxygen carrier requires high temperature(ty...Chemical looping technology holds great potential on efficient CO2 splitting with much higher CO production and CO2 splitting rate than photocatalytic processes.Conventional oxygen carrier requires high temperature(typically 850–1000°C)to ensure sufficient redox activity,but the stable and high CO2 conversion is favored at a lower temperature,leading to the degrading on the reaction kinetics as well as the low CO production and CO2 splitting rate.In this paper,we prepared several ternary spinels and demonstrated their performance for chemical looping CO2 splitting at moderate temperatures.Using the promotion effect of Cu to cobalt ferrite reduction and reversible phase change of the reduced metals,Cu0.4 Co0.6 Fe2 O4 exhibits high CO2 splitting rate(144.6μmol g–1 min–1)and total CO production(9100μmol g–1)at 650°C.The high performance of this earth-abundant spinel material is also consistent in repeated redox cycles,enabling their potential in industrial use.展开更多
Operating chemical looping process at mid-temperatures(550–750℃)presents exciting potential for the stable production of hydrogen.However,the reactivity of oxygen carriers is compromised by the detrimental effect of...Operating chemical looping process at mid-temperatures(550–750℃)presents exciting potential for the stable production of hydrogen.However,the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics.Although the reactivity at mid-temperature can be improved by the addition of noble metals,the high cost of these noble metal containing materials significantly hindered their scalable applications.In the current work,we propose to incorporate earth-abundant metals into the ironbased spinel for hydrogen production in a chemical looping scheme at mid-temperatures.Mn0.2Co0.4Fe2.4O4 shows a high hydrogen production performance at the average rate of~0.62 mmol g^(-1) min^(-1) and a hydrogen yield of~9.29 mmol g^(-1) with satisfactory stability over 20 cycles at 550℃.The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam.The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials,enabling their potential for industrial applications.展开更多
The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting effi...The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting efficiency than solar electrocatalytic and photocatalytic process.A typical oxygen carrier has to comprise a significant amount of inert support,to maintain stability in multiple redox cycles,thereby resulting in a trade-off between the reaction reactivity and stability.Herein,we proposed the use of ion-conductive yttria-stabilized zirconia(YSZ)support Fe_(2)O_(3)to prepare oxygen carriers materials.The obtained Fe_(2)O_(3)/YSZ composites showed high reactivity and stability.Particularly,Fe_(2)O_(3)/YSZ-20(oxygen storage capacity,24.13%)exhibited high hydrogen yield of~10.30 mmol g^(-1) and hydrogen production rate of~0.66 mmol g^(-1) min^(-1) which was twice as high as that of Fe_(2)O_(3)/Al_(2)O_(3).Further,the transient pulse test indicated that active oxygen diffusion was the ratelimiting step during the redox process.The electrochemical impedance spectroscopy(EIS)measurement revealed that the YSZ support addition facilitated oxygen diffusion of materials,which contributed to the improved hydrogen production performance.The support effect obtained in this work provides a potentially efficient route for the modification of oxygen carrier materials.展开更多
As industrialization accelerates and the amount of hazardous waste generated gradually increases,the means of disposal of hazardous waste is of increasing concern.In this paper,a 40 t/d counter-fow rotary kiln inciner...As industrialization accelerates and the amount of hazardous waste generated gradually increases,the means of disposal of hazardous waste is of increasing concern.In this paper,a 40 t/d counter-fow rotary kiln incineration system owned by a Jiangsu environmental protection company was researched.The software Aspen Plus was used to build the mixed pyrolysis model and the software Fluent was used to build the computational fuid dynamics model of the incineration system.The infuence of the calorifc value of the hazardous waste,the operating temperature and the air supply on the operational efectiveness of the incineration system were analyzed by varying the simulation conditions.The results show that the SO_(x)and NO_(x)content of the product is lower when the operating temperature is above 800℃.The incineration system could only operate above 800℃when the calorifc value of the hazardous waste is not less than 1500 kcal/kg.The incineration system operated best at a primary air velocity of 1.5 m/s.The simulation results in this paper serve as a guide for the operation of counter-fow rotary kiln incineration systems.展开更多
基金National Natural Science Foundation of China(Grant No.51706041)the National Natural Science Foundation of China(NSFC)Projects(Grant No.51661145011)the National Science Foundation for Distinguished Young Scholars of China(Grant No.51525601)。
文摘Chemical looping technology holds great potential on efficient CO2 splitting with much higher CO production and CO2 splitting rate than photocatalytic processes.Conventional oxygen carrier requires high temperature(typically 850–1000°C)to ensure sufficient redox activity,but the stable and high CO2 conversion is favored at a lower temperature,leading to the degrading on the reaction kinetics as well as the low CO production and CO2 splitting rate.In this paper,we prepared several ternary spinels and demonstrated their performance for chemical looping CO2 splitting at moderate temperatures.Using the promotion effect of Cu to cobalt ferrite reduction and reversible phase change of the reduced metals,Cu0.4 Co0.6 Fe2 O4 exhibits high CO2 splitting rate(144.6μmol g–1 min–1)and total CO production(9100μmol g–1)at 650°C.The high performance of this earth-abundant spinel material is also consistent in repeated redox cycles,enabling their potential in industrial use.
基金The authors gratefully acknowledge the National Natural Science Foundation of China(Grant No.51906041)the Natural Science Foundation of Jiangsu Province(Grant NO.BK20190360)the National Science Foundation for Distinguished Young Scholars of China(Grant No.51525601).
文摘Operating chemical looping process at mid-temperatures(550–750℃)presents exciting potential for the stable production of hydrogen.However,the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics.Although the reactivity at mid-temperature can be improved by the addition of noble metals,the high cost of these noble metal containing materials significantly hindered their scalable applications.In the current work,we propose to incorporate earth-abundant metals into the ironbased spinel for hydrogen production in a chemical looping scheme at mid-temperatures.Mn0.2Co0.4Fe2.4O4 shows a high hydrogen production performance at the average rate of~0.62 mmol g^(-1) min^(-1) and a hydrogen yield of~9.29 mmol g^(-1) with satisfactory stability over 20 cycles at 550℃.The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam.The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials,enabling their potential for industrial applications.
基金the National Natural Science Foundation of China(Grant No.51906041)the Natural Science Foundation of Jiangsu Province(Grant NO.BK20190360)the National Science Foundation for Distinguished Young Scholars of China(Grant No.51525601)。
文摘The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting efficiency than solar electrocatalytic and photocatalytic process.A typical oxygen carrier has to comprise a significant amount of inert support,to maintain stability in multiple redox cycles,thereby resulting in a trade-off between the reaction reactivity and stability.Herein,we proposed the use of ion-conductive yttria-stabilized zirconia(YSZ)support Fe_(2)O_(3)to prepare oxygen carriers materials.The obtained Fe_(2)O_(3)/YSZ composites showed high reactivity and stability.Particularly,Fe_(2)O_(3)/YSZ-20(oxygen storage capacity,24.13%)exhibited high hydrogen yield of~10.30 mmol g^(-1) and hydrogen production rate of~0.66 mmol g^(-1) min^(-1) which was twice as high as that of Fe_(2)O_(3)/Al_(2)O_(3).Further,the transient pulse test indicated that active oxygen diffusion was the ratelimiting step during the redox process.The electrochemical impedance spectroscopy(EIS)measurement revealed that the YSZ support addition facilitated oxygen diffusion of materials,which contributed to the improved hydrogen production performance.The support effect obtained in this work provides a potentially efficient route for the modification of oxygen carrier materials.
基金supported by the National Key R&D Program of China(No.2018YFC1902600)。
文摘As industrialization accelerates and the amount of hazardous waste generated gradually increases,the means of disposal of hazardous waste is of increasing concern.In this paper,a 40 t/d counter-fow rotary kiln incineration system owned by a Jiangsu environmental protection company was researched.The software Aspen Plus was used to build the mixed pyrolysis model and the software Fluent was used to build the computational fuid dynamics model of the incineration system.The infuence of the calorifc value of the hazardous waste,the operating temperature and the air supply on the operational efectiveness of the incineration system were analyzed by varying the simulation conditions.The results show that the SO_(x)and NO_(x)content of the product is lower when the operating temperature is above 800℃.The incineration system could only operate above 800℃when the calorifc value of the hazardous waste is not less than 1500 kcal/kg.The incineration system operated best at a primary air velocity of 1.5 m/s.The simulation results in this paper serve as a guide for the operation of counter-fow rotary kiln incineration systems.