Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we...Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we prepared mesoporous carbon nanofibers(mCNFs)functionalized with ordered PtFe alloys(O-PtFe-mCNFs)by a composite micelle interface-induced co-assembly method using poly(ethylene oxide)-block-polystyrene(PEO-b-PS)as a template.When employed as electrocatalysts,O-PtFe-mCNFs exhibited superior electrocatalytic performance for the NO_(3RR)compared to the mCNFs functionalized with disordered PtFe alloys(D-PtFe-mCNFs).Notably,the NH_(3)production performance was particularly outstanding,with a maximum NH_(3)yield of up to 959.6μmol/(h·cm~2).Furthermore,the Faraday efficiency(FE)was even 88.0%at-0.4 V vs.reversible hydrogen electrode(RHE).This finding provides compelling evidence of the potential of ordered PtFe alloy catalysts for the electrocatalytic NO_(3)RR.展开更多
Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reacto...Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH<sub>3</sub> dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH<sub>3</sub> conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH<sub>3</sub> dissociation, was observed as the NH<sub>3</sub> feed concentration and reactor temperature increased. During NH<sub>3</sub> oxidation, a predominantly greater exothermic effect with increasing NH<sub>3</sub> feed concentration and reactor temperature was also evident;however, it was apparent that NH<sub>3</sub> dissociation occurred near the reactor inlet, preceding the downstream NH<sub>3</sub> and H<sub>2</sub> oxidation. For both NH<sub>3</sub> dissociation and oxidation, NH<sub>3</sub> conversion increased with increasing temperature and decreasing initial NH<sub>3</sub> concentration. Significant levels of NO<sub>X</sub> emissions were observed during NH<sub>3</sub> oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH<sub>3</sub> dissociation and thus changed the reaction chemistry during NH<sub>3</sub> oxidation.展开更多
This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both...This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both Cu-SAPO-34 and Cu-ZSM-5. The catalytic activities of fresh, aged and poisoned samples were tested in ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) of NO<sub>x</sub> conditions. The XRD, TG and N<sub>2</sub>-desorption results showed that the structures of the Cu-SAPO-34 and Cu-ZSM-5 remained intact after 750˚C hydrothermally aged, SO<sub>2</sub> and propene poisoned. After hydrothermal aging at 750˚C for 12 h, the NO reduction performance of Cu-ZSM-5 was significantly reduced at lower temperatures, while that of Cu-SAPO-34 was less affected. Moreover, Cu-SAPO-34 catalyst showed high NO conversion with SO<sub>2</sub> or propene compared to Cu-ZSM-5. However, Cu-ZSM-5 showed a larger drop in catalytic activity with SO<sub>2</sub> or propene compared to Cu-SAPO-34 catalyst. The H<sub>2</sub>-TPR results showed that Cu<sup>2 </sup> ions could be reduced to Cu<sup> </sup> and Cu<sup>0</sup> for Cu-ZSM-5, while no significant transformation of copper species was observed for Cu-SAPO-34. Meanwhile, the UV-vis DRS results showed that CuO species were formed in Cu-ZSM-5, while little changes were observed for the Cu-SAPO-34. Cu-SAPO-34 showed high sulfur and hydrocarbon poison resistance compared to Cu-ZSM-5. In summary, Cu-SAPO-34 with small-pore zeolite showed higher hydrothermal stability and better hydrocarbon and sulfur poison resistant than Cu-ZSM-5 with medium-pore.展开更多
Aqueous ammonia(NH3) is a promising alternative solvent for the capture of industrial CO_2 emissions, given its high chemical stability and CO_2 removal capacity, and low material costs and regeneration energy. NH3 al...Aqueous ammonia(NH3) is a promising alternative solvent for the capture of industrial CO_2 emissions, given its high chemical stability and CO_2 removal capacity, and low material costs and regeneration energy. NH3 also has potential for capturing multiple flue gas components, including NOx, SOxand CO_2, and producing value-added chemicals. However, its high volatility and low reactivity towards CO_2 limit its economic viability. Considerable efforts have been made to advance aqueous NH3-based post-combustion capture technologies in the last few years: in particular, General Electric's chilled NH3 process, CSIRO's mild-temperature aqueous NH3 process and SRI International's mixed-salts(NH3 and potassium carbonate) technology. Here, we review these research activities and other developments in the field, and outline future research needed to further improve aqueous NH3-based CO_2 capture technologies.展开更多
In order to completely evaluate ammonia emission from greenhouse vegetable fields,crop canopy absorption should not be neglected.The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N t...In order to completely evaluate ammonia emission from greenhouse vegetable fields,crop canopy absorption should not be neglected.The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N translocation to other plant components were investigated under greenhouse conditions using chambers covered with the soil of a tomato field.Treatments comprised three NH3-N application rates(70,140,and 210 mg/plot) using 15N-labeled ammonium sulfate.Plants were harvested immediately after exposure for 24 h,and the total N concentrations and 15N/14 N ratios were determined.With increased NH3 concentration,total 15NH3-N absorption increased considerably,whereas the applied 15NH3-N uptake decreased gradually.The tomato plants absorbed 33-38% and 24-31% of the 15NH3-N generated at the anthesis and fruit growth stages,respectively.A total of 71-80% of the recovered NH3 was observed in the leaves and 20-30% of the recovered NH3 was remobilized to other components.Among them,an average of 10% of the absorbed 15NH3-N was transferred into the tomato fruits.All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric 15NH3 and the distribution of 15N-labeled vegetative N among different plant components.The results are of great importance for the complete evaluation of nitrogen use efficiency in the greenhouse tomato fields.展开更多
The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the ...The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl2, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl2.mNH3) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl2 alone.展开更多
Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recen...Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and research.However,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various electrocatalysts.Given this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V vs.reversible hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.展开更多
The upland agricultural soils in North China are distributed north of a line between the Kunlun Mountains, the Qinling Mountains and the Huaihe River. They occur in arid, semi-arid and semi-humid regions and crop prod...The upland agricultural soils in North China are distributed north of a line between the Kunlun Mountains, the Qinling Mountains and the Huaihe River. They occur in arid, semi-arid and semi-humid regions and crop production often depends on rain-fed or irrigation to supplement rainfall. This paper summarizes the characteristics of gross nitrogen（N） transformation, the fate of N fertilizer and soil N as well as the N loss pathway, and makes suggestions for proper N management in the region. The soils of the region are characterized by strong N mineralization and nitrification, and weak immobilization and denitrification ability, which lead to the production and accumulation of nitrate in the soil profile. Large amounts of accumulated nitrate have been observed in the vadose-zone in soils due to excess N fertilization in the past three decades, and this nitrate is subject to occasional leaching which leads to groundwater nitrate contamination. Under farmer＇s conventional high N fertilization practice in the winter wheat-summer maize rotation system（N application rate was approximately 600 kg ha–1 yr–1）, crop N uptake, soil residual N, NH_3 volatilization, NO_3~– leaching, and denitrification loss accounted for around 27, 30, 23, 18 and 2% of the applied fertilizer N, respectively. NH_3 volatilization and NO_3~– leaching were the most important N loss pathways while soil residual N was an important fate of N fertilizer for replenishing soil N depletion from crop production. The upland agricultural soils in North China are a large source of N_2O and total emissions in this region make up a large proportion（approximately 54%） of Chinese cropland N_2O emissions. The “non-coupled strong ammonia oxidation” process is an important mechanism of N_2O production. Slowing down ammonia oxidation after ammonium-N fertilizer or urea application and avoiding transient high soil NH4＋ concentrations are key measures for reducing N_2O emissions in this region. Further N management should aim to minimize N losses from crop and livestock production, and increase the recycling of manure and straw back to cropland. We also recommend adoption of the 4 R（Right soure, Right rate, Right time, Right place） fertilization techniques to realize proper N fertilizer management, and improving application methods or modifying fertilizer types to reduce NH_3 volatilization, improving water management to reduce NO_3~– leaching, and controlling the strong ammonia oxidation process to abate N_2O emission. Future research should focus on the study of the trade-off effects among different N loss pathways under different N application methods or fertilizer products.展开更多
基金National Natural Science Foundation of China(Nos.52225204,52173233 and 52202085)Innovation Program of Shanghai Municipal Education Commission,China(No.2021-01-07-00-03-E00109)+3 种基金Natural Science Foundation of Shanghai,China(No.23ZR1479200)“Shuguang Program”Supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission,China(No.20SG33)Fundamental Research Funds for the Central Universities,China(No.2232024Y-01)DHU Distinguished Young Professor Program,China(Nos.LZA2022001 and LZB2023002)。
文摘Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we prepared mesoporous carbon nanofibers(mCNFs)functionalized with ordered PtFe alloys(O-PtFe-mCNFs)by a composite micelle interface-induced co-assembly method using poly(ethylene oxide)-block-polystyrene(PEO-b-PS)as a template.When employed as electrocatalysts,O-PtFe-mCNFs exhibited superior electrocatalytic performance for the NO_(3RR)compared to the mCNFs functionalized with disordered PtFe alloys(D-PtFe-mCNFs).Notably,the NH_(3)production performance was particularly outstanding,with a maximum NH_(3)yield of up to 959.6μmol/(h·cm~2).Furthermore,the Faraday efficiency(FE)was even 88.0%at-0.4 V vs.reversible hydrogen electrode(RHE).This finding provides compelling evidence of the potential of ordered PtFe alloy catalysts for the electrocatalytic NO_(3)RR.
文摘Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH<sub>3</sub> dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH<sub>3</sub> conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH<sub>3</sub> dissociation, was observed as the NH<sub>3</sub> feed concentration and reactor temperature increased. During NH<sub>3</sub> oxidation, a predominantly greater exothermic effect with increasing NH<sub>3</sub> feed concentration and reactor temperature was also evident;however, it was apparent that NH<sub>3</sub> dissociation occurred near the reactor inlet, preceding the downstream NH<sub>3</sub> and H<sub>2</sub> oxidation. For both NH<sub>3</sub> dissociation and oxidation, NH<sub>3</sub> conversion increased with increasing temperature and decreasing initial NH<sub>3</sub> concentration. Significant levels of NO<sub>X</sub> emissions were observed during NH<sub>3</sub> oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH<sub>3</sub> dissociation and thus changed the reaction chemistry during NH<sub>3</sub> oxidation.
文摘This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both Cu-SAPO-34 and Cu-ZSM-5. The catalytic activities of fresh, aged and poisoned samples were tested in ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) of NO<sub>x</sub> conditions. The XRD, TG and N<sub>2</sub>-desorption results showed that the structures of the Cu-SAPO-34 and Cu-ZSM-5 remained intact after 750˚C hydrothermally aged, SO<sub>2</sub> and propene poisoned. After hydrothermal aging at 750˚C for 12 h, the NO reduction performance of Cu-ZSM-5 was significantly reduced at lower temperatures, while that of Cu-SAPO-34 was less affected. Moreover, Cu-SAPO-34 catalyst showed high NO conversion with SO<sub>2</sub> or propene compared to Cu-ZSM-5. However, Cu-ZSM-5 showed a larger drop in catalytic activity with SO<sub>2</sub> or propene compared to Cu-SAPO-34 catalyst. The H<sub>2</sub>-TPR results showed that Cu<sup>2 </sup> ions could be reduced to Cu<sup> </sup> and Cu<sup>0</sup> for Cu-ZSM-5, while no significant transformation of copper species was observed for Cu-SAPO-34. Meanwhile, the UV-vis DRS results showed that CuO species were formed in Cu-ZSM-5, while little changes were observed for the Cu-SAPO-34. Cu-SAPO-34 showed high sulfur and hydrocarbon poison resistance compared to Cu-ZSM-5. In summary, Cu-SAPO-34 with small-pore zeolite showed higher hydrothermal stability and better hydrocarbon and sulfur poison resistant than Cu-ZSM-5 with medium-pore.
文摘Aqueous ammonia(NH3) is a promising alternative solvent for the capture of industrial CO_2 emissions, given its high chemical stability and CO_2 removal capacity, and low material costs and regeneration energy. NH3 also has potential for capturing multiple flue gas components, including NOx, SOxand CO_2, and producing value-added chemicals. However, its high volatility and low reactivity towards CO_2 limit its economic viability. Considerable efforts have been made to advance aqueous NH3-based post-combustion capture technologies in the last few years: in particular, General Electric's chilled NH3 process, CSIRO's mild-temperature aqueous NH3 process and SRI International's mixed-salts(NH3 and potassium carbonate) technology. Here, we review these research activities and other developments in the field, and outline future research needed to further improve aqueous NH3-based CO_2 capture technologies.
基金funded by the National Key Research and Development Program of China (2017YFD0200106)
文摘In order to completely evaluate ammonia emission from greenhouse vegetable fields,crop canopy absorption should not be neglected.The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N translocation to other plant components were investigated under greenhouse conditions using chambers covered with the soil of a tomato field.Treatments comprised three NH3-N application rates(70,140,and 210 mg/plot) using 15N-labeled ammonium sulfate.Plants were harvested immediately after exposure for 24 h,and the total N concentrations and 15N/14 N ratios were determined.With increased NH3 concentration,total 15NH3-N absorption increased considerably,whereas the applied 15NH3-N uptake decreased gradually.The tomato plants absorbed 33-38% and 24-31% of the 15NH3-N generated at the anthesis and fruit growth stages,respectively.A total of 71-80% of the recovered NH3 was observed in the leaves and 20-30% of the recovered NH3 was remobilized to other components.Among them,an average of 10% of the absorbed 15NH3-N was transferred into the tomato fruits.All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric 15NH3 and the distribution of 15N-labeled vegetative N among different plant components.The results are of great importance for the complete evaluation of nitrogen use efficiency in the greenhouse tomato fields.
文摘The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl2, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl2.mNH3) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl2 alone.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.20720210010)the National Natural Science Foundation of China(Nos.22001081,22075236)the Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM,No.HRTP-[2022]-7).
文摘Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and research.However,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various electrocatalysts.Given this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V vs.reversible hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.
基金supported by the National Natural Science Foundation of China (41471190)the National Key Research and Development Program of China (2016YFD0800102)+2 种基金the Special Fund for the Agricultural Public Welfare Profession of China (201503106)the Newton Fund, United Kingdom (BB/N013484/1)the GEF on the ‘Towards INMS’
文摘The upland agricultural soils in North China are distributed north of a line between the Kunlun Mountains, the Qinling Mountains and the Huaihe River. They occur in arid, semi-arid and semi-humid regions and crop production often depends on rain-fed or irrigation to supplement rainfall. This paper summarizes the characteristics of gross nitrogen（N） transformation, the fate of N fertilizer and soil N as well as the N loss pathway, and makes suggestions for proper N management in the region. The soils of the region are characterized by strong N mineralization and nitrification, and weak immobilization and denitrification ability, which lead to the production and accumulation of nitrate in the soil profile. Large amounts of accumulated nitrate have been observed in the vadose-zone in soils due to excess N fertilization in the past three decades, and this nitrate is subject to occasional leaching which leads to groundwater nitrate contamination. Under farmer＇s conventional high N fertilization practice in the winter wheat-summer maize rotation system（N application rate was approximately 600 kg ha–1 yr–1）, crop N uptake, soil residual N, NH_3 volatilization, NO_3~– leaching, and denitrification loss accounted for around 27, 30, 23, 18 and 2% of the applied fertilizer N, respectively. NH_3 volatilization and NO_3~– leaching were the most important N loss pathways while soil residual N was an important fate of N fertilizer for replenishing soil N depletion from crop production. The upland agricultural soils in North China are a large source of N_2O and total emissions in this region make up a large proportion（approximately 54%） of Chinese cropland N_2O emissions. The “non-coupled strong ammonia oxidation” process is an important mechanism of N_2O production. Slowing down ammonia oxidation after ammonium-N fertilizer or urea application and avoiding transient high soil NH4＋ concentrations are key measures for reducing N_2O emissions in this region. Further N management should aim to minimize N losses from crop and livestock production, and increase the recycling of manure and straw back to cropland. We also recommend adoption of the 4 R（Right soure, Right rate, Right time, Right place） fertilization techniques to realize proper N fertilizer management, and improving application methods or modifying fertilizer types to reduce NH_3 volatilization, improving water management to reduce NO_3~– leaching, and controlling the strong ammonia oxidation process to abate N_2O emission. Future research should focus on the study of the trade-off effects among different N loss pathways under different N application methods or fertilizer products.
