In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical propertie...In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and CaCl2.mNH3 + Ti. It reveals that the thermophysical properties in this measurement would be the valuable design factors to develop energy and H2 storage systems utilizing natural resources such as solar energy.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
This work describes the environmentally friendly technology for oxidation of ammonia （NH3） to form nitrogen at temperatures range from 423K to 673K by selective catalytic oxidation （SCO） over a nanosized Pt- Rh/γ...This work describes the environmentally friendly technology for oxidation of ammonia （NH3） to form nitrogen at temperatures range from 423K to 673K by selective catalytic oxidation （SCO） over a nanosized Pt- Rh/γ-A12O3 catalyst prepared by the incipient wetness impregnation method of hexachloroplatinic acid （H2PtC16） and rhodium （Ⅲ） nitrate （Rh（NO3）3） with γ-A12O3 in a tubular fixed-bed flow quartz reactor （TFBR）. The characterization of catalysts were thoroughly measured using transmission electron microscopy （TEM）, three- dimensional excitation-emission fluorescent matrix （EEFM） spectroscopy, UV-Vis absorption, dynamic light- scattering （DLS）, zeta potential meter, and cyclic voltam- metry （CV）. The results demonstrated that at a temperature of 673K and an oxygen content of4%, approximately 99% of the NH3 was removed by catalytic oxidation over the nanosized Pt-Rh/γ-A12O3 catalyst. N2 was the main product in NH3-SCO process. Further, it reveals that the oxidation of NH3 was proceeds by the over-oxidation of NH3 into NO, which was conversely reacted with the NH3 to yield N2. Therefore, the application ofnanosized Pt-Rh/γ-A12O3 catalyst can significantly enhance the catalytic activity toward NH3 oxidation. One fluorescent peak for fresh catalyst was different with that of exhausted catalyst. It indicates that EEFM spectroscopy was proven to be an appropriate and effective method to characterize the Pt clusters in intrinsic emission from nanosized Pt-Rh/γ-A12O3 catalyst. Results obtained from the CV may explain the significant catalytic activity of the catalysts.展开更多
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
The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a...The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a catalyst, Cu2+ loading SAPO-17, synthesized using cyclohexylamine(CHA), which is commercially available and inexpensive and is utilized in NH3-SCR reduction for the first time. After systematic investigations on the optimization of Si and Cu2+ contents, it was concluded that Cu-SAPO-17-8.0%-0.22 displays favorable catalytic performance, even after being heated at 353 K for 24 h and at 973 K for 16 h. Moreover, the locations of CHAs, host–guest interaction and the Bronsted acid sites were explored by Rietveld refinement against powder X-ray diffraction data of as-made SAPO-17-8.0%. The refinement results showed that two CHAs exist within one eri cage and that the protonated CHA forms a hydrogen bond with O4, which indicates that the proton bonding with O4 will form the Bronsted acid site after the calcination.展开更多
Fertilizer-intensive agriculture is a leading source of reactive nitrogen(Nr)emissions that damage climate,air quality,and human health.Biochar has long been studied as a soil amendment,but its influence on Nr emissio...Fertilizer-intensive agriculture is a leading source of reactive nitrogen(Nr)emissions that damage climate,air quality,and human health.Biochar has long been studied as a soil amendment,but its influence on Nr emissions remains insufficiently characterized.More recently,the pyrolysis of light hydrocarbons has been suggested as a source of hydrogen fuel,resulting in a solid zero-valent carbon(ZVC)byproduct whose impact on soil emissions has yet to be tested.We incorporate carbon amendment algorithms into an agroecosystem model to simulate emission changes in the year following the application of biochar or ZVC to the US.fertilized soils.Our simulations predicted that the impacts of biochar amendments on Nr emissions would vary widely(−17%to+27%under 5 ton ha^(−1) applications,−38%to+18%under 20 ton ha^(−1) applications)and depend mostly on how nitrification is affected.Low-dose biochar application(5 ton ha^(−1))stimulated emissions of all three nitrogen species in 75%of simulated agricultural areas,while high-dose applications(20 ton ha^(−1))mitigated emissions in 76%of simulated areas.Applying zero-valent carbon at 20 ton ha^(−1) exhibited similar effects on nitrogen emissions as biochar applications at 5 ton ha^(−1).Biochar amendments are most likely to mitigate emissions if applied at high rates in acidic soils(pH<5.84)with low organic carbon(<55.9 kg C ha^(−1))and inorganic nitrogen(<101.5 kg N ha^(−1))content.Our simulations could inform where the application of carbon amendments would most likely mitigate Nr emissions and their associated adverse impacts.展开更多
Ammonia(NH_(3))is ubiquitous in the atmosphere,it can affect the formation of secondary aerosols and particulate matter,and cause soil eutrophication through sedimentation.Currently,the use of radioactive primary reag...Ammonia(NH_(3))is ubiquitous in the atmosphere,it can affect the formation of secondary aerosols and particulate matter,and cause soil eutrophication through sedimentation.Currently,the use of radioactive primary reagent ion source and the humidity interference on the sensitivity and stability are the two major issues faced by chemical ionization mass spectrometer(CIMS)in the analysis of atmospheric ammonia.In this work,a vacuum ultraviolet(VUV)Kr lamp was used to replace the radioactive source,and acetone was ionized under atmospheric pressure to obtain protonated acetone reagent ions to ionize ammonia.The ionization source is designed as a separated three-zone structure,and even 90 vol.%high-humidity samples can still be directly analyzed with a sensitivity of sub-ppbv.A signal normalization processing method was designed,and with this new method,the quantitative relative standard deviation(RSD)of the instrument was decreased from 17.5%to9.1%,and the coefficient of determination was increased from 0.8340 to 0.9856.The humidity correction parameters of the instrument were calculated from different humidity,and the ammonia concentrations obtained under different humidity were converted to its concentration under zero humidity condition with these correction parameters.The analytical time for a single sample is only 60 sec,and the limit of detection(LOD)was 8.59 pptv(signalto-noise ratio S/N=3).The ambient measurement made in Qingdao,China,in January 2021 with this newly designed CIMS,showed that the concentration of ammonia ranged from 1 to 130 ppbv.展开更多
文摘In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and CaCl2.mNH3 + Ti. It reveals that the thermophysical properties in this measurement would be the valuable design factors to develop energy and H2 storage systems utilizing natural resources such as solar energy.
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.
文摘This work describes the environmentally friendly technology for oxidation of ammonia （NH3） to form nitrogen at temperatures range from 423K to 673K by selective catalytic oxidation （SCO） over a nanosized Pt- Rh/γ-A12O3 catalyst prepared by the incipient wetness impregnation method of hexachloroplatinic acid （H2PtC16） and rhodium （Ⅲ） nitrate （Rh（NO3）3） with γ-A12O3 in a tubular fixed-bed flow quartz reactor （TFBR）. The characterization of catalysts were thoroughly measured using transmission electron microscopy （TEM）, three- dimensional excitation-emission fluorescent matrix （EEFM） spectroscopy, UV-Vis absorption, dynamic light- scattering （DLS）, zeta potential meter, and cyclic voltam- metry （CV）. The results demonstrated that at a temperature of 673K and an oxygen content of4%, approximately 99% of the NH3 was removed by catalytic oxidation over the nanosized Pt-Rh/γ-A12O3 catalyst. N2 was the main product in NH3-SCO process. Further, it reveals that the oxidation of NH3 was proceeds by the over-oxidation of NH3 into NO, which was conversely reacted with the NH3 to yield N2. Therefore, the application ofnanosized Pt-Rh/γ-A12O3 catalyst can significantly enhance the catalytic activity toward NH3 oxidation. One fluorescent peak for fresh catalyst was different with that of exhausted catalyst. It indicates that EEFM spectroscopy was proven to be an appropriate and effective method to characterize the Pt clusters in intrinsic emission from nanosized Pt-Rh/γ-A12O3 catalyst. Results obtained from the CV may explain the significant catalytic activity of the catalysts.
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The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a catalyst, Cu2+ loading SAPO-17, synthesized using cyclohexylamine(CHA), which is commercially available and inexpensive and is utilized in NH3-SCR reduction for the first time. After systematic investigations on the optimization of Si and Cu2+ contents, it was concluded that Cu-SAPO-17-8.0%-0.22 displays favorable catalytic performance, even after being heated at 353 K for 24 h and at 973 K for 16 h. Moreover, the locations of CHAs, host–guest interaction and the Bronsted acid sites were explored by Rietveld refinement against powder X-ray diffraction data of as-made SAPO-17-8.0%. The refinement results showed that two CHAs exist within one eri cage and that the protonated CHA forms a hydrogen bond with O4, which indicates that the proton bonding with O4 will form the Bronsted acid site after the calcination.
基金The Carbon Hub at Rice University provided funding for this study.
文摘Fertilizer-intensive agriculture is a leading source of reactive nitrogen(Nr)emissions that damage climate,air quality,and human health.Biochar has long been studied as a soil amendment,but its influence on Nr emissions remains insufficiently characterized.More recently,the pyrolysis of light hydrocarbons has been suggested as a source of hydrogen fuel,resulting in a solid zero-valent carbon(ZVC)byproduct whose impact on soil emissions has yet to be tested.We incorporate carbon amendment algorithms into an agroecosystem model to simulate emission changes in the year following the application of biochar or ZVC to the US.fertilized soils.Our simulations predicted that the impacts of biochar amendments on Nr emissions would vary widely(−17%to+27%under 5 ton ha^(−1) applications,−38%to+18%under 20 ton ha^(−1) applications)and depend mostly on how nitrification is affected.Low-dose biochar application(5 ton ha^(−1))stimulated emissions of all three nitrogen species in 75%of simulated agricultural areas,while high-dose applications(20 ton ha^(−1))mitigated emissions in 76%of simulated areas.Applying zero-valent carbon at 20 ton ha^(−1) exhibited similar effects on nitrogen emissions as biochar applications at 5 ton ha^(−1).Biochar amendments are most likely to mitigate emissions if applied at high rates in acidic soils(pH<5.84)with low organic carbon(<55.9 kg C ha^(−1))and inorganic nitrogen(<101.5 kg N ha^(−1))content.Our simulations could inform where the application of carbon amendments would most likely mitigate Nr emissions and their associated adverse impacts.
基金partially supported by the National Special Fund for the Development of Major Research Equipment and Instrument(No.2020YFF01014503)NSF of China(No.21874134)Young Taishan Scholars(No.tsqn201909039)
文摘Ammonia(NH_(3))is ubiquitous in the atmosphere,it can affect the formation of secondary aerosols and particulate matter,and cause soil eutrophication through sedimentation.Currently,the use of radioactive primary reagent ion source and the humidity interference on the sensitivity and stability are the two major issues faced by chemical ionization mass spectrometer(CIMS)in the analysis of atmospheric ammonia.In this work,a vacuum ultraviolet(VUV)Kr lamp was used to replace the radioactive source,and acetone was ionized under atmospheric pressure to obtain protonated acetone reagent ions to ionize ammonia.The ionization source is designed as a separated three-zone structure,and even 90 vol.%high-humidity samples can still be directly analyzed with a sensitivity of sub-ppbv.A signal normalization processing method was designed,and with this new method,the quantitative relative standard deviation(RSD)of the instrument was decreased from 17.5%to9.1%,and the coefficient of determination was increased from 0.8340 to 0.9856.The humidity correction parameters of the instrument were calculated from different humidity,and the ammonia concentrations obtained under different humidity were converted to its concentration under zero humidity condition with these correction parameters.The analytical time for a single sample is only 60 sec,and the limit of detection(LOD)was 8.59 pptv(signalto-noise ratio S/N=3).The ambient measurement made in Qingdao,China,in January 2021 with this newly designed CIMS,showed that the concentration of ammonia ranged from 1 to 130 ppbv.
