Plasma-based NO_(x) synthesis has been considered as a sustainable alternative to the conventional HaberBosch process.Despite the advancements in research achieved in recent years,limited attention has been paid to th...Plasma-based NO_(x) synthesis has been considered as a sustainable alternative to the conventional HaberBosch process.Despite the advancements in research achieved in recent years,limited attention has been paid to the reversible dimerization reaction of NO_(2) to N_(2)O_(4).This reaction can significantly alter the parameters considered with the process’output,such as the concentration or volume fraction of products and the energy consumption.This work aims to investigate the significance of dimerization through theoretical analysis and experimentation.Experiments were conducted with a 2D-gliding arc reactor to evaluate the influence of dimerization in the case of plasma reactor operation.It was observed that the dimerization reaction reached equilibrium in microseconds,resulting in a maximum hypothetical NO_(2) equilibrium conversion of 48.8%.For plasma experiments,the dimerization could cause a maximum error of 14.1%in product detection,which needs to be carefully considered along with the influence of temperature variations on the measurement.展开更多
This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LF...This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LFC） and no fertilizer （CK） to measure the dynamic emissions of CO2 and N2O from a summer maize-winter wheat field by static chamber-gas chromatography method. The results showed that the soil CO2 emission was 21.8-1 022.7 mg/（m^2·h）, and was mainly influenced by soil temperature and moisture content. During the growth of summer maize, the soil CO2 emission was more significantly affected by soil moisture con-tent; and in winter wheat growing season, it was more significantly affected by soil temperature in the top 5 cm. The LF and LFC treatments significantly reduced the soil cumulative CO2 emission, especial y during the growth of winter wheat. Fertiliza-tion and irrigation were the main factors influencing the soil N2O emission. The soil N2O emission during the fertilization period accounted for 73.9%-74.5% and 40.5%-43.6% of the soil cumulative N2O emission during the summer maize-and winter wheat-growing season, respectively. The peak of emission fluxes was determined by fertilization amount, while the occurrence time of emission peak and emission re-duction effect were influenced by irrigation. The LF treatment reduced the soil cu-mulative N2O emission by 15.7%-16.8% and 18.1%-18.5% during the growth period of summer maize and winter wheat, respectively. Reduced nitrogen fertilization is an effective way for reducing N2O emission in intensive high-yielding farmland. Under a suitable nitrogen level （200 kg/hm^2）, the application of biochar showed no significant effect on the soil N2O emission in a short term. The N2O emission factors of the L and LF treatments were 0.60% and 0.56%, respectively. ln the intensive high-yield-ing farmland of North China, reducing the nitrogen application amount is an appro-priate measure to mitigate greenhouse gas emissions without crop yield loss.展开更多
Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and frag...Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.展开更多
To improve the efficiency of the carbon dioxide cycling process and to reduce the regeneration energy consumption, a sterically hindered amine of 2-amino-2-methyl-1- propranol （AMP） was investigated to determine its...To improve the efficiency of the carbon dioxide cycling process and to reduce the regeneration energy consumption, a sterically hindered amine of 2-amino-2-methyl-1- propranol （AMP） was investigated to determine its regeneration behavior as a CO2 absorbent. The CO2 absorption and amine regeneration characteristics were experimentally examined under various operating conditions. The regeneration efficiency increased from 86.2% to 98.3% during the temperature range of 358 to 403 K. The most suitable regeneration temperature for AMP was 383 K, in this experiment condition, and the regeneration efficiency of absorption/regeneration runs descended from 98.3% to 94.0%. A number of heat-stable salts （HSS） could cause a reduction in CO2 absorption capacity and regeneration efficiency. The results indicated that aqueous AMP was easier to regenerate with less loss of absorption capacity than other amines, such as, monoethanolamine （MEA）, diethanolamine （DEA）, diethylenetriamine （DETA）, and N-methyldiethanolamine （MDEA）.展开更多
The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results in...The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.展开更多
Electrochemical reduction of CO2 to produce value-added feedstock chemicals using high-performance electrocatalysts is a promising protocol to address the excessive CO2 in the atmosphere and the energy crisis. However...Electrochemical reduction of CO2 to produce value-added feedstock chemicals using high-performance electrocatalysts is a promising protocol to address the excessive CO2 in the atmosphere and the energy crisis. However, the high overpotential, low current density, and poor product selectivity for CO2 electroreduction greatly impede their practical applications. In this work, we develop an efficient catalyst for CO2 reduction to CO consisting of well-dispersed ZrO2 nanoparticles tightly anchored on nitrogendoped carbon nanosheets(ZrO2/N-C) for the first time. Importantly, the ZrO2 nanoparticles possess oxygen vacancies and defects, which regulate the electronic structure of catalyst and thus greatly enhance the electrocatalytic activity. Specifically, ZrO2/N-C demonstrates a high CO Faradaic efficiency(FE) of 64% at-0.4 V vs. the reversible hydrogen electrode(RHE) and a respectable current density of ~2.6 m A cm-2 in CO2-saturated 0.5 M KHCO 3 solution. This work opens a new avenue for developing excellent catalysts for CO2 electroreduction with metal oxide/heteroatom-doped carbon composite structure.展开更多
CO_(2) methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route.Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were...CO_(2) methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route.Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were synthesized by impregnation,calcination and reduction and characterized by elemental analysis,X-ray powder diffraction,H_(2) temperature-programmed reduction,CO pulse chemisorption and transmission electron microscopy.The Ni/NCNT catalysts were highly active in CO_(2) methanation at atmospheric pressure,reaching over 50% CO_(2) conversion and over 95% CH_(4) selectivity at 340℃ and a GHSV of50,000 mL g^(-1) h^(-1) under kinetically controlled conditions.The small Ni particle sizes below 10 nm despite the high Ni loading is ascribed to the efficient anchoring on the N-doped CNTs.The optimum loading of 30 wt%-40 wt% Ni was found to result in the highest Ni surface area,the highest degree of conversion and the highest selectivity to methane.A constant TOF of 0.3 s^(-1) was obtained indicating similar catalytic properties of the Ni nanoparticles in the range from 10 wt%to 50 wt% Ni loading.Long-term experiments showed that the Ni/NCNT catalyst with 30 wt% Ni was highly stable for 100 h time on stream.展开更多
Tin/tin oxide materials are key electrocatalysts for selective conversion of CO;to formate/formic acid.Herein we report a tin oxide material with nitrogen doping by using ammonia treatment at elevated temperature. The...Tin/tin oxide materials are key electrocatalysts for selective conversion of CO;to formate/formic acid.Herein we report a tin oxide material with nitrogen doping by using ammonia treatment at elevated temperature. The N doped material demonstrated enhanced electrocatalytic CO;reduction activity, showing high Faradaic efficiency（90%） for formate at -0.65 V vs. RHE with partial current density of 4 mA/cm;.The catalysis was contributed to increased electron negativity of N atom compared to O atom. Additionally, the N-doped catalyst demonstrates sulfur tolerance with retained formate selectivity. The analysis after electrolysis shows that the catalyst structure partially converts to metallic Sn, and thus the combined Sn/N-SnO;is the key for the active CO;catalysis.展开更多
基金supported by the NOW’s Prescient project(16271)the LEAP-AGRI project AFRICA。
文摘Plasma-based NO_(x) synthesis has been considered as a sustainable alternative to the conventional HaberBosch process.Despite the advancements in research achieved in recent years,limited attention has been paid to the reversible dimerization reaction of NO_(2) to N_(2)O_(4).This reaction can significantly alter the parameters considered with the process’output,such as the concentration or volume fraction of products and the energy consumption.This work aims to investigate the significance of dimerization through theoretical analysis and experimentation.Experiments were conducted with a 2D-gliding arc reactor to evaluate the influence of dimerization in the case of plasma reactor operation.It was observed that the dimerization reaction reached equilibrium in microseconds,resulting in a maximum hypothetical NO_(2) equilibrium conversion of 48.8%.For plasma experiments,the dimerization could cause a maximum error of 14.1%in product detection,which needs to be carefully considered along with the influence of temperature variations on the measurement.
基金Supported by National Key Technology Research and Development Program(2013BAD11B03)National Natural Science Foundation(31272249,31071865,41505100)~~
文摘This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LFC） and no fertilizer （CK） to measure the dynamic emissions of CO2 and N2O from a summer maize-winter wheat field by static chamber-gas chromatography method. The results showed that the soil CO2 emission was 21.8-1 022.7 mg/（m^2·h）, and was mainly influenced by soil temperature and moisture content. During the growth of summer maize, the soil CO2 emission was more significantly affected by soil moisture con-tent; and in winter wheat growing season, it was more significantly affected by soil temperature in the top 5 cm. The LF and LFC treatments significantly reduced the soil cumulative CO2 emission, especial y during the growth of winter wheat. Fertiliza-tion and irrigation were the main factors influencing the soil N2O emission. The soil N2O emission during the fertilization period accounted for 73.9%-74.5% and 40.5%-43.6% of the soil cumulative N2O emission during the summer maize-and winter wheat-growing season, respectively. The peak of emission fluxes was determined by fertilization amount, while the occurrence time of emission peak and emission re-duction effect were influenced by irrigation. The LF treatment reduced the soil cu-mulative N2O emission by 15.7%-16.8% and 18.1%-18.5% during the growth period of summer maize and winter wheat, respectively. Reduced nitrogen fertilization is an effective way for reducing N2O emission in intensive high-yielding farmland. Under a suitable nitrogen level （200 kg/hm^2）, the application of biochar showed no significant effect on the soil N2O emission in a short term. The N2O emission factors of the L and LF treatments were 0.60% and 0.56%, respectively. ln the intensive high-yield-ing farmland of North China, reducing the nitrogen application amount is an appro-priate measure to mitigate greenhouse gas emissions without crop yield loss.
基金This project was financially supported by the National Natural Science Foundation of China(31601244 and 31971843)the Guangdong Provincial Key Field Research and Development Plan Project,China(2019B020221003)the Modern Agricultural Industrial Technology System of Guangdong Province,China(2020KJ105).
文摘Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.
文摘To improve the efficiency of the carbon dioxide cycling process and to reduce the regeneration energy consumption, a sterically hindered amine of 2-amino-2-methyl-1- propranol （AMP） was investigated to determine its regeneration behavior as a CO2 absorbent. The CO2 absorption and amine regeneration characteristics were experimentally examined under various operating conditions. The regeneration efficiency increased from 86.2% to 98.3% during the temperature range of 358 to 403 K. The most suitable regeneration temperature for AMP was 383 K, in this experiment condition, and the regeneration efficiency of absorption/regeneration runs descended from 98.3% to 94.0%. A number of heat-stable salts （HSS） could cause a reduction in CO2 absorption capacity and regeneration efficiency. The results indicated that aqueous AMP was easier to regenerate with less loss of absorption capacity than other amines, such as, monoethanolamine （MEA）, diethanolamine （DEA）, diethylenetriamine （DETA）, and N-methyldiethanolamine （MDEA）.
文摘基于Sentinel-5P卫星TROPOMI数据,利用随机森林方法反演2018~2020年淮河流域地面NO_(2)浓度,采用推算法获得淮河流域2018~2020年NO_(2)干沉降通量,并通过划分不同集水区(水域、农田、城区和植被覆盖区)估算大气NO_(2)干沉降对淮河流域水体氮素的贡献.结果显示,卫星反演地面NO_(2)浓度与地面站点实测资料一致性较高,相关系数(R)为0.94,平均绝对误差(MAE)为2.7,均方根误差(RSME)为4.1.淮河流域地面NO_(2)浓度和NO_(2)干沉降通量均有明显的季节变化,春夏秋冬4个季节地面NO_(2)平均浓度分别为13.7,12.2,17.6,23.1μg/m^(3);NO_(2)平均干沉降通量分别为1.25,1.13,1.61,2.13kg N/(hm^(2)·a).淮河流域地面NO_(2)浓度和干沉降通量均表现为南北部高,东西部低.农田区域NO_(2)干沉降对流域水体氮素的贡献最大,占比83.47%.2019年淮河流域大气NO_(2)干沉降总量为1.34×10^(5)t,对水体氮素的贡献为1.36×10^(4)t N;2020年大气NO_(2)干沉降总量为1.25×10^(5)t,对水体氮素的贡献为1.18×10^(4)t N.
基金supported by the National Natural Science Foundation of China (Grant No. 20906034)the Key Academic Program of the 3rd Phase "211 Project" of South China Agricultural University (Grant No. 2009B010100001)China Postdoctoral Science Foundation (Grant No. 20080430820)
文摘The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.
基金The financial supports from the National 1000 Young Talents Program of Chinathe National Natural Science Foundation of China (Grant no. 21603078)
文摘Electrochemical reduction of CO2 to produce value-added feedstock chemicals using high-performance electrocatalysts is a promising protocol to address the excessive CO2 in the atmosphere and the energy crisis. However, the high overpotential, low current density, and poor product selectivity for CO2 electroreduction greatly impede their practical applications. In this work, we develop an efficient catalyst for CO2 reduction to CO consisting of well-dispersed ZrO2 nanoparticles tightly anchored on nitrogendoped carbon nanosheets(ZrO2/N-C) for the first time. Importantly, the ZrO2 nanoparticles possess oxygen vacancies and defects, which regulate the electronic structure of catalyst and thus greatly enhance the electrocatalytic activity. Specifically, ZrO2/N-C demonstrates a high CO Faradaic efficiency(FE) of 64% at-0.4 V vs. the reversible hydrogen electrode(RHE) and a respectable current density of ~2.6 m A cm-2 in CO2-saturated 0.5 M KHCO 3 solution. This work opens a new avenue for developing excellent catalysts for CO2 electroreduction with metal oxide/heteroatom-doped carbon composite structure.
基金supported by the Ministry of Economic Affairs,Innovation,Digitalization and Energy of the State of North Rhine-Westphalia,W041A。
文摘CO_(2) methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route.Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were synthesized by impregnation,calcination and reduction and characterized by elemental analysis,X-ray powder diffraction,H_(2) temperature-programmed reduction,CO pulse chemisorption and transmission electron microscopy.The Ni/NCNT catalysts were highly active in CO_(2) methanation at atmospheric pressure,reaching over 50% CO_(2) conversion and over 95% CH_(4) selectivity at 340℃ and a GHSV of50,000 mL g^(-1) h^(-1) under kinetically controlled conditions.The small Ni particle sizes below 10 nm despite the high Ni loading is ascribed to the efficient anchoring on the N-doped CNTs.The optimum loading of 30 wt%-40 wt% Ni was found to result in the highest Ni surface area,the highest degree of conversion and the highest selectivity to methane.A constant TOF of 0.3 s^(-1) was obtained indicating similar catalytic properties of the Ni nanoparticles in the range from 10 wt%to 50 wt% Ni loading.Long-term experiments showed that the Ni/NCNT catalyst with 30 wt% Ni was highly stable for 100 h time on stream.
基金financially supported by Key Research Program of the Chinese Academy of Sciences (ZDRW-ZS-2016-3)the National Key Research and Development Program of China (2016YFB0600901)the Instrument Developing Project of the Chinese Academy of Sciences
文摘Tin/tin oxide materials are key electrocatalysts for selective conversion of CO;to formate/formic acid.Herein we report a tin oxide material with nitrogen doping by using ammonia treatment at elevated temperature. The N doped material demonstrated enhanced electrocatalytic CO;reduction activity, showing high Faradaic efficiency（90%） for formate at -0.65 V vs. RHE with partial current density of 4 mA/cm;.The catalysis was contributed to increased electron negativity of N atom compared to O atom. Additionally, the N-doped catalyst demonstrates sulfur tolerance with retained formate selectivity. The analysis after electrolysis shows that the catalyst structure partially converts to metallic Sn, and thus the combined Sn/N-SnO;is the key for the active CO;catalysis.
