Wet scrubbing combined with ozone oxidation has become a promising technology for simultaneous removal of SO_2 and NO_x in exhaust gas.In this paper,a new 20-species,76-step detailed kinetic mechanism was proposed bet...Wet scrubbing combined with ozone oxidation has become a promising technology for simultaneous removal of SO_2 and NO_x in exhaust gas.In this paper,a new 20-species,76-step detailed kinetic mechanism was proposed between O_3 and NO_x.The concentration of N_2O_5 was measured using an in-situ IR spectrometer.The numerical evaluation results kept good pace with both the public experiment results and our experiment results.Key reaction parameters for the generation of NO_2 and N_2O_5 during the NO ozonation process were investigated by a numerical simulation method.The effect of temperature on producing NO_2 was found to be negligible.To produce NO_2,the optimal residence time was1.25 sec and the molar ratio of O_3/NO about 1.For the generation of N_2O_5,the residence time should be about 8 sec while the temperature of the exhaust gas should be strictly controlled and the molar ratio of O_3/NO about 1.75.This study provided detailed investigations on the reaction parameters of ozonation of NO_x by a numerical simulation method,and the results obtained should be helpful for the design and optimization of ozone oxidation combined with the wet flue gas desulfurization methods（WFGD） method for the removal of NO_x.展开更多
A mild,efficient and eco-friendly process for the electrophilic nitration is described using N_2O_5 as a green nitrating agent in the presence of rare earth metal triflates[RE（OTf）_3]under mild conditions.
Comprehensive observations of the nocturnal atmospheric oxidation of NO_(3)and N_(2)O_(5)were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy(CRDS)from 27 May to 24 June,2019.H...Comprehensive observations of the nocturnal atmospheric oxidation of NO_(3)and N_(2)O_(5)were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy(CRDS)from 27 May to 24 June,2019.High concentrations of NO_(3)precursors were observed,and the nocturnal production rate of NO_(3)was determined to be 1.7±1.2 ppbv/hr.However,the nighttime NO_(3)and N_(2)O_(5)concentrations were relatively low,with maximum values of 17.7 and 304.7 pptv,respectively,illustrating the rapid loss ofNO_(3)andN_(2)O_(5).Itwas found that NO_(3)dominated the nighttime atmospheric oxidation,accounting for 50.7%,whileO3 andOH only contributed 34.1%and 15.2%,respectively.For the reactions of NO_(3)with volatile organic compounds(VOCs),styrenewas found to account for 60.3%,highlighting its dominant role in the NO_(3)reactivity.In general,the contributions of the reactions between NO_(3)and VOCs and the N_(2)O_(5)uptake to NO_(3)losswere found to be about 39.5%and 60.5%,respectively,indicating that N_(2)O_(5)uptake also played an important role in the loss of NO_(3)and N_(2)O_(5),especially under the high humidity conditions in China.The formation of nitrate at night mainly originated from N_(2)O_(5)uptake,and the maximum production rate of NO_(3)^(-)reached 6.5 ppbv/hr.The average NOx consumption rate via NO_(3)and N_(2)O_(5)chemistry was found to be 0.4 ppbv/h,accounting for 47.9%of the total NO_(x)removal.The predominant roles of NO_(3)and N_(2)O_(5)in nitrate formation and NO_(x)removal in the YRD region was highlighted in this study.展开更多
The UCD/CIT model was modified to include a process analysis(PA)scheme for gas and particulate matter(PM)to study the formation of secondary nitrate aerosol during a stagnant wintertime air pollution episode during th...The UCD/CIT model was modified to include a process analysis(PA)scheme for gas and particulate matter(PM)to study the formation of secondary nitrate aerosol during a stagnant wintertime air pollution episode during the California Regional PM_(2.5)/PM_(10) Air Quality Study(CRPAQS)where detailed measurements of PM components are available at a few sites.Secondary nitrate is formed in the urban areas from near the ground to a few hundred meters above the surface during the day with a maximum modeled net increase rate of 4μg·m^(-3)·d^(-1) during the study episode.The secondary nitrate formation rate in rural areas is lower due to lower NO_(2).In the afternoon hours,near-surface temperature can be high enough to evaporate the particulate nitrate.In the nighttime hours,both the gas phase N_(2)O_(5) reactions with water vapor and the N_(2)O_(5) heterogeneous reactions with particle-bound water are important for secondary nitrate formation.The N_(2)O_(5) reactions are most import near the surface to a few hundred meters above surface with a maximum modeled net secondary nitrate increase rate of 1μg·m^(-3)·d^(-1) and are more significant in the rural areas where the O3 concentrations are high at night.In general,vertical transport during the day moves the nitrate formed near the surface to higher elevations.During the stagnant days,process analysis indicates that the nitrate concentration in the upper air builds up and leads to a net downward flux of nitrate through vertical diffusion and a rapid increase of surface nitrate concentration.展开更多
基金financially supported by the National High Tech Research and Development Program(863)of China(No.2011AA060801)the Program for Zhejiang Leading Team of S&T Innovation(No.2013TD07)
文摘Wet scrubbing combined with ozone oxidation has become a promising technology for simultaneous removal of SO_2 and NO_x in exhaust gas.In this paper,a new 20-species,76-step detailed kinetic mechanism was proposed between O_3 and NO_x.The concentration of N_2O_5 was measured using an in-situ IR spectrometer.The numerical evaluation results kept good pace with both the public experiment results and our experiment results.Key reaction parameters for the generation of NO_2 and N_2O_5 during the NO ozonation process were investigated by a numerical simulation method.The effect of temperature on producing NO_2 was found to be negligible.To produce NO_2,the optimal residence time was1.25 sec and the molar ratio of O_3/NO about 1.For the generation of N_2O_5,the residence time should be about 8 sec while the temperature of the exhaust gas should be strictly controlled and the molar ratio of O_3/NO about 1.75.This study provided detailed investigations on the reaction parameters of ozonation of NO_x by a numerical simulation method,and the results obtained should be helpful for the design and optimization of ozone oxidation combined with the wet flue gas desulfurization methods（WFGD） method for the removal of NO_x.
基金the financial support from the National Nature Science Foundation of China Academy of Engineering Physics(No.10976014)Nature Science Foundation of Jiangsu Province(No.BK2011697)
文摘A mild,efficient and eco-friendly process for the electrophilic nitration is described using N_2O_5 as a green nitrating agent in the presence of rare earth metal triflates[RE（OTf）_3]under mild conditions.
基金supported by the National Natural Science Foundation of China(Nos.42030609,91644107,61905003,and U19A2044)the Natural Science Foundation of Anhui Province(No.2008085J20)+1 种基金the National Key Research and Development Program of China(No.2017YFC0209403)the Cultivating Project of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDPB1901)
文摘Comprehensive observations of the nocturnal atmospheric oxidation of NO_(3)and N_(2)O_(5)were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy(CRDS)from 27 May to 24 June,2019.High concentrations of NO_(3)precursors were observed,and the nocturnal production rate of NO_(3)was determined to be 1.7±1.2 ppbv/hr.However,the nighttime NO_(3)and N_(2)O_(5)concentrations were relatively low,with maximum values of 17.7 and 304.7 pptv,respectively,illustrating the rapid loss ofNO_(3)andN_(2)O_(5).Itwas found that NO_(3)dominated the nighttime atmospheric oxidation,accounting for 50.7%,whileO3 andOH only contributed 34.1%and 15.2%,respectively.For the reactions of NO_(3)with volatile organic compounds(VOCs),styrenewas found to account for 60.3%,highlighting its dominant role in the NO_(3)reactivity.In general,the contributions of the reactions between NO_(3)and VOCs and the N_(2)O_(5)uptake to NO_(3)losswere found to be about 39.5%and 60.5%,respectively,indicating that N_(2)O_(5)uptake also played an important role in the loss of NO_(3)and N_(2)O_(5),especially under the high humidity conditions in China.The formation of nitrate at night mainly originated from N_(2)O_(5)uptake,and the maximum production rate of NO_(3)^(-)reached 6.5 ppbv/hr.The average NOx consumption rate via NO_(3)and N_(2)O_(5)chemistry was found to be 0.4 ppbv/h,accounting for 47.9%of the total NO_(x)removal.The predominant roles of NO_(3)and N_(2)O_(5)in nitrate formation and NO_(x)removal in the YRD region was highlighted in this study.
基金This research was partially supported by the California Air Resources Board and the San Joaquin Valleywide Air Pollution Study Agency under contract 2000-2005 PM.
文摘The UCD/CIT model was modified to include a process analysis(PA)scheme for gas and particulate matter(PM)to study the formation of secondary nitrate aerosol during a stagnant wintertime air pollution episode during the California Regional PM_(2.5)/PM_(10) Air Quality Study(CRPAQS)where detailed measurements of PM components are available at a few sites.Secondary nitrate is formed in the urban areas from near the ground to a few hundred meters above the surface during the day with a maximum modeled net increase rate of 4μg·m^(-3)·d^(-1) during the study episode.The secondary nitrate formation rate in rural areas is lower due to lower NO_(2).In the afternoon hours,near-surface temperature can be high enough to evaporate the particulate nitrate.In the nighttime hours,both the gas phase N_(2)O_(5) reactions with water vapor and the N_(2)O_(5) heterogeneous reactions with particle-bound water are important for secondary nitrate formation.The N_(2)O_(5) reactions are most import near the surface to a few hundred meters above surface with a maximum modeled net secondary nitrate increase rate of 1μg·m^(-3)·d^(-1) and are more significant in the rural areas where the O3 concentrations are high at night.In general,vertical transport during the day moves the nitrate formed near the surface to higher elevations.During the stagnant days,process analysis indicates that the nitrate concentration in the upper air builds up and leads to a net downward flux of nitrate through vertical diffusion and a rapid increase of surface nitrate concentration.
