CO_(2)reduction under simulated sunlight over photocatalysts has become an attractive researcher area recently.In this work,carbon nitride compounds modified by TiO_(2)nanoparticles(TNPs)have been used for the photore...CO_(2)reduction under simulated sunlight over photocatalysts has become an attractive researcher area recently.In this work,carbon nitride compounds modified by TiO_(2)nanoparticles(TNPs)have been used for the photoreduction of CO_(2)in the presence of CH_(4)at room temperature.Briefly,a series of noble-metal-free TNP-graphitic-carbon nitride(g-C_(3)N_(4),also abbreviated CN)photocatalysts with different TNPs loadings and calcination temperatures have been synthesized by a wet-chemical method.The characterization results of XRD,FTIR,SEM,TEM,BET,XPS,CO_(2)Adsorption,UV-vis,and PL demonstrate that the BET surface area and CO_(2)adsorption capacity have been improved after the calcination.Besides,the g-C_(3)N_(4)has been successfully coupled with the TNPs and a heterojunction has formed at their interface.These characters contribute to increase the photocatalytic activity of TNPs-CN toward reducing CO_(2)in the presence of CH_(4),and its'performance is better than bare g-C_(3)N_(4),Titania(P_(25))-CN,MgO-CN,or Cu_(2)O-CN.Orthogonal experiments are then carried out to investigate the sensitivity factors and optimum conditions.The sensitivity results show that the reaction pressure makes little difference on the photocatalysis results,which verifies the photoinduced CO_(2)-CH_(4)reaction has a tiny change in gas volume.In addition,under the optimum conditions,the turnover frequency(TOF)of CO after 4 h reaction can reach 9.98μmol g-cat.^(-1)h^(-1),and traces of ethane and ethylene have been detected during the reactions.In addition,surface acetate and carbonaceous deposit are found on the(20)TNPs-CN/450 surface after continuous 24 h irradiation under the optimum conditions,which resulting in the inactivation of the catalyst.Finally,possible reaction mechanisms have been proposed based on the results.展开更多
Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geol...Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geological parameters.This work studies nine injection well(IW)and CH_(4)production well(PW)combinations of CO_(2)to determine the influence of IW and PW locations on the dynamic interaction of multiphase CH_(4)during 10000 d of CO_(2)injection.The results indicate that the content of both the adsorbed CH_(4)and free CH_(4)is strongly variable before(and during)the CO_(2)-CH_(4)displacement.In addition,during the simulation process,the proportion of the adsorbed CH_(4)among all extracted CH_(4)phases dynamically increases first and then tends to stabilize at 70%-80%.Moreover,the IW-PWs combinations signifi-cantly affect the outcomes of CO_(2)enhanced shale gas recovery-for both the proportion of adsorbed/free CH_(4)and the recovery efficiency.A longer IW-PW distance enables more adsorbed CH_(4)to be recovered but results in a lower efficiency of shale gas recovery.Basically,a shorter IW-PWs distance helps recover CH_(4)via CO_(2)injection if the IW targets the bottom layer of the Wufeng-Longmaxi shale formation.This numerical work expands the knowl-edge of CO_(2)enhanced gas recovery from depleted shale reservoirs.展开更多
基金financial support from the National Natural Science Foundation of China(21536003,21938002 and 21776065)Natural Science Foundation of Hunan Province in China(2019JJ20006)。
文摘CO_(2)reduction under simulated sunlight over photocatalysts has become an attractive researcher area recently.In this work,carbon nitride compounds modified by TiO_(2)nanoparticles(TNPs)have been used for the photoreduction of CO_(2)in the presence of CH_(4)at room temperature.Briefly,a series of noble-metal-free TNP-graphitic-carbon nitride(g-C_(3)N_(4),also abbreviated CN)photocatalysts with different TNPs loadings and calcination temperatures have been synthesized by a wet-chemical method.The characterization results of XRD,FTIR,SEM,TEM,BET,XPS,CO_(2)Adsorption,UV-vis,and PL demonstrate that the BET surface area and CO_(2)adsorption capacity have been improved after the calcination.Besides,the g-C_(3)N_(4)has been successfully coupled with the TNPs and a heterojunction has formed at their interface.These characters contribute to increase the photocatalytic activity of TNPs-CN toward reducing CO_(2)in the presence of CH_(4),and its'performance is better than bare g-C_(3)N_(4),Titania(P_(25))-CN,MgO-CN,or Cu_(2)O-CN.Orthogonal experiments are then carried out to investigate the sensitivity factors and optimum conditions.The sensitivity results show that the reaction pressure makes little difference on the photocatalysis results,which verifies the photoinduced CO_(2)-CH_(4)reaction has a tiny change in gas volume.In addition,under the optimum conditions,the turnover frequency(TOF)of CO after 4 h reaction can reach 9.98μmol g-cat.^(-1)h^(-1),and traces of ethane and ethylene have been detected during the reactions.In addition,surface acetate and carbonaceous deposit are found on the(20)TNPs-CN/450 surface after continuous 24 h irradiation under the optimum conditions,which resulting in the inactivation of the catalyst.Finally,possible reaction mechanisms have been proposed based on the results.
基金supported by the Project funded by China Postdoctoral Science Foundation(No.2020M683253)the Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources(No.KLSGE-MLR-202003)the National Natural Science Foundation of China(Grant No.51704197).
文摘Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geological parameters.This work studies nine injection well(IW)and CH_(4)production well(PW)combinations of CO_(2)to determine the influence of IW and PW locations on the dynamic interaction of multiphase CH_(4)during 10000 d of CO_(2)injection.The results indicate that the content of both the adsorbed CH_(4)and free CH_(4)is strongly variable before(and during)the CO_(2)-CH_(4)displacement.In addition,during the simulation process,the proportion of the adsorbed CH_(4)among all extracted CH_(4)phases dynamically increases first and then tends to stabilize at 70%-80%.Moreover,the IW-PWs combinations signifi-cantly affect the outcomes of CO_(2)enhanced shale gas recovery-for both the proportion of adsorbed/free CH_(4)and the recovery efficiency.A longer IW-PW distance enables more adsorbed CH_(4)to be recovered but results in a lower efficiency of shale gas recovery.Basically,a shorter IW-PWs distance helps recover CH_(4)via CO_(2)injection if the IW targets the bottom layer of the Wufeng-Longmaxi shale formation.This numerical work expands the knowl-edge of CO_(2)enhanced gas recovery from depleted shale reservoirs.
