Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually sig...Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually significance in enabling a rebuilt ecological system for unconventional fuels. This concept is appealing when the process is considered as a solution for the storage of renewable energy, which may also find a variety of potential end uses for the outer space exploration. However, a big challenge to this issue is the rational design of high temperature endurable RWGS catalysts with desirable CO product selectivity. In this work, we present a comprehensive overview of recent publications on this research topic,mainly focusing on the catalytic performance of RWGS reaction over three major kinds of heterogeneous catalysts, including supported metal catalysts, mixed oxide catalysts and transition metal carbides. The reaction thermodynamic analysis, kinetics and mechanisms are also described in detail. The present review attempts to provide a general guideline about the construction of well-performed heterogeneous catalysts for the RWGS reaction, as well as discussing the challenges and further prospects of this process.展开更多
A full-wave analysis of the electromagnetic problem of a three-dimensional （3-D） antenna radiating through a 3-D dielectric radome is preserued. The problem is formulated using the Poggio-Miller-Chang-Harrington- Wu...A full-wave analysis of the electromagnetic problem of a three-dimensional （3-D） antenna radiating through a 3-D dielectric radome is preserued. The problem is formulated using the Poggio-Miller-Chang-Harrington- Wu（PMCHW） approach for homogeneous dielectric objects and the electric field integral equation for conducting objects. The integral equations are discretized by the method of moment （MoM）, in which the conducting and dielectric surface/interfaces are represented by curvilinear triangular patches and the unknown equivalent electric and magnetic currents are expanded using curvilinear RWG basis functions. The resultant matrix equation is then solved by the multilevel fast multipole algorithm （MLFMA） and fast far-field approximation （FAFFA） is used to further accelerate the computation. The radiation patterns of dipole arrays in the presence of radomes are presented. The numerical results demonstrate the accuracy and versatility of this method.展开更多
Fe-based catalysts are efficient systems for CO_(2)conversion via reverse water-gas shift(rWGS)reaction.Nevertheless,the nature of the active phase,namely metallic iron,iron oxide or iron carbide remains a subject of ...Fe-based catalysts are efficient systems for CO_(2)conversion via reverse water-gas shift(rWGS)reaction.Nevertheless,the nature of the active phase,namely metallic iron,iron oxide or iron carbide remains a subject of debate which our paper is meant to close.Fe0 is a much better catalyst for the rWGS than Fe_(3)C.The activity of Fe0 can be promoted by the addition of Cs and Cu whose presence hinders iron carburisation while favouring both higher conversion and enhanced selectivity.When the samples are aged in the rWGS reaction mixture during stability test a new phase appear:Fe_(5)C_(2),resulting in a more active but less selective catalysts than Fe0 for the rWGS reaction.Hence our results indicate that we could potentially achieve an optimal activity/selective balance upon finely tuning the proportion Fe/Fe_(5)C_(2).Beyond the fundamental information concerning active phase we have observed the presence of advanced Fischer-Tropsch-like products at ambient pressure opening new opportunities for the design of hybrid rWGS/Fischer-Tropsch systems.展开更多
CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS acti...CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21506204 and 21476226)China Ministry of Science and Technology under contact of 2016YFB0600902+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020400)State Grid Cooperation of China(SGRI-DL-71-16-015)Dalian Science Foundation for Distinguished Young Scholars(2016RJ04)the Youth Innovation Promotion Association of CAS
文摘Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually significance in enabling a rebuilt ecological system for unconventional fuels. This concept is appealing when the process is considered as a solution for the storage of renewable energy, which may also find a variety of potential end uses for the outer space exploration. However, a big challenge to this issue is the rational design of high temperature endurable RWGS catalysts with desirable CO product selectivity. In this work, we present a comprehensive overview of recent publications on this research topic,mainly focusing on the catalytic performance of RWGS reaction over three major kinds of heterogeneous catalysts, including supported metal catalysts, mixed oxide catalysts and transition metal carbides. The reaction thermodynamic analysis, kinetics and mechanisms are also described in detail. The present review attempts to provide a general guideline about the construction of well-performed heterogeneous catalysts for the RWGS reaction, as well as discussing the challenges and further prospects of this process.
基金the National Natural Science Foundation of China (60431010)
文摘A full-wave analysis of the electromagnetic problem of a three-dimensional （3-D） antenna radiating through a 3-D dielectric radome is preserued. The problem is formulated using the Poggio-Miller-Chang-Harrington- Wu（PMCHW） approach for homogeneous dielectric objects and the electric field integral equation for conducting objects. The integral equations are discretized by the method of moment （MoM）, in which the conducting and dielectric surface/interfaces are represented by curvilinear triangular patches and the unknown equivalent electric and magnetic currents are expanded using curvilinear RWG basis functions. The resultant matrix equation is then solved by the multilevel fast multipole algorithm （MLFMA） and fast far-field approximation （FAFFA） is used to further accelerate the computation. The radiation patterns of dipole arrays in the presence of radomes are presented. The numerical results demonstrate the accuracy and versatility of this method.
基金provided by the Royal Society Research Grant RSGR1180353partially sponsored by the CO2Chem UK through the Engineering and Physical Sciences Research Council(EPSRC)grant EP/P026435/1the Spanish Ministry of Science and Innovation through the projects RYC2018-024387-I and PID2019-108502RJ-I00.
文摘Fe-based catalysts are efficient systems for CO_(2)conversion via reverse water-gas shift(rWGS)reaction.Nevertheless,the nature of the active phase,namely metallic iron,iron oxide or iron carbide remains a subject of debate which our paper is meant to close.Fe0 is a much better catalyst for the rWGS than Fe_(3)C.The activity of Fe0 can be promoted by the addition of Cs and Cu whose presence hinders iron carburisation while favouring both higher conversion and enhanced selectivity.When the samples are aged in the rWGS reaction mixture during stability test a new phase appear:Fe_(5)C_(2),resulting in a more active but less selective catalysts than Fe0 for the rWGS reaction.Hence our results indicate that we could potentially achieve an optimal activity/selective balance upon finely tuning the proportion Fe/Fe_(5)C_(2).Beyond the fundamental information concerning active phase we have observed the presence of advanced Fischer-Tropsch-like products at ambient pressure opening new opportunities for the design of hybrid rWGS/Fischer-Tropsch systems.
基金The research was carried out within the State Assignment of the Ministry of Science and Higher Education of the Russian Federation(project No.FFUG-2024-0036)。
文摘CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) utilization.This work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of NH 4 NO_(3),and the addition of alumina or silica as supports.Various techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,N 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained composites.Each specifi c perovskite-containing system(either bulk or supported)has its own optimalφand NH_(4) NO_(3) amount to achieve the highest yield and dispersion of the perovskite phase.Among all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)<Y<Ce<La(SCS).The diff erences in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide presence.In situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quantity of adsorbed H_(2) and CO_(2).This led to a signifi cant increase in CO_(2) conversion for supported CeFeO_(3) but not for the La-based system compared to bulk and SiO_(2)-supported perovskite catalysts.However,adding alumina increased the activity per mass for both Ce-and La-based perovskite systems,reducing the amount of rare-earth components in the catalyst and thereby lowering the cost without substantially compromising stability.
