Coal gasification fine slag(CGFS)is a solid waste generated from entrained-flow coal gasification,characterized by fine particles and rich in silicon and aluminum elements.Using CGFS as a raw material for the preparat...Coal gasification fine slag(CGFS)is a solid waste generated from entrained-flow coal gasification,characterized by fine particles and rich in silicon and aluminum elements.Using CGFS as a raw material for the preparation of ZSM-5 molecular sieves enables the high-value utilization of coal-based solid waste,offering significant economic and environmental benefits.This study proposes a simple and economical hydrothermal synthesis process for ZSM-5 using CGFS as the raw material.In this process,impurities in CGFS were first removed by acid washing,which facilitated the subsequent alkaline extraction of silicon and aluminum species.The extracted Si-Al precursors were then converted into ZSM-5 via hydrothermal crystallization at 170℃for 48 h,yielding a product with a high specific surface area of 358 m2/g.Adsorption experiments demonstrated that the synthesized ZSM-5 exhibited excellent adsorption performance for Pb2+in aqueous solutions.At 25℃,the removal efficiency for a 50 mg/L Pb2+solution reached 83.7%,with an adsorption capacity of 104.625 mg/g under optimized conditions.The adsorption process is mainly governed by chemisorption mechanisms,including surface complexation,precipitation,and ion exchange.The synthesized ZSM-5 shows promising potential for application in the treatment of lead-containing wastewater.展开更多
Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the C...Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the CO2adsorption mechanism.A novel CO2adsorbent with high capacity was obtained by grafting 3-aminopropyltriethoxysilane(APTES)on a micro-mesoporous composite molecular sieve ZSM-5/MCM-48 as the support,and then impregnated with tetraethylenepentamine(TEPA)or polyethyleneimine(PEI).The maximum adsorption capacity of APTES-ZSM-5/MCM-48-TEPA-60(A-ZM-T60),loaded with 60%(in mass)TEPA,for CO2reaches 5.82 mmol·g-1 at 60℃in 15%(in volume)CO2.Carbamate,alkyl ammonium carbamate and carbonate are generated during the chemical adsorption,which is dominant for CO2adsorption because of the reaction between CO2and amino groups on the adsorbent,simultaneously accompanied by weak physical adsorption.All above data confirm that these composites display an outstanding adsorption performance with a bright future for CO2capture from flue gas after desulfurization.展开更多
The adsorption and desorption of N 2 O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out...The adsorption and desorption of N 2 O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out to determine the desorbed temperature T max corresponding to the maximum mass intensity of N 2 O desorption peak and adsorption capacity of N 2 O on metal-ion-exchanged ZSM- 5s. The results indicated that T max followed a sequence of Ba 2+ Ca 2+ Cs + K + Na + Mg 2+ and the amount of adsorbed N 2 O on main-group metal cation followed a sequence of Ba 2+ Mg 2+ Ca 2+ Na + K + Cs + . The DFT calculations were performed to obtain the adsorption energy (E ads ), which represents the strength of the interaction between metal cations and the N-end or O-end of N 2 O. The calculation results showed that the N-end of the N 2 O molecule was favorably adsorbed on ion-exchanged ZSM-5, except for Cs-ZSM-5. For alkali metal cations, the E ads of N 2 O on cations followed the order which was the same to that of T max : Cs + K + Na + . The calculated and experimental results consistently showed that the adsorption performances of alkaline-earth metal cations were better than those of alkali metal cations.展开更多
The shale gas revolution and the carbon-neutrality goal are motivating the landscape toward the synthesis of value-added chemicals or fuels from underutilized ethane with the assistance of greenhouse gas CO2.Combin...The shale gas revolution and the carbon-neutrality goal are motivating the landscape toward the synthesis of value-added chemicals or fuels from underutilized ethane with the assistance of greenhouse gas CO2.Combining ethane aromatization with CO2reduction offers an opportunity to directly produce liquid products for facile separation,storage,and transportation.In the present work,Fe/ZSM-5 catalysts showed promise in the simultaneous CO2reduction and ethane aromatization at atmospheric pressure and 873 K.The catalysts were further investigated using X-ray diffraction(XRD)and X-ray absorption fine structure(XAFS)measurements under in-situ conditions,indicating that most of Fe species existed in the form of Fe oxides and a portion of Fe was incorporated into the ZSM-5 framework generating Lewis acid sites.Both types of Fe species remained almost unchanged under reaction conditions,contributing to an enhanced aromatization activity of Fe/ZSM-5.The effects of CO2and steam on the acid sites and in turn aromatization activity were also investigated by transient studies,which exhibited a reversible modification behavior.Moreover,CO2was identified to be critical to enhance coke resistance and in turn catalyst stability.This work highlights the feasibility of using CO2to assist the upgrading of abundant ethane from shale gas to aromatics over non-precious Fe-based zeolite catalysts.展开更多
Dry reforming of methane(DRM)has gained significant attention as a promising route to convert two major greenhouse gases(CO2 and CH4)to syngas.The development of efficient catalysts is critical for the engineering ...Dry reforming of methane(DRM)has gained significant attention as a promising route to convert two major greenhouse gases(CO2 and CH4)to syngas.The development of efficient catalysts is critical for the engineering applications.In this study,the CexZr1-xO2/ZSM-5 composites with different oxygen vacancy concentrations were synthesized by tuning the Ce/Zr ratio,followed by the deposition of metal Ni to island-like CexZr1-xO2on ZSM-5,forming a variety of Ni-CexZr1-xO2/ZSM-5 catalysts,which were applied for the DRM reaction under 750◦C.Combined with various characterizations,it was found that the oxygen vacancy concentration illustrated the volcanic tendency with the decreased Ce/Zr ratio,and the interaction between metal Ni and CexZr1-xO2exhibited a positive relationship with oxygen vacancy concentration.The enhanced between Ni and CexZr1-xO2interaction could improve the strength and amount of Ni-O-M(M=Ce/Zr)species,making the d-band centers of catalysts closer to the Fermi energy level,which was beneficial to the CH4 and CO2 activation,along with the improved capacity to resist sintering and coking.Especially,the C1Z3(Ni-Ce0.25Zr0.75O2/ZSM-5)catalyst with the Ce/Zr ratio of 1/3 demonstrated the optimal catalytic performance with 91.9%CH4 and 93.8%CO2 conversions within 50 h,accompanied by the best structural and catalytic stability after 100 h.In-situ DRIFTS was employed to study the reaction path and mechanism,discovering that significant amounts of strengthened Ni-O-M species were conducive to activating adsorbed CH4 and CO2,and desorbing the linear CO species.展开更多
Cu/ZSM-5 and CeO_2-modified Cu/ZSM-5 catalysts were prepared by a wetness impregnation method. The addition of CeO_2 was found to enhance the NO_x selective catalytic reduction(SCR) activity of the catalyst at low t...Cu/ZSM-5 and CeO_2-modified Cu/ZSM-5 catalysts were prepared by a wetness impregnation method. The addition of CeO_2 was found to enhance the NO_x selective catalytic reduction(SCR) activity of the catalyst at low temperatures, but the high-temperature activity was weakened. The catalysts were characterized by X-ray diffraction(XRD), nitrogen physisorption, inductively coupled plasma optical emission spectrometry(ICP-OES), X-ray photoelectron spectroscopy(XPS), electron paramagnetic resonance(EPR), H_2 temperature-programmed reduction(TPR) and NH_3 temperature-programmed desorption(TPD). The results showed that more CuO clusters instead of isolated Cu^(2+) species were obtained on the modified catalyst. These active CuO clusters, as well as the Cu-Ce synergistic effect, improved the redox property of the catalyst and low-temperatures SCR activity via promoting the oxidation of NO to NO_2 and fast SCR reaction. The loss in high-temperatures activity was attributed to the enhanced competitive oxidation of NH_3 by O_2 and decreased surface acidity of the catalyst.展开更多
基金Supported by the National Natural Science Foundation of China(52200139)the Open Research Fund Program of Engineering Technology Research Center of Coal Resources Comprehensive Utilization,Anhui University of Science and Technology(MTYJZX202203).
摘要Coal gasification fine slag(CGFS)is a solid waste generated from entrained-flow coal gasification,characterized by fine particles and rich in silicon and aluminum elements.Using CGFS as a raw material for the preparation of ZSM-5 molecular sieves enables the high-value utilization of coal-based solid waste,offering significant economic and environmental benefits.This study proposes a simple and economical hydrothermal synthesis process for ZSM-5 using CGFS as the raw material.In this process,impurities in CGFS were first removed by acid washing,which facilitated the subsequent alkaline extraction of silicon and aluminum species.The extracted Si-Al precursors were then converted into ZSM-5 via hydrothermal crystallization at 170℃for 48 h,yielding a product with a high specific surface area of 358 m2/g.Adsorption experiments demonstrated that the synthesized ZSM-5 exhibited excellent adsorption performance for Pb2+in aqueous solutions.At 25℃,the removal efficiency for a 50 mg/L Pb2+solution reached 83.7%,with an adsorption capacity of 104.625 mg/g under optimized conditions.The adsorption process is mainly governed by chemisorption mechanisms,including surface complexation,precipitation,and ion exchange.The synthesized ZSM-5 shows promising potential for application in the treatment of lead-containing wastewater.
基金National Natural Science Foundation of China(51966002)Natural Science Foundation of Guangxi Province(2020GXNSFAA159144)。
摘要Adsorption by solid amine adsorbent is a promising technology for decarbonization of flue gas.However,adsorption properties of many solid amine adsorbents need to be enhanced,and it is necessary to further study the CO2adsorption mechanism.A novel CO2adsorbent with high capacity was obtained by grafting 3-aminopropyltriethoxysilane(APTES)on a micro-mesoporous composite molecular sieve ZSM-5/MCM-48 as the support,and then impregnated with tetraethylenepentamine(TEPA)or polyethyleneimine(PEI).The maximum adsorption capacity of APTES-ZSM-5/MCM-48-TEPA-60(A-ZM-T60),loaded with 60%(in mass)TEPA,for CO2reaches 5.82 mmol·g-1 at 60℃in 15%(in volume)CO2.Carbamate,alkyl ammonium carbamate and carbonate are generated during the chemical adsorption,which is dominant for CO2adsorption because of the reaction between CO2and amino groups on the adsorbent,simultaneously accompanied by weak physical adsorption.All above data confirm that these composites display an outstanding adsorption performance with a bright future for CO2capture from flue gas after desulfurization.
基金financially supported by the National Natural Science Foundation of China(No.50921064,20906081)the National High Technology Research and Development Program(863)of China(No.2007AA06Z314,2009AA06Z301)
摘要The adsorption and desorption of N 2 O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out to determine the desorbed temperature T max corresponding to the maximum mass intensity of N 2 O desorption peak and adsorption capacity of N 2 O on metal-ion-exchanged ZSM- 5s. The results indicated that T max followed a sequence of Ba 2+ Ca 2+ Cs + K + Na + Mg 2+ and the amount of adsorbed N 2 O on main-group metal cation followed a sequence of Ba 2+ Mg 2+ Ca 2+ Na + K + Cs + . The DFT calculations were performed to obtain the adsorption energy (E ads ), which represents the strength of the interaction between metal cations and the N-end or O-end of N 2 O. The calculation results showed that the N-end of the N 2 O molecule was favorably adsorbed on ion-exchanged ZSM-5, except for Cs-ZSM-5. For alkali metal cations, the E ads of N 2 O on cations followed the order which was the same to that of T max : Cs + K + Na + . The calculated and experimental results consistently showed that the adsorption performances of alkaline-earth metal cations were better than those of alkali metal cations.
基金financial support from the US Department of Energy,Basic Energy Sciences,Catalysis Science Program under contract number DE-SC0012704。
摘要The shale gas revolution and the carbon-neutrality goal are motivating the landscape toward the synthesis of value-added chemicals or fuels from underutilized ethane with the assistance of greenhouse gas CO2.Combining ethane aromatization with CO2reduction offers an opportunity to directly produce liquid products for facile separation,storage,and transportation.In the present work,Fe/ZSM-5 catalysts showed promise in the simultaneous CO2reduction and ethane aromatization at atmospheric pressure and 873 K.The catalysts were further investigated using X-ray diffraction(XRD)and X-ray absorption fine structure(XAFS)measurements under in-situ conditions,indicating that most of Fe species existed in the form of Fe oxides and a portion of Fe was incorporated into the ZSM-5 framework generating Lewis acid sites.Both types of Fe species remained almost unchanged under reaction conditions,contributing to an enhanced aromatization activity of Fe/ZSM-5.The effects of CO2and steam on the acid sites and in turn aromatization activity were also investigated by transient studies,which exhibited a reversible modification behavior.Moreover,CO2was identified to be critical to enhance coke resistance and in turn catalyst stability.This work highlights the feasibility of using CO2to assist the upgrading of abundant ethane from shale gas to aromatics over non-precious Fe-based zeolite catalysts.
基金the following financial supports:National Natural Science Foundation of China(22075225 and 22038011)Innovative Scientific Program of CNNC,State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology(MJNYSKL202401,MJNYSKL202404).
摘要Dry reforming of methane(DRM)has gained significant attention as a promising route to convert two major greenhouse gases(CO2 and CH4)to syngas.The development of efficient catalysts is critical for the engineering applications.In this study,the CexZr1-xO2/ZSM-5 composites with different oxygen vacancy concentrations were synthesized by tuning the Ce/Zr ratio,followed by the deposition of metal Ni to island-like CexZr1-xO2on ZSM-5,forming a variety of Ni-CexZr1-xO2/ZSM-5 catalysts,which were applied for the DRM reaction under 750◦C.Combined with various characterizations,it was found that the oxygen vacancy concentration illustrated the volcanic tendency with the decreased Ce/Zr ratio,and the interaction between metal Ni and CexZr1-xO2exhibited a positive relationship with oxygen vacancy concentration.The enhanced between Ni and CexZr1-xO2interaction could improve the strength and amount of Ni-O-M(M=Ce/Zr)species,making the d-band centers of catalysts closer to the Fermi energy level,which was beneficial to the CH4 and CO2 activation,along with the improved capacity to resist sintering and coking.Especially,the C1Z3(Ni-Ce0.25Zr0.75O2/ZSM-5)catalyst with the Ce/Zr ratio of 1/3 demonstrated the optimal catalytic performance with 91.9%CH4 and 93.8%CO2 conversions within 50 h,accompanied by the best structural and catalytic stability after 100 h.In-situ DRIFTS was employed to study the reaction path and mechanism,discovering that significant amounts of strengthened Ni-O-M species were conducive to activating adsorbed CH4 and CO2,and desorbing the linear CO species.
基金Project supported by the the National Natural Science Foundation of China(51372137)Ministry of Science and Technology,China(2015AA034603)
摘要Cu/ZSM-5 and CeO_2-modified Cu/ZSM-5 catalysts were prepared by a wetness impregnation method. The addition of CeO_2 was found to enhance the NO_x selective catalytic reduction(SCR) activity of the catalyst at low temperatures, but the high-temperature activity was weakened. The catalysts were characterized by X-ray diffraction(XRD), nitrogen physisorption, inductively coupled plasma optical emission spectrometry(ICP-OES), X-ray photoelectron spectroscopy(XPS), electron paramagnetic resonance(EPR), H_2 temperature-programmed reduction(TPR) and NH_3 temperature-programmed desorption(TPD). The results showed that more CuO clusters instead of isolated Cu^(2+) species were obtained on the modified catalyst. These active CuO clusters, as well as the Cu-Ce synergistic effect, improved the redox property of the catalyst and low-temperatures SCR activity via promoting the oxidation of NO to NO_2 and fast SCR reaction. The loss in high-temperatures activity was attributed to the enhanced competitive oxidation of NH_3 by O_2 and decreased surface acidity of the catalyst.