Aromatization of alkanes represents an important process in the chemical industry,traditionally relying on noble metal catalysts.Developing a non-noble metal catalyst and a relevant new process offers significant pote...Aromatization of alkanes represents an important process in the chemical industry,traditionally relying on noble metal catalysts.Developing a non-noble metal catalyst and a relevant new process offers significant potential for promoting technologic progress in this field.Herein,we present Cu-ZSM-5 zeolite as a highly effective catalyst for alkane aromatization,achieving outstanding aromatics selectivity.In-situ Fourier transform infrared spectra of adsorbed nitric oxide,high-angle annular dark field scanning transmission electron microscopy,X-ray absorption spectroscopy,and electron paramagnetic resonance analyses reveal that the Cu^(2+)species act as the primary active centers for aromatics formation.During aromatization of alkanes,the reduction of Cu^(2+)to Cu^(+)species correlates with diminished aromatics selectivity.Notably,introducing CO_(2)into the reaction feed not only enhances aromatics selectivity by maintaining Cu^(2+)species in their active oxidation state under reducing conditions,but also improves catalytic stability by eliminating coke.Furthermore,CO_(2)is converted into CO and aromatic products during the reaction,offering a novel way for CO_(2)utilization through the coupling reaction of alkane and CO_(2).展开更多
A continuous online in situ attenuated total reflection Fourier-transform infrared(ATR-FTIR)spectroscopic technique was used to investigate the adsorption and desorption kinetics of heptyl xanthate(KHX)on the surface ...A continuous online in situ attenuated total reflection Fourier-transform infrared(ATR-FTIR)spectroscopic technique was used to investigate the adsorption and desorption kinetics of heptyl xanthate(KHX)on the surface of ZnO and Cu(Ⅱ)activated ZnO.The results showed that Cu(Ⅱ)facilitated the xanthate adsorption process on the surface,and led to the formation of cuprous xanthate(CuX),dixanthogen(X_(2))and xanthate aggregates.The adsorption of xanthate on the surface of ZnO and Cu(Ⅱ)activated ZnO was found to both follow the pseudo-first-order kinetic model.When the NaOH solution was used as a desorption agent,the adsorbed xanthate can largely be removed due to the competition between OH^(−)and HX−.However,for Cu(Ⅱ)activated ZnO,the peak intensities at 1197 and 1082 cm^(−1) had no obvious weakening,and the absorption intensities at 1261 and 1026 cm^(−1) increased in the first 5 min,indicating an ion-exchange reaction between OH^(−)and surface zinc bonded xanthate HX−and the reorganization of adsorbed xanthate.展开更多
Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action tim...Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action time,simple process and no pollution.In this study,Cu/ACF(activated carbon fiber loaded with copper)adsorbent was modified with NTP to remove H_(2)S and PH_(3) simultaneously under low temperature and micro-oxygen condition.Meanwhile,the effects of different modified atmosphere(air,N_(2) and NH_(3)),specific energy input(0–13 J/mL)and modification time(0–30 min)on the removal of H_(2)S and PH_(3) were investigated.Performance test results indicated that under the same reaction conditions,the adsorbent modified by NH_(3) plasma with 5 J/mL for 10 min had the best removal effect on H_(2)S and PH_(3).CO_(2) temperature-programmed desorption and X-ray photoelectron spectroscopy(XPS)analyzes showed that NH_(3) plasma modification could introduce amino functional groups on the surface of the adsorbent,and increase the types and number of alkaline sites on the surface.Brunauer-Emmett-Teller and scanning electron microscopy showed that NH_(3) plasma modification did not significantly change the pore size structure of the adsorbent,but more active components were evenly exposed to the surface,thus improving the adsorption performance.In addition,X-ray diffraction and XPS analysis indicated that the consumption of active components(Cu and Cu_(2)O)and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.展开更多
Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress （stress exponent n） and temperature （activation energy Q）. Various values of constan...Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress （stress exponent n） and temperature （activation energy Q）. Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for εmin. in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile εmin. result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile εmin, and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.展开更多
A new kind of Schiff base HL（HL= 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-Leucine methyl ester） and complexes Ni L′_2·0.75C_2H_5OH·0.25H_2O,Cu L′′2（L′ = 1-phenyl-3-methyl-4-（p-meth...A new kind of Schiff base HL（HL= 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-Leucine methyl ester） and complexes Ni L′_2·0.75C_2H_5OH·0.25H_2O,Cu L′′2（L′ = 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-leucine ethyl,L′′ = 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-leucine） have been synthesized and structurally determined by X-ray diffraction. For HL： crystal structure determination indicates that there are two independent HLs with different conformations in one asymmetric unit. For complex 1： the Ni（Ⅱ） ion is six-coordinated by two carbonyl oxygen atoms from pyrazolone ring,two nitrogen atoms from different HL′ and two oxygen atoms from L-Leucine ethyl ester to form a distorted octahedral geometry. For complex 2： the Cu（Ⅱ） ion is four-coordinated by one carbonyl oxygen atom from the pyrazolone ring,one nitrogen atom from HL′′,and two different carboxylic oxygen atoms from L-leucine with the same conformation to form a distorted quadrilateral geometry.展开更多
Photo-switchable metal-organic frameworks(PMOFs)as energy-saving adsorbents for tailorable vip capture show admirable potentials for various applications like adsorptive desulfurization.However,the regulation behavi...Photo-switchable metal-organic frameworks(PMOFs)as energy-saving adsorbents for tailorable vip capture show admirable potentials for various applications like adsorptive desulfurization.However,the regulation behavior of most reported PMOFs is based on weak physical interaction,and it is highly desired to introduce specific active sites to satisfy the demand of higher adsorption capacity and selectivity.Herein,for the first time,we prepared the PMOFs,azobenzene-functionalized HKUST-1(HK-Azo),simultaneously decorated with Cu_(2)O active sites that possess strong interaction with vip molecules.Due toπ-complexation interaction of Cu^(+)with aromatic sulfur compounds,the obtained HK-Azo shows obviously higher adsorption capacity on benzothiophene compared with HKUST-1.Upon ultraviolet(UV)and visible irradiation,azobenzene moieties in the PMOFs can transform their configuration freely and reversibly.Such trans/cis isomerization of azobenzene causes exposure/shelter of Cu_(2)O active sites,leading to controllable benzothiophene capture.The HK-Azo exhibits the change of benzothiophene uptake up to 29.7%upon trans and cis isomerization,which is obviously higher than HKUST-1 with negligible change.This work may inspire the development of new adsorption process regulated by light for adsorptive desulfurization that is impossible to realize by conventional PMOFs.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.22288101,22472016)the National Key Research and Development Program of the Ministry of Science and Technology(No.2022YFE0116000)+1 种基金the Chinese Academy of Sciences Strategy Leading Technology Project(No.XDA29000000)the Youth Innovation Promotion Association CAS(No.2021182)。
文摘Aromatization of alkanes represents an important process in the chemical industry,traditionally relying on noble metal catalysts.Developing a non-noble metal catalyst and a relevant new process offers significant potential for promoting technologic progress in this field.Herein,we present Cu-ZSM-5 zeolite as a highly effective catalyst for alkane aromatization,achieving outstanding aromatics selectivity.In-situ Fourier transform infrared spectra of adsorbed nitric oxide,high-angle annular dark field scanning transmission electron microscopy,X-ray absorption spectroscopy,and electron paramagnetic resonance analyses reveal that the Cu^(2+)species act as the primary active centers for aromatics formation.During aromatization of alkanes,the reduction of Cu^(2+)to Cu^(+)species correlates with diminished aromatics selectivity.Notably,introducing CO_(2)into the reaction feed not only enhances aromatics selectivity by maintaining Cu^(2+)species in their active oxidation state under reducing conditions,but also improves catalytic stability by eliminating coke.Furthermore,CO_(2)is converted into CO and aromatic products during the reaction,offering a novel way for CO_(2)utilization through the coupling reaction of alkane and CO_(2).
基金supported by the National Natural Science Foundation of China (Nos.51274104,50874052)the National Basic Research Program of China (No.2011CB933700)。
文摘A continuous online in situ attenuated total reflection Fourier-transform infrared(ATR-FTIR)spectroscopic technique was used to investigate the adsorption and desorption kinetics of heptyl xanthate(KHX)on the surface of ZnO and Cu(Ⅱ)activated ZnO.The results showed that Cu(Ⅱ)facilitated the xanthate adsorption process on the surface,and led to the formation of cuprous xanthate(CuX),dixanthogen(X_(2))and xanthate aggregates.The adsorption of xanthate on the surface of ZnO and Cu(Ⅱ)activated ZnO was found to both follow the pseudo-first-order kinetic model.When the NaOH solution was used as a desorption agent,the adsorbed xanthate can largely be removed due to the competition between OH^(−)and HX−.However,for Cu(Ⅱ)activated ZnO,the peak intensities at 1197 and 1082 cm^(−1) had no obvious weakening,and the absorption intensities at 1261 and 1026 cm^(−1) increased in the first 5 min,indicating an ion-exchange reaction between OH^(−)and surface zinc bonded xanthate HX−and the reorganization of adsorbed xanthate.
基金funding for this study received from the Fundamental Research Funds for the National Natural Science Foundation of China(Nos.21876071,51968034,41807373 and 21667015)Science and Technology Program of Yunnan province(No.2019FB069).
文摘Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action time,simple process and no pollution.In this study,Cu/ACF(activated carbon fiber loaded with copper)adsorbent was modified with NTP to remove H_(2)S and PH_(3) simultaneously under low temperature and micro-oxygen condition.Meanwhile,the effects of different modified atmosphere(air,N_(2) and NH_(3)),specific energy input(0–13 J/mL)and modification time(0–30 min)on the removal of H_(2)S and PH_(3) were investigated.Performance test results indicated that under the same reaction conditions,the adsorbent modified by NH_(3) plasma with 5 J/mL for 10 min had the best removal effect on H_(2)S and PH_(3).CO_(2) temperature-programmed desorption and X-ray photoelectron spectroscopy(XPS)analyzes showed that NH_(3) plasma modification could introduce amino functional groups on the surface of the adsorbent,and increase the types and number of alkaline sites on the surface.Brunauer-Emmett-Teller and scanning electron microscopy showed that NH_(3) plasma modification did not significantly change the pore size structure of the adsorbent,but more active components were evenly exposed to the surface,thus improving the adsorption performance.In addition,X-ray diffraction and XPS analysis indicated that the consumption of active components(Cu and Cu_(2)O)and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.
基金supported by the project CZ.1.05/1.1.00/02.0068 granted by the European Regional Development Fund
文摘Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress （stress exponent n） and temperature （activation energy Q）. Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for εmin. in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile εmin. result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile εmin, and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.
文摘A new kind of Schiff base HL（HL= 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-Leucine methyl ester） and complexes Ni L′_2·0.75C_2H_5OH·0.25H_2O,Cu L′′2（L′ = 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-leucine ethyl,L′′ = 1-phenyl-3-methyl-4-（p-methylbenzoyl）-5-pyrazolone with L-leucine） have been synthesized and structurally determined by X-ray diffraction. For HL： crystal structure determination indicates that there are two independent HLs with different conformations in one asymmetric unit. For complex 1： the Ni（Ⅱ） ion is six-coordinated by two carbonyl oxygen atoms from pyrazolone ring,two nitrogen atoms from different HL′ and two oxygen atoms from L-Leucine ethyl ester to form a distorted octahedral geometry. For complex 2： the Cu（Ⅱ） ion is four-coordinated by one carbonyl oxygen atom from the pyrazolone ring,one nitrogen atom from HL′′,and two different carboxylic oxygen atoms from L-leucine with the same conformation to form a distorted quadrilateral geometry.
基金supproted by the National Science Fund for Distinguished Young Scholars(No.22125804)the National Natural Science Foundation of China(Nos.22001122,22178163,22078155,and 21878149)we were also grateful to the High Performance Computing Center of Nanjing Tech University for providing the computational resources.
文摘Photo-switchable metal-organic frameworks(PMOFs)as energy-saving adsorbents for tailorable vip capture show admirable potentials for various applications like adsorptive desulfurization.However,the regulation behavior of most reported PMOFs is based on weak physical interaction,and it is highly desired to introduce specific active sites to satisfy the demand of higher adsorption capacity and selectivity.Herein,for the first time,we prepared the PMOFs,azobenzene-functionalized HKUST-1(HK-Azo),simultaneously decorated with Cu_(2)O active sites that possess strong interaction with vip molecules.Due toπ-complexation interaction of Cu^(+)with aromatic sulfur compounds,the obtained HK-Azo shows obviously higher adsorption capacity on benzothiophene compared with HKUST-1.Upon ultraviolet(UV)and visible irradiation,azobenzene moieties in the PMOFs can transform their configuration freely and reversibly.Such trans/cis isomerization of azobenzene causes exposure/shelter of Cu_(2)O active sites,leading to controllable benzothiophene capture.The HK-Azo exhibits the change of benzothiophene uptake up to 29.7%upon trans and cis isomerization,which is obviously higher than HKUST-1 with negligible change.This work may inspire the development of new adsorption process regulated by light for adsorptive desulfurization that is impossible to realize by conventional PMOFs.
