The construction of electrocatalysts with exceptional intrinsic activity and rich active sites has proven to be an effective strategy for remarkably enhancing the activity of the hydrogen evolution reaction(HER).Here,...The construction of electrocatalysts with exceptional intrinsic activity and rich active sites has proven to be an effective strategy for remarkably enhancing the activity of the hydrogen evolution reaction(HER).Here,self-supporting cerium(Ce)and nitrogen(N)-doped rhenium disulfide nanosheets(denoted Ce,N-ReS_(2))grown on carbon fiber paper have been successfully synthesized.Ce and N doping modulates the lattice irregularity and adjusts the electronic configuration of rhenium disulfide,resulting in reduced hydrogen adsorption/desorption energy and enhanced catalytic stability.The optimized Ce,N-ReS_(2) electrocatalysts exhibit superior catalytic activities of 44/130 and 79/139 mV at 10/100 mA/cm^(2) for HER in alkaline and acidic media,respectively,along with robust durability.Both experimental results and density functional theory calculations indicate that the electronic structure of ReS_(2) can be significantly altered by strategically incorporating Ce and N into the lattice,which in turn optimizes the Gibbs free energy of HER intermediates and accelerates the electrochemical kinetics.This study provides a potentially effective approach for the design and optimization of innovative electrocatalysts involving the regulation of anion and cation dual-doping and architectural engineering.展开更多
The refractory metal rhenium(Re),with content of 0−2 at.%,was introduced into a typicalγ-TiAl alloy of Ti−48Al−2Cr−2Nb(at.%)through vacuum arc melting.The effect of Re content on the microstructure and mechanical pro...The refractory metal rhenium(Re),with content of 0−2 at.%,was introduced into a typicalγ-TiAl alloy of Ti−48Al−2Cr−2Nb(at.%)through vacuum arc melting.The effect of Re content on the microstructure and mechanical properties of theγ-TiAl alloy was investigated.The results show that theγ-TiAl−xRe alloy is composed ofγ,α2,andβphases.As the Re content increases,the proportion ofβphase increases,while the content and size ofα2+γlamellar structure decrease gradually.Furthermore,the compressive strength increases with increasing Re content.A maximum compressive strength of 2282 MPa is achieved for theγ-TiAl−2Re alloy.Theγ-TiAl−2Re alloy exhibits a fracture strain of 36.7%,considerably higher than that of theγ-TiAl alloy(31.0%).Moreover,compared with theγ-TiAl alloy,the hardness and compressive strength of theγ-TiAl−2Re alloy considerably increase by 17.5%and 34.2%,respectively.展开更多
A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized un...A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized under a controlled oxidizing atmosphere via the pyrolysis of ammonium perrhenate, and carried into reduction zone by carrier gas, and there reduced into rhenium powders by hydrogen gas. Thermodynamic calculations indicated that Re207 could be prevented from further decomposition through controlling the oxygen partial pressure higher than 10 1.248 Pa in the pyrolysis of ammonium perrhenate. This result was further validated via DSC-TGA analysis of ammonium perrhenate. The typical rhenium powders prepared by the CVD method proposed show irregular polyhedron morphology with particle size in the range of 100-800 nm and a Ds0 of 308 nm. The specific surface area and oxygen content were measured to be 4.37 m^2/g and 0.45%, respectively.展开更多
The effects of 4 wt% rhenium （Re） addition on isothermal oxidation behavior of Tribaloy T-800 alloy have been studied at 800 °C and 1 000 °C in air. At 800 °C,T-800 shows nonuniform oxidation between ...The effects of 4 wt% rhenium （Re） addition on isothermal oxidation behavior of Tribaloy T-800 alloy have been studied at 800 °C and 1 000 °C in air. At 800 °C,T-800 shows nonuniform oxidation between dendritic and eutectic areas. Re addition clearly promotes the nonuniform oxidation,leading to considerably higher mass gains than that of T-800 at this temperature. At 1 000 °C exposure,the thickness of scale on T-800 increases significantly,accompanied by severe scale spallation during cooling to room temperature. On the contrary,T-800Re shows a marked decrease of oxide growth rate compared to the linear one of T-800 at 1 000 °C. The scale adhesion is also improved with Re addition at this higher temperature. Therefore,the role of Re depends on the exposure temperature. Re addition gives high oxidation rate at 800 °C,however,the excellent oxidation resistance is obtained by the addition of Re at a higher temperature of 1 000 °C.展开更多
In this paper, a weak-base resin was adopted to recycle rhenium because of its excellent adsorption and desorption properties for rhenium, while the kinetics and thermodynamics properties of adsorbing rhenium from the...In this paper, a weak-base resin was adopted to recycle rhenium because of its excellent adsorption and desorption properties for rhenium, while the kinetics and thermodynamics properties of adsorbing rhenium from the rhenium stock solution were systematically investigated. The kinetics investigations confirm that the adsorption process of Re belongs to kinetic control by particle diffusion process and the corresponding reaction rate constant is 2.68 × 10-s s^-1. Then, the Langmuir and Freundlich models were used to describe the adsorption equilibrium behaviors of Re and the thermodynamics parameters are obtained. The results show that the Langmuir model is the best-fitted model, and the Gibbs free energy change of Re adsorption onto ZS 15 weak-base resin is AGO = - 10.59 ＋ 12.66T. To verify the weak-base resins for extracting rhenium in industrial application, the column experiments were operated in the spray solution generating by roasting the molybdenum concentrates. The results indicate that the weak-base resins possess excellent adsorptive selectivity for rhenium, and the ammonia solution with low concentration could sufficiently desorb rhe- nium from the resins.展开更多
The adsorption and mechanism of Re(Ⅶ)on resin D318 were studied using chemical methods and IR spectrometry.At pH 5.2,the static and dynamic saturation adsorption capacities were 351.4 and 366.5 mg·g-1,respective...The adsorption and mechanism of Re(Ⅶ)on resin D318 were studied using chemical methods and IR spectrometry.At pH 5.2,the static and dynamic saturation adsorption capacities were 351.4 and 366.5 mg·g-1,respectively.The adsorption behavior obeyed the Freundlich empirical equation and the adsorption rate constant k298 was 6.37×10-4s-1.The desorption percentage was up to 99.7%when 2.0 mol·L-1KSCN was used for dynamic desorption.展开更多
Amine functional group was grafted to obtain modified persimmon waste gel （NH2-CPT） with the focus of development of selective recovery of molybdenum from rhenium. The adsorption behavior of the NH2-CPT gel for vari...Amine functional group was grafted to obtain modified persimmon waste gel （NH2-CPT） with the focus of development of selective recovery of molybdenum from rhenium. The adsorption behavior of the NH2-CPT gel for various metal ions at varying hydrochloric acid concen-trations was studied. It is found that the NH2-CPT exhibits high affinity for Mo（VI） and no affinity for Re（VII）, Cu（II）, Fe（III）, Mn（VII）, and Zn（II） under the operating conditions. The maximum adsorption capacity for Mo（VI） is 172 mg·g^-1, and the adsorption behavior obeys the Langmuir model. Owing to Mo（VI） as poly-anions, the adsorption mechanism of molybdenum anions could be explained as the anion exchange reactions at weak acid concentration, while neutral molecules could be explained as the complexation reactions at strong acid concentration, respectively. In addition, its excellent adsorption characteristics for Mo（VI） are confirmed by separation of Mo（VI） from Mo to Re containing industrial effluent.展开更多
The oxidation roasting process of molybdenum concentrate has significant advantages in industrial applications.However,utilization of low-grade mineral has many problems because it is more complex than the standard co...The oxidation roasting process of molybdenum concentrate has significant advantages in industrial applications.However,utilization of low-grade mineral has many problems because it is more complex than the standard concentrate.In this study,the oxidation behaviors of powdery rhenium-bearing low-grade molybdenum concentrate were investigated through thermodynamic calculation,roasting experiments,thermogravimetric analysis,and phase analysis.The results obtained show that oxidation of MoS2 begins at 450℃,and MoO3 reacts with metal-oxide forming molybdate at 600℃.Finally,MoO3 can be dissolved in ammonia with a maximum content of approximately 80%.The volatile speed of Re was considerably slower than the oxidation speed of MoS2 because the nonvolatile products ReO2 and ReO3 were generated in reactions among MoS2,SO2,and Re2O7.The final volatilization rate of Re was almost 70%.This study determined the problems related to the roasting of low-grade molybdenum concentrate,which lays the scientific foundations for subsequent enhancement of molybdenum and rhenium extraction.展开更多
Rhenium is one of important components for heterogeneous catalysts,which has been recently used for the catalytic reactions related to the production of biomass-derived chemicals such as deoxydehydration of vicinal OH...Rhenium is one of important components for heterogeneous catalysts,which has been recently used for the catalytic reactions related to the production of biomass-derived chemicals such as deoxydehydration of vicinal OH groups,C-O hydrogenolysis,and hydrogenation of carboxylic acids,and so on.Suitable oxidation state of Re as a catalytic active species is strongly dependent on the catalytic reactions.The control of the oxidation state of Re species on the catalysts is crucial on the catalyst development.展开更多
Methyltrioxorhenium (MTO) and its derivatives were utilized as catalysts for a broad variety of organic reactions after the discovery of an easy synthetic access way to this class of compounds. Among the numerous char...Methyltrioxorhenium (MTO) and its derivatives were utilized as catalysts for a broad variety of organic reactions after the discovery of an easy synthetic access way to this class of compounds. Among the numerous characterization techniques, 17O-NMR spectroscopy and vibrational spectroscopy were exemplary discussed. The immobilization of MTO and its derivatives is of significant current interest as is the synthesis of chiral derivatives.展开更多
Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloy...Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloys for its special strengthening effects. The addition of Re could effectively enhance the creep properties of the single-crystal superalloys; thus, the content of Re is considered as one of the characteristics in different-generation single-crystal superalloys. Owing to the fundamental importance of rhenium to nickel-based single-crystal superalloys, much progress has been made on understanding of the effect of rhenium in the single-crystal superalloys. While the effect of Re doping on the nickelbased superalloys is well documented, the origins of the socalled rhenium effect are still under debate. In this paper,the effect of Re doping on the single-crystal superalloys and progress in understanding the rhenium effect are reviewed. The characteristics of the d-states occupancy in the electronic structure of Re make it the slowest diffusion elements in the single-crystal superalloys, which is undoubtedly responsible for the rhenium effect, while the postulates of Re cluster and the enrichment of Re at the c/c0 interface are still under debate, and the synergistic action of Re with other alloying elements should be further studied.Additionally, the interaction of Re with interfacial dislocations seems to be a promising explanation for the rhenium effect. Finally, the addition of Ru could help suppress topologically close-packed（TCP） phase formation and strengthen the Re doping single-crystal superalloys.Understanding the mechanism of rhenium effect will be beneficial for the effective utilization of Re and the design of low-cost single-crystal superalloys.展开更多
China is a major producer of rhenium, which is widely used in aerospace technologies （as superalloy） and petrochemical industries （as catalyst）. There is a gap between the demand and fact for the enrichment of rhe...China is a major producer of rhenium, which is widely used in aerospace technologies （as superalloy） and petrochemical industries （as catalyst）. There is a gap between the demand and fact for the enrichment of rhenium, due to its rather small content （10-9） in the earth＇s crust. Also, there is no available single occurrence of mineral rhenium. Instead, the rhenium is associated with either molybdenum or copper （of up to 0.2% in content） as a by-product in metallurgical industry. This makes the separation of rhenium from the major mineral metals a challenge. The recent progresses in the separation and enrichment of rhenium were reviewed in this paper, especially, the advances in China. The details of varied separation methods used either in laboratories or factories, such as ion-exchange, solvent extraction, separation utilizing extractive resins, liquid membrane, or novel materials, etc., were elaborated. Comparison of the different methods was disclosed and an outlook on the rhenium chemistry and industry in the future was brought forward.展开更多
This study deals with the first application of the isotope dilution - inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in China. The chemical separation procedure included decompositio...This study deals with the first application of the isotope dilution - inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for 187Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ)of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re-Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application.展开更多
A new 1,3,4-oxadiazole-contanining rhenium（I） complex, with the formula [Re（CO）a（Bphen）（PTOP）], （Bphen = bathophe- nardine, PTOP = 4-（5-p-tolyl-1,3, 4-oxadiazd-2-yl） pyridine）, is synthesized and character...A new 1,3,4-oxadiazole-contanining rhenium（I） complex, with the formula [Re（CO）a（Bphen）（PTOP）], （Bphen = bathophe- nardine, PTOP = 4-（5-p-tolyl-1,3, 4-oxadiazd-2-yl） pyridine）, is synthesized and characterized by elemental analysis, IR, 1H NMR, UV-vis and luminescence spectroscopy. The double-layer electroluminescence devices based on the Re（l） complex have been fabricated by spin-coating technique. The turn-on voltage, maximum efficiency, and brightness for green emission obtained from the devices are 9 V, 2.1 cd/A and 165 cd/m^2, respectively.展开更多
The separation of rhenium from molybdenum in aqueous solution has always been a problem in hydrometallurgy. The separation of rhenium from the electro-oxidation leachate of molybdenite and its mechanism were investiga...The separation of rhenium from molybdenum in aqueous solution has always been a problem in hydrometallurgy. The separation of rhenium from the electro-oxidation leachate of molybdenite and its mechanism were investigated. The results show that pH of the leachate significantly affects adsorption rate compared with other experimental parameters. When temperature is 30℃, pH=8, and adsorbing time is 1 h, adsorption rates of rhenium and molybdenum are 93.46% and 3.57%, respectively, and separation factor of D301 resin for rhenium and molybdenum is 169.56. In addition, the separation factor is higher when the initial molybdenum concentration in model solution is increased. The saturated adsorption capacity of D301 resin for molybdenum and rhenium calculated based on simulated results are 4.263 3 mmol/g and 4.235 5 mmol/g, respectively. D301 resin is an effective separation material of rhenium from electric-oxidation leachate of molybdenite. The adsorption kinetics results also show that the adsorption of rhenium is easier than that of molybdenum, and the adsorption process of D301 for rhenium and molybdenum may be controlled by liquid film diffusion.展开更多
Rhenium diselenide(ReSe_(2))has gathered much attention due to its low symmetry of lattice structure,which makes it possess in-plane anisotropic optical,electrical as well as excitonic properties and further enables R...Rhenium diselenide(ReSe_(2))has gathered much attention due to its low symmetry of lattice structure,which makes it possess in-plane anisotropic optical,electrical as well as excitonic properties and further enables ReSe_(2)have an important application in optoelectronic devices.Here,we report the thickness-dependent exciton relaxation dynamics of mechanically exfoliated few-layer ReSe_(2)flakes by using time-resolved pump–probe transient transmission spectroscopies.The results reveal two thickness-dependent relaxation processes of the excitons.The fast one correlates with the exciton formation(i.e.,the conversion of hot carriers to excitons),while the slow one is attributed to the exciton recombination dominated by defect-assisted exciton trapping besides photon emission channel.The decrease of scattering probability caused by defects leads to the increase of fast lifetime with thickness,and the increase of slow lifetime with thickness is related to the trap-mediated exciton depopulation induced by surface defects.Polarization-dependent transient spectroscopy indicates the isotropic exciton dynamics in the two-dimensional(2D)plane.These results are insightful for better understanding of excitonic dynamics of ReSe_(2)materials and its application in future optoelectronic and electronic devices.展开更多
High-pressure Raman scattering from hexagonal close-packed(HCP) metals Os and Re have been extended up to 200 GPa, and the pressure-dependent shear modulus C_(44)has been deduced from the Raman-active mode E_(28), whi...High-pressure Raman scattering from hexagonal close-packed(HCP) metals Os and Re have been extended up to 200 GPa, and the pressure-dependent shear modulus C_(44)has been deduced from the Raman-active mode E_(28), which is generated from the adjacent vibration of atoms in hexagonal planes, providing the valuable information about the elastic properties for HCP metals under high pressure. Combined with the available data of HCP metals from previous works,a further study indicates that the C_(44)/C_(44)ratio would be close to a constant value, 0.01, with increasing atomic number of metals. The results obtained from high-pressure Raman scattering will allow us to probe the elastic anisotropy of the HCP metals at very high pressure.展开更多
The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption （NH3-TPD） and H2 t...The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption （NH3-TPD） and H2 temperature-programmed reduction （H2-TPR） results showed that Re2O7/SiO2-Al2O3 exhibited stronger acidity and weaker metal-support interaction than Re2O7/γ-Al2O3. At 35 60℃, isomerization free metathesis was observed only over Re2O7/γ-Al2O3, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re2O7/SiO2-Al2O3, hydrido-rhenium species （[Re]-H） were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.展开更多
Mesoporous γ-aluminas with large pore size （up to 19 nm, denoted as MAI9） are prepared from dispersed pseudo-boehmite using pluronic P123 as template. It is found that these mesoporous alumina supported rhenium oxi...Mesoporous γ-aluminas with large pore size （up to 19 nm, denoted as MAI9） are prepared from dispersed pseudo-boehmite using pluronic P123 as template. It is found that these mesoporous alumina supported rhenium oxide catalysts were more active and have far longer working life-span in gas-phase metathesis of 1-butene and 2-butene to propene than rhenium oxide on conventional alumina with small pore size （5 nm）. At 60 ℃ and atmospheric pressure with WHSV = 1 h^-1, the similar stable conversions of butene （ca. 55%） for all the 13 wt% Re207/alumina catalysts were obtained near the chemical equilibrium, and the stable working life-spans of Re2OT/MA19 were far longer than that of Re2O7/A1203, being about 70 h and 20 h, respectively.展开更多
Two novel rhenium(I) 2, 2'-bipyridyl complexes, [(4,4'-di-COOEt-bipy) Re(CO)3 (NCCH3)PF6] and [(4,4'-di-COOEt-bipy) Re (CO)3 (NCS)], a model complex [(4,4'-di- COOEt-bipy) Re (CO)3 (pyridine)PF6], were...Two novel rhenium(I) 2, 2'-bipyridyl complexes, [(4,4'-di-COOEt-bipy) Re(CO)3 (NCCH3)PF6] and [(4,4'-di-COOEt-bipy) Re (CO)3 (NCS)], a model complex [(4,4'-di- COOEt-bipy) Re (CO)3 (pyridine)PF6], were synthesized. Their ground stat?electronic spectra and emission spectra were measured in acetonitrile. The MLCT absorption maximum of the complex exhibited a considerable red shift as the ligand changed from pyridine to CNCH3, or SCN.展开更多
基金supported by the Six Talent Peaks Project of Jiangsu Province(No.XCL-103)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Yangzhou University,No.SJCX22_1727)the‘High-End Talent Project’of Yangzhou University。
文摘The construction of electrocatalysts with exceptional intrinsic activity and rich active sites has proven to be an effective strategy for remarkably enhancing the activity of the hydrogen evolution reaction(HER).Here,self-supporting cerium(Ce)and nitrogen(N)-doped rhenium disulfide nanosheets(denoted Ce,N-ReS_(2))grown on carbon fiber paper have been successfully synthesized.Ce and N doping modulates the lattice irregularity and adjusts the electronic configuration of rhenium disulfide,resulting in reduced hydrogen adsorption/desorption energy and enhanced catalytic stability.The optimized Ce,N-ReS_(2) electrocatalysts exhibit superior catalytic activities of 44/130 and 79/139 mV at 10/100 mA/cm^(2) for HER in alkaline and acidic media,respectively,along with robust durability.Both experimental results and density functional theory calculations indicate that the electronic structure of ReS_(2) can be significantly altered by strategically incorporating Ce and N into the lattice,which in turn optimizes the Gibbs free energy of HER intermediates and accelerates the electrochemical kinetics.This study provides a potentially effective approach for the design and optimization of innovative electrocatalysts involving the regulation of anion and cation dual-doping and architectural engineering.
基金Natural Science Foundation of Zhejiang Province,China(No.LQ21E040004)National Natural Science Foundation of China(No.52271040)+1 种基金State Key Lab of Advanced Metals and Materials,China(No.2021-Z03)State Key Laboratory of Powder Metallurgy,Central South University,China。
文摘The refractory metal rhenium(Re),with content of 0−2 at.%,was introduced into a typicalγ-TiAl alloy of Ti−48Al−2Cr−2Nb(at.%)through vacuum arc melting.The effect of Re content on the microstructure and mechanical properties of theγ-TiAl alloy was investigated.The results show that theγ-TiAl−xRe alloy is composed ofγ,α2,andβphases.As the Re content increases,the proportion ofβphase increases,while the content and size ofα2+γlamellar structure decrease gradually.Furthermore,the compressive strength increases with increasing Re content.A maximum compressive strength of 2282 MPa is achieved for theγ-TiAl−2Re alloy.Theγ-TiAl−2Re alloy exhibits a fracture strain of 36.7%,considerably higher than that of theγ-TiAl alloy(31.0%).Moreover,compared with theγ-TiAl alloy,the hardness and compressive strength of theγ-TiAl−2Re alloy considerably increase by 17.5%and 34.2%,respectively.
文摘A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized under a controlled oxidizing atmosphere via the pyrolysis of ammonium perrhenate, and carried into reduction zone by carrier gas, and there reduced into rhenium powders by hydrogen gas. Thermodynamic calculations indicated that Re207 could be prevented from further decomposition through controlling the oxygen partial pressure higher than 10 1.248 Pa in the pyrolysis of ammonium perrhenate. This result was further validated via DSC-TGA analysis of ammonium perrhenate. The typical rhenium powders prepared by the CVD method proposed show irregular polyhedron morphology with particle size in the range of 100-800 nm and a Ds0 of 308 nm. The specific surface area and oxygen content were measured to be 4.37 m^2/g and 0.45%, respectively.
文摘The effects of 4 wt% rhenium （Re） addition on isothermal oxidation behavior of Tribaloy T-800 alloy have been studied at 800 °C and 1 000 °C in air. At 800 °C,T-800 shows nonuniform oxidation between dendritic and eutectic areas. Re addition clearly promotes the nonuniform oxidation,leading to considerably higher mass gains than that of T-800 at this temperature. At 1 000 °C exposure,the thickness of scale on T-800 increases significantly,accompanied by severe scale spallation during cooling to room temperature. On the contrary,T-800Re shows a marked decrease of oxide growth rate compared to the linear one of T-800 at 1 000 °C. The scale adhesion is also improved with Re addition at this higher temperature. Therefore,the role of Re depends on the exposure temperature. Re addition gives high oxidation rate at 800 °C,however,the excellent oxidation resistance is obtained by the addition of Re at a higher temperature of 1 000 °C.
基金financially supported by the National Natural Science Foundation of China (Nos.51404220 and 51504225)
文摘In this paper, a weak-base resin was adopted to recycle rhenium because of its excellent adsorption and desorption properties for rhenium, while the kinetics and thermodynamics properties of adsorbing rhenium from the rhenium stock solution were systematically investigated. The kinetics investigations confirm that the adsorption process of Re belongs to kinetic control by particle diffusion process and the corresponding reaction rate constant is 2.68 × 10-s s^-1. Then, the Langmuir and Freundlich models were used to describe the adsorption equilibrium behaviors of Re and the thermodynamics parameters are obtained. The results show that the Langmuir model is the best-fitted model, and the Gibbs free energy change of Re adsorption onto ZS 15 weak-base resin is AGO = - 10.59 ＋ 12.66T. To verify the weak-base resins for extracting rhenium in industrial application, the column experiments were operated in the spray solution generating by roasting the molybdenum concentrates. The results indicate that the weak-base resins possess excellent adsorptive selectivity for rhenium, and the ammonia solution with low concentration could sufficiently desorb rhe- nium from the resins.
基金Supported by the National Natural Science Foundation of China （30972405） and the Natural Science Foundation of Zhejiang Province （Y3090531）.
文摘The adsorption and mechanism of Re(Ⅶ)on resin D318 were studied using chemical methods and IR spectrometry.At pH 5.2,the static and dynamic saturation adsorption capacities were 351.4 and 366.5 mg·g-1,respectively.The adsorption behavior obeyed the Freundlich empirical equation and the adsorption rate constant k298 was 6.37×10-4s-1.The desorption percentage was up to 99.7%when 2.0 mol·L-1KSCN was used for dynamic desorption.
基金financially supported by the National Natural Science Foundation of China(Nos.21171080 and21201094)the National Science and Technology Pillar Program(No.2012BAF03B02)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(No.2011-1139)the Program for Liaoning Excellent Talents in University(No.LJQ2012001)
文摘Amine functional group was grafted to obtain modified persimmon waste gel （NH2-CPT） with the focus of development of selective recovery of molybdenum from rhenium. The adsorption behavior of the NH2-CPT gel for various metal ions at varying hydrochloric acid concen-trations was studied. It is found that the NH2-CPT exhibits high affinity for Mo（VI） and no affinity for Re（VII）, Cu（II）, Fe（III）, Mn（VII）, and Zn（II） under the operating conditions. The maximum adsorption capacity for Mo（VI） is 172 mg·g^-1, and the adsorption behavior obeys the Langmuir model. Owing to Mo（VI） as poly-anions, the adsorption mechanism of molybdenum anions could be explained as the anion exchange reactions at weak acid concentration, while neutral molecules could be explained as the complexation reactions at strong acid concentration, respectively. In addition, its excellent adsorption characteristics for Mo（VI） are confirmed by separation of Mo（VI） from Mo to Re containing industrial effluent.
基金Projects(U1760107,U1660206)supported by the National Natural Science Foundation of ChinaProject(2013zzts064)supported by the Innovation Foundation for Postgraduate of Central South University,China
文摘The oxidation roasting process of molybdenum concentrate has significant advantages in industrial applications.However,utilization of low-grade mineral has many problems because it is more complex than the standard concentrate.In this study,the oxidation behaviors of powdery rhenium-bearing low-grade molybdenum concentrate were investigated through thermodynamic calculation,roasting experiments,thermogravimetric analysis,and phase analysis.The results obtained show that oxidation of MoS2 begins at 450℃,and MoO3 reacts with metal-oxide forming molybdate at 600℃.Finally,MoO3 can be dissolved in ammonia with a maximum content of approximately 80%.The volatile speed of Re was considerably slower than the oxidation speed of MoS2 because the nonvolatile products ReO2 and ReO3 were generated in reactions among MoS2,SO2,and Re2O7.The final volatilization rate of Re was almost 70%.This study determined the problems related to the roasting of low-grade molybdenum concentrate,which lays the scientific foundations for subsequent enhancement of molybdenum and rhenium extraction.
文摘Rhenium is one of important components for heterogeneous catalysts,which has been recently used for the catalytic reactions related to the production of biomass-derived chemicals such as deoxydehydration of vicinal OH groups,C-O hydrogenolysis,and hydrogenation of carboxylic acids,and so on.Suitable oxidation state of Re as a catalytic active species is strongly dependent on the catalytic reactions.The control of the oxidation state of Re species on the catalysts is crucial on the catalyst development.
基金This work was financially supported by FEK is grateful to the Funds of Chemical Industrie for continuous support KRJ thanks BASF for financial support.
文摘Methyltrioxorhenium (MTO) and its derivatives were utilized as catalysts for a broad variety of organic reactions after the discovery of an easy synthetic access way to this class of compounds. Among the numerous characterization techniques, 17O-NMR spectroscopy and vibrational spectroscopy were exemplary discussed. The immobilization of MTO and its derivatives is of significant current interest as is the synthesis of chiral derivatives.
基金financially supported by the National Basic Research Program of China(No.2009CB623701)the National Natural Science Foundation of China(Nos.11374174,50971075 and 51390471)
文摘Nickel-based single-crystal superalloys are the key materials for the manufacturing and development of advanced aeroengines. Rhenium is a crucial alloying element in the advanced nickel-based single-crystal superalloys for its special strengthening effects. The addition of Re could effectively enhance the creep properties of the single-crystal superalloys; thus, the content of Re is considered as one of the characteristics in different-generation single-crystal superalloys. Owing to the fundamental importance of rhenium to nickel-based single-crystal superalloys, much progress has been made on understanding of the effect of rhenium in the single-crystal superalloys. While the effect of Re doping on the nickelbased superalloys is well documented, the origins of the socalled rhenium effect are still under debate. In this paper,the effect of Re doping on the single-crystal superalloys and progress in understanding the rhenium effect are reviewed. The characteristics of the d-states occupancy in the electronic structure of Re make it the slowest diffusion elements in the single-crystal superalloys, which is undoubtedly responsible for the rhenium effect, while the postulates of Re cluster and the enrichment of Re at the c/c0 interface are still under debate, and the synergistic action of Re with other alloying elements should be further studied.Additionally, the interaction of Re with interfacial dislocations seems to be a promising explanation for the rhenium effect. Finally, the addition of Ru could help suppress topologically close-packed（TCP） phase formation and strengthen the Re doping single-crystal superalloys.Understanding the mechanism of rhenium effect will be beneficial for the effective utilization of Re and the design of low-cost single-crystal superalloys.
基金supported by the National Natural Science Foundation of China(Nos.21472194,21701073 and 21772202)the Fundamental Research Funds for the Central Universities(No. lzujbky-2017-12)
文摘China is a major producer of rhenium, which is widely used in aerospace technologies （as superalloy） and petrochemical industries （as catalyst）. There is a gap between the demand and fact for the enrichment of rhenium, due to its rather small content （10-9） in the earth＇s crust. Also, there is no available single occurrence of mineral rhenium. Instead, the rhenium is associated with either molybdenum or copper （of up to 0.2% in content） as a by-product in metallurgical industry. This makes the separation of rhenium from the major mineral metals a challenge. The recent progresses in the separation and enrichment of rhenium were reviewed in this paper, especially, the advances in China. The details of varied separation methods used either in laboratories or factories, such as ion-exchange, solvent extraction, separation utilizing extractive resins, liquid membrane, or novel materials, etc., were elaborated. Comparison of the different methods was disclosed and an outlook on the rhenium chemistry and industry in the future was brought forward.
基金This research was supported jointly by the Foundation for Development of Geological Science and Technology (Project No. 49173164)
文摘This study deals with the first application of the isotope dilution - inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for 187Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ)of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re-Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application.
文摘A new 1,3,4-oxadiazole-contanining rhenium（I） complex, with the formula [Re（CO）a（Bphen）（PTOP）], （Bphen = bathophe- nardine, PTOP = 4-（5-p-tolyl-1,3, 4-oxadiazd-2-yl） pyridine）, is synthesized and characterized by elemental analysis, IR, 1H NMR, UV-vis and luminescence spectroscopy. The double-layer electroluminescence devices based on the Re（l） complex have been fabricated by spin-coating technique. The turn-on voltage, maximum efficiency, and brightness for green emission obtained from the devices are 9 V, 2.1 cd/A and 165 cd/m^2, respectively.
基金Foundation item： Project（21106188） supported by the National Natural Science Foundation of China Project（12JJ4013） supported by Htman Provincial Natural Science Foundation of China+2 种基金 Projects（2011M501299, 2012T50709） supported by China Postdoctoral Science Foundation Project（2011QNZT050） supported by the Special Fund from the Central Collegiate Basic Scientific Research Bursary of Central South University, China Project（CSUZC2012038） supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University, China
文摘The separation of rhenium from molybdenum in aqueous solution has always been a problem in hydrometallurgy. The separation of rhenium from the electro-oxidation leachate of molybdenite and its mechanism were investigated. The results show that pH of the leachate significantly affects adsorption rate compared with other experimental parameters. When temperature is 30℃, pH=8, and adsorbing time is 1 h, adsorption rates of rhenium and molybdenum are 93.46% and 3.57%, respectively, and separation factor of D301 resin for rhenium and molybdenum is 169.56. In addition, the separation factor is higher when the initial molybdenum concentration in model solution is increased. The saturated adsorption capacity of D301 resin for molybdenum and rhenium calculated based on simulated results are 4.263 3 mmol/g and 4.235 5 mmol/g, respectively. D301 resin is an effective separation material of rhenium from electric-oxidation leachate of molybdenite. The adsorption kinetics results also show that the adsorption of rhenium is easier than that of molybdenum, and the adsorption process of D301 for rhenium and molybdenum may be controlled by liquid film diffusion.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074202,12174207,and 11974190)the Natural Science Foundation of Tianjin City(Grant Nos.20JCQNJC00020 and 22JCYBJC00390)。
文摘Rhenium diselenide(ReSe_(2))has gathered much attention due to its low symmetry of lattice structure,which makes it possess in-plane anisotropic optical,electrical as well as excitonic properties and further enables ReSe_(2)have an important application in optoelectronic devices.Here,we report the thickness-dependent exciton relaxation dynamics of mechanically exfoliated few-layer ReSe_(2)flakes by using time-resolved pump–probe transient transmission spectroscopies.The results reveal two thickness-dependent relaxation processes of the excitons.The fast one correlates with the exciton formation(i.e.,the conversion of hot carriers to excitons),while the slow one is attributed to the exciton recombination dominated by defect-assisted exciton trapping besides photon emission channel.The decrease of scattering probability caused by defects leads to the increase of fast lifetime with thickness,and the increase of slow lifetime with thickness is related to the trap-mediated exciton depopulation induced by surface defects.Polarization-dependent transient spectroscopy indicates the isotropic exciton dynamics in the two-dimensional(2D)plane.These results are insightful for better understanding of excitonic dynamics of ReSe_(2)materials and its application in future optoelectronic and electronic devices.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 11774247 and U2030107)Sichuan University Innovation Research Program of China (Grant No. 2020SCUNL107)。
文摘High-pressure Raman scattering from hexagonal close-packed(HCP) metals Os and Re have been extended up to 200 GPa, and the pressure-dependent shear modulus C_(44)has been deduced from the Raman-active mode E_(28), which is generated from the adjacent vibration of atoms in hexagonal planes, providing the valuable information about the elastic properties for HCP metals under high pressure. Combined with the available data of HCP metals from previous works,a further study indicates that the C_(44)/C_(44)ratio would be close to a constant value, 0.01, with increasing atomic number of metals. The results obtained from high-pressure Raman scattering will allow us to probe the elastic anisotropy of the HCP metals at very high pressure.
基金supports from the Thailand Research Fund (TRF)the Office of Higher Education Commission
文摘The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption （NH3-TPD） and H2 temperature-programmed reduction （H2-TPR） results showed that Re2O7/SiO2-Al2O3 exhibited stronger acidity and weaker metal-support interaction than Re2O7/γ-Al2O3. At 35 60℃, isomerization free metathesis was observed only over Re2O7/γ-Al2O3, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re2O7/SiO2-Al2O3, hydrido-rhenium species （[Re]-H） were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.
基金financially supported by SINOPEC Jiujiang Petrochemical Company and from the National Nature Science Foundation of China (No.20976192)
文摘Mesoporous γ-aluminas with large pore size （up to 19 nm, denoted as MAI9） are prepared from dispersed pseudo-boehmite using pluronic P123 as template. It is found that these mesoporous alumina supported rhenium oxide catalysts were more active and have far longer working life-span in gas-phase metathesis of 1-butene and 2-butene to propene than rhenium oxide on conventional alumina with small pore size （5 nm）. At 60 ℃ and atmospheric pressure with WHSV = 1 h^-1, the similar stable conversions of butene （ca. 55%） for all the 13 wt% Re207/alumina catalysts were obtained near the chemical equilibrium, and the stable working life-spans of Re2OT/MA19 were far longer than that of Re2O7/A1203, being about 70 h and 20 h, respectively.
文摘Two novel rhenium(I) 2, 2'-bipyridyl complexes, [(4,4'-di-COOEt-bipy) Re(CO)3 (NCCH3)PF6] and [(4,4'-di-COOEt-bipy) Re (CO)3 (NCS)], a model complex [(4,4'-di- COOEt-bipy) Re (CO)3 (pyridine)PF6], were synthesized. Their ground stat?electronic spectra and emission spectra were measured in acetonitrile. The MLCT absorption maximum of the complex exhibited a considerable red shift as the ligand changed from pyridine to CNCH3, or SCN.
