TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporti...Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporting molybdenum complex on C_(3)N_(4)-K and characterized by FT-IR,XRD,SEM,XPS and ICP-OES.Heterogeneous CN–Mo-Bpy catalyst can be applied to the direct amination of nitroarenes and arylboronic acid,thus constructing various valuable diarylamines in high to excellent yields with a wide substrate scope and good functional group tolerance.It is worth noting that this heterogeneous catalyst has high chemical stability and can be recycled for at least five times without reducing its activity.展开更多
Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability mak...Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.展开更多
A direct hydrometallurgical route for nickel and molybdenum extraction from a nickel-molybdenum （Ni-Mo） ore using pressure acid leaching was studied. The nickel and molybdenum were extracted by acid leaching under o...A direct hydrometallurgical route for nickel and molybdenum extraction from a nickel-molybdenum （Ni-Mo） ore using pressure acid leaching was studied. The nickel and molybdenum were extracted by acid leaching under oxygen pressure. Compared with traditional roasting methods, this hydrometallurgical method eliminates SO2 and As203 emission （the Ni-Mo ore containing 15%-25% S）. Compared with existing alkali leaching recovery of molybdenum process, almost all the nickel and considerable molybdenum were extracted in the acid leaching process. Under oxygen pressure conditions, almost all the nickel and a substantial part of the molybdenum were dissolved into the acid leaching liquor and the other part of the molybdenum was left in the acid leach residue. The acid leach residue was further leached under alkaline （NaOH） conditions. Under optimal experimental conditions, the extraction rates nickel and molybdenum reached 97% and 96%, respectively.展开更多
The influence of Ti and Zr,Nb alloying on the microstructures and performance of laser-welded molybdenum socket joints was investigated.Following Nb alloying,the average microhardness of the fusion zone(FZ)increased f...The influence of Ti and Zr,Nb alloying on the microstructures and performance of laser-welded molybdenum socket joints was investigated.Following Nb alloying,the average microhardness of the fusion zone(FZ)increased from HV 194.7 to HV 283.3.Additionally,Nb can react with O to form dispersed Nb_(2)O_(5) along grain boundaries,impeding grain boundary migration and dislocation movement while reducing the content of volatile Mo oxide along these boundaries.The incorporation of Nb in FZ partially inhibits pore defects and enhances joint load-bearing capacity.In comparison to the laser-welded joints without adding Nb(LW),the tensile strength of the laser-welded joints with Nb alloying(LW-Nb)was significantly improved by approximately 69%from 327.5 to 551.7 MPa.Furthermore,the fracture mechanism of the joints transitioned from intergranular fracture to transgranular fracture.展开更多
Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in th...Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.展开更多
Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility...Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility to secondary pollution in application.Calcium sulfite(CaSO_(3)),one of the byproducts of flue gas desulfurization,is of interest in AOPs because of its ability to slowly release S(Ⅳ),low toxicity,and costeffectiveness.Therefore,a heterogenous activator,molybdenum carbide(Mo_(2)C)was selected to stimulate Ca SO3for typical antibiotic elimination.Benefiting from the dissociation form of HSO_(3^(-))from CaSO_(3)and improved electron transfer of Mo_(2)C at pH 6,the simulated target metronidazole(MTZ)can be removed by 85.65%with rate constant of 0.02424 min^(-1)under near-neutral circumstance.The combining determinations of quenching test,electron spin resonance spectrum,and reactive species probe demonstrated singlet oxygen(^(1)O_(2))and sulfate radicals played leading role for MTZ decontamination.Characterization and theoretical calculation suggested the alteration of Mo valence state drove the activation of S(Ⅳ),and revealed that dissolved oxygen promoted the adsorption of HSO_(3^(-))on the surface of Mo_(2)C,then facilitating production of^(1)O_(2).The favorable stability and applicability for Mo_(2)C/CaSO_(3)process indicated an applied prospect in actual pharmaceutical wastewater.展开更多
Integrating electrochemical upgrading of glycerol and water electrolysis is regarded as a promising and energy-saving approach for the co-production of chemicals and hydrogen.However,developing efficient electrocataly...Integrating electrochemical upgrading of glycerol and water electrolysis is regarded as a promising and energy-saving approach for the co-production of chemicals and hydrogen.However,developing efficient electrocatalyst towards this technology remains challenging.Herein,a metallic cobalt mediated molybdenum nitride heterostructural material has been exploited on nickel foam(Co@Mo_(2)N/NF)for the glycerol oxidation reaction(GOR)and hydrogen evolution reaction(HER).Remarkably,the obtained Co@Mo_(2)N/NF realizes eminent performance with low overpotential of 49 mV at 50 mA/cm^(2)for HER and high Faradaic efficiency of formate of 95.03%at 1.35 V vs.RHE for GOR,respectively.The systematic in-situ experiments reveal that the Co@Mo_(2)N heterostructure promotes the cleavage of C-C bond in glycerol by active CoOOH species and boosts the conversion of glycerol to aldehyde intermediates to formate product.Moreover,the density functional theory(DFT)calculations confirm the strong interaction at Co@Mo_(2)N interface,which contributes to the optimized water dissociation and the transformation of H^(*)to H^(2).Benefiting from those advantages,the built HER||GOR electrolyzer delivers a low voltage of 1.61 V at 50 mA/cm^(2),high Faradaic efficiency,and robust stability over 120 h for sustained and stable electrolysis.展开更多
The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of...The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of α-MoC and β-Mo_(2)C catalysts with different Mo/C ratios were synthesized,and their ammonia decomposition performance as well as structural evolution in ADR was investigated.The β-Mo_(2)C catalyst,characterized by a higher Mo/C ratio,demonstrated a remarkable turnover frequency of 1.3 s^(-1),which is over tenfold higher than that ofα-MoC(0.1 s^(-1)).An increase in the Mo/C ratio of molybdenum carbide revealed a direct correlation between the surface Mo/C ratio and the hydrogen yield.The transient response surface reaction indicated that the combination of N*and N*derived from NH_(3) dissociation represents the rate-determining step in the ADR,andβ-Mo2C exhibited exceptional proficiency in facilitating this pivotal step.Concurrently,the accumulation of N*species on the carbide surface could induce the phase transition of molybdenum carbide to nitride,which follows a topological transformation.It is discovered that such phase evolution was affected by the Mo-C surface and reaction temperature simultaneously.When the kinetics of combination of N*was accelerated by rising temperatures and its accumulation on the carbide surface was mitigated,β-Mo_(2)C maintained its carbide phase,preventing nitridation during the ADR at 810℃.Our results contribute to an in-depth understanding of the molybdenum carbides’catalytic properties in ADR and highlight the nature of the carbide-nitride phase transition in the reaction.展开更多
Molybdenum nitride,renowned for its exceptional physical and chemical properties,has garnered extensive attention and research interest.In this study,we employed first-principles calculations and the CALYPSO structure...Molybdenum nitride,renowned for its exceptional physical and chemical properties,has garnered extensive attention and research interest.In this study,we employed first-principles calculations and the CALYPSO structure prediction method to conduct a comprehensive analysis of the crystal structures and electronic properties of molybdenum nitride(Mo_(x)N_(1-x))under high pressure.We discovered two novel high-pressure phases:Imm2-MoN_(3) and Cmmm-MoN_(4),and confirmed their stability through the analysis of elastic constants and phonon dispersion curves.Notably,the MoN_(4) phase,with its high Vickers hardness of 36.9 GPa,demonstrates potential as a hard material.The results of this study have broadened the range of known high-pressure phases of molybdenum nitride,providing the groundwork for future theoretical and experimental researches.展开更多
Pre-harvest sprouting(PHS)or vivipary is a major problem affecting cereal quality and grain quantity and is primarily linked to the dysregulation of abscisic acid(ABA)biosynthesis in plants.Therefore,elucidating the m...Pre-harvest sprouting(PHS)or vivipary is a major problem affecting cereal quality and grain quantity and is primarily linked to the dysregulation of abscisic acid(ABA)biosynthesis in plants.Therefore,elucidating the molecular mechanisms governing seed dormancy is crucial for developing strategies to improve crop productivity.In this study,we identified a novel viviparous maize mutant,viviparous-like 5(vp-like5),which exhibits precocious germination in developing seeds.Through map-based cloning,we discovered that ZmCNX6,which encodes a small subunit of molybdopterin synthase essential for molybdenum cofactor(MoCo)biosynthesis,is the causal gene responsible for the vp-like5 phenotype.Biochemical assays have demonstrated significantly reduced activities of MoCo-dependent enzymes,including aldehyde oxidase(AO),xanthine dehydrogenase(XDH),and nitrate reductase(NR),in vplike5.AO is essential for the ABA biosynthesis,and the observed ABA deficiency in vp-like5 likely drives the viviparous phenotype.Expression analysis showed that ZmCNX6 was stably expressed during seed development,indicating its significant role in seed development.Furthermore,overexpression of ZmCNX6 not only enhanced the activities of MoCo-dependent enzymes but also improved drought tolerance in maize.Collectively,our study revealed ZmCNX6 as a multifunctional hub coordinating MoCo metabolism,ABA-dependent dormancy regulation,and abiotic stress responses,offering a potential target for simultaneously mitigating vivipary and improving drought resistance in maize.展开更多
Molybdenum tailings are the solid waste left from ore processing,which damages soil and water resources.To address that,molybdenum tailings(MTs)powder obtained from molybdenum tailings sands was processed as an admixt...Molybdenum tailings are the solid waste left from ore processing,which damages soil and water resources.To address that,molybdenum tailings(MTs)powder obtained from molybdenum tailings sands was processed as an admixture.Compared with moisture-cured conditions,the influence of MTs on the steam-cured mortar’s mechanical properties,surface and internal pore characteristics,and microscopic morphology was investigated.The results show that steam-cured mortar containing appropriate MTs can still have high early strength.When the content of MTs doesn’t exceed 15%,the mechanical strength of mortar steam-cured for 3 d can reach 85%of that of corresponding mortar moisture-cured for 28 d,and that of mortar steam-cured for 28 d isn’t lower than 90%of that of pure cement mortar.The proportion of harmful pores(HFP)and more harmful pores(MHFP)and most probable pore diameters(MPD)on the mortar surface containing MTs steam-cured for 28 d are significantly decreased.When MTs’content is 15%,the proportion of HFP and MHFP on the surface of paste is decreased by 71.4%and 72.2%,respectively,with MPS decreasing from 12.7 nm to 10.8 nm.SEM analysis shows that the surfaces of steam-cured paste containing 15%MTs have more hydration products and dense microstructures.The effect of pozzolanic and dense filling of MTs effectively refines the pore structure,reducing the large pore-size pores.展开更多
This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in sit...This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.展开更多
Lithium-sulfur batteries(LSBs)have undoubtedly become one of the most promising battery systems due to their high energy density and the cost-effectiveness of sulfur cathodes.However,challenges,such as the shuttle eff...Lithium-sulfur batteries(LSBs)have undoubtedly become one of the most promising battery systems due to their high energy density and the cost-effectiveness of sulfur cathodes.However,challenges,such as the shuttle effect from soluble long-chain lithium polysulfides(LiPSs)and the low conductivity of active materials,hinder their commercialization.Under this circumstance,molybdenum sulfide(MoS_(2))has attracted widespread attention due to its unique physicochemical properties,particularly its capability to mitigate the shuttle effect in LSBs through electrostatic or chemical bonds.Nonetheless,the industrial application of MoS_(2)in LSBs is limited by the inertness of its basal surface and inadequate electron transfer properties.This review mainly introduces various modification strategies of MoS_(2)materials in LSBs and their effects on electrochemical and catalytic performance.Unlike previous reviews and related papers,detailed discussions were conducted on the specific mechanisms of each modification strategy,including(1)shape manipulation,(2)support engineering,(3)heterostructure engineering,(4)defect engineering,(5)interlayer engineering,(6)phase engineering,(7)strain engineering,(8)hybridization.Comprehensive conclusions and outlook on the development of MoS_(2)as an abundant electrocatalyst for LSBs are also discussed in the end.展开更多
Due to its high electrical conductivity and platinum-like electronic structure,molybdenum phosphide(MoP)has attracted extensive attention as a potential catalyst for the hydrogen evolution reaction(HER)by water splitt...Due to its high electrical conductivity and platinum-like electronic structure,molybdenum phosphide(MoP)has attracted extensive attention as a potential catalyst for the hydrogen evolution reaction(HER)by water splitting.Nevertheless,in the oxygen evolution reaction(OER),the electrocatalytic performance of MoP did not achieve satisfactory results.Therefore,novel nitrogen-doped carbon-encapsulated Ladoped MoP nanoparticles(La-MoP@N/C)are synthesized,which show outstanding durability and electrocatalytic activity in both HER and OER.Detailed structural characterization and calculations confirm that La doping not only effectively adjusts the electron density around Mo and P atoms,accelerates the adsorption and desorption processes,but also increases the number of active sites.Low overpotentials of 113 and 388 mV for HER and OER at 10 mA cm−2 are achieved with the optimized La0.025-Mo0.975P@N/C.Furthermore,the two-electrode electrolyzer assembled with La0.025-Mo0.975P@N/C also presents impressive water splitting performance.This study indicates that rare earth doping can be used as an efficient strategy to control the local electronic structure of phosphides precisely,which can also be extended to other electrocatalysts.展开更多
The bioleaching of molybdenum from its sulfide ore using a Mo-resistant thermophilic bacterium sulfolobus metallics combined with a membrane biological reactor（MBR） was studied.The experimental results showed that t...The bioleaching of molybdenum from its sulfide ore using a Mo-resistant thermophilic bacterium sulfolobus metallics combined with a membrane biological reactor（MBR） was studied.The experimental results showed that the concentration of Mo can be controlled by filter of the membrane in MBR and the toxicity of Mo to microorganism is decreased in the process of bioleaching.It was also evidenced that there were different leaching rates of Ni and Mo when the concentration of Mo was different.After leaching for 20 d in the MBR at Mo concentration of 395 mg/L,the leaching rates of Ni and Mo reached the maximum of 79.57% and 56.23% respectively under the conditions of 100 g/L of mineral density,65 ℃,pH=2 and 1.0 L/min of the aeration rate.While 75.59% Ni and 54.33% Mo were leached out in column without membrane under the same conditions.展开更多
Molybdenum(Mo)alloys are essential for applications requiring outstanding mechanical properties at high temperatures across various industrial sectors.Understanding and predicting the creep properties of Mo alloys is ...Molybdenum(Mo)alloys are essential for applications requiring outstanding mechanical properties at high temperatures across various industrial sectors.Understanding and predicting the creep properties of Mo alloys is crucial for service safety and the design of new materials.This study introduces a physicsbased crystallographic creep model dedicated to the characteristic hierarchical microstructure of Mo–La_(2)O_(3)alloys.By sourcing most parameters from existing literature and calibrating others within recommended ranges,the model efficiently predicts creep behavior beyond its initial calibration scope.Through the integration of microstructure descriptors,we systematically explored the impact of different microstructural features on the creep behavior and identified the underlying mechanisms.This analysis yielded two pivotal concepts:the minimum acceptable grain size and the necessary nanoparticle number density.These metrics,readily obtainable from the model,quantify the requisite grain size and nanoparticle content to achieve the target steady-state creep rates for operational demands,thus providing essential insights for the creep condition-oriented design of Mo–La_(2)O_(3)alloys.The model is also expected to be adaptable for developing other Mo alloys reinforced by second phase particles,aimed at achieving desired creep properties under specified conditions,assuming that relevant parameters are accessible through literature or lower-scale simulations.展开更多
This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-...This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.展开更多
The adsorption behavior of D301 for molybdenum blue was investigated.The thermodynamics parameters in adsorption process were calculated and the adsorption kinetics was studied.The experimental results show that the a...The adsorption behavior of D301 for molybdenum blue was investigated.The thermodynamics parameters in adsorption process were calculated and the adsorption kinetics was studied.The experimental results show that the adsorption characteristic of D301 for molybdenum blue fits well with the Freundlich adsorption isotherm equation.In the adsorption process of D301 for molybdenum blue,both the enthalpy change ΔH and entropy change ΔS are positive,while the free energy change ΔG is negative when temperatures are in the range of 303-333 K.It is indicated that the adsorption is a spontaneous and endothermic process,and the elevated temperatures benefit to the adsorption.Kinetic studies show that the kinetic data are well described by double driving-force model,and the adsorption rate of molybdenum blue on D301 is controlled by the intraparticle diffusion during the adsorption process.The total kinetic equation is determined.展开更多
The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. T...The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidationtemperature of MoS2 is 450℃, while the formation of CaMoO4 and CaSO4 occurs above 500℃. The whole calcification reactionsare nearly completed between 600 and 650℃. However, raising the temperature further helps for the formation of CaMoO4 but isdisadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows theorder： Ca（OH）2〉CaO〉CaCO3. With increasing the dosage of Ca（OH）2, the molybdenum retention rate and sulfur-fixing rate rise, butexcessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca（OH）2 to molybdenumconcentrate is 1：1. When roasted at 650 ℃ for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grademolybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% withcalcines being leached by sulphuric acid.展开更多
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金support for this work by Hebei Education Department(No.JZX2024004)Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.236Z1404G)+3 种基金the National Natural Science Foundation of China(Nos.22301060 and 21272053)China Postdoctoral Science Foundation(No.2023M730914)the Natural Science Foundation of Hebei Province(Biopharmaceutical Joint Fund No.B2022206008)Project of Science and Technology Department of Hebei Province(No.22567622H)。
文摘Heterogeneous metal-catalyzed chemical conversions with a recyclable catalyst are very ideal and challenging for sustainable organic synthesis.A new bipyridyl-Mo(IV)-carbon nitride(CN-K/Mo-Bpy)was prepared by supporting molybdenum complex on C_(3)N_(4)-K and characterized by FT-IR,XRD,SEM,XPS and ICP-OES.Heterogeneous CN–Mo-Bpy catalyst can be applied to the direct amination of nitroarenes and arylboronic acid,thus constructing various valuable diarylamines in high to excellent yields with a wide substrate scope and good functional group tolerance.It is worth noting that this heterogeneous catalyst has high chemical stability and can be recycled for at least five times without reducing its activity.
基金National Natural Science Foundation of China(52071165,52475347)National Program of Foreign Experts of China(G2023026003L)+4 种基金China Postdoctoral Fund(2023M740475)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(22HASTIT026)Program for the Top Young Talents of Henan Province,China,Frontier Exploration Projects of Longmen Laboratory,China(LMQYTSKT016)Key Scientific Research Projects of Colleges and Universities in Henan Province,China(24A460008)Key Science and Technology Project of Henan Province,China(242102220064,222102230111)。
文摘Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.
基金Projects(51174104,50874053)supported by the National Natural Science Foundation of ChinaProject(2009AA06Z106)supported by Hi-Tech Research and Development Program of ChinaProject(20115314110001)supported by Doctoral Fund of Ministry of Education of China
文摘A direct hydrometallurgical route for nickel and molybdenum extraction from a nickel-molybdenum （Ni-Mo） ore using pressure acid leaching was studied. The nickel and molybdenum were extracted by acid leaching under oxygen pressure. Compared with traditional roasting methods, this hydrometallurgical method eliminates SO2 and As203 emission （the Ni-Mo ore containing 15%-25% S）. Compared with existing alkali leaching recovery of molybdenum process, almost all the nickel and considerable molybdenum were extracted in the acid leaching process. Under oxygen pressure conditions, almost all the nickel and a substantial part of the molybdenum were dissolved into the acid leaching liquor and the other part of the molybdenum was left in the acid leach residue. The acid leach residue was further leached under alkaline （NaOH） conditions. Under optimal experimental conditions, the extraction rates nickel and molybdenum reached 97% and 96%, respectively.
基金National Key Research and Development Project of China (No. 2022YFB3707602)National Natural Science Foundation of China (Nos. 52005393, 51775416)。
文摘The influence of Ti and Zr,Nb alloying on the microstructures and performance of laser-welded molybdenum socket joints was investigated.Following Nb alloying,the average microhardness of the fusion zone(FZ)increased from HV 194.7 to HV 283.3.Additionally,Nb can react with O to form dispersed Nb_(2)O_(5) along grain boundaries,impeding grain boundary migration and dislocation movement while reducing the content of volatile Mo oxide along these boundaries.The incorporation of Nb in FZ partially inhibits pore defects and enhances joint load-bearing capacity.In comparison to the laser-welded joints without adding Nb(LW),the tensile strength of the laser-welded joints with Nb alloying(LW-Nb)was significantly improved by approximately 69%from 327.5 to 551.7 MPa.Furthermore,the fracture mechanism of the joints transitioned from intergranular fracture to transgranular fracture.
文摘Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.
基金the support received from the National Natural Science Foundation of China(No.51908485)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(Nos.246Z3603G and 226Z3603G)。
文摘Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility to secondary pollution in application.Calcium sulfite(CaSO_(3)),one of the byproducts of flue gas desulfurization,is of interest in AOPs because of its ability to slowly release S(Ⅳ),low toxicity,and costeffectiveness.Therefore,a heterogenous activator,molybdenum carbide(Mo_(2)C)was selected to stimulate Ca SO3for typical antibiotic elimination.Benefiting from the dissociation form of HSO_(3^(-))from CaSO_(3)and improved electron transfer of Mo_(2)C at pH 6,the simulated target metronidazole(MTZ)can be removed by 85.65%with rate constant of 0.02424 min^(-1)under near-neutral circumstance.The combining determinations of quenching test,electron spin resonance spectrum,and reactive species probe demonstrated singlet oxygen(^(1)O_(2))and sulfate radicals played leading role for MTZ decontamination.Characterization and theoretical calculation suggested the alteration of Mo valence state drove the activation of S(Ⅳ),and revealed that dissolved oxygen promoted the adsorption of HSO_(3^(-))on the surface of Mo_(2)C,then facilitating production of^(1)O_(2).The favorable stability and applicability for Mo_(2)C/CaSO_(3)process indicated an applied prospect in actual pharmaceutical wastewater.
基金financially supported by the National Natural Science Foundation of China(No.22205205)the Natural Science Foundation of Zhejiang Province(No.LQ24E040002)the Science Foundation of Zhejiang Sci-Tech University(ZSTU)(Nos.21062337Y,LW-YP2024076)。
文摘Integrating electrochemical upgrading of glycerol and water electrolysis is regarded as a promising and energy-saving approach for the co-production of chemicals and hydrogen.However,developing efficient electrocatalyst towards this technology remains challenging.Herein,a metallic cobalt mediated molybdenum nitride heterostructural material has been exploited on nickel foam(Co@Mo_(2)N/NF)for the glycerol oxidation reaction(GOR)and hydrogen evolution reaction(HER).Remarkably,the obtained Co@Mo_(2)N/NF realizes eminent performance with low overpotential of 49 mV at 50 mA/cm^(2)for HER and high Faradaic efficiency of formate of 95.03%at 1.35 V vs.RHE for GOR,respectively.The systematic in-situ experiments reveal that the Co@Mo_(2)N heterostructure promotes the cleavage of C-C bond in glycerol by active CoOOH species and boosts the conversion of glycerol to aldehyde intermediates to formate product.Moreover,the density functional theory(DFT)calculations confirm the strong interaction at Co@Mo_(2)N interface,which contributes to the optimized water dissociation and the transformation of H^(*)to H^(2).Benefiting from those advantages,the built HER||GOR electrolyzer delivers a low voltage of 1.61 V at 50 mA/cm^(2),high Faradaic efficiency,and robust stability over 120 h for sustained and stable electrolysis.
文摘The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of α-MoC and β-Mo_(2)C catalysts with different Mo/C ratios were synthesized,and their ammonia decomposition performance as well as structural evolution in ADR was investigated.The β-Mo_(2)C catalyst,characterized by a higher Mo/C ratio,demonstrated a remarkable turnover frequency of 1.3 s^(-1),which is over tenfold higher than that ofα-MoC(0.1 s^(-1)).An increase in the Mo/C ratio of molybdenum carbide revealed a direct correlation between the surface Mo/C ratio and the hydrogen yield.The transient response surface reaction indicated that the combination of N*and N*derived from NH_(3) dissociation represents the rate-determining step in the ADR,andβ-Mo2C exhibited exceptional proficiency in facilitating this pivotal step.Concurrently,the accumulation of N*species on the carbide surface could induce the phase transition of molybdenum carbide to nitride,which follows a topological transformation.It is discovered that such phase evolution was affected by the Mo-C surface and reaction temperature simultaneously.When the kinetics of combination of N*was accelerated by rising temperatures and its accumulation on the carbide surface was mitigated,β-Mo_(2)C maintained its carbide phase,preventing nitridation during the ADR at 810℃.Our results contribute to an in-depth understanding of the molybdenum carbides’catalytic properties in ADR and highlight the nature of the carbide-nitride phase transition in the reaction.
基金Project supported by the National Natural Science Foundation of China(Grant No.11964026)the Natural Science Foundation of Inner Mongolia,China(Grant Nos.2019MS01010 and 2023LHMS01014)+4 种基金Higher Educational Scientific Research Projects of Inner Mongolia(Grant Nos.NJZZ19145 and NJZZ22470)the Educational Scientific Research Project of Liaoning Province(Grant No.LJKZ0452)the Doctoral Starting up Foundation of Inner Mongolia Minzu University of Science and Technology(Grant No.BSZ023)Inner Mongolia Autonomous Region Youth Capacity Improvement Project(Grant No.GXKY22157)Higher Physics Major Teaching Steering Committee of the Ministry of Education Project(Grant No.JZW-23-GT-21)。
文摘Molybdenum nitride,renowned for its exceptional physical and chemical properties,has garnered extensive attention and research interest.In this study,we employed first-principles calculations and the CALYPSO structure prediction method to conduct a comprehensive analysis of the crystal structures and electronic properties of molybdenum nitride(Mo_(x)N_(1-x))under high pressure.We discovered two novel high-pressure phases:Imm2-MoN_(3) and Cmmm-MoN_(4),and confirmed their stability through the analysis of elastic constants and phonon dispersion curves.Notably,the MoN_(4) phase,with its high Vickers hardness of 36.9 GPa,demonstrates potential as a hard material.The results of this study have broadened the range of known high-pressure phases of molybdenum nitride,providing the groundwork for future theoretical and experimental researches.
基金supported by the Open Project of Key Laboratory,Xinjiang Uygur Autonomous Region(2023D04070)the Agricultural Science and Technology Innovation Program of CAAS(CAAS-CSCB-202403)。
文摘Pre-harvest sprouting(PHS)or vivipary is a major problem affecting cereal quality and grain quantity and is primarily linked to the dysregulation of abscisic acid(ABA)biosynthesis in plants.Therefore,elucidating the molecular mechanisms governing seed dormancy is crucial for developing strategies to improve crop productivity.In this study,we identified a novel viviparous maize mutant,viviparous-like 5(vp-like5),which exhibits precocious germination in developing seeds.Through map-based cloning,we discovered that ZmCNX6,which encodes a small subunit of molybdopterin synthase essential for molybdenum cofactor(MoCo)biosynthesis,is the causal gene responsible for the vp-like5 phenotype.Biochemical assays have demonstrated significantly reduced activities of MoCo-dependent enzymes,including aldehyde oxidase(AO),xanthine dehydrogenase(XDH),and nitrate reductase(NR),in vplike5.AO is essential for the ABA biosynthesis,and the observed ABA deficiency in vp-like5 likely drives the viviparous phenotype.Expression analysis showed that ZmCNX6 was stably expressed during seed development,indicating its significant role in seed development.Furthermore,overexpression of ZmCNX6 not only enhanced the activities of MoCo-dependent enzymes but also improved drought tolerance in maize.Collectively,our study revealed ZmCNX6 as a multifunctional hub coordinating MoCo metabolism,ABA-dependent dormancy regulation,and abiotic stress responses,offering a potential target for simultaneously mitigating vivipary and improving drought resistance in maize.
基金Project(LM(2022)-F-053)supported by the China Railway Resources Science and Technology。
文摘Molybdenum tailings are the solid waste left from ore processing,which damages soil and water resources.To address that,molybdenum tailings(MTs)powder obtained from molybdenum tailings sands was processed as an admixture.Compared with moisture-cured conditions,the influence of MTs on the steam-cured mortar’s mechanical properties,surface and internal pore characteristics,and microscopic morphology was investigated.The results show that steam-cured mortar containing appropriate MTs can still have high early strength.When the content of MTs doesn’t exceed 15%,the mechanical strength of mortar steam-cured for 3 d can reach 85%of that of corresponding mortar moisture-cured for 28 d,and that of mortar steam-cured for 28 d isn’t lower than 90%of that of pure cement mortar.The proportion of harmful pores(HFP)and more harmful pores(MHFP)and most probable pore diameters(MPD)on the mortar surface containing MTs steam-cured for 28 d are significantly decreased.When MTs’content is 15%,the proportion of HFP and MHFP on the surface of paste is decreased by 71.4%and 72.2%,respectively,with MPS decreasing from 12.7 nm to 10.8 nm.SEM analysis shows that the surfaces of steam-cured paste containing 15%MTs have more hydration products and dense microstructures.The effect of pozzolanic and dense filling of MTs effectively refines the pore structure,reducing the large pore-size pores.
基金the financial support from the Science, Technology, and Innovation Funding Authority (STIFA, STDF previously) through project number 42691 entitled “Microstructure-Based, Multi-Physics Simulation and Optimization to Improve Battery Performance”supported by the U.S. DOE (Department of Energy), Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357supported by the U.S. DOE Vehicle Technologies office, under contract number DE-AC02-06CH11357
文摘This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.
基金supported by the Macao Science and Technology Development Fund(FDCT)for funding of the Macao Centre for Research and Development in Advanced Materials(2022-2024)(Nos.0026/2022/AMJ,0098/2020/A2 and 006/2022/ALC)the Natural Science Foundation of Guangdong Province(No.2023A1515010765)+2 种基金Science and Technology Planning Project of Shenzhen of China(Shenzhen-Hong Kong-Macao Category C)(No.SGDX20220530111004028)the Science and Technology Planning Project of Guangdong Province of China(No.2023A0505030001)the School-level Research Projects of Yancheng Institute of Technology(No.xjr2023023).
文摘Lithium-sulfur batteries(LSBs)have undoubtedly become one of the most promising battery systems due to their high energy density and the cost-effectiveness of sulfur cathodes.However,challenges,such as the shuttle effect from soluble long-chain lithium polysulfides(LiPSs)and the low conductivity of active materials,hinder their commercialization.Under this circumstance,molybdenum sulfide(MoS_(2))has attracted widespread attention due to its unique physicochemical properties,particularly its capability to mitigate the shuttle effect in LSBs through electrostatic or chemical bonds.Nonetheless,the industrial application of MoS_(2)in LSBs is limited by the inertness of its basal surface and inadequate electron transfer properties.This review mainly introduces various modification strategies of MoS_(2)materials in LSBs and their effects on electrochemical and catalytic performance.Unlike previous reviews and related papers,detailed discussions were conducted on the specific mechanisms of each modification strategy,including(1)shape manipulation,(2)support engineering,(3)heterostructure engineering,(4)defect engineering,(5)interlayer engineering,(6)phase engineering,(7)strain engineering,(8)hybridization.Comprehensive conclusions and outlook on the development of MoS_(2)as an abundant electrocatalyst for LSBs are also discussed in the end.
基金financially supported by the Natural Science Foundation of Jiangsu Province(BK20240972)the Changzhou Leading Innovative Talents Introduction and Cultivation Project(Nos.CQ20230109 and CQ20230108)+1 种基金the Jiangsu Provincial Double-Innovation Doctor(No.JSSCBS20230439)the National Natural Science Foundation of China Key Program(No.U22A20420).
文摘Due to its high electrical conductivity and platinum-like electronic structure,molybdenum phosphide(MoP)has attracted extensive attention as a potential catalyst for the hydrogen evolution reaction(HER)by water splitting.Nevertheless,in the oxygen evolution reaction(OER),the electrocatalytic performance of MoP did not achieve satisfactory results.Therefore,novel nitrogen-doped carbon-encapsulated Ladoped MoP nanoparticles(La-MoP@N/C)are synthesized,which show outstanding durability and electrocatalytic activity in both HER and OER.Detailed structural characterization and calculations confirm that La doping not only effectively adjusts the electron density around Mo and P atoms,accelerates the adsorption and desorption processes,but also increases the number of active sites.Low overpotentials of 113 and 388 mV for HER and OER at 10 mA cm−2 are achieved with the optimized La0.025-Mo0.975P@N/C.Furthermore,the two-electrode electrolyzer assembled with La0.025-Mo0.975P@N/C also presents impressive water splitting performance.This study indicates that rare earth doping can be used as an efficient strategy to control the local electronic structure of phosphides precisely,which can also be extended to other electrocatalysts.
文摘The bioleaching of molybdenum from its sulfide ore using a Mo-resistant thermophilic bacterium sulfolobus metallics combined with a membrane biological reactor（MBR） was studied.The experimental results showed that the concentration of Mo can be controlled by filter of the membrane in MBR and the toxicity of Mo to microorganism is decreased in the process of bioleaching.It was also evidenced that there were different leaching rates of Ni and Mo when the concentration of Mo was different.After leaching for 20 d in the MBR at Mo concentration of 395 mg/L,the leaching rates of Ni and Mo reached the maximum of 79.57% and 56.23% respectively under the conditions of 100 g/L of mineral density,65 ℃,pH=2 and 1.0 L/min of the aeration rate.While 75.59% Ni and 54.33% Mo were leached out in column without membrane under the same conditions.
基金financially supported by the National Natural Science Foundation of China(Nos.52371119,51901173,U23A6013,92360301,U2330203,and 51801147)National Key Research and Development Program of China(No.2017YFB0702301)+1 种基金Shaanxi Province Youth Innovation Team(No.22JP042)Shaanxi Province Innovation Team Project(No.2024RS-CXTD-58).
文摘Molybdenum(Mo)alloys are essential for applications requiring outstanding mechanical properties at high temperatures across various industrial sectors.Understanding and predicting the creep properties of Mo alloys is crucial for service safety and the design of new materials.This study introduces a physicsbased crystallographic creep model dedicated to the characteristic hierarchical microstructure of Mo–La_(2)O_(3)alloys.By sourcing most parameters from existing literature and calibrating others within recommended ranges,the model efficiently predicts creep behavior beyond its initial calibration scope.Through the integration of microstructure descriptors,we systematically explored the impact of different microstructural features on the creep behavior and identified the underlying mechanisms.This analysis yielded two pivotal concepts:the minimum acceptable grain size and the necessary nanoparticle number density.These metrics,readily obtainable from the model,quantify the requisite grain size and nanoparticle content to achieve the target steady-state creep rates for operational demands,thus providing essential insights for the creep condition-oriented design of Mo–La_(2)O_(3)alloys.The model is also expected to be adaptable for developing other Mo alloys reinforced by second phase particles,aimed at achieving desired creep properties under specified conditions,assuming that relevant parameters are accessible through literature or lower-scale simulations.
文摘This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.
基金Project(2007AA06Z129) supported by the High-tech Research and Development Program of China
文摘The adsorption behavior of D301 for molybdenum blue was investigated.The thermodynamics parameters in adsorption process were calculated and the adsorption kinetics was studied.The experimental results show that the adsorption characteristic of D301 for molybdenum blue fits well with the Freundlich adsorption isotherm equation.In the adsorption process of D301 for molybdenum blue,both the enthalpy change ΔH and entropy change ΔS are positive,while the free energy change ΔG is negative when temperatures are in the range of 303-333 K.It is indicated that the adsorption is a spontaneous and endothermic process,and the elevated temperatures benefit to the adsorption.Kinetic studies show that the kinetic data are well described by double driving-force model,and the adsorption rate of molybdenum blue on D301 is controlled by the intraparticle diffusion during the adsorption process.The total kinetic equation is determined.
基金Project(51304245)supported by the National Natural Science Foundation of ChinaProject(2014T70691)supported by the Postdoctoral Science Foundation of China+1 种基金Project(2015CX005)supported by the Innovation Driven Plan of Central South University,ChinaProject supported by the Hunan Provincial Co-innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China
文摘The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidationtemperature of MoS2 is 450℃, while the formation of CaMoO4 and CaSO4 occurs above 500℃. The whole calcification reactionsare nearly completed between 600 and 650℃. However, raising the temperature further helps for the formation of CaMoO4 but isdisadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows theorder： Ca（OH）2〉CaO〉CaCO3. With increasing the dosage of Ca（OH）2, the molybdenum retention rate and sulfur-fixing rate rise, butexcessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca（OH）2 to molybdenumconcentrate is 1：1. When roasted at 650 ℃ for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grademolybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% withcalcines being leached by sulphuric acid.
