Low-overpotential layered hydroxides(LDHs)with high theoretical capacity are promising electrodes for supercapaterry and oxygen evolution reaction;however,the low electronic conductivity and insufficient active sites ...Low-overpotential layered hydroxides(LDHs)with high theoretical capacity are promising electrodes for supercapaterry and oxygen evolution reaction;however,the low electronic conductivity and insufficient active sites of bulk LDHs increase the internal resistance and reduce the capacity and oxygen-production efficiency of electrodes.Herein,we prepared a polyaniline-coated Ni-Co-layered double hydroxide intercalated with MoO_(4)^(2−)(M-LDH@PANI)composite electrode using a two-step method.As the amount of MoO_(4)^(2−)in the LDH increases,acicular microspheres steadily evolve into flaky microspheres with a high surface area,providing more active electrochemical sites.Moreover,the amorphous PANI coating of M-LDH boosts the electronic conductivity of the composite electrode.Accordingly,the M-LDH@PANI at an appropriate level of MoO_(4)^(2−)exhibits significantly enhanced energy storage and catalytic performance.Experimental analyses and theoretical calculations reveal that a small amount of MoO_(4)^(2−)is conducive to the expansion of LDH interlayer spacing,while an excessive amount of MoO_(4)^(2−)combines with the H atoms of LDH,thus competing with OH^(−),resulting in reduced electrochemical performance.Moreover,M-LDH flaky microspheres can efficiently modulate deprotonation energy,greatly accelerating surface redox reactions.This study provides an explanation for an unconventional mechanism,and a method for the modification of LDH-based materials for anion intercalation.展开更多
The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable sche...The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable scheme of the process. The revealed features of the process and its mathematical description make it possible to more competently design a reactor unit for the commercial production of isoprene according to the developed scheme. The main kinetic constants were calculated.展开更多
The reduction of an aqueous solution of sodium molybdate by iron powder at low pH value (～0.83), in the presence of ethylenediaminetetraacetate (EDTA) ligand, gives the title compound [Fe(H 2O) 6][Mo 2O 4(EDTA)]·...The reduction of an aqueous solution of sodium molybdate by iron powder at low pH value (～0.83), in the presence of ethylenediaminetetraacetate (EDTA) ligand, gives the title compound [Fe(H 2O) 6][Mo 2O 4(EDTA)]·5H 2O 1, which was characterized by elemental analysis, IR and X ray single crystal diffraction techniques. Compound 1 crystallizes in monoclinic system, space group P2 1/c, C 10 H 34 N 2FeMo 2O 23 , M r=798.12, a=8.781(1), b=14.081(1), c=21.353(1) , β= 92\^688(1)°, V = 2637.2(3) 3, Z = 4, D c = 2.010 g·cm -3 , μ = 1.579 mm -1 , F (000)=1608, the final R =0.0530 and wR =0.1271 for 3312 observed reflections. The binuclear oxomolybdenum(V) anion and the six coordinated Fe(II) cation are linked to infinite three dimensional network through several hydrogen bonds towards different directions between crystal waters, Fe(II) cation and Mo(V) anion.展开更多
The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time,liquid to solid ratio,leaching temperature,agitation speed,and sodium hypoc...The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time,liquid to solid ratio,leaching temperature,agitation speed,and sodium hypochlorite and sodium hydroxide concentrations all have a significant effect on the removal of molybdenum.The optimum process operating parameters were found to be：time,4 h;sodium hydroxide concentration,10%;sodium hypochlorite concentration,8%;liquid to solid ratio,10：1;temperature,50℃;and, agitation speed,500 r/min.Under these conditions the extraction of molybdenum is greater than 99,9%and the extraction of copper is less than 0.01%.A shrinking particle model could be used to describe the leaching process.The apparent activation energy of the dissolution reaction was found to be approximately 8.8 kJ/mol.展开更多
文摘Low-overpotential layered hydroxides(LDHs)with high theoretical capacity are promising electrodes for supercapaterry and oxygen evolution reaction;however,the low electronic conductivity and insufficient active sites of bulk LDHs increase the internal resistance and reduce the capacity and oxygen-production efficiency of electrodes.Herein,we prepared a polyaniline-coated Ni-Co-layered double hydroxide intercalated with MoO_(4)^(2−)(M-LDH@PANI)composite electrode using a two-step method.As the amount of MoO_(4)^(2−)in the LDH increases,acicular microspheres steadily evolve into flaky microspheres with a high surface area,providing more active electrochemical sites.Moreover,the amorphous PANI coating of M-LDH boosts the electronic conductivity of the composite electrode.Accordingly,the M-LDH@PANI at an appropriate level of MoO_(4)^(2−)exhibits significantly enhanced energy storage and catalytic performance.Experimental analyses and theoretical calculations reveal that a small amount of MoO_(4)^(2−)is conducive to the expansion of LDH interlayer spacing,while an excessive amount of MoO_(4)^(2−)combines with the H atoms of LDH,thus competing with OH^(−),resulting in reduced electrochemical performance.Moreover,M-LDH flaky microspheres can efficiently modulate deprotonation energy,greatly accelerating surface redox reactions.This study provides an explanation for an unconventional mechanism,and a method for the modification of LDH-based materials for anion intercalation.
文摘The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable scheme of the process. The revealed features of the process and its mathematical description make it possible to more competently design a reactor unit for the commercial production of isoprene according to the developed scheme. The main kinetic constants were calculated.
文摘The reduction of an aqueous solution of sodium molybdate by iron powder at low pH value (～0.83), in the presence of ethylenediaminetetraacetate (EDTA) ligand, gives the title compound [Fe(H 2O) 6][Mo 2O 4(EDTA)]·5H 2O 1, which was characterized by elemental analysis, IR and X ray single crystal diffraction techniques. Compound 1 crystallizes in monoclinic system, space group P2 1/c, C 10 H 34 N 2FeMo 2O 23 , M r=798.12, a=8.781(1), b=14.081(1), c=21.353(1) , β= 92\^688(1)°, V = 2637.2(3) 3, Z = 4, D c = 2.010 g·cm -3 , μ = 1.579 mm -1 , F (000)=1608, the final R =0.0530 and wR =0.1271 for 3312 observed reflections. The binuclear oxomolybdenum(V) anion and the six coordinated Fe(II) cation are linked to infinite three dimensional network through several hydrogen bonds towards different directions between crystal waters, Fe(II) cation and Mo(V) anion.
基金the 11th Five-Year Plan of the National Scientific and Technological Program of China(No. 2007BAB22B01)the National Natural Science Foundation of China(No.50704036).
文摘The removal of molybdenum from a copper ore concentrate by sodium hypochlorite leaching was investigated. The results show that leaching time,liquid to solid ratio,leaching temperature,agitation speed,and sodium hypochlorite and sodium hydroxide concentrations all have a significant effect on the removal of molybdenum.The optimum process operating parameters were found to be：time,4 h;sodium hydroxide concentration,10%;sodium hypochlorite concentration,8%;liquid to solid ratio,10：1;temperature,50℃;and, agitation speed,500 r/min.Under these conditions the extraction of molybdenum is greater than 99,9%and the extraction of copper is less than 0.01%.A shrinking particle model could be used to describe the leaching process.The apparent activation energy of the dissolution reaction was found to be approximately 8.8 kJ/mol.
