Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to...Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.展开更多
Pyridine(Py)-modified Keggin-type vanadium-substituted heteropoly acids(PynPMo10V2O40,n=1 to 5) were prepared by a precipitation method as organic/inorganic hybrid catalysts for direct hydroxylation of benzene to phen...Pyridine(Py)-modified Keggin-type vanadium-substituted heteropoly acids(PynPMo10V2O40,n=1 to 5) were prepared by a precipitation method as organic/inorganic hybrid catalysts for direct hydroxylation of benzene to phenol in a pressured batch reactor and their structures were detected by FT-IR.Among various catalysts,Py3PMo10V2O40 exhibits the highest catalytic activity(yield of phenol,11.5%),without observing the formation of catechol,hydroquinone and benzoquinone in the reaction with 80 vol% aqueous acetic acid,molecular oxygen and ascorbic acid used as the solvent,oxidant and reducing reagent,respectively.Influences of reaction temperature,reaction time,oxygen pressure,amount of ascorbic acid and catalyst on yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation.Pyridine can greatly promote the catalytic activity of the Py-free catalyst(H5PMo10V2O40),mostly because the organic π electrons in the hybrid catalyst may extend their conjugation to the inorganic framework of heteropoly acid and dramatically modify the redox properties,at the same time,pyridine adsorbed on heteropoly acids can promote the effect of "pseudo-liquid phase",thus accounting for the enhancement of phenol yield.展开更多
Title molybdogadolinium heteropoly compound has been synthesized and used to catalize the hydroxylation of phenol with hydrogen peroxide. The effects of reaction time, temperature, pH value, n(phOH)/n(H 2O 2) and solv...Title molybdogadolinium heteropoly compound has been synthesized and used to catalize the hydroxylation of phenol with hydrogen peroxide. The effects of reaction time, temperature, pH value, n(phOH)/n(H 2O 2) and solvent on the catalytic activity for phenol hydroxylation have been investigated. The results show that the title compound in the presence of V 2O 5 shows an excellent catalytic activity for phenol hydroxylation. When methanol is used as solvent at n(phOH)/n(H 2O 2)=1∶2, pH=5, at 343 K and for 4 h, hydroquinone in yield of 42 10% is obtained with phenol conversion of 40.50%.展开更多
Four nano heteropolymolybdovanadoarsenics were synthesized by solidstate reaction at room temperature.Their general molecular formulas are H3MAsMo10V2O40·xH2O(M=Co2+,Ni2+,Cu2+,Zn2+).The catalytic behaviour of the...Four nano heteropolymolybdovanadoarsenics were synthesized by solidstate reaction at room temperature.Their general molecular formulas are H3MAsMo10V2O40·xH2O(M=Co2+,Ni2+,Cu2+,Zn2+).The catalytic behaviour of the nano heteropoly compound for hydroxylation of benzene to phenol with H2O2 and the reaction parameters were studied in detail.The experimental results showed that the yield of phenol was over 50% and the selectivity for phenol was over 98% under the optimum conditions with the H2O2/C6H6 molar ratios of 2.0,C6H6/catalyst（mass ratios）of 23,reaction time of 2.5h,and temperature of 70℃.The four nano catalysts had high activity for the hydroxylation of benzene to phenol.展开更多
基金Supported by the National Natural Science Foundation of China （Nos.20306011, 20476046） and the Ph.D. Program Foundation for Chinese Universities （No.20040291002）.
文摘Keggin type molybdovanadophosphoric heteropoly acids, H3＋nPMo12-nVnO40（n=1-3）, were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst con- centration, were changed to obtain an optimal reaction conditions. H3＋nPMo12-nVnO40（n=1-3） are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20476046 and 20776069)the "Qinglan" Project of Jiangsu Province for Young Researchers
文摘Pyridine(Py)-modified Keggin-type vanadium-substituted heteropoly acids(PynPMo10V2O40,n=1 to 5) were prepared by a precipitation method as organic/inorganic hybrid catalysts for direct hydroxylation of benzene to phenol in a pressured batch reactor and their structures were detected by FT-IR.Among various catalysts,Py3PMo10V2O40 exhibits the highest catalytic activity(yield of phenol,11.5%),without observing the formation of catechol,hydroquinone and benzoquinone in the reaction with 80 vol% aqueous acetic acid,molecular oxygen and ascorbic acid used as the solvent,oxidant and reducing reagent,respectively.Influences of reaction temperature,reaction time,oxygen pressure,amount of ascorbic acid and catalyst on yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation.Pyridine can greatly promote the catalytic activity of the Py-free catalyst(H5PMo10V2O40),mostly because the organic π electrons in the hybrid catalyst may extend their conjugation to the inorganic framework of heteropoly acid and dramatically modify the redox properties,at the same time,pyridine adsorbed on heteropoly acids can promote the effect of "pseudo-liquid phase",thus accounting for the enhancement of phenol yield.
文摘Title molybdogadolinium heteropoly compound has been synthesized and used to catalize the hydroxylation of phenol with hydrogen peroxide. The effects of reaction time, temperature, pH value, n(phOH)/n(H 2O 2) and solvent on the catalytic activity for phenol hydroxylation have been investigated. The results show that the title compound in the presence of V 2O 5 shows an excellent catalytic activity for phenol hydroxylation. When methanol is used as solvent at n(phOH)/n(H 2O 2)=1∶2, pH=5, at 343 K and for 4 h, hydroquinone in yield of 42 10% is obtained with phenol conversion of 40.50%.
文摘Four nano heteropolymolybdovanadoarsenics were synthesized by solidstate reaction at room temperature.Their general molecular formulas are H3MAsMo10V2O40·xH2O(M=Co2+,Ni2+,Cu2+,Zn2+).The catalytic behaviour of the nano heteropoly compound for hydroxylation of benzene to phenol with H2O2 and the reaction parameters were studied in detail.The experimental results showed that the yield of phenol was over 50% and the selectivity for phenol was over 98% under the optimum conditions with the H2O2/C6H6 molar ratios of 2.0,C6H6/catalyst（mass ratios）of 23,reaction time of 2.5h,and temperature of 70℃.The four nano catalysts had high activity for the hydroxylation of benzene to phenol.
基金Project supported by the National Basic Research Program of China(No.2009CB623506)the National Natural Science Foundation of China(No.21173050)+1 种基金the Program of Shanghai Subject Chief Scientist(No.10XD1400300)Shanghai Leading Academic Discipline Project(B108)~~
