The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such ...The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids (HPAs), viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] (TPA), Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P+aq] (DMAA), Dodeca-Molyhdo Phosphoric acid (PMA) on clay (MontmoriUonite, K-10) and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.展开更多
Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydroc...Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.展开更多
Four new vanadium substituted Dawson-type heteropoly acids H7[P2Mo17VO62]·39H2O(1), H8[P2Mo16V2O62]·41H2O(2), H9[P2Mo15V3O62]·51H2O(3) and H8[P2Mo14V4O62H2]·45H2O(4) were prepared respec-ti...Four new vanadium substituted Dawson-type heteropoly acids H7[P2Mo17VO62]·39H2O(1), H8[P2Mo16V2O62]·41H2O(2), H9[P2Mo15V3O62]·51H2O(3) and H8[P2Mo14V4O62H2]·45H2O(4) were prepared respec-tively. Their structures were determined by IR and ICP. The inhibition effects of vanadium substituted Dawson-type heteropoly acids(Mo, P) on free radical polymerization of methyl methacrylate(MMA) were investigated by dilatometry. The results show that the rate of the polymerization of MMA decreases and the inhibition effects of the four heteropoly acids reach the inhibitor performance of hydroquinone at a certain ratio.展开更多
,d,l-a-Tocopherol (vitamin E) isfound to be synthesized by condensingtrimethylhydroquinone with isophytol catalyzed by heteropoly acids (HPA) H3:PW12O40 andH3PMo12O40 at room temperature. These HPA are efficient cata...,d,l-a-Tocopherol (vitamin E) isfound to be synthesized by condensingtrimethylhydroquinone with isophytol catalyzed by heteropoly acids (HPA) H3:PW12O40 andH3PMo12O40 at room temperature. These HPA are efficient catalysts for the synthesis of d l-a-Tocopherol and can easily be separated from the reaction mixture and roused,展开更多
The ternary germanic heteropoly acids H_5GeW_(11)O_(40) centre dot 22H_2O andH_5GeMo_(11)VO_(40) centre dot 24H_2O were synthesized for the first time by the stepwiseacidification and the stepwise addition of solution...The ternary germanic heteropoly acids H_5GeW_(11)O_(40) centre dot 22H_2O andH_5GeMo_(11)VO_(40) centre dot 24H_2O were synthesized for the first time by the stepwiseacidification and the stepwise addition of solution of the component elements. The products werecharacterized by ICP, IR, UV, XRD and TG-DTA. The proton conductibility and the activation energy ofproton conduction of the heteropoly acids were investigated.展开更多
Direct hydroxylation of benzene catalyzed by vanadium-con- taining heteropoly compounds with Keggin or Dawson structure has been investigated.The effects of several factors upon the hydroxylation reaction have also be...Direct hydroxylation of benzene catalyzed by vanadium-con- taining heteropoly compounds with Keggin or Dawson structure has been investigated.The effects of several factors upon the hydroxylation reaction have also been examined.It is indicated that the highest yield of phenol reached 76%(based on H_2O_(?))with 99.4~100% selectivity.展开更多
Five novel vanadium substituted series of Dawson-type heteropoly acid H7 [As2Mo17VO62 ]·10H2O (1), H8 [ As2Mo16 V2O62 ]· 7H2O(2), Ha [ As2MO15 V3O62 ]·8H2O(3), H8 [ As2Mo14 V4O62 H2 ]·7H2O(...Five novel vanadium substituted series of Dawson-type heteropoly acid H7 [As2Mo17VO62 ]·10H2O (1), H8 [ As2Mo16 V2O62 ]· 7H2O(2), Ha [ As2MO15 V3O62 ]·8H2O(3), H8 [ As2Mo14 V4O62 H2 ]·7H2O( 4 ), H9[As2Mo13V5O62H2] ·10H2O(5) were prepared respectively in aqueous solution. When magnetic stirring and pH meter monitoring, all reactants mixed and controled different pH, then the mixture was refluxed for 10 h, later extracted by aether when it cooled, finally, it could be recrystaled by 0.5 % sulphuic acid solution, then yielded productions that we need. Compounds ( 1 ) - (5) were characterized by elemental analysis, thermogravimetic analysis (TGA), infrared spectroscopy (IR), ultraviolet and visible spectroscopy(UV-Vis), X-ray powder diffraction analysis, ^51V nuclear magnetic resonance (SIV NMR) structure analysis. The study indicates that these compounds possess Dawson structures, ^51V NMR spectra reveals that V atom is polar-site substituted indeed.展开更多
INTRODUCTIONThough potassium salts of rare earth substituted silicotungsticacids were synthesized early in 1971 by R.D.Peacock etc.,sofar the reports about the application of the corresponding acidshave not been found...INTRODUCTIONThough potassium salts of rare earth substituted silicotungsticacids were synthesized early in 1971 by R.D.Peacock etc.,sofar the reports about the application of the corresponding acidshave not been found.We prepared fourteen rare earth substitutedsilicotungstic acids and determined their thermal stability,IRabsorption Spectra and x-ray diffraction spectra.Furthermore,thecatalytic activities of the fourteen heteropoly acids in acid cata-lytic reaction were investigated.Our experimental results demonstrated rare earth substituted silico-tungstic acids have very high catalytic activity in the reaction of展开更多
Preyssler-type heteropoly acid is introduced as a new,mild and efficient catalyst for protection of a variety of carbonyl compounds with 1,3-propane dithiol.
An environmentally benign method for the syn-thesis of heteropoly acids H3+nPMo12–nVnO40·xH2O(PMoVn,n=1–3)was developed by the reaction of an aqueous slurry which contained stoichiometric amounts of MoO3,V2O5 a...An environmentally benign method for the syn-thesis of heteropoly acids H3+nPMo12–nVnO40·xH2O(PMoVn,n=1–3)was developed by the reaction of an aqueous slurry which contained stoichiometric amounts of MoO3,V2O5 and H3PO4.Characterization of the as-synthesized catalysts with inductively coupled plasma(ICP)elemental analysis,thermogravimetry(TG),X-ray diffraction(XRD)and infra-red(IR)spectroscopy indicated that V ions substituted for Mo ions in Keggin-type phosphomolybdic acid.The as-synthesized samples were found to be an efficient catalyst for the hydroxylation of benzene which was carried out in a mixed solvent of acetonitrile and acetic acid with aqueous hydrogen peroxide as oxidant.PMoV2 exhibited the highest benzene conversion of 34.5%with phenol selectivity of 100%.展开更多
The ternary undecatungstozincoaluminic heteropoly acid H-7[Al(H2O)ZnW11O39](.)12H(2)O was prepared by the ion exchanging-cooling method. The optimal proportion of solutions of the component elements and the pH of the ...The ternary undecatungstozincoaluminic heteropoly acid H-7[Al(H2O)ZnW11O39](.)12H(2)O was prepared by the ion exchanging-cooling method. The optimal proportion of solutions of the component elements and the pH of the synthesis reaction were given. The product was characterized by chemical analysis, potentiometric titration, IR, UV, XRD and TG-DTA. AC impedance measurement results show that its proton conductivity is 1.37x10(-4) S/cm at 18 degreesC.展开更多
A method of C(sp^3)-H bond functionalization of methyl azaarenes catalyzed by alumina-supported heteropoly acid and addition to isatins was developed. This transformation could be used for the synthesis of biologica...A method of C(sp^3)-H bond functionalization of methyl azaarenes catalyzed by alumina-supported heteropoly acid and addition to isatins was developed. This transformation could be used for the synthesis of biologically important 3-hydroxy-2-oxindole derivatives in good to excellent yields and the catalyst could be reused for six times without significant decrease in activity.展开更多
The title compounds 2ac were synthesized and characterized for the first time. Their proton numbers are around 3.2±0.15 and are not in proportion with the valid acidity-basicity of the central phosphonic acids. ...The title compounds 2ac were synthesized and characterized for the first time. Their proton numbers are around 3.2±0.15 and are not in proportion with the valid acidity-basicity of the central phosphonic acids. The entirety of phosphonic acids 1a-c is as the coordinate center of heteropoly anions of 2ac.展开更多
Five kinds of molybdovanadophosphoric acids H_7[P_2Mo_(17)VO_(62)],H_8[P_2Mo_(16)·V_2O_(62)],H_9 [P_2Mo_(15)V_3O_(62)],H_8[P_2Mo_(14)V_4O_(61)(H_2O)]and H_9[P_2Mo_(13)V_5O_(61)(H_2O)]have been synthesized.Their p...Five kinds of molybdovanadophosphoric acids H_7[P_2Mo_(17)VO_(62)],H_8[P_2Mo_(16)·V_2O_(62)],H_9 [P_2Mo_(15)V_3O_(62)],H_8[P_2Mo_(14)V_4O_(61)(H_2O)]and H_9[P_2Mo_(13)V_5O_(61)(H_2O)]have been synthesized.Their protop conductivities(C) have been measured.The effects of three main factors (frequency,hydration numbers,temperature)on the conductivity have been investigated.In some degree,heteropoly compounds with different structures give a different conductivity.展开更多
Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fu...Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).展开更多
Heteropoly acid H3PW12040 (PW) has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4(3H)-one derivatives. The present methodology offers several advantages, such as high yields, shor...Heteropoly acid H3PW12040 (PW) has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4(3H)-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.展开更多
Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ...Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ^1H NMR spectra. The results indicated that the catalyst showed excellent catalytic activity for the condensation reactions. The yield of 12 classes of acetals and ketals reached 56.3%-96.3% under the typical reaction conditions (the molar ratio of aldehyde/ketone and glycol was 1:1.5, the quantity of catalyst was 0.5% of feed stock, the reaction time was 1.0 h, and the reaction temperature was 80-116℃). The catalyst was easily recovered and reused to give almost the same yield of the product as that given by fresh TiSiW12O10/TiO2.展开更多
A kind of heteropoly compound film supported on Ce0.5Zr0.5O2 oxide was prepared on a porous titanium tube. The catalytic activity of the film for the selective oxidation of iso-butylene was tested and compared with th...A kind of heteropoly compound film supported on Ce0.5Zr0.5O2 oxide was prepared on a porous titanium tube. The catalytic activity of the film for the selective oxidation of iso-butylene was tested and compared with the fixed-bed reactor. Results show that the catalytic film increases the yield of the target product-methacrylic acid, and avoids the temperature fluctuation caused by the reaction heat.展开更多
Aniline oligomer composite materials using heteropolyacid H4SiW12O40 as dopant was synthesized, and the effect of the doping concentration on the photoluminescence and surface photovoltaic properties were investigated.
An efficient method for the preparation of 1,3-dioxolanes via the coupling of epoxides with ketones catalyzed by heteropolyacids at ambient temperature has been described.
文摘The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids (HPAs), viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] (TPA), Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P+aq] (DMAA), Dodeca-Molyhdo Phosphoric acid (PMA) on clay (MontmoriUonite, K-10) and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.
文摘Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.
基金Supported by the National Natural Science Foundation of China(Nos.20971031, 21071035)the Key Natural Science Foundation of the Heilongjiang Province, China(No.ZD201009)
文摘Four new vanadium substituted Dawson-type heteropoly acids H7[P2Mo17VO62]·39H2O(1), H8[P2Mo16V2O62]·41H2O(2), H9[P2Mo15V3O62]·51H2O(3) and H8[P2Mo14V4O62H2]·45H2O(4) were prepared respec-tively. Their structures were determined by IR and ICP. The inhibition effects of vanadium substituted Dawson-type heteropoly acids(Mo, P) on free radical polymerization of methyl methacrylate(MMA) were investigated by dilatometry. The results show that the rate of the polymerization of MMA decreases and the inhibition effects of the four heteropoly acids reach the inhibitor performance of hydroquinone at a certain ratio.
文摘,d,l-a-Tocopherol (vitamin E) isfound to be synthesized by condensingtrimethylhydroquinone with isophytol catalyzed by heteropoly acids (HPA) H3:PW12O40 andH3PMo12O40 at room temperature. These HPA are efficient catalysts for the synthesis of d l-a-Tocopherol and can easily be separated from the reaction mixture and roused,
文摘The ternary germanic heteropoly acids H_5GeW_(11)O_(40) centre dot 22H_2O andH_5GeMo_(11)VO_(40) centre dot 24H_2O were synthesized for the first time by the stepwiseacidification and the stepwise addition of solution of the component elements. The products werecharacterized by ICP, IR, UV, XRD and TG-DTA. The proton conductibility and the activation energy ofproton conduction of the heteropoly acids were investigated.
文摘Direct hydroxylation of benzene catalyzed by vanadium-con- taining heteropoly compounds with Keggin or Dawson structure has been investigated.The effects of several factors upon the hydroxylation reaction have also been examined.It is indicated that the highest yield of phenol reached 76%(based on H_2O_(?))with 99.4~100% selectivity.
文摘Five novel vanadium substituted series of Dawson-type heteropoly acid H7 [As2Mo17VO62 ]·10H2O (1), H8 [ As2Mo16 V2O62 ]· 7H2O(2), Ha [ As2MO15 V3O62 ]·8H2O(3), H8 [ As2Mo14 V4O62 H2 ]·7H2O( 4 ), H9[As2Mo13V5O62H2] ·10H2O(5) were prepared respectively in aqueous solution. When magnetic stirring and pH meter monitoring, all reactants mixed and controled different pH, then the mixture was refluxed for 10 h, later extracted by aether when it cooled, finally, it could be recrystaled by 0.5 % sulphuic acid solution, then yielded productions that we need. Compounds ( 1 ) - (5) were characterized by elemental analysis, thermogravimetic analysis (TGA), infrared spectroscopy (IR), ultraviolet and visible spectroscopy(UV-Vis), X-ray powder diffraction analysis, ^51V nuclear magnetic resonance (SIV NMR) structure analysis. The study indicates that these compounds possess Dawson structures, ^51V NMR spectra reveals that V atom is polar-site substituted indeed.
文摘INTRODUCTIONThough potassium salts of rare earth substituted silicotungsticacids were synthesized early in 1971 by R.D.Peacock etc.,sofar the reports about the application of the corresponding acidshave not been found.We prepared fourteen rare earth substitutedsilicotungstic acids and determined their thermal stability,IRabsorption Spectra and x-ray diffraction spectra.Furthermore,thecatalytic activities of the fourteen heteropoly acids in acid cata-lytic reaction were investigated.Our experimental results demonstrated rare earth substituted silico-tungstic acids have very high catalytic activity in the reaction of
文摘Preyssler-type heteropoly acid is introduced as a new,mild and efficient catalyst for protection of a variety of carbonyl compounds with 1,3-propane dithiol.
基金supported by the National Natural Science Foundation of China(Grant No.20306011,Grant No.20476046)the Ph.D.Program Foundation of Chinese University(Grant No.20040291002).
文摘An environmentally benign method for the syn-thesis of heteropoly acids H3+nPMo12–nVnO40·xH2O(PMoVn,n=1–3)was developed by the reaction of an aqueous slurry which contained stoichiometric amounts of MoO3,V2O5 and H3PO4.Characterization of the as-synthesized catalysts with inductively coupled plasma(ICP)elemental analysis,thermogravimetry(TG),X-ray diffraction(XRD)and infra-red(IR)spectroscopy indicated that V ions substituted for Mo ions in Keggin-type phosphomolybdic acid.The as-synthesized samples were found to be an efficient catalyst for the hydroxylation of benzene which was carried out in a mixed solvent of acetonitrile and acetic acid with aqueous hydrogen peroxide as oxidant.PMoV2 exhibited the highest benzene conversion of 34.5%with phenol selectivity of 100%.
基金This work was financially supported by China Postdoctoral Science Foundation and the Natural Science Foundationof Zhejiang Uni
文摘The ternary undecatungstozincoaluminic heteropoly acid H-7[Al(H2O)ZnW11O39](.)12H(2)O was prepared by the ion exchanging-cooling method. The optimal proportion of solutions of the component elements and the pH of the synthesis reaction were given. The product was characterized by chemical analysis, potentiometric titration, IR, UV, XRD and TG-DTA. AC impedance measurement results show that its proton conductivity is 1.37x10(-4) S/cm at 18 degreesC.
基金Financial support from the National Natural Science Foundation of China(No.21402103)the research fund of Qingdao Agricultural University's High-level Person(No.631303)the Scientific Research Foundation of Shandong Province Outstanding Young Scientist Award(No.BS2013YY024) were gratefully acknowledged
文摘A method of C(sp^3)-H bond functionalization of methyl azaarenes catalyzed by alumina-supported heteropoly acid and addition to isatins was developed. This transformation could be used for the synthesis of biologically important 3-hydroxy-2-oxindole derivatives in good to excellent yields and the catalyst could be reused for six times without significant decrease in activity.
文摘The title compounds 2ac were synthesized and characterized for the first time. Their proton numbers are around 3.2±0.15 and are not in proportion with the valid acidity-basicity of the central phosphonic acids. The entirety of phosphonic acids 1a-c is as the coordinate center of heteropoly anions of 2ac.
文摘Five kinds of molybdovanadophosphoric acids H_7[P_2Mo_(17)VO_(62)],H_8[P_2Mo_(16)·V_2O_(62)],H_9 [P_2Mo_(15)V_3O_(62)],H_8[P_2Mo_(14)V_4O_(61)(H_2O)]and H_9[P_2Mo_(13)V_5O_(61)(H_2O)]have been synthesized.Their protop conductivities(C) have been measured.The effects of three main factors (frequency,hydration numbers,temperature)on the conductivity have been investigated.In some degree,heteropoly compounds with different structures give a different conductivity.
基金financialy supported by the National Key R&D Program of China(No.2018YFB1502303)the National Natural Science Foundation of China(No.21722601,U19A2017)China Postdoctoral Science Foundation(No.2019M660389)。
文摘Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).
文摘Heteropoly acid H3PW12040 (PW) has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4(3H)-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.
基金This work was financially supported by the Natural Science Foundation of Hubei Province, China (No. 2005ABA053) and the National Natural Science Foundation of China (No. 20471044).
文摘Twelve classes of acetals and ketals were synthesized from aldehyde/ketone and glycol using ZiSiW12O40/TiO2 as a novel eco-friendly catalyst. The physical characterizations were carried out by TG/DTA, FT-IR, XRD, and ^1H NMR spectra. The results indicated that the catalyst showed excellent catalytic activity for the condensation reactions. The yield of 12 classes of acetals and ketals reached 56.3%-96.3% under the typical reaction conditions (the molar ratio of aldehyde/ketone and glycol was 1:1.5, the quantity of catalyst was 0.5% of feed stock, the reaction time was 1.0 h, and the reaction temperature was 80-116℃). The catalyst was easily recovered and reused to give almost the same yield of the product as that given by fresh TiSiW12O10/TiO2.
文摘A kind of heteropoly compound film supported on Ce0.5Zr0.5O2 oxide was prepared on a porous titanium tube. The catalytic activity of the film for the selective oxidation of iso-butylene was tested and compared with the fixed-bed reactor. Results show that the catalytic film increases the yield of the target product-methacrylic acid, and avoids the temperature fluctuation caused by the reaction heat.
基金We gratefully acknowledge the support of the National Natural Science Foundation of China (29671004).
文摘Aniline oligomer composite materials using heteropolyacid H4SiW12O40 as dopant was synthesized, and the effect of the doping concentration on the photoluminescence and surface photovoltaic properties were investigated.
文摘An efficient method for the preparation of 1,3-dioxolanes via the coupling of epoxides with ketones catalyzed by heteropolyacids at ambient temperature has been described.