In this study,a catalyst was synthesized using a two-step in-situ molecular beam epitaxy method to grow H_(4)PMo_(11)VO_(40)(HPAV)on amination-treated SiO_(2) nanoparticles,which served as both dopant and host agents....In this study,a catalyst was synthesized using a two-step in-situ molecular beam epitaxy method to grow H_(4)PMo_(11)VO_(40)(HPAV)on amination-treated SiO_(2) nanoparticles,which served as both dopant and host agents.SiO_(2) dopant was modified with(3-aminopropyl)triethoxysilane(APTS),facilitating the formation of ammonium ions that enhanced the overall positive charge.This modification enabled the effective dispersion and exposure of HPAV's active species and induced a structural transformation of HPAV from a triclinic to a cubic crystal phase.The two-step hosting growth process optimized the proportions of Cs^(+),H^(+)and NH_(4)^(+)antinuclear ions,thereby fine-tuning the synergistic catalysis of oxidation and acidity,as well as the oxidative sensitivity at HPAV catalytic interface.The resultant 8(HPAV)&4(Cs_(3)PAV)-NH_(2)-SiO_(2) catalyst achieved a methacrolein(MAL)conversion rate of 84%and a methacrylic acid(MAA)selectivity of 71%.Even after 10.5 h of reaction time,the catalyst retained its high dispersion,cubic crystal structure,and Keggin configuration,demonstrating stable catalytic performance over a continuous 200-h reaction period.展开更多
Exploring novel materials with excellent photothermal conversion capabilities for solar photothermal water evaporation is considered as an ideal strategy to simultaneously realize the direct and full use of the widely...Exploring novel materials with excellent photothermal conversion capabilities for solar photothermal water evaporation is considered as an ideal strategy to simultaneously realize the direct and full use of the widely distributed solar energy and alleviate the world's freshwater scarcity.Herein,an amphiphilic photothermal membrane is prepared through the self-assembly of hydrophilic heteropoly blue(HPB,H_(3)PMo_(12)O_(40))and hydrophobic surfactant(dioctadecyl dimethyl ammonium bromide,DODA).Benefiting from the synergistic effects of alternating functional hydrophilic HPB and hydrophobic DODA layers,the flexible membrane based on two-dimensional DODA-HPB self-assemblies(DODA-HPB/Nylon66)exhibits superior photothermal conversion properties,showing promising prospects in applications of solar desalination and wastewater treatment.展开更多
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
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.
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
Heteropoly acids efficiently catalyzed the cyclocondensation reaction of anthranilamide with aldehydes in water at ambient temperature and afforded the corresponding 2,3-dihydro-4（1H）-quinazolinones compounds in goo...Heteropoly acids efficiently catalyzed the cyclocondensation reaction of anthranilamide with aldehydes in water at ambient temperature and afforded the corresponding 2,3-dihydro-4（1H）-quinazolinones compounds in good to excellent yields.This method provides mild reaction conditions and clean reaction profiles,using a small quantity of catalyst and a simple workup procedure.展开更多
Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty ac...Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst of sodium salt of tungstic acid with Co as central atom （Na5CoW12O40） showed optimum activity towards transesterification compared with other heteropoly tungstates. The catalysts activities were correlated with the observed physico-chemical characteristics derived from FT-infrared （FT-IR）, X-ray diffraction （XRD）, temperature-programmed desorption of ammonia （NH3-TPD） and carbon dioxide （CO2-TPD）. The Na5CoW12O40 catalyst exhibiting high activity even at 65 ℃ is due to the presence of strong acidic as well as basic sites. The disclosed catalyst is tolerable towards water and free fatty acids present in the oils. The influence of catalyst loading, reaction time and reaction temperature is studied to optimize the reaction parameters.展开更多
Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of ...Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.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
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
Lanthanide heteropoly compounds K15[Ln(HSiW9O34)2]·28H2O(Ln = La, Ce, Nd), denoted as Ln(SiW9)2, were synthesized and characterized by element analysis, TG-DTA, IR, UV, XPS and XRD. The results show that partial ...Lanthanide heteropoly compounds K15[Ln(HSiW9O34)2]·28H2O(Ln = La, Ce, Nd), denoted as Ln(SiW9)2, were synthesized and characterized by element analysis, TG-DTA, IR, UV, XPS and XRD. The results show that partial oxygen in Ln(SiW9)2 was coordinated with Ln3- , where Ln-3 was in the inner side of the heteropoly anions, while the fundamental structure of SiW9 had little change. The result was supported by ion exchange experiment.展开更多
Several kinds of Tungstophosphates of Heteropoly Compounds （TPHC） with different compositions and the same structure were synthesized using the method of solid-phase reaction to change the tool ratio of Na4P2O7·...Several kinds of Tungstophosphates of Heteropoly Compounds （TPHC） with different compositions and the same structure were synthesized using the method of solid-phase reaction to change the tool ratio of Na4P2O7·10H2O, WO3 and Na2WO4 · 2H2O. TPHC, as a catalyst, was used in oxidative desulfurization of diesel. The results show that TPHC has catalytic activity. With THPC existing, the highest desulfurization rate reaches 51.85%, 32.6% higher than that yield without TPHC. And the desulfiarization rate increases with decreasing WO3. FT-IR spectra of TPHC shows that the catalytic activity is related to the activity of end oxygen（Od）.The more active Od is, the stronger the capability of obtaining or losing electron is. It means that TPHC has a good catalytic activity. FT-IR spectra of TPHC indicates that desulfurization rate is in linear correlation with Iw-Od/Ip-Od/ Iw-Od is intensity of W-Od vibration band, Ip-Od is intensity of P-Od vibration band） and correlation coefficient reaches 0.965.展开更多
The development of polyoxometalates for olefin oxidation is critical to achieving the green chemical process of the C5 fraction further processing.Di-lacunary silicotungstic anions were easily obtained by continuously...The development of polyoxometalates for olefin oxidation is critical to achieving the green chemical process of the C5 fraction further processing.Di-lacunary silicotungstic anions were easily obtained by continuously adjusting the p H instead of the traditional step-by-step method,which exhibited excellent performance in the catalytic oxidation of cyclopentene(CPE)to aldehydes or alcohols.The 93.69%CPE conversion and 97.15%total product selectivity(41.38%for glutaraldehyde(GA)and 55.77%for 1,2-cyclopentanediol(1,2-diol)were achieved by using H_(2)O_(2)as the oxidant and acetonitrile as the solvent.Through complementary characterization,it was found that the optimized di-lacunary silicotungstic polyoxometalate retained a complete Keggin structure,and exhibited better catalytic activity and stability than the mono-lacunary or saturated silicodecatungstate because it exposed more catalytic active centers.Furthermore,in situ FT-IR spectra was utilized to monitor the reaction process,revealing the formation of the active species W(O_(2))on the di-lacunary silicotungstic polyoxometalate and the intermediate epoxycyclopentane during the catalytic oxidation of cyclopentene.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
Electrochemical transfer behavior of V ⅤW 11 -V Ⅴ 3W 9 heteropoly anions on the water/nitrobenzene interface was investigated by means of cyclic voltammetry. The effect of the solution acidity on the transfe...Electrochemical transfer behavior of V ⅤW 11 -V Ⅴ 3W 9 heteropoly anions on the water/nitrobenzene interface was investigated by means of cyclic voltammetry. The effect of the solution acidity on the transfer behavior and the stable pH range for the heteropoly anions were studied. The stability of mixed tungstovanadate decreases with increasing the number of vanadium atoms. The main transfer species within the potential window have the negative charges of 4 and the transfer process is diffusion controlled. The apparent transfer potential Δ w o Ψ 0 and the free energy Δ G 0 w→o tr for the heteropoly anions can be obtained from the experimental data. For the different anions, the Δ w o Ψ 1/2 pH relationship can be expressed as: Δ w o Ψ 1/2 =constant-53pH.展开更多
New indium heteropoly undecatungstometalate complexes of general formula K_n In( H_2O) MW_(11)O_(39) .xH_2O (M = Cr(Ⅲ) , Fe( Ⅲ ), Co(Ⅱ) or Zn( Ⅱ) ) were prepared by the stepwise acidification and the stepwise addi...New indium heteropoly undecatungstometalate complexes of general formula K_n In( H_2O) MW_(11)O_(39) .xH_2O (M = Cr(Ⅲ) , Fe( Ⅲ ), Co(Ⅱ) or Zn( Ⅱ) ) were prepared by the stepwise acidification and the stepwise addition of materials. The products were characterized by elemental analysis, ion-exchange, IRspectra, UV spectra, X-ray powder diffraction and thermal analysis. The results show that the structure ofthe products derives from the Keggin structure. Their themial stability is higher than that of the homolo-gous dedecatungstometalates .展开更多
MCM-41 supported heteropoly acids （HPAs） catalysts were synthesized, characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at ro...MCM-41 supported heteropoly acids （HPAs） catalysts were synthesized, characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at room temperature. 50 wt% PW/MCM-41 showed the highest activity （up to 96% yield）. The catalyst was used in six consecutive experiments without obvious loss of activity, confirming the success of the anchoring process and the catalyst stability.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
Poly(vinyl alcohol) (PVA) fiber mats containing unsaturated heteropoly salt was prepared for the first time. IR, X-ray diffraction and SEM photographs characterized the beaded fiber mats. The viscoelasticity and the c...Poly(vinyl alcohol) (PVA) fiber mats containing unsaturated heteropoly salt was prepared for the first time. IR, X-ray diffraction and SEM photographs characterized the beaded fiber mats. The viscoelasticity and the conductivity of the solution were the key factors that influence the formation of the beaded fiber mats.展开更多
基金supported by the Taishan Scholars Program of Shandong Province(tsqn202103051)Tianshan Talents Training Program of Xinjiang(Science and Technology Innovation Team,2022TSYCTD0021)+2 种基金the Science and Technology Project of Xinjiang Bingtuan Supported by Central Government(2022BC001)the project of scientific research in Shihezi University(CXFZ202205)special funds for over provincial level leading talent of Yantai City.
文摘In this study,a catalyst was synthesized using a two-step in-situ molecular beam epitaxy method to grow H_(4)PMo_(11)VO_(40)(HPAV)on amination-treated SiO_(2) nanoparticles,which served as both dopant and host agents.SiO_(2) dopant was modified with(3-aminopropyl)triethoxysilane(APTS),facilitating the formation of ammonium ions that enhanced the overall positive charge.This modification enabled the effective dispersion and exposure of HPAV's active species and induced a structural transformation of HPAV from a triclinic to a cubic crystal phase.The two-step hosting growth process optimized the proportions of Cs^(+),H^(+)and NH_(4)^(+)antinuclear ions,thereby fine-tuning the synergistic catalysis of oxidation and acidity,as well as the oxidative sensitivity at HPAV catalytic interface.The resultant 8(HPAV)&4(Cs_(3)PAV)-NH_(2)-SiO_(2) catalyst achieved a methacrolein(MAL)conversion rate of 84%and a methacrylic acid(MAA)selectivity of 71%.Even after 10.5 h of reaction time,the catalyst retained its high dispersion,cubic crystal structure,and Keggin configuration,demonstrating stable catalytic performance over a continuous 200-h reaction period.
基金supported by the National Natural Science Foundation of China(22071020,22171041,22271043,22205034)Natural Science Foundation of Jilin Province Science and Technology Department(20220101045JC)the Fundamental Research Funds for the Central Universities(2412021QD008,2412022QD012)
文摘Exploring novel materials with excellent photothermal conversion capabilities for solar photothermal water evaporation is considered as an ideal strategy to simultaneously realize the direct and full use of the widely distributed solar energy and alleviate the world's freshwater scarcity.Herein,an amphiphilic photothermal membrane is prepared through the self-assembly of hydrophilic heteropoly blue(HPB,H_(3)PMo_(12)O_(40))and hydrophobic surfactant(dioctadecyl dimethyl ammonium bromide,DODA).Benefiting from the synergistic effects of alternating functional hydrophilic HPB and hydrophobic DODA layers,the flexible membrane based on two-dimensional DODA-HPB self-assemblies(DODA-HPB/Nylon66)exhibits superior photothermal conversion properties,showing promising prospects in applications of solar desalination and wastewater treatment.
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.
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.
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.
基金the financial support of Key Laboratory of Resources and Environment Chemistry of West China(No.XZ0704).
文摘Heteropoly acids efficiently catalyzed the cyclocondensation reaction of anthranilamide with aldehydes in water at ambient temperature and afforded the corresponding 2,3-dihydro-4（1H）-quinazolinones compounds in good to excellent yields.This method provides mild reaction conditions and clean reaction profiles,using a small quantity of catalyst and a simple workup procedure.
文摘Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst of sodium salt of tungstic acid with Co as central atom （Na5CoW12O40） showed optimum activity towards transesterification compared with other heteropoly tungstates. The catalysts activities were correlated with the observed physico-chemical characteristics derived from FT-infrared （FT-IR）, X-ray diffraction （XRD）, temperature-programmed desorption of ammonia （NH3-TPD） and carbon dioxide （CO2-TPD）. The Na5CoW12O40 catalyst exhibiting high activity even at 65 ℃ is due to the presence of strong acidic as well as basic sites. The disclosed catalyst is tolerable towards water and free fatty acids present in the oils. The influence of catalyst loading, reaction time and reaction temperature is studied to optimize the reaction parameters.
基金supported by the Deanship of Scientific Research,King Saud University(No.M/202) and SABIC Company
文摘Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.
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.
文摘Lanthanide heteropoly compounds K15[Ln(HSiW9O34)2]·28H2O(Ln = La, Ce, Nd), denoted as Ln(SiW9)2, were synthesized and characterized by element analysis, TG-DTA, IR, UV, XPS and XRD. The results show that partial oxygen in Ln(SiW9)2 was coordinated with Ln3- , where Ln-3 was in the inner side of the heteropoly anions, while the fundamental structure of SiW9 had little change. The result was supported by ion exchange experiment.
基金Supported by the Natural Science Foundation of Hubei Province (2004ABA090)
文摘Several kinds of Tungstophosphates of Heteropoly Compounds （TPHC） with different compositions and the same structure were synthesized using the method of solid-phase reaction to change the tool ratio of Na4P2O7·10H2O, WO3 and Na2WO4 · 2H2O. TPHC, as a catalyst, was used in oxidative desulfurization of diesel. The results show that TPHC has catalytic activity. With THPC existing, the highest desulfurization rate reaches 51.85%, 32.6% higher than that yield without TPHC. And the desulfiarization rate increases with decreasing WO3. FT-IR spectra of TPHC shows that the catalytic activity is related to the activity of end oxygen（Od）.The more active Od is, the stronger the capability of obtaining or losing electron is. It means that TPHC has a good catalytic activity. FT-IR spectra of TPHC indicates that desulfurization rate is in linear correlation with Iw-Od/Ip-Od/ Iw-Od is intensity of W-Od vibration band, Ip-Od is intensity of P-Od vibration band） and correlation coefficient reaches 0.965.
基金the Science and Technology Project of Maoming(China)(200203094555139)for financial support。
文摘The development of polyoxometalates for olefin oxidation is critical to achieving the green chemical process of the C5 fraction further processing.Di-lacunary silicotungstic anions were easily obtained by continuously adjusting the p H instead of the traditional step-by-step method,which exhibited excellent performance in the catalytic oxidation of cyclopentene(CPE)to aldehydes or alcohols.The 93.69%CPE conversion and 97.15%total product selectivity(41.38%for glutaraldehyde(GA)and 55.77%for 1,2-cyclopentanediol(1,2-diol)were achieved by using H_(2)O_(2)as the oxidant and acetonitrile as the solvent.Through complementary characterization,it was found that the optimized di-lacunary silicotungstic polyoxometalate retained a complete Keggin structure,and exhibited better catalytic activity and stability than the mono-lacunary or saturated silicodecatungstate because it exposed more catalytic active centers.Furthermore,in situ FT-IR spectra was utilized to monitor the reaction process,revealing the formation of the active species W(O_(2))on the di-lacunary silicotungstic polyoxometalate and the intermediate epoxycyclopentane during the catalytic oxidation of cyclopentene.
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.
基金Supported by the NaturalScienceFoundation of China( No.2 0 2 75 0 31) ,the Teaching and Research Award Programfor Outstanding Young Techers in High Education of MOE of China and KJCX- 0 1of Northwest Normal University
文摘Electrochemical transfer behavior of V ⅤW 11 -V Ⅴ 3W 9 heteropoly anions on the water/nitrobenzene interface was investigated by means of cyclic voltammetry. The effect of the solution acidity on the transfer behavior and the stable pH range for the heteropoly anions were studied. The stability of mixed tungstovanadate decreases with increasing the number of vanadium atoms. The main transfer species within the potential window have the negative charges of 4 and the transfer process is diffusion controlled. The apparent transfer potential Δ w o Ψ 0 and the free energy Δ G 0 w→o tr for the heteropoly anions can be obtained from the experimental data. For the different anions, the Δ w o Ψ 1/2 pH relationship can be expressed as: Δ w o Ψ 1/2 =constant-53pH.
文摘New indium heteropoly undecatungstometalate complexes of general formula K_n In( H_2O) MW_(11)O_(39) .xH_2O (M = Cr(Ⅲ) , Fe( Ⅲ ), Co(Ⅱ) or Zn( Ⅱ) ) were prepared by the stepwise acidification and the stepwise addition of materials. The products were characterized by elemental analysis, ion-exchange, IRspectra, UV spectra, X-ray powder diffraction and thermal analysis. The results show that the structure ofthe products derives from the Keggin structure. Their themial stability is higher than that of the homolo-gous dedecatungstometalates .
基金the financial support from the National Natural Science Foundation of China(Nos.21162026 and 20962018)Xinjiang Autonomous Region Youth Science Foundation(No. 2011211B05)Doctoral Fund of Xinjiang University(No. BS100109)
文摘MCM-41 supported heteropoly acids （HPAs） catalysts were synthesized, characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at room temperature. 50 wt% PW/MCM-41 showed the highest activity （up to 96% yield）. The catalyst was used in six consecutive experiments without obvious loss of activity, confirming the success of the anchoring process and the catalyst stability.
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Poly(vinyl alcohol) (PVA) fiber mats containing unsaturated heteropoly salt was prepared for the first time. IR, X-ray diffraction and SEM photographs characterized the beaded fiber mats. The viscoelasticity and the conductivity of the solution were the key factors that influence the formation of the beaded fiber mats.
