A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the ...A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.展开更多
Ammonium salts, (NH4)6HPMo11MO40 (M = Ni, Co, Fe), have been investigated for the oxidation of propane, with molecular oxygen, at temperature ranging between 380 ℃ and 420 ℃ after in-situ pre-treatment performed...Ammonium salts, (NH4)6HPMo11MO40 (M = Ni, Co, Fe), have been investigated for the oxidation of propane, with molecular oxygen, at temperature ranging between 380 ℃ and 420 ℃ after in-situ pre-treatment performed at two heating rate of 5 or 9 ℃/min. They were characterized by BET method, XRD, 31p NMR, UV-Vis and IR techniques. The catalysts were found active in the propane oxidation and selective to propene or acrolein, in particular for samples pre-treated with the heating rate of 9 ℃/min.展开更多
Mixed ammonium-transition metal salts with formula of (NH4)xMyHzPMo12O40 (M = Ni^2+, Co^2+ or Fe ^3+) denoted as MPMo12 have been investigated for the oxidation of propane, with molecular oxygen, at temperature...Mixed ammonium-transition metal salts with formula of (NH4)xMyHzPMo12O40 (M = Ni^2+, Co^2+ or Fe ^3+) denoted as MPMo12 have been investigated for the oxidation of propane, with molecular oxygen, at temperature range between 380 ℃ and 420 ℃ after in-situ pre-treatment performed at two heating rate of 5 or 9℃/min. They were characterized by BET method, XRD, UV-Vis and IR techniques. The catalysts were found to be active in the propane oxidation and selective to propene or acrolein, in particular for samples pre-treated with the heating rate of 9℃/min. FePMo12 was found to be a more active catalyst for propene (17.2% yield) with minimal over deep oxidation (0.3% yield in COx).展开更多
A novel compound [H-IDP]4[PMo12O40]·8H2O 1 based on Keggin-type phosphor- molybdate has been synthesized by hydrothermal method and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray di...A novel compound [H-IDP]4[PMo12O40]·8H2O 1 based on Keggin-type phosphor- molybdate has been synthesized by hydrothermal method and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. The composite crystallizes in the mono- clinic system, space group C2/m with a = 13.937(5), b = 27.033(5), c = 10.857(5) A, β = 122.489(5)°, V = 3450(2)A^3, Mr = 2611.11, Z = 2, Dc = 2.498 g/cm^3, F(000) = 2486,μ = 2.243 mm^-1, the final R = 0.0568 and wR = 0.1216 for 2707 observed reflections with I 〉 2σ(I). X-ray structural study shows that 1 consists of a [PMo12O40]^4- polyanion, four protonated IDP cations and eight H2O molecules. In the structure of 1, a 3D network forms by hydrogen bond of [PMo12O40]^4- polyanion, HIDP^+ cation and H2O molecules. Upon excitation wavelength of 280 nrn in hydroxylic solvents at room temperature, 1 shows fluorescence property.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
Phospbomolybdate (PMo) with varying Mo loadings ranging from 5-30 wt% on alumina were prepared by incipient wetness impregnation method. 0.5 wt% of Pt was further loaded in order to prepare the bifunctional (metal-...Phospbomolybdate (PMo) with varying Mo loadings ranging from 5-30 wt% on alumina were prepared by incipient wetness impregnation method. 0.5 wt% of Pt was further loaded in order to prepare the bifunctional (metal-acid) Pt-PMo/Al2O3 catalysts. Thus prepared catalysts showed very high catalytic activities for n-heptane hydroisomerization compared with Pt impregnated MoO3 catalysts supported either on Al2O3 or on AIPO4. The conversion of n-heptane increased with Mo loading up to 20 wt% and slightly decreased with further Mo loading. However, the selectivity towards isomers showed an increasing trend up to 30 wt% of Mo in the catalyst. A relationship between catalytic activity and acidic strength was established in the present study.展开更多
Two unusual complexes [Cda(Do)4(H2O)2CI](PW12O4O)'2H2O (1) and [Aga(Do)6(PW12O40)][Ag(Do)2]2(PW12O4O)'2H2O (2) were hydrothermally synthesized by the combination of two different metallic salts, Ke...Two unusual complexes [Cda(Do)4(H2O)2CI](PW12O4O)'2H2O (1) and [Aga(Do)6(PW12O40)][Ag(Do)2]2(PW12O4O)'2H2O (2) were hydrothermally synthesized by the combination of two different metallic salts, Keggin-type polyoxometalate and 1,10-phen-5,6-dione (Do), and characterized by elemental analyses, inductively coupled plasma analyses, infrared spectra, X-ray photoelectron spectroscopy, thermal gravimetry, photoluminescent spectra and single-crystal X-ray diffraction analyses. Crystal 1 is of monoclinic, space group P21/n with a = 12.383(3), b = 18.326(4), c = 16.437(3) A, β = 90.29(3)°, V = 3730.1(13) A3, Z = 2, CdzCasH32NsC1052PW12, Mr. = 4050.24, Dc = 3.604 g'cm-3,μ(MoKa) = 19.145 mm1, F(000) = 3608, GOOF = 1.168, the final R = 0.0569 and wR = 0.0745 for 5715 observed reflections (1 〉 2σ(I)). Crystal 2 is of triclinic, space group Pi with a = 13.959(5), b = 16.972(5), c = 17.647(5)A, α = 85.970(5), β = 81.353(5), γ = 86.316(5)°, V = 4117(2) A3 Z = 1, Ag6C120H64N200102P2W24, Mr. = 8539.47, Dc = 3.444 g-cm-3,μ(MoKa) = 17.511 mm-1, F(000) = 3828, GOOF = 1.033, the final R = 0.0981 and wR = 0.1658 for 9906 observed reflections (I 〉 2σ(I)). Structural analyses show that complex 1 has a zero dimensional structure, which is further assembled into a one-dimensional ladder-like structure through hydrogen bonds. Complex 2 possesses a one-dimensional chain structure. Furthermore, solid-state luminescent spectra of complexes 1 and 2 indicate red and green fluorescent emission, respectively.展开更多
A highly active catalyst of phosphomolybdic acid ~HPMo) was prepared and applied in the catalytic oxidative desulfurization (CODS) system. The catalyst was characterized by FT-IR, XRD, XPS and superconducting NMR. ...A highly active catalyst of phosphomolybdic acid ~HPMo) was prepared and applied in the catalytic oxidative desulfurization (CODS) system. The catalyst was characterized by FT-IR, XRD, XPS and superconducting NMR. The influences of rn(catalyst)/m(oil), V(H202)fV(oil), reaction temperature and reaction time on the fractional conversion of benzothiophene (BT) and dibenzothiophene (DBT) were investigated. GC-MS and micra-coulometric methods were employed to investigate the reaction. The catalyst has high desulfurization activity in the removal of BT and DBT under mild conditions. The recycling experiments indicated that DBT and BT removal could still reach 95.2% and 95.7% after 10 cycles.展开更多
Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-...Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-dimethylformamide) were synthesized by the conventional solution method.Structure analyses indicate that four compounds are isostructural and are all built from three [SiW_(12)O_(40)]^(4-) polyoxoanions and DMF ligands linked by RE^(3+).Compounds 1-4 are extremely sensitive to UV light and present excellent photochromic properties,in which the coloring and fading time of samples are both no more than 2 min,and the reversible coloring-fading process can be repeated for at least 10 cycles with little fatigue,suggesting that compounds 1-4 can be a series of fast-responsive and durable photochromic materials.Moreover,the solid-state photoluminescence spectra of compounds 3(Sm) and 4(Eu)display strong characteristic emissions of rare earth ions based on f-f transitions.Meanwhile,compound4(Eu) has a longer fluorescence lifetime up to 566.74 μs.Notably,co mpounds 3(Sm) and 4(Eu) exhibit the switchable luminescence behavior induced by photochromism,which allows them to be used as potential molecular switches.展开更多
The existence of alkali metals in fl ue gases originating from stationary sources can result in catalyst deactivation in the low-temperature selective catalytic reduction(SCR)of nitrogen oxides(NO_(x)).It is widely ac...The existence of alkali metals in fl ue gases originating from stationary sources can result in catalyst deactivation in the low-temperature selective catalytic reduction(SCR)of nitrogen oxides(NO_(x)).It is widely accepted that alkali metal poisoning causes damage to the acidic sites of catalysts.Therefore,in this study,a series of CoMn catalysts doped with heteropolyacids(HPAs)were prepared using the coprecipitation method.Among these,CoMnHPMo exhibited superior catalytic performance for SCR and over 95%NO_(x) conversion at 150-300.Moreover,it exhibited excellent catalytic activity and stability after alkali poisoning,demonstrating outstanding alkali metal resistance.The characterization indicated that HPMo increased the specifi c surface area of the catalyst,which provided abundant adsorption sites for NO_(x) and NH_(3).Comparing catalysts before and after poisoning,CoMnHPMo enhanced its alkali metal resistance by sacrifi cing Brønsted acid sites to protect its Lewis acid sites.In situ DRIFTS was used to study the reaction pathways of the catalysts.The results showed that CoMnHPMo maintained high NH_(3) adsorption capacity after K poisoning and then reacted rapidly with NO intermediates to ensure that the active sites were not covered.Consequently,SCR performance was ensured even after alkali metal poisoning.In sum-mary,this research proposed a simple method for the design of an alkali-resistant NH_(3)-SCR catalyst with high activity at low temperatures.展开更多
Hydroisomerization of n-heptane is an efficient method for producing gasoline with a high octane number.The focus of this study was to find a highly efficient catalyst that could both promote the conversion of n-hepta...Hydroisomerization of n-heptane is an efficient method for producing gasoline with a high octane number.The focus of this study was to find a highly efficient catalyst that could both promote the conversion of n-heptane and inhibit the cracking side reaction.MIL-101(Cr)is a chromium-based metal-organic framework(MOF)with good hydrothermal stability,and exhibits a three-dimensional pore structure that is similar to that of zeolites.Using phosphomolybdic acid(PMA;H3PMo12O40·xH2O)can increase the number of Brønsted acid sites on MIL-101(Cr),which contributes to improving the catalytic performance during isomerization.In this study,0.4%Pt/PMA-MIL-101(Cr)catalyst was successfully crystallized at 220℃using a hydrothermal synthetic method.The results showed that the synthesized samples were mesoporousmicroporous composite materials with the typical octahedral structure,and the MIL-101(Cr)framework was not damaged following modification with PMA.It was found that 0.4%Pt30%PMA-MIL-101(Cr)exhibited the best performance for isomerization of n-heptane,with a conversion rate and selectivity at 260°C of 47.6%and 96.6%,respectively.After five hours of reaction,the conversion rate and selectivity of the catalyst remained above 38%and 80%,respectively.展开更多
Due to its properties of mutagenic,teratogenic,and carcinogenic,the detection of furazolidone(FZD)in aquaculture is of great importance for food safety and human health.In this study,molecularly imprinted fi lms modif...Due to its properties of mutagenic,teratogenic,and carcinogenic,the detection of furazolidone(FZD)in aquaculture is of great importance for food safety and human health.In this study,molecularly imprinted fi lms modifi ed with carboxylated multi-walled carbon nanotube-phosphomolybdic acid composite were used to fabricate an electrochemical sensor for the determination of FZD.The nanocomposites were characterized using infrared spectroscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and X-ray diff raction.The electrochemical characteristics of the modifi ed electrodes were examined using electrochemical impedance spectroscopy,cyclic voltammetry,and diff erential pulse voltammetry.The sensor exhibited exceptional catalytic performance.The calibration curves were acquired in the concentration range of 6 nmol·L^(−1)to 0.6μmol·L^(−1),with a limit of detection of 3.38 nmol·L^(−1).Additionally,the sensor proved successful in recognizing FZD in shrimp samples with satisfactory recoveries and precision.The method provides a strategy to construct a molecularly imprinted electrochemical sensing platform using nanomaterials,which has great promise in the field of food safety.展开更多
Hybrid proton conducting membranes of poly(vinyl alcohol) (PVA) and phosphomolybdic acid (PMA) were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane prop...Hybrid proton conducting membranes of poly(vinyl alcohol) (PVA) and phosphomolybdic acid (PMA) were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde (GA) was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.展开更多
In this work, the removal of thiophene from simulated oil has been studied by using the adsorption, extraction and oxidation/adsorption methods, respectively. In the adsorptive desulfurization process, different comme...In this work, the removal of thiophene from simulated oil has been studied by using the adsorption, extraction and oxidation/adsorption methods, respectively. In the adsorptive desulfurization process, different commercial adsorbents were used to eliminate thiophene at ambient pressure and mild temperature, and the results showed that carbon powder had the best adsorption ability. In the extractive desulfurization process, the best desulfurization result was obtained when DMF is used. In the oxidative/adsorptive desulfurization procedure using synthesized potassium ferrate as the oxidant and phosphomolybdic acid solution as the catalyst, thiophene was oxidized and removed from hydrocarbons in combination with active carbon adsorption, and the residual sulfur content of simulated oil could be reduced to 15.3mg/L from the original level of 200mg/L, with the desulfurization rate reaching 92.3%.展开更多
基金National Natural Science Foundation of China(Grant No.52006225).
文摘A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.
文摘Ammonium salts, (NH4)6HPMo11MO40 (M = Ni, Co, Fe), have been investigated for the oxidation of propane, with molecular oxygen, at temperature ranging between 380 ℃ and 420 ℃ after in-situ pre-treatment performed at two heating rate of 5 or 9 ℃/min. They were characterized by BET method, XRD, 31p NMR, UV-Vis and IR techniques. The catalysts were found active in the propane oxidation and selective to propene or acrolein, in particular for samples pre-treated with the heating rate of 9 ℃/min.
文摘Mixed ammonium-transition metal salts with formula of (NH4)xMyHzPMo12O40 (M = Ni^2+, Co^2+ or Fe ^3+) denoted as MPMo12 have been investigated for the oxidation of propane, with molecular oxygen, at temperature range between 380 ℃ and 420 ℃ after in-situ pre-treatment performed at two heating rate of 5 or 9℃/min. They were characterized by BET method, XRD, UV-Vis and IR techniques. The catalysts were found to be active in the propane oxidation and selective to propene or acrolein, in particular for samples pre-treated with the heating rate of 9℃/min. FePMo12 was found to be a more active catalyst for propene (17.2% yield) with minimal over deep oxidation (0.3% yield in COx).
基金This project was supported by the NNSFC (No 20771023)the State 863 Program Project (No 2007AA03z218)Analysis and Testing Foundation of Northeast Normal University
文摘A novel compound [H-IDP]4[PMo12O40]·8H2O 1 based on Keggin-type phosphor- molybdate has been synthesized by hydrothermal method and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. The composite crystallizes in the mono- clinic system, space group C2/m with a = 13.937(5), b = 27.033(5), c = 10.857(5) A, β = 122.489(5)°, V = 3450(2)A^3, Mr = 2611.11, Z = 2, Dc = 2.498 g/cm^3, F(000) = 2486,μ = 2.243 mm^-1, the final R = 0.0568 and wR = 0.1216 for 2707 observed reflections with I 〉 2σ(I). X-ray structural study shows that 1 consists of a [PMo12O40]^4- polyanion, four protonated IDP cations and eight H2O molecules. In the structure of 1, a 3D network forms by hydrogen bond of [PMo12O40]^4- polyanion, HIDP^+ cation and H2O molecules. Upon excitation wavelength of 280 nrn in hydroxylic solvents at room temperature, 1 shows fluorescence property.
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Phospbomolybdate (PMo) with varying Mo loadings ranging from 5-30 wt% on alumina were prepared by incipient wetness impregnation method. 0.5 wt% of Pt was further loaded in order to prepare the bifunctional (metal-acid) Pt-PMo/Al2O3 catalysts. Thus prepared catalysts showed very high catalytic activities for n-heptane hydroisomerization compared with Pt impregnated MoO3 catalysts supported either on Al2O3 or on AIPO4. The conversion of n-heptane increased with Mo loading up to 20 wt% and slightly decreased with further Mo loading. However, the selectivity towards isomers showed an increasing trend up to 30 wt% of Mo in the catalyst. A relationship between catalytic activity and acidic strength was established in the present study.
基金Program for New Century Excellent Talents in University(NCET-10-0176)of ChinaNatural Science Foundation Project of Jiangsu University(No.09JDG001,No.11jdg104 and BK2011528)
文摘Two unusual complexes [Cda(Do)4(H2O)2CI](PW12O4O)'2H2O (1) and [Aga(Do)6(PW12O40)][Ag(Do)2]2(PW12O4O)'2H2O (2) were hydrothermally synthesized by the combination of two different metallic salts, Keggin-type polyoxometalate and 1,10-phen-5,6-dione (Do), and characterized by elemental analyses, inductively coupled plasma analyses, infrared spectra, X-ray photoelectron spectroscopy, thermal gravimetry, photoluminescent spectra and single-crystal X-ray diffraction analyses. Crystal 1 is of monoclinic, space group P21/n with a = 12.383(3), b = 18.326(4), c = 16.437(3) A, β = 90.29(3)°, V = 3730.1(13) A3, Z = 2, CdzCasH32NsC1052PW12, Mr. = 4050.24, Dc = 3.604 g'cm-3,μ(MoKa) = 19.145 mm1, F(000) = 3608, GOOF = 1.168, the final R = 0.0569 and wR = 0.0745 for 5715 observed reflections (1 〉 2σ(I)). Crystal 2 is of triclinic, space group Pi with a = 13.959(5), b = 16.972(5), c = 17.647(5)A, α = 85.970(5), β = 81.353(5), γ = 86.316(5)°, V = 4117(2) A3 Z = 1, Ag6C120H64N200102P2W24, Mr. = 8539.47, Dc = 3.444 g-cm-3,μ(MoKa) = 17.511 mm-1, F(000) = 3828, GOOF = 1.033, the final R = 0.0981 and wR = 0.1658 for 9906 observed reflections (I 〉 2σ(I)). Structural analyses show that complex 1 has a zero dimensional structure, which is further assembled into a one-dimensional ladder-like structure through hydrogen bonds. Complex 2 possesses a one-dimensional chain structure. Furthermore, solid-state luminescent spectra of complexes 1 and 2 indicate red and green fluorescent emission, respectively.
基金supported by the National Natural Science Foundation of China (21473126)~~
文摘A highly active catalyst of phosphomolybdic acid ~HPMo) was prepared and applied in the catalytic oxidative desulfurization (CODS) system. The catalyst was characterized by FT-IR, XRD, XPS and superconducting NMR. The influences of rn(catalyst)/m(oil), V(H202)fV(oil), reaction temperature and reaction time on the fractional conversion of benzothiophene (BT) and dibenzothiophene (DBT) were investigated. GC-MS and micra-coulometric methods were employed to investigate the reaction. The catalyst has high desulfurization activity in the removal of BT and DBT under mild conditions. The recycling experiments indicated that DBT and BT removal could still reach 95.2% and 95.7% after 10 cycles.
基金Project supported by the National Natural Science Foundation of China(22172022,21872021,21671033,21901135)。
文摘Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-dimethylformamide) were synthesized by the conventional solution method.Structure analyses indicate that four compounds are isostructural and are all built from three [SiW_(12)O_(40)]^(4-) polyoxoanions and DMF ligands linked by RE^(3+).Compounds 1-4 are extremely sensitive to UV light and present excellent photochromic properties,in which the coloring and fading time of samples are both no more than 2 min,and the reversible coloring-fading process can be repeated for at least 10 cycles with little fatigue,suggesting that compounds 1-4 can be a series of fast-responsive and durable photochromic materials.Moreover,the solid-state photoluminescence spectra of compounds 3(Sm) and 4(Eu)display strong characteristic emissions of rare earth ions based on f-f transitions.Meanwhile,compound4(Eu) has a longer fluorescence lifetime up to 566.74 μs.Notably,co mpounds 3(Sm) and 4(Eu) exhibit the switchable luminescence behavior induced by photochromism,which allows them to be used as potential molecular switches.
基金This work was supported by the National Key R&D Program of China(Nos.2022YFB3504100 and 2022YFB3504102)Natural National Science Foundation of China(No.22276133)+1 种基金Natural National Science Foundation of China(No.U20A20132)Natural National Science Foundation of China(No.52106180).
文摘The existence of alkali metals in fl ue gases originating from stationary sources can result in catalyst deactivation in the low-temperature selective catalytic reduction(SCR)of nitrogen oxides(NO_(x)).It is widely accepted that alkali metal poisoning causes damage to the acidic sites of catalysts.Therefore,in this study,a series of CoMn catalysts doped with heteropolyacids(HPAs)were prepared using the coprecipitation method.Among these,CoMnHPMo exhibited superior catalytic performance for SCR and over 95%NO_(x) conversion at 150-300.Moreover,it exhibited excellent catalytic activity and stability after alkali poisoning,demonstrating outstanding alkali metal resistance.The characterization indicated that HPMo increased the specifi c surface area of the catalyst,which provided abundant adsorption sites for NO_(x) and NH_(3).Comparing catalysts before and after poisoning,CoMnHPMo enhanced its alkali metal resistance by sacrifi cing Brønsted acid sites to protect its Lewis acid sites.In situ DRIFTS was used to study the reaction pathways of the catalysts.The results showed that CoMnHPMo maintained high NH_(3) adsorption capacity after K poisoning and then reacted rapidly with NO intermediates to ensure that the active sites were not covered.Consequently,SCR performance was ensured even after alkali metal poisoning.In sum-mary,this research proposed a simple method for the design of an alkali-resistant NH_(3)-SCR catalyst with high activity at low temperatures.
基金National Natural Science Foundation of China(Grant No.22272129).
文摘Hydroisomerization of n-heptane is an efficient method for producing gasoline with a high octane number.The focus of this study was to find a highly efficient catalyst that could both promote the conversion of n-heptane and inhibit the cracking side reaction.MIL-101(Cr)is a chromium-based metal-organic framework(MOF)with good hydrothermal stability,and exhibits a three-dimensional pore structure that is similar to that of zeolites.Using phosphomolybdic acid(PMA;H3PMo12O40·xH2O)can increase the number of Brønsted acid sites on MIL-101(Cr),which contributes to improving the catalytic performance during isomerization.In this study,0.4%Pt/PMA-MIL-101(Cr)catalyst was successfully crystallized at 220℃using a hydrothermal synthetic method.The results showed that the synthesized samples were mesoporousmicroporous composite materials with the typical octahedral structure,and the MIL-101(Cr)framework was not damaged following modification with PMA.It was found that 0.4%Pt30%PMA-MIL-101(Cr)exhibited the best performance for isomerization of n-heptane,with a conversion rate and selectivity at 260°C of 47.6%and 96.6%,respectively.After five hours of reaction,the conversion rate and selectivity of the catalyst remained above 38%and 80%,respectively.
基金Supported by the National Natural Science Foundation of China(Grant No.22271119).
文摘Due to its properties of mutagenic,teratogenic,and carcinogenic,the detection of furazolidone(FZD)in aquaculture is of great importance for food safety and human health.In this study,molecularly imprinted fi lms modifi ed with carboxylated multi-walled carbon nanotube-phosphomolybdic acid composite were used to fabricate an electrochemical sensor for the determination of FZD.The nanocomposites were characterized using infrared spectroscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and X-ray diff raction.The electrochemical characteristics of the modifi ed electrodes were examined using electrochemical impedance spectroscopy,cyclic voltammetry,and diff erential pulse voltammetry.The sensor exhibited exceptional catalytic performance.The calibration curves were acquired in the concentration range of 6 nmol·L^(−1)to 0.6μmol·L^(−1),with a limit of detection of 3.38 nmol·L^(−1).Additionally,the sensor proved successful in recognizing FZD in shrimp samples with satisfactory recoveries and precision.The method provides a strategy to construct a molecularly imprinted electrochemical sensing platform using nanomaterials,which has great promise in the field of food safety.
文摘Hybrid proton conducting membranes of poly(vinyl alcohol) (PVA) and phosphomolybdic acid (PMA) were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde (GA) was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.
基金financially supported by the Science and Technology Program of the Department of Education,Heilongjiang Province(11531012)
文摘In this work, the removal of thiophene from simulated oil has been studied by using the adsorption, extraction and oxidation/adsorption methods, respectively. In the adsorptive desulfurization process, different commercial adsorbents were used to eliminate thiophene at ambient pressure and mild temperature, and the results showed that carbon powder had the best adsorption ability. In the extractive desulfurization process, the best desulfurization result was obtained when DMF is used. In the oxidative/adsorptive desulfurization procedure using synthesized potassium ferrate as the oxidant and phosphomolybdic acid solution as the catalyst, thiophene was oxidized and removed from hydrocarbons in combination with active carbon adsorption, and the residual sulfur content of simulated oil could be reduced to 15.3mg/L from the original level of 200mg/L, with the desulfurization rate reaching 92.3%.