Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Co...Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.展开更多
In order to efficiently remove volatile organic compounds（VOCs） from indoor air, onedimensional titanate nanotubes（Ti NTs） were hydrothermally treated to prepare TiO2 nanocrystals with different crystalline phases...In order to efficiently remove volatile organic compounds（VOCs） from indoor air, onedimensional titanate nanotubes（Ti NTs） were hydrothermally treated to prepare TiO2 nanocrystals with different crystalline phases, shapes and sizes. The influences of various acids such as CH3 COOH, HNO3, HCl, HF and H2SO4 used in the treatment were separately compared to optimize the performance of the TiO2 nanocrystals. Compared with the strong and corrosive inorganic acids, CH3COOH was not only safer and more environmentally friendly, but also more efficient in promoting the photocatalytic activity of the obtained TiO2. It was observed that the anatase TiO2 synthesized in 15 mol/L CH3COOH solution exhibited the highest photodegradation rate of gaseous toluene（94%）, exceeding that of P25（44%） by a factor of more than two. The improved photocatalytic activity was attributed to the small crystallite size and surface modification by CH3COOH. The influence of relative humidity（20%–80%） on the performance of TiO2 nanocrystals was also studied. The anatase TiO2 synthesized in 15 mol/L CH3COOH solution was more tolerant to moisture than the other TiO2 nanocrystals and P25.展开更多
Assays of stress enzymes related to active oxygen species were performed by using an in vitro preparation from the liver of a monkey (Japanese Macaque). Ge-132, an organic germanium compound, viz. poly-trans-[(2-carbo...Assays of stress enzymes related to active oxygen species were performed by using an in vitro preparation from the liver of a monkey (Japanese Macaque). Ge-132, an organic germanium compound, viz. poly-trans-[(2-carboxyethyl) germasesquioxane] [(GeCH2CH2COOH)2O3]n, suppressed the activities of NADH-dependent oxidase and NADPH-dependent oxidase [NAD(P)H-OD] and xanthine oxidase (XOD) as superoxide-forming enzymes, while promoting the activities of superoxide dismutase (SOD) as a superoxide-scavenging enzyme and catalase (CAT) as an enzyme responsible for degradation of hydrogen peroxide (H2O2). The evidence suggests that the levels of active oxygen species such as and H2O2 would be reduced by Ge-132. The possible connection between Ge-132 and activities of stress enzymes is discussed on the basis of these results.展开更多
The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to mo...The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to monoclinic, space group C2/m, a=2.0654(4)nm, b=1.3306(3)nm, c=1.3194(3)nm, β=119.59(3)°, V=3.1531(11)nm3, Dc=3.606Mg·m-3, Z=2, R=0.0462, Rw=0.0836. The title compound comprises of a 2+ unit, a polyanion and a free (CH3)2NH molecule. The ESR spectrum of the title compound shows that charge transfer between organic groups and polyanion takes place under irradiation of the sunlight in solid state. The TG study of the title compound shows that it had four stages of the weight loss, and the increase of the decomposition temperature for the polyanion shows that the stability of the polyanion was enhanced due to the influence of Zn2+ ion. CCDC:175866.展开更多
A novel three dimensional fluorinated gallium phosphate has been hydrothermally synthesized by using diethylenetriamine as an organic structure directing agent. X ray single crystal structure analysis indicates this c...A novel three dimensional fluorinated gallium phosphate has been hydrothermally synthesized by using diethylenetriamine as an organic structure directing agent. X ray single crystal structure analysis indicates this compound crystallizes in the orthorhombic space group Pbca, a =1.605 6(7) nm, b = 1 011 4 (4) nm, c =1.854 6(5) nm, V =3.011 6(19) nm 3, Z =4. The three dimensional framework based on linkage of corner sharing polyhedron PO 4, GaO 4F and GaO 4F 2 delimit ten ring channels along b axis in which the triply protonated amines are located serving as charge compensating vips and supporters.展开更多
In this paper, a novel polymeric complex [MnNa（Salicylate）2（CH3OH）（H2O）]n·0.5nH2O was obtained and characterized by IR spectra, elemental analysis and single crystal X-ray diffraction. The titled complex is...In this paper, a novel polymeric complex [MnNa（Salicylate）2（CH3OH）（H2O）]n·0.5nH2O was obtained and characterized by IR spectra, elemental analysis and single crystal X-ray diffraction. The titled complex is crystallized in triclinic system, space group P1 with a=0.763 82（15） nm, b= 1.037 1（2） nm, c=1.290 9（3） nm, α= 103.59（3）°, β=104.65（3）°, γ=109.50（3）°, V=0.873 6（3） nm 3, Z=2, Dc=1.556 Mg/m 3, Mr=409.20, μ=0.823 mm -1, F（000）=418, R=0.0614, wR= 0.147 6. The activity in catalyzing the superoxygen anionic free radical dismutation was determinated.展开更多
A new molybdophosphate, (NH3CH2CH2NH3)2Mo5O15(HPO4)2 has been synthesized under hydrothermal conditions and structurally characterized by single crystal X ray diffractions. The compound crystallizes in the monoclinic,...A new molybdophosphate, (NH3CH2CH2NH3)2Mo5O15(HPO4)2 has been synthesized under hydrothermal conditions and structurally characterized by single crystal X ray diffractions. The compound crystallizes in the monoclinic, space group C2/c, a=1.7633(2)nm, b=1.00122(11) nm, c=1.37624(13)nm, β=96.974(5)°, V=2.4117(5)nm3, Z=4, Dc=2.853g·cm-3, μ(MoKα)=2.766mm-1, F(000)=1992. The structure contains the isolated polyanions of [Mo5O15(HPO4)2]4- units around which the portonated ethylenediamine ions are pos itioned. By hydrogen bond interactions the polyanions are interconnected to form a three dimensional network. Other characterizations by powder XRD, IR and thermal analysis are also described. CCDC: 206321.展开更多
基金supported by the National Natural Science Foundation of China(22302115,22072079)the Fundamental Research Program of Shanxi Province(202303021221056).
文摘Heterogeneous solid frustrated-Lewis-pair(FLP)catalyst is of great promise in practical hydrogenation applications.It has been found that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation.Consequently,it is desired to investigate the mechanisms of the FLP-catalyzed hydrogenation of C=C and C=O and provide insight into the modification of CeO_(2)catalysts for the selective hydrogenation.In this work,the reaction mechanism of the hydrogenation of CH_(2)=CH_(2)and CH_(3)CH=O at the FLP sites constructed on CeO_(2)(110)surface was investigated by density functional theory(DFT),with the classical Lewis acid-base pairs(CLP)site as the reference.The results illustrate that at the CLP site,the dissociated hydride(H^(δ−))forms a stable H−O bond with the surface O atom,while at the FLP site,H^(δ−)is stabilized by Ce,displaying higher activity on the one hand.On the other hand,the electron cloud density of the Ce atom at the FLP site is higher,which can transfer more electrons to the adsorbed C_(C=C)and O_(C=O)atoms,leading to a higher degree of activation for C=C and C=O bonds,as indicated by the Bader charge analysis.Therefore,compared to the CLP site,the FLP site exhibits higher hydrogenation activity for CH_(2)=CH_(2)and CH_(3)CH=O.Furthermore,at the FLP sites,it demonstrates high efficiency in catalyzing the hydrogenation of CH_(2)=CH_(2)with the rate-determining barrier of 1.04 eV,but it shows limited activity for the hydrogenation of CH_(3)CH=O with the rate-determining barrier of 1.94 eV.It means that the selective hydrogenation of C=C can be effectively achieved at the FLP sites concerning selective hydrogenation catalysis.The insights shown in this work help to clarify the reaction mechanism of the hydrogenation of C=C and C=O at FLP site on CeO_(2)(110)and reveal the relationship between the catalytic performance and the nature of the active site,which is of great benefit to development of rational design of heterogeneous FLP catalysts.
基金supported by grants from National High Technology Research and Development Program of China (863) (No. 2012AA062702 and 2010AA064902)the Key Innovation Team for Science and Technology of Zhejiang Province (No. 2009R50047)
文摘In order to efficiently remove volatile organic compounds（VOCs） from indoor air, onedimensional titanate nanotubes（Ti NTs） were hydrothermally treated to prepare TiO2 nanocrystals with different crystalline phases, shapes and sizes. The influences of various acids such as CH3 COOH, HNO3, HCl, HF and H2SO4 used in the treatment were separately compared to optimize the performance of the TiO2 nanocrystals. Compared with the strong and corrosive inorganic acids, CH3COOH was not only safer and more environmentally friendly, but also more efficient in promoting the photocatalytic activity of the obtained TiO2. It was observed that the anatase TiO2 synthesized in 15 mol/L CH3COOH solution exhibited the highest photodegradation rate of gaseous toluene（94%）, exceeding that of P25（44%） by a factor of more than two. The improved photocatalytic activity was attributed to the small crystallite size and surface modification by CH3COOH. The influence of relative humidity（20%–80%） on the performance of TiO2 nanocrystals was also studied. The anatase TiO2 synthesized in 15 mol/L CH3COOH solution was more tolerant to moisture than the other TiO2 nanocrystals and P25.
文摘Assays of stress enzymes related to active oxygen species were performed by using an in vitro preparation from the liver of a monkey (Japanese Macaque). Ge-132, an organic germanium compound, viz. poly-trans-[(2-carboxyethyl) germasesquioxane] [(GeCH2CH2COOH)2O3]n, suppressed the activities of NADH-dependent oxidase and NADPH-dependent oxidase [NAD(P)H-OD] and xanthine oxidase (XOD) as superoxide-forming enzymes, while promoting the activities of superoxide dismutase (SOD) as a superoxide-scavenging enzyme and catalase (CAT) as an enzyme responsible for degradation of hydrogen peroxide (H2O2). The evidence suggests that the levels of active oxygen species such as and H2O2 would be reduced by Ge-132. The possible connection between Ge-132 and activities of stress enzymes is discussed on the basis of these results.
文摘The title compound H2SiW12O40·(CH3)2NH was synthesized in mixed solvent of aqueous and acetonitrile, and its crystal structure had been determined using single crystal X ray diffraction. The crystal belongs to monoclinic, space group C2/m, a=2.0654(4)nm, b=1.3306(3)nm, c=1.3194(3)nm, β=119.59(3)°, V=3.1531(11)nm3, Dc=3.606Mg·m-3, Z=2, R=0.0462, Rw=0.0836. The title compound comprises of a 2+ unit, a polyanion and a free (CH3)2NH molecule. The ESR spectrum of the title compound shows that charge transfer between organic groups and polyanion takes place under irradiation of the sunlight in solid state. The TG study of the title compound shows that it had four stages of the weight loss, and the increase of the decomposition temperature for the polyanion shows that the stability of the polyanion was enhanced due to the influence of Zn2+ ion. CCDC:175866.
文摘A novel three dimensional fluorinated gallium phosphate has been hydrothermally synthesized by using diethylenetriamine as an organic structure directing agent. X ray single crystal structure analysis indicates this compound crystallizes in the orthorhombic space group Pbca, a =1.605 6(7) nm, b = 1 011 4 (4) nm, c =1.854 6(5) nm, V =3.011 6(19) nm 3, Z =4. The three dimensional framework based on linkage of corner sharing polyhedron PO 4, GaO 4F and GaO 4F 2 delimit ten ring channels along b axis in which the triply protonated amines are located serving as charge compensating vips and supporters.
文摘In this paper, a novel polymeric complex [MnNa（Salicylate）2（CH3OH）（H2O）]n·0.5nH2O was obtained and characterized by IR spectra, elemental analysis and single crystal X-ray diffraction. The titled complex is crystallized in triclinic system, space group P1 with a=0.763 82（15） nm, b= 1.037 1（2） nm, c=1.290 9（3） nm, α= 103.59（3）°, β=104.65（3）°, γ=109.50（3）°, V=0.873 6（3） nm 3, Z=2, Dc=1.556 Mg/m 3, Mr=409.20, μ=0.823 mm -1, F（000）=418, R=0.0614, wR= 0.147 6. The activity in catalyzing the superoxygen anionic free radical dismutation was determinated.
文摘A new molybdophosphate, (NH3CH2CH2NH3)2Mo5O15(HPO4)2 has been synthesized under hydrothermal conditions and structurally characterized by single crystal X ray diffractions. The compound crystallizes in the monoclinic, space group C2/c, a=1.7633(2)nm, b=1.00122(11) nm, c=1.37624(13)nm, β=96.974(5)°, V=2.4117(5)nm3, Z=4, Dc=2.853g·cm-3, μ(MoKα)=2.766mm-1, F(000)=1992. The structure contains the isolated polyanions of [Mo5O15(HPO4)2]4- units around which the portonated ethylenediamine ions are pos itioned. By hydrogen bond interactions the polyanions are interconnected to form a three dimensional network. Other characterizations by powder XRD, IR and thermal analysis are also described. CCDC: 206321.
