The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron sp...The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible（Fe2＋,Mo6＋） and （Fe3＋,Mo5＋）valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.展开更多
The feasibility of photocatalytic degradation of X 3B azo dye by TiO 2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO 2/beads, airflow, as well as the concentrations of H ...The feasibility of photocatalytic degradation of X 3B azo dye by TiO 2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO 2/beads, airflow, as well as the concentrations of H 2O 2, Fe 3+ , Mg 2+ and Na + on the photocatalytic degradation of X 3B azo dye were also studied. The results showed that 25 mg/dm 3 X 3B azo dye can be photocatalytically degraded completely by 30 min illumination with a 375W medium pressure mercury lamp. Adding a small amount of H 2O 2 or Fe 3+ , the efficiencies of photocatalytic degradation of X 3B azo dye were increased rapidly. The mechanisms of the reaction and the role of the additives were also investigated. After 120 hours TiO 2/beads showed no significant loss of the photocatalytic activity.展开更多
We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization pro...We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.展开更多
Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess unif...Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess uniform, continuous, and permeable channels, they are valu- able candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks （ZIF-8） nanoparticles inside the pore of an as-formed 3D reduced graphene oxide （rGO） hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in allmline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity.展开更多
The Ni/CeO_2-ZrO_2-Al_2O_3 catalyst with different Al_2O_3 and NiO contentswere prepared by hydrothermal synthesis method. The catalytic performance for CO_2 reforming of CH_4reaction, the interaction among components...The Ni/CeO_2-ZrO_2-Al_2O_3 catalyst with different Al_2O_3 and NiO contentswere prepared by hydrothermal synthesis method. The catalytic performance for CO_2 reforming of CH_4reaction, the interaction among components and the relation between Ni content and catalyst surfacebasicity were investigated. Results show that the interaction between NiO and Al_2O_3 is strongerthan that between NiO and CeO_2-ZrO_2. The addition of Al_2O_3 can prevent the formation of largemetallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excessAl_2O_3 causes the catalyst to deactivate easily. The interaction between NiO and CeO_2 results inmore facile reduction of surface CeO_2. The existence of a small amount of metallic Ni can increasethe number of basic sites. As metallic Ni may preferentially reside on the strong basic sites,increasing Ni content can weaken the catalyst basicity.展开更多
Mixed alcohol is of great promise as octane improver in automotive fuel,and hopeful to replace the MTBE to reduce the environmental pollution,In this field,alkali-promted molybdenum-based catalysts have been given spe...Mixed alcohol is of great promise as octane improver in automotive fuel,and hopeful to replace the MTBE to reduce the environmental pollution,In this field,alkali-promted molybdenum-based catalysts have been given special interest because of their excellent sulfur-tolerance for synthesis of mixed alcohol from CO+H2,It was reported that the coblat is a favorable promoter for enhancing alcohol production,especially for improving the selectivity for C2+ alcohol[1-3],moreover,strong interaction between Con and Mo is in favor of mixed alcohol synthesis[4].Recently,we prpared a kind of K-Co-Mo ultrafine particles by sol-gel method and it shows much smaller particle size but higher activty and selectivity toward alcohol formation than the one prepared by conventional method[5],The aim of the present work is to research the micostructures of the Mo and Co species in the K-Co-Mo samples prepared by different method.展开更多
Pulsed laser photolysis/laser-induced fluores-cence 0LP-LIF) is utilized to measure rate constants for C2(a^3Пu) reactions with NO, N2O, O2, H2 and NH3. Multiphoton dissociation of C2C!4 at 266 nm is employed for the...Pulsed laser photolysis/laser-induced fluores-cence 0LP-LIF) is utilized to measure rate constants for C2(a^3Пu) reactions with NO, N2O, O2, H2 and NH3. Multiphoton dissociation of C2C!4 at 266 nm is employed for the generation of C2(a^3Пu) radicals. The C2(a^3Пu) concentration is monitored by the fluorescence of the (0, 0) band of the (d^3Пg←→a^3Пu) transition at 516.5 nm. C2(a^3Пu) removal rate constants for the reactions are determined as kNO = (5.46 × 0.10) × 10^-11- cm^3 molecule^-1 s^-1, kN2O = (1.63 × 0.20) × 10^-13 cm^3 molecule^-1 s^-1, kN2O = (1.58 × 0.16) × 10^-11 cm^3 molecule^-l s^-1, kO2 = (5.92 × 1.00) × 10^-14 cm^3 molecule^-1 s^-1, kH2 < 1.0× 10^-14 cm^3 molecule^-1 s^-1. Based on the data analysis and theoretical calculation, we suggest that the C2(a^3Пu) reactions with H2 and NH3 proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C2(a^3Пu) with H2 and NH3.展开更多
The UV-Vis spectra, HRTEM and AFM images of cationic fullerene derivative 1 with ammonium head group directly connected to C60 skeleton in tetrahydrofuran (THF)-water (H2O) binary mixtures and in pure H2O were investi...The UV-Vis spectra, HRTEM and AFM images of cationic fullerene derivative 1 with ammonium head group directly connected to C60 skeleton in tetrahydrofuran (THF)-water (H2O) binary mixtures and in pure H2O were investigated. It was found that the UV-Vis spectra of ammo-nium 1 in the THF-H2O mixtures with THF% ≥ 20% were nearly overlapped, while those with THF% < 20% showed broadened and red-shifted peaks, indicating the formation of aggregates. Corresponding to the UV-Vis spectral changes, the solvatochromism of ammonium 1 in THF-H2O mixtures was observed. Ammonium 1 in binary THF-H2O mixtures existing as the monomer state could aggregate upon pro-longed standing. Higher temperature and lower concentra-tion speeded up the aggregation process.展开更多
基金the financial supports from the National Natural Science Foundation of China(No.20703042)National Basic Research Program of China(No.2010CB923300)+1 种基金USTC-NSRL Association Funding(No.KY2060030009)the Fundamental Research Funds for the Central Universities
文摘The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible（Fe2＋,Mo6＋） and （Fe3＋,Mo5＋）valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.
文摘The feasibility of photocatalytic degradation of X 3B azo dye by TiO 2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO 2/beads, airflow, as well as the concentrations of H 2O 2, Fe 3+ , Mg 2+ and Na + on the photocatalytic degradation of X 3B azo dye were also studied. The results showed that 25 mg/dm 3 X 3B azo dye can be photocatalytically degraded completely by 30 min illumination with a 375W medium pressure mercury lamp. Adding a small amount of H 2O 2 or Fe 3+ , the efficiencies of photocatalytic degradation of X 3B azo dye were increased rapidly. The mechanisms of the reaction and the role of the additives were also investigated. After 120 hours TiO 2/beads showed no significant loss of the photocatalytic activity.
文摘We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.
文摘Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks （MOFs） possess uniform, continuous, and permeable channels, they are valu- able candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks （ZIF-8） nanoparticles inside the pore of an as-formed 3D reduced graphene oxide （rGO） hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in allmline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity.
文摘The Ni/CeO_2-ZrO_2-Al_2O_3 catalyst with different Al_2O_3 and NiO contentswere prepared by hydrothermal synthesis method. The catalytic performance for CO_2 reforming of CH_4reaction, the interaction among components and the relation between Ni content and catalyst surfacebasicity were investigated. Results show that the interaction between NiO and Al_2O_3 is strongerthan that between NiO and CeO_2-ZrO_2. The addition of Al_2O_3 can prevent the formation of largemetallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excessAl_2O_3 causes the catalyst to deactivate easily. The interaction between NiO and CeO_2 results inmore facile reduction of surface CeO_2. The existence of a small amount of metallic Ni can increasethe number of basic sites. As metallic Ni may preferentially reside on the strong basic sites,increasing Ni content can weaken the catalyst basicity.
文摘Mixed alcohol is of great promise as octane improver in automotive fuel,and hopeful to replace the MTBE to reduce the environmental pollution,In this field,alkali-promted molybdenum-based catalysts have been given special interest because of their excellent sulfur-tolerance for synthesis of mixed alcohol from CO+H2,It was reported that the coblat is a favorable promoter for enhancing alcohol production,especially for improving the selectivity for C2+ alcohol[1-3],moreover,strong interaction between Con and Mo is in favor of mixed alcohol synthesis[4].Recently,we prpared a kind of K-Co-Mo ultrafine particles by sol-gel method and it shows much smaller particle size but higher activty and selectivity toward alcohol formation than the one prepared by conventional method[5],The aim of the present work is to research the micostructures of the Mo and Co species in the K-Co-Mo samples prepared by different method.
文摘Pulsed laser photolysis/laser-induced fluores-cence 0LP-LIF) is utilized to measure rate constants for C2(a^3Пu) reactions with NO, N2O, O2, H2 and NH3. Multiphoton dissociation of C2C!4 at 266 nm is employed for the generation of C2(a^3Пu) radicals. The C2(a^3Пu) concentration is monitored by the fluorescence of the (0, 0) band of the (d^3Пg←→a^3Пu) transition at 516.5 nm. C2(a^3Пu) removal rate constants for the reactions are determined as kNO = (5.46 × 0.10) × 10^-11- cm^3 molecule^-1 s^-1, kN2O = (1.63 × 0.20) × 10^-13 cm^3 molecule^-1 s^-1, kN2O = (1.58 × 0.16) × 10^-11 cm^3 molecule^-l s^-1, kO2 = (5.92 × 1.00) × 10^-14 cm^3 molecule^-1 s^-1, kH2 < 1.0× 10^-14 cm^3 molecule^-1 s^-1. Based on the data analysis and theoretical calculation, we suggest that the C2(a^3Пu) reactions with H2 and NH3 proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C2(a^3Пu) with H2 and NH3.
文摘The UV-Vis spectra, HRTEM and AFM images of cationic fullerene derivative 1 with ammonium head group directly connected to C60 skeleton in tetrahydrofuran (THF)-water (H2O) binary mixtures and in pure H2O were investigated. It was found that the UV-Vis spectra of ammo-nium 1 in the THF-H2O mixtures with THF% ≥ 20% were nearly overlapped, while those with THF% < 20% showed broadened and red-shifted peaks, indicating the formation of aggregates. Corresponding to the UV-Vis spectral changes, the solvatochromism of ammonium 1 in THF-H2O mixtures was observed. Ammonium 1 in binary THF-H2O mixtures existing as the monomer state could aggregate upon pro-longed standing. Higher temperature and lower concentra-tion speeded up the aggregation process.
