A series of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(NixW/SBA-15, Ni-5%, x=1, 10, 50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), ...A series of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(NixW/SBA-15, Ni-5%, x=1, 10, 50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H2-temperature programmed reduction(H2-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H2-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H2WO4 can significantly improve Ni dispersion on SBA-15 (Ni50W/SBA-15) with Ni0 and non-stoichiometric WOx species as small as ca. 3.6 nm. The prepared NixW/SBA-15 was utilized for CO_(2) hydrogenation, which showed that a higher W content restrained the CO_(2) hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni50W/SBA-15 catalyst showed the best performance with a 93.3% CO_(2) conversion rate and 99.7% selectivity for methane at 400 oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH4. This work provides a new clue to fabricating efficient CO_(2) conversion bimetallic materials.展开更多
Thiacalixarene-supported Co_(32) nanoclusters encapsulated in polyacrylonitrile nanofibers(Co_(32)@PAN-NFs)by electrospinning have been utilized as precursors to fabricate N-doped CoO@Co_(9)S_(8) carbon nanofibers(CoO...Thiacalixarene-supported Co_(32) nanoclusters encapsulated in polyacrylonitrile nanofibers(Co_(32)@PAN-NFs)by electrospinning have been utilized as precursors to fabricate N-doped CoO@Co_(9)S_(8) carbon nanofibers(CoO@Co_(9)S_(8)@CNFs)for superior Li-ion storage.The S-rich Co_(32) clusters capped by organic sheets afforded the well dispersed cobalt oxide/sulfide nanoparticles embedded in carbon nanofiber composites by direct calcination.The N-doped CoO@Co_(9)S_(8)@CNFs nanocomposites have been utilized as anode materials for lithium ion battery with the reversible capabilities being of 1051.8,967.6,894.7,782.7,669.5 and 525.4 mA·h/g at 0.1,0.2,0.5,1,2 and 3 A/g,respectively.The CoO@Co_(9)S_(8)@CNFs also showed a relatively high stable capacity of 551.7 mA·h/g at the current density of 1 A/g after 200 cycles of rate experiments.The as-obtained N-doped CoO@Co_(9)S_(8)@CNFs nanocomposites exhibited superior reversible capacity,rate performance,Coulomb efficiency(74.5%vs.63.9%)and cyclic stability comparing with the CoO@Co_(9)S_(8)@C derived from simple annealing of Co_(32) templates.展开更多
基金supported by the National Natural Science Foundation of China (No.91961110).
文摘A series of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(NixW/SBA-15, Ni-5%, x=1, 10, 50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H2-temperature programmed reduction(H2-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H2-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H2WO4 can significantly improve Ni dispersion on SBA-15 (Ni50W/SBA-15) with Ni0 and non-stoichiometric WOx species as small as ca. 3.6 nm. The prepared NixW/SBA-15 was utilized for CO_(2) hydrogenation, which showed that a higher W content restrained the CO_(2) hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni50W/SBA-15 catalyst showed the best performance with a 93.3% CO_(2) conversion rate and 99.7% selectivity for methane at 400 oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH4. This work provides a new clue to fabricating efficient CO_(2) conversion bimetallic materials.
基金supported by the National Natural Science Foundation of China(No.91961110)the Liaoning Revitalization Talents Program,China(No.XLYC1807059)the Talent Scientific Research/Scientific Research Cultivation Fund of Liaoning Petrochemical University,China(Nos.2016XJJ-001/2016PY-014).
文摘Thiacalixarene-supported Co_(32) nanoclusters encapsulated in polyacrylonitrile nanofibers(Co_(32)@PAN-NFs)by electrospinning have been utilized as precursors to fabricate N-doped CoO@Co_(9)S_(8) carbon nanofibers(CoO@Co_(9)S_(8)@CNFs)for superior Li-ion storage.The S-rich Co_(32) clusters capped by organic sheets afforded the well dispersed cobalt oxide/sulfide nanoparticles embedded in carbon nanofiber composites by direct calcination.The N-doped CoO@Co_(9)S_(8)@CNFs nanocomposites have been utilized as anode materials for lithium ion battery with the reversible capabilities being of 1051.8,967.6,894.7,782.7,669.5 and 525.4 mA·h/g at 0.1,0.2,0.5,1,2 and 3 A/g,respectively.The CoO@Co_(9)S_(8)@CNFs also showed a relatively high stable capacity of 551.7 mA·h/g at the current density of 1 A/g after 200 cycles of rate experiments.The as-obtained N-doped CoO@Co_(9)S_(8)@CNFs nanocomposites exhibited superior reversible capacity,rate performance,Coulomb efficiency(74.5%vs.63.9%)and cyclic stability comparing with the CoO@Co_(9)S_(8)@C derived from simple annealing of Co_(32) templates.
