Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the cryst...Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.展开更多
A new quenching process using the cold pyrolysis gas has been proposed for the partial oxidation(POX) of methane to recover the heat. The mixing of hot product gas and cold pyrolysis gas in milliseconds is critical to...A new quenching process using the cold pyrolysis gas has been proposed for the partial oxidation(POX) of methane to recover the heat. The mixing of hot product gas and cold pyrolysis gas in milliseconds is critical to this new approach. Two most widely-used rapid mixing configurations, i.e. the jet-in-cross-flow(JICF) and impinging flow configurations, are compared in terms of mixing and quenching performances using computational fluid dynamics(CFD) coupled with detailed reaction mechanism Leeds 1.5. The mixedness, residence time distribution, temperature decreasing rate and loss ratio of acetylene during the quenching are systematically studied. The results show that the impinging flow has a more uniform mixing and narrower residence time distribution than the JICF.However, the temperature decreasing rate of the mainstream is faster in the JICF than in the impinging flow. The loss ratio of acetylene in the quenching process is 2.89% for the JICF and 1.45% for the impinging flow, showing that the impinging flow configuration is better and feasible for the quenching of POX of methane.展开更多
Mesoporous Ce-Mn-Co ternary metal oxide was fabricated via an efficient oxalate-precursor-based soft reactive grinding route and used to activate H_(2)O_(2) for advanced oxidation of methylene blue in water.In additio...Mesoporous Ce-Mn-Co ternary metal oxide was fabricated via an efficient oxalate-precursor-based soft reactive grinding route and used to activate H_(2)O_(2) for advanced oxidation of methylene blue in water.In addition,Mn-Co binary oxide and pure Co_(3)O_(4) and Mn_(3)O_(4) were also synthesized as reference catalysts.These catalysts were characterized by X-ray diffraction,N_(2) adsorption-desorption,H_(2)-temperature programmed reduction,transmission electron microscopy,scanning electron microscopy and X-ray photoelectron spectroscopy.The results demonstrate that part of the Ce and Mn can be incorporated into the lattice of Co_(3)O_(4) and cause severe lattice distortion of the unit cell.Compared with the single or binary system,Ce-Mn-Co ternary metal oxide exhibits the best activity in methylene blue removal and nearly 100% decomposition rate and 84% COD removal rate can be achieved in 12 h,and with degradation rate of 93.5% after three rounds.These results are primarily attributed to the synergistic effect of Ce,Mn and Co,which can promote the formation of more lattice defects,higher specific surface area and smaller particle size.Quenching tests show that hydroxyl radicals(·OH) play more dominant role than superoxide radicals(·O_(2)^(-)).Kinetic studies were studied and the activation energies of all the catalysts were calculated.展开更多
文摘Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.
基金Supported by the National Natural Science Foundation of China(21276135)the Project of Chinese Ministry of Education(113004A)
文摘A new quenching process using the cold pyrolysis gas has been proposed for the partial oxidation(POX) of methane to recover the heat. The mixing of hot product gas and cold pyrolysis gas in milliseconds is critical to this new approach. Two most widely-used rapid mixing configurations, i.e. the jet-in-cross-flow(JICF) and impinging flow configurations, are compared in terms of mixing and quenching performances using computational fluid dynamics(CFD) coupled with detailed reaction mechanism Leeds 1.5. The mixedness, residence time distribution, temperature decreasing rate and loss ratio of acetylene during the quenching are systematically studied. The results show that the impinging flow has a more uniform mixing and narrower residence time distribution than the JICF.However, the temperature decreasing rate of the mainstream is faster in the JICF than in the impinging flow. The loss ratio of acetylene in the quenching process is 2.89% for the JICF and 1.45% for the impinging flow, showing that the impinging flow configuration is better and feasible for the quenching of POX of methane.
基金Project supported by the National Natural Science Foundation of China(21403093,21563014)the Foundation of Jiangxi Educational Committee(GJJ170278,GJJ190241)Jiangxi Province Key Research and Development Project(20192BBEL50029)。
文摘Mesoporous Ce-Mn-Co ternary metal oxide was fabricated via an efficient oxalate-precursor-based soft reactive grinding route and used to activate H_(2)O_(2) for advanced oxidation of methylene blue in water.In addition,Mn-Co binary oxide and pure Co_(3)O_(4) and Mn_(3)O_(4) were also synthesized as reference catalysts.These catalysts were characterized by X-ray diffraction,N_(2) adsorption-desorption,H_(2)-temperature programmed reduction,transmission electron microscopy,scanning electron microscopy and X-ray photoelectron spectroscopy.The results demonstrate that part of the Ce and Mn can be incorporated into the lattice of Co_(3)O_(4) and cause severe lattice distortion of the unit cell.Compared with the single or binary system,Ce-Mn-Co ternary metal oxide exhibits the best activity in methylene blue removal and nearly 100% decomposition rate and 84% COD removal rate can be achieved in 12 h,and with degradation rate of 93.5% after three rounds.These results are primarily attributed to the synergistic effect of Ce,Mn and Co,which can promote the formation of more lattice defects,higher specific surface area and smaller particle size.Quenching tests show that hydroxyl radicals(·OH) play more dominant role than superoxide radicals(·O_(2)^(-)).Kinetic studies were studied and the activation energies of all the catalysts were calculated.
