It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. ...It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline Ti O2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3.The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline Ti O2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline Ti O2,due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline Ti O2 prepared at R HNO3= 0.8, containing80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity,about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline Ti O2 will enrich the chemistry of the Ti O2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.展开更多
OMS-2 nanorod catalysts were synthesized by a hydrothermal redox reaction method using Mn SO4（OMS-2-SO4） and Mn（CH3COO）2（OMS-2-AC） as precursors. SO4^2--doped OMS-2-AC catalysts with different SO4^2-concentratio...OMS-2 nanorod catalysts were synthesized by a hydrothermal redox reaction method using Mn SO4（OMS-2-SO4） and Mn（CH3COO）2（OMS-2-AC） as precursors. SO4^2--doped OMS-2-AC catalysts with different SO4^2-concentrations were prepared next by adding（NH4）2SO4solution into OMS-2-AC samples to investigate the effect of the anion SO4^2-on the OMS-2-AC catalyst. All catalysts were then tested for the catalytic oxidation of ethanol. The OMS-2-SO4 catalyst synthesized demonstrated much better activity than OMS-2-AC. The SO4^2-doping greatly influenced the activity of the OMS-2-AC catalyst, with a dramatic promotion of activity for suitable concentration of SO4^2-（SO4/catalyst = 0.5% W/W）. The samples were characterized by X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）,inductively coupled plasma optical emission spectroscopy（ICP-OES）, NH3-TPD and H2-TPR techniques. The results showed that the presence of a suitable amount of SO4^2-species in the OMS-2-AC catalyst could decrease the Mn–O bond strength and also enhance the lattice oxygen and acid site concentrations, which then effectively promoted the catalytic activity of OMS-2-AC toward ethanol oxidation. Thus it was confirmed that the better catalytic performance of OMS-2-SO4 compared to OMS-2-AC is due to the presence of some residual SO4^2-species in OMS-2-SO4 samples.展开更多
The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light e...The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light exposure, and hydrodynamics. For scale up purposes, continuous reactors with high capacity are required for treating large amounts of feedstock. In this work, two types of reactors based on different hydrodynamics, fluidized and spouted reactors, were designed to work under light irradiation inside the reactor. The efficiency of the reactors for volatile organic compound removal from high flow rates of air under Hg lamp irradiation using N-F-TiO2 photocatalyst was investigated. The performance of the fluidized bed and spouted bed were evaluated and compared at the same weight hourly space velocity of feed stream through the reactor. The results revealed that 80% of the initial acetaldehyde was removed in the fluidized bed after about 200 min, while in the spouted bed the acetaldehyde was totally removed after about 120 min.展开更多
基金supported by grants from the National High Technology Research and Development Program (863) of China (Nos. 2010AA064902 and 2012AA062702)the Key Innovation Team for Science and Technology of Zhejiang Province (No. 2009R50047)
文摘It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline Ti O2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3.The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline Ti O2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline Ti O2,due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline Ti O2 prepared at R HNO3= 0.8, containing80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity,about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline Ti O2 will enrich the chemistry of the Ti O2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.
基金financially supported by the National Natural Science Foundation of China (No. 21422706)the Program of the Ministry of Science and Technology of China (No. 2012AA062702)
文摘OMS-2 nanorod catalysts were synthesized by a hydrothermal redox reaction method using Mn SO4（OMS-2-SO4） and Mn（CH3COO）2（OMS-2-AC） as precursors. SO4^2--doped OMS-2-AC catalysts with different SO4^2-concentrations were prepared next by adding（NH4）2SO4solution into OMS-2-AC samples to investigate the effect of the anion SO4^2-on the OMS-2-AC catalyst. All catalysts were then tested for the catalytic oxidation of ethanol. The OMS-2-SO4 catalyst synthesized demonstrated much better activity than OMS-2-AC. The SO4^2-doping greatly influenced the activity of the OMS-2-AC catalyst, with a dramatic promotion of activity for suitable concentration of SO4^2-（SO4/catalyst = 0.5% W/W）. The samples were characterized by X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）,inductively coupled plasma optical emission spectroscopy（ICP-OES）, NH3-TPD and H2-TPR techniques. The results showed that the presence of a suitable amount of SO4^2-species in the OMS-2-AC catalyst could decrease the Mn–O bond strength and also enhance the lattice oxygen and acid site concentrations, which then effectively promoted the catalytic activity of OMS-2-AC toward ethanol oxidation. Thus it was confirmed that the better catalytic performance of OMS-2-SO4 compared to OMS-2-AC is due to the presence of some residual SO4^2-species in OMS-2-SO4 samples.
文摘The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light exposure, and hydrodynamics. For scale up purposes, continuous reactors with high capacity are required for treating large amounts of feedstock. In this work, two types of reactors based on different hydrodynamics, fluidized and spouted reactors, were designed to work under light irradiation inside the reactor. The efficiency of the reactors for volatile organic compound removal from high flow rates of air under Hg lamp irradiation using N-F-TiO2 photocatalyst was investigated. The performance of the fluidized bed and spouted bed were evaluated and compared at the same weight hourly space velocity of feed stream through the reactor. The results revealed that 80% of the initial acetaldehyde was removed in the fluidized bed after about 200 min, while in the spouted bed the acetaldehyde was totally removed after about 120 min.
