The studies are conducted in laboratory to determine the adsorption-desorption behavior of BTX (benzene, toluene and o-xylene) in gas phase on Fe, Fe-Al pillared clays adsorbents. In experimental conditions of constan...The studies are conducted in laboratory to determine the adsorption-desorption behavior of BTX (benzene, toluene and o-xylene) in gas phase on Fe, Fe-Al pillared clays adsorbents. In experimental conditions of constant atmospheric pressure, initial concentrations with an increasing volume (0.5 - 2 ml) injected benzene (2.25), toluene (1.89) and o-xylene (1.66) μmol/L at T (40℃, 60℃ and 80℃), and the adsorption increases with increase of temperature, indicating that the adsorption process would be a chemical adsorption rather than physical one. The results are shown that the BTX adsorption data fitted very well (R2 > 0.999) to the both equations Langmuire and Elovitch for the three samples: bentonite (B), Fe-bentonite () and Fe-Al/bentonite (). At 80℃, the BTX adsorption capacity increased in the following order: . The maximum adsorption capacity () at 80℃ is 175.13, 171.84 and 171.81 μg/g respectively for benzene, toluene and o-xylene for;the last is a good adsorbent of BTX removal. The benzene diffuses faster than toluene and o-xylene. Thermodynamic parameters, such as ,and are also discussed and the results suggested that the BTX adsorption on all samples used is a spontaneous and endothermic process. Desorption studies show that BTX is very easily desorbed with .展开更多
Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidati...Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidation of formaldehyde (HCHO) at low temperatures. The Ag/TiO<sub>2</sub> catalyst exhibited strong catalytic performance, converting HCHO to CO<sub>2</sub> and H<sub>2</sub>O at around 95°C. However, the Ag/Al<sub>2</sub>O<sub>3</sub> catalysts showed much lower activity and reached 100% conversion at 125°C. The Ag-based catalysts were next characterized by several methods (XRD, TEM, FT-R, BET and H<sub>2</sub>-TPR). Results of characterization revealed that support dramatically impacts the size and dispersion of Ag particles. The XRD analysis showed the existence of different peaks of the silver on the surface of Al<sub>2</sub>O<sub>3</sub> in the contrast with TiO<sub>2</sub> no specific peaks exist. Therefore, the size of the Ag particles and their dispersion are the most important factors that affect their catalytic performance for formaldehyde oxidation. In terms of catalytic performance for HCHO oxidation, the Ag/TiO<sub>2 </sub>catalyst possesses the best Ag dispersion, as well as the smallest Ag particle size.展开更多
文摘The studies are conducted in laboratory to determine the adsorption-desorption behavior of BTX (benzene, toluene and o-xylene) in gas phase on Fe, Fe-Al pillared clays adsorbents. In experimental conditions of constant atmospheric pressure, initial concentrations with an increasing volume (0.5 - 2 ml) injected benzene (2.25), toluene (1.89) and o-xylene (1.66) μmol/L at T (40℃, 60℃ and 80℃), and the adsorption increases with increase of temperature, indicating that the adsorption process would be a chemical adsorption rather than physical one. The results are shown that the BTX adsorption data fitted very well (R2 > 0.999) to the both equations Langmuire and Elovitch for the three samples: bentonite (B), Fe-bentonite () and Fe-Al/bentonite (). At 80℃, the BTX adsorption capacity increased in the following order: . The maximum adsorption capacity () at 80℃ is 175.13, 171.84 and 171.81 μg/g respectively for benzene, toluene and o-xylene for;the last is a good adsorbent of BTX removal. The benzene diffuses faster than toluene and o-xylene. Thermodynamic parameters, such as ,and are also discussed and the results suggested that the BTX adsorption on all samples used is a spontaneous and endothermic process. Desorption studies show that BTX is very easily desorbed with .
文摘Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidation of formaldehyde (HCHO) at low temperatures. The Ag/TiO<sub>2</sub> catalyst exhibited strong catalytic performance, converting HCHO to CO<sub>2</sub> and H<sub>2</sub>O at around 95°C. However, the Ag/Al<sub>2</sub>O<sub>3</sub> catalysts showed much lower activity and reached 100% conversion at 125°C. The Ag-based catalysts were next characterized by several methods (XRD, TEM, FT-R, BET and H<sub>2</sub>-TPR). Results of characterization revealed that support dramatically impacts the size and dispersion of Ag particles. The XRD analysis showed the existence of different peaks of the silver on the surface of Al<sub>2</sub>O<sub>3</sub> in the contrast with TiO<sub>2</sub> no specific peaks exist. Therefore, the size of the Ag particles and their dispersion are the most important factors that affect their catalytic performance for formaldehyde oxidation. In terms of catalytic performance for HCHO oxidation, the Ag/TiO<sub>2 </sub>catalyst possesses the best Ag dispersion, as well as the smallest Ag particle size.
