The influences of binder and molding method on the catalytic performance of methane aromatization in the absence of O2 over MoO3/ZSM-5 catalysts were investigated.SEM,NH3-TPD,FT-IR of adsorbed pyridine,N2 adsorption-d...The influences of binder and molding method on the catalytic performance of methane aromatization in the absence of O2 over MoO3/ZSM-5 catalysts were investigated.SEM,NH3-TPD,FT-IR of adsorbed pyridine,N2 adsorption-desorption,cyclohexane adsorption and XPS were employed to characterize the physical and chemical properties of the catalysts.It was found that SiO2 was a suitable binder for the catalyst due to its appropriate weak acidity.The laminar catalyst comprising of an inert spherical core and a MoO3/ZSM-5 laminar shell with 0.1 0.2 mm in thickness showed a better catalytic performance than the extruded catalyst.The improved activity of the laminar catalyst could be attributed to the easy carbonization of Mo species and the quick removal of reaction products from the catalyst surface.展开更多
The selective catalytic reduction(SCR) of NO_(x) with NH_(3)(NH_(3)-SCR) technology has been widely applied for reducing NO_(x) emissions from stationary and mobile sources.In this work,the extruded monolith MnO_(x)-C...The selective catalytic reduction(SCR) of NO_(x) with NH_(3)(NH_(3)-SCR) technology has been widely applied for reducing NO_(x) emissions from stationary and mobile sources.In this work,the extruded monolith MnO_(x)-CeO_(2)-TiO_(2) catalyst was installed in a cement kiln for NH_(3)-SCR of NO_(x),where the flue gas temperature was 110-140℃.It is found that the monolith catalyst is severely deactivated after operating for about 200 h with almost no NO_(x) conversion at 160℃ under GHSV of 50000 h^(-1),while the fresh monolith catalyst remains 60% NO_(x) conversion.Scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS),X-ray photoelectron spectroscopy(XPS),temperature-programmed desorption of SO_(2)(SO_(2)-TPD) and thermogravimetric-differential thermal analysis(TG-DTG) experiments reveal that both MnO_(x) and CeO_(2) oxides in monolith are severely sulfated to manganese sulfate and cerium sulfate,and the external monolith walls are covered by massive ceria sulfate and little ammonium nitrate.In situ diffuse reflectance infrared Fourier trans form spectroscopy(DRIFTS) analysis demonstrates that the formation of nitrates at low temperatures is inhibited due to the occupation of active sites in MnO_(x)-CeO_(2)-TiO_(2) by sulfates,resulting in the decrease of low temperature activity.After washing with water,the activity of deactivated monolith catalyst can be partially recovered,together with significant loss of manganese and cerium from monolith.展开更多
基金supported by the National Basic Research Program of China(Grant 2005CB 221405)
文摘The influences of binder and molding method on the catalytic performance of methane aromatization in the absence of O2 over MoO3/ZSM-5 catalysts were investigated.SEM,NH3-TPD,FT-IR of adsorbed pyridine,N2 adsorption-desorption,cyclohexane adsorption and XPS were employed to characterize the physical and chemical properties of the catalysts.It was found that SiO2 was a suitable binder for the catalyst due to its appropriate weak acidity.The laminar catalyst comprising of an inert spherical core and a MoO3/ZSM-5 laminar shell with 0.1 0.2 mm in thickness showed a better catalytic performance than the extruded catalyst.The improved activity of the laminar catalyst could be attributed to the easy carbonization of Mo species and the quick removal of reaction products from the catalyst surface.
基金supported by the National Natural Science Foundation of China (22188102,22072179)Cultivating Project of Strategic Priority Research Program of Chinese Academy of Sciences (XDPB190201)。
文摘The selective catalytic reduction(SCR) of NO_(x) with NH_(3)(NH_(3)-SCR) technology has been widely applied for reducing NO_(x) emissions from stationary and mobile sources.In this work,the extruded monolith MnO_(x)-CeO_(2)-TiO_(2) catalyst was installed in a cement kiln for NH_(3)-SCR of NO_(x),where the flue gas temperature was 110-140℃.It is found that the monolith catalyst is severely deactivated after operating for about 200 h with almost no NO_(x) conversion at 160℃ under GHSV of 50000 h^(-1),while the fresh monolith catalyst remains 60% NO_(x) conversion.Scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS),X-ray photoelectron spectroscopy(XPS),temperature-programmed desorption of SO_(2)(SO_(2)-TPD) and thermogravimetric-differential thermal analysis(TG-DTG) experiments reveal that both MnO_(x) and CeO_(2) oxides in monolith are severely sulfated to manganese sulfate and cerium sulfate,and the external monolith walls are covered by massive ceria sulfate and little ammonium nitrate.In situ diffuse reflectance infrared Fourier trans form spectroscopy(DRIFTS) analysis demonstrates that the formation of nitrates at low temperatures is inhibited due to the occupation of active sites in MnO_(x)-CeO_(2)-TiO_(2) by sulfates,resulting in the decrease of low temperature activity.After washing with water,the activity of deactivated monolith catalyst can be partially recovered,together with significant loss of manganese and cerium from monolith.
