A reconstruction strategy has been developed to synthesize Cu-SAPO-34 with a wide crystallization phase region,high solid yield,and tunable Si and Cu contents.Cu-rich SAPO-34 was prepared from a Cu-amine complex,which...A reconstruction strategy has been developed to synthesize Cu-SAPO-34 with a wide crystallization phase region,high solid yield,and tunable Si and Cu contents.Cu-rich SAPO-34 was prepared from a Cu-amine complex,which acted as a precursor and Cu source for the reconstruction synthesis.The role of the Cu-amine complex as a template was restricted,which allowed easier control over the Cu and Si contents than in the previously reported"one-pot"synthesis method.Characterization of the material revealed that the Si(4Al)coordination environment dominates the synthesized Cu-SAPO-34 catalysts.High-temperature hydrothermal treatment increased the isolated Cu2+content slightly,and the acid sites in the low-silica catalyst are more resistant to hydrothermal treatment than those of the existing catalysts.The obtained materials,especially the low-silica Cu-SAPO-34 sample,exhibit excellent catalytic activity and hydrothermal stability for the selective catalytic reduction of NOx by NH3(NH3-SCR).In addition,the influence of the catalyst acidity on the NH3-SCR reaction was also investigated and is discussed.The high synthetic efficiency and outstanding catalytic performance make Cu-SAPO-34 synthesized by the reconstruction method a promising catalyst for the NH3-SCR process.展开更多
The influence of the various preparation methods of Cu-SAPO-34 nanocatalysts on the selective catalytic reduction of NO with NH3 under excess oxygen was studied. Cu-SAPO-34 nanocatalysts were prepared by using four te...The influence of the various preparation methods of Cu-SAPO-34 nanocatalysts on the selective catalytic reduction of NO with NH3 under excess oxygen was studied. Cu-SAPO-34 nanocatalysts were prepared by using four techniques： conventional impregnation（IM）,ultrasound-enhanced impregnation（UIM）, conventional deposition precipitation（DP） using Na OH and homogeneous deposition precipitation（HDP） using urea. These catalysts were characterized in detail by various techniques such as N2-sorption, XRD, TEM, H2-TPR,NH3-TPD and XPS to understand the catalyst structure, the nature and the dispersed state of the copper species, and the acid sites for NH3 adsorption. All of the nanocatalysts showed high activities for NO removal. However, the activities were different and followed the sequence of Cu-SAPO-34（UIM） 〉 Cu-SAPO-34（HDP） 〉 Cu-SAPO-34（IM） 〉 Cu-SAPO-34（DP）.Based on the obtained results, it was concluded that the NO conversion on Cu-SAPO-34 nanocatalysts was mainly related to the high reducibility of the isolated Cu^2＋ions and Cu O species, the number of the acid sites and the dispersion of Cu O species on SAPO-34.展开更多
文摘A reconstruction strategy has been developed to synthesize Cu-SAPO-34 with a wide crystallization phase region,high solid yield,and tunable Si and Cu contents.Cu-rich SAPO-34 was prepared from a Cu-amine complex,which acted as a precursor and Cu source for the reconstruction synthesis.The role of the Cu-amine complex as a template was restricted,which allowed easier control over the Cu and Si contents than in the previously reported"one-pot"synthesis method.Characterization of the material revealed that the Si(4Al)coordination environment dominates the synthesized Cu-SAPO-34 catalysts.High-temperature hydrothermal treatment increased the isolated Cu2+content slightly,and the acid sites in the low-silica catalyst are more resistant to hydrothermal treatment than those of the existing catalysts.The obtained materials,especially the low-silica Cu-SAPO-34 sample,exhibit excellent catalytic activity and hydrothermal stability for the selective catalytic reduction of NOx by NH3(NH3-SCR).In addition,the influence of the catalyst acidity on the NH3-SCR reaction was also investigated and is discussed.The high synthetic efficiency and outstanding catalytic performance make Cu-SAPO-34 synthesized by the reconstruction method a promising catalyst for the NH3-SCR process.
基金financial support from University of Tabriz and Iranian Nanotechnology Initiative
文摘The influence of the various preparation methods of Cu-SAPO-34 nanocatalysts on the selective catalytic reduction of NO with NH3 under excess oxygen was studied. Cu-SAPO-34 nanocatalysts were prepared by using four techniques： conventional impregnation（IM）,ultrasound-enhanced impregnation（UIM）, conventional deposition precipitation（DP） using Na OH and homogeneous deposition precipitation（HDP） using urea. These catalysts were characterized in detail by various techniques such as N2-sorption, XRD, TEM, H2-TPR,NH3-TPD and XPS to understand the catalyst structure, the nature and the dispersed state of the copper species, and the acid sites for NH3 adsorption. All of the nanocatalysts showed high activities for NO removal. However, the activities were different and followed the sequence of Cu-SAPO-34（UIM） 〉 Cu-SAPO-34（HDP） 〉 Cu-SAPO-34（IM） 〉 Cu-SAPO-34（DP）.Based on the obtained results, it was concluded that the NO conversion on Cu-SAPO-34 nanocatalysts was mainly related to the high reducibility of the isolated Cu^2＋ions and Cu O species, the number of the acid sites and the dispersion of Cu O species on SAPO-34.
