The selective catalytic reduction （SCR） of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning...The selective catalytic reduction （SCR） of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning which seriously limits their practical application. This review summarized sulfur poisoning mechanisms of various SCR deNG catalysts and strategies to reduce deactivation caused by SO2 such as doping metals, controlling the structures and morphologies of the catalysts, and selecting appropriate supports. The methods and procedures of catalysts preparation and the reaction conditions also have effect on SO2-resistance of the catalysts. Several novel catalyst systems that exhibited good SO2 resistance are also introduced. This paper could provide guidance for the development of highly efficient sulfur-tolerant deNOx catalysts.展开更多
The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also dete...The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.展开更多
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministrythe National Natural Science Foundation of China(21506150)
文摘The selective catalytic reduction （SCR） of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning which seriously limits their practical application. This review summarized sulfur poisoning mechanisms of various SCR deNG catalysts and strategies to reduce deactivation caused by SO2 such as doping metals, controlling the structures and morphologies of the catalysts, and selecting appropriate supports. The methods and procedures of catalysts preparation and the reaction conditions also have effect on SO2-resistance of the catalysts. Several novel catalyst systems that exhibited good SO2 resistance are also introduced. This paper could provide guidance for the development of highly efficient sulfur-tolerant deNOx catalysts.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.
