The regeneration of commercial SCR（Selective Catalyst Reduction） catalysts deactivated by Pb and other elements was studied.The deactivated catalyst samples were prepared by chemical impregnation with mixed solution...The regeneration of commercial SCR（Selective Catalyst Reduction） catalysts deactivated by Pb and other elements was studied.The deactivated catalyst samples were prepared by chemical impregnation with mixed solution containing K_2SO_4,Na_2SO_4,CaSO_4,Pb（NO_3）_2and NH_4H_2PO_4.A novel method combining Ethylenediaminetetraacetic acid disodium salt（EDTA-2Na） and H_2SO_4solution（viz.catalysts treated by dilute EDTA-2Na and H_2SO_4 solution in sequence） was used to recover the activity of deactivated samples,and the effect was compared with single H_2SO_4,oxalic acid,acetic acid,EDTA or HNO_3 solutions.The surface structure,acidity and reducibility of samples were characterized by N_2adsorption–desorption,inductively coupled plasma optical emission spectrometer（ICP-OES）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,X-ray fluorescence（XRF）,H-2-temperature programmed section（H_2-TPR）,NH3-temperature programmed desorption（NH3-TPD） and in situ DRIFTS.Impurities caused a decrease of specific surface area and surface reducibility,as well as Br？nsted acid sites,and therefore led to severe deactivation of the SCR catalyst.The use of an acid solution alone possibly eliminated the impurities on the deactivated catalyst to some extent,and also increased the specific surface area and Br？nsted acid sites and promoted the surface reducibility,thus recovered the activity partially.The combination of EDTA-2Na and H_2SO_4 could remove most of the impurities and improve the activity significantly.The removal of Pb should be an important factor for regeneration.Due to a high removal rate for Pb and other impurities,the combination of EDTA-2Na and H_2SO_4 solutions provided the best efficiency.展开更多
CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catal...CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO4/TiO2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH3,temperature-programmed reduction of H2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO4 changed surface reducibility of the catalyst and favored the process of NH3 oxidation to nitrogen oxides(NOx).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃)decreased largely.展开更多
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB05050500)the National Natural Science Foundation(No.21403210)the Bureau of Science and Technology,Fujian Province,China(No.2015H0043)
文摘The regeneration of commercial SCR（Selective Catalyst Reduction） catalysts deactivated by Pb and other elements was studied.The deactivated catalyst samples were prepared by chemical impregnation with mixed solution containing K_2SO_4,Na_2SO_4,CaSO_4,Pb（NO_3）_2and NH_4H_2PO_4.A novel method combining Ethylenediaminetetraacetic acid disodium salt（EDTA-2Na） and H_2SO_4solution（viz.catalysts treated by dilute EDTA-2Na and H_2SO_4 solution in sequence） was used to recover the activity of deactivated samples,and the effect was compared with single H_2SO_4,oxalic acid,acetic acid,EDTA or HNO_3 solutions.The surface structure,acidity and reducibility of samples were characterized by N_2adsorption–desorption,inductively coupled plasma optical emission spectrometer（ICP-OES）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,X-ray fluorescence（XRF）,H-2-temperature programmed section（H_2-TPR）,NH3-temperature programmed desorption（NH3-TPD） and in situ DRIFTS.Impurities caused a decrease of specific surface area and surface reducibility,as well as Br？nsted acid sites,and therefore led to severe deactivation of the SCR catalyst.The use of an acid solution alone possibly eliminated the impurities on the deactivated catalyst to some extent,and also increased the specific surface area and Br？nsted acid sites and promoted the surface reducibility,thus recovered the activity partially.The combination of EDTA-2Na and H_2SO_4 could remove most of the impurities and improve the activity significantly.The removal of Pb should be an important factor for regeneration.Due to a high removal rate for Pb and other impurities,the combination of EDTA-2Na and H_2SO_4 solutions provided the best efficiency.
基金supported by the National Natural Science Foundation of China(Nos.21906127,21677114,21876139 and 21922606)the Key R&D Program of Shaanxi Province(Nos.2019SF-244 and 2019ZDLSF05-05-02)+4 种基金the China PostdoctoralScience Foundation(No.2016M602831)Natural Science Foundation of Shaanxi Province,China(No.2019JQ-502)the Fundamental Research Funds for the Central Universities(Nos.xjj2017113 and xjj2017170)financial supports from the China Scholarship Councilthe support of K.C.Wong Education Foundation
文摘CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO4/TiO2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH3,temperature-programmed reduction of H2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO4 changed surface reducibility of the catalyst and favored the process of NH3 oxidation to nitrogen oxides(NOx).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃)decreased largely.
