Alkali metal K in exhaust gas has a deactivation effect on NH_(3)-SCR catalysts.In this work,it is discovered that the addition of Ho on CeTi catalyst can remarkably strengthen its K tolerance.The conclusions of Bruna...Alkali metal K in exhaust gas has a deactivation effect on NH_(3)-SCR catalysts.In this work,it is discovered that the addition of Ho on CeTi catalyst can remarkably strengthen its K tolerance.The conclusions of Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),NH_(3) temperature programmed desorption(NH_(3)-TPD)and H_(2)temperature programmed reduction(H_(2)-TPR)analyses demonstrate that the enhancement of K resistance mainly originates from its stronger surface acidity and redox capability,the higher concentration of Ce^(3+)species and surface chemisorbed oxygen.In situ DRIFT analysis reveals that the introduction of Ho on CeTi can remarkably improve the adsorption of NH_(3) and NO_(x) species on catalyst surface,accompanied by the intensified reactivity of ad-NH_(3) species,which should also administer to improve the K resistance.展开更多
A Ce（0.3）TiOxoxide carrier was synthesized via a sol–gel process,and Ce（0.3）TiOxsupported metal（M=Cd,Mn,Fe,W,Mo）oxide catalysts were prepared by the method of incipient-wetness impregnation.The catalysts were c...A Ce（0.3）TiOxoxide carrier was synthesized via a sol–gel process,and Ce（0.3）TiOxsupported metal（M=Cd,Mn,Fe,W,Mo）oxide catalysts were prepared by the method of incipient-wetness impregnation.The catalysts were characterized by means of X-ray diffraction（XRD）,Brunauer–Emmett–Teller（BET）analysis,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared（FT–IR）spectroscopy,UV–Visdiffusereflectancespectroscopy（UV–VisDRS）,and Temperature-programmed reduction with H2（H2-TPR）.The catalytic activities for de-NO（x ）were evaluated by the NH3-SCR reaction.Among all the catalysts tested,the 2 wt.%Cd/Ce（0.3）TiOxcatalyst exhibited the best NH3-SCR performance,with a wide temperature window of 250–450℃ for NO conversion above 90%.Moreover,the catalyst showed N2 selectivity greater than 99%from 200 to 450℃.展开更多
Ce x Ti 1- x O 2 mixed oxides of different mole ratios ( x =0, 0.1, 0.2～0.9, 1.0) were prepared by co precipitation of TiCl 4 with Ce(NO 3) 3 and then loaded with different amounts of CuO. The effe...Ce x Ti 1- x O 2 mixed oxides of different mole ratios ( x =0, 0.1, 0.2～0.9, 1.0) were prepared by co precipitation of TiCl 4 with Ce(NO 3) 3 and then loaded with different amounts of CuO. The effects of CuO on NO+CO reaction were investigated, and the structure and reductive properties of various CuO/Ce x Ti 1- x O 2 were characterized by the methodologies of BET, TPR and XRD. The results show that different Ce/Ti mole ratios and calcination temperatures induce changes of structure and reductive properties of the Ce x Ti 1- x O 2 mixed oxides. When x =0.1～0.5, amorphous CeTi 2O 6 phase mainly forms at 650 ℃ compared to the formation of CeTi 2O 6 which crystallizes at 800 ℃. When x >0.6, some TiO 2 enters the CeO 2 lattice and a CeO 2 TiO 2 solid solution is formed. The activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 650 ℃ is largely affected by the x values, which is the highest when x =0.3, 0.4 and 0.9. The NO conversion reaches 70% at a reaction temperature of 150 ℃. By comparison, the x values have little effect on the activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 800 ℃ . There are strong interactions between CuO and CeTi 2O 6, i.e., formation of the CeTi 2O 6 phase shifts the CuO reduction peak temperature from 380 to 200 ℃, and CuO, in turn, shifts the CeTi 2O 6 reduction peak temperature from 600 to 300 ℃.展开更多
A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane （DMDS） as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalys...A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane （DMDS） as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm^3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.展开更多
基金Project supported by the National Key R&D Program of China(2018YFB0605002)。
文摘Alkali metal K in exhaust gas has a deactivation effect on NH_(3)-SCR catalysts.In this work,it is discovered that the addition of Ho on CeTi catalyst can remarkably strengthen its K tolerance.The conclusions of Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),NH_(3) temperature programmed desorption(NH_(3)-TPD)and H_(2)temperature programmed reduction(H_(2)-TPR)analyses demonstrate that the enhancement of K resistance mainly originates from its stronger surface acidity and redox capability,the higher concentration of Ce^(3+)species and surface chemisorbed oxygen.In situ DRIFT analysis reveals that the introduction of Ho on CeTi can remarkably improve the adsorption of NH_(3) and NO_(x) species on catalyst surface,accompanied by the intensified reactivity of ad-NH_(3) species,which should also administer to improve the K resistance.
基金financially supported by the National Natural Science Foundation of China (Nos. 21673290, u1162103 and 21376261)the National Hi-Tech Research and Development Program (863) of China (No. 2015AA034603)the China Offshore Oil Fund (No. LHYJYKJSA2016002)
文摘A Ce（0.3）TiOxoxide carrier was synthesized via a sol–gel process,and Ce（0.3）TiOxsupported metal（M=Cd,Mn,Fe,W,Mo）oxide catalysts were prepared by the method of incipient-wetness impregnation.The catalysts were characterized by means of X-ray diffraction（XRD）,Brunauer–Emmett–Teller（BET）analysis,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared（FT–IR）spectroscopy,UV–Visdiffusereflectancespectroscopy（UV–VisDRS）,and Temperature-programmed reduction with H2（H2-TPR）.The catalytic activities for de-NO（x ）were evaluated by the NH3-SCR reaction.Among all the catalysts tested,the 2 wt.%Cd/Ce（0.3）TiOxcatalyst exhibited the best NH3-SCR performance,with a wide temperature window of 250–450℃ for NO conversion above 90%.Moreover,the catalyst showed N2 selectivity greater than 99%from 200 to 450℃.
文摘Ce x Ti 1- x O 2 mixed oxides of different mole ratios ( x =0, 0.1, 0.2～0.9, 1.0) were prepared by co precipitation of TiCl 4 with Ce(NO 3) 3 and then loaded with different amounts of CuO. The effects of CuO on NO+CO reaction were investigated, and the structure and reductive properties of various CuO/Ce x Ti 1- x O 2 were characterized by the methodologies of BET, TPR and XRD. The results show that different Ce/Ti mole ratios and calcination temperatures induce changes of structure and reductive properties of the Ce x Ti 1- x O 2 mixed oxides. When x =0.1～0.5, amorphous CeTi 2O 6 phase mainly forms at 650 ℃ compared to the formation of CeTi 2O 6 which crystallizes at 800 ℃. When x >0.6, some TiO 2 enters the CeO 2 lattice and a CeO 2 TiO 2 solid solution is formed. The activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 650 ℃ is largely affected by the x values, which is the highest when x =0.3, 0.4 and 0.9. The NO conversion reaches 70% at a reaction temperature of 150 ℃. By comparison, the x values have little effect on the activity of 6%CuO/Ce x Ti 1- x O 2 calcined at 800 ℃ . There are strong interactions between CuO and CeTi 2O 6, i.e., formation of the CeTi 2O 6 phase shifts the CuO reduction peak temperature from 380 to 200 ℃, and CuO, in turn, shifts the CeTi 2O 6 reduction peak temperature from 600 to 300 ℃.
基金supported by the Program for New Century Excellent Talents in Universities(NCET-07-0142)the Program for New Century Excellent Talents in Heilongjiang Provincial Universities(NCET-06-010)+1 种基金the National Natural Science Foundation of China(No.20972025)the Science Foundation of Tianjin University of Science & Technology(No.20090420).
文摘A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane （DMDS） as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm^3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.
