This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both...This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both Cu-SAPO-34 and Cu-ZSM-5. The catalytic activities of fresh, aged and poisoned samples were tested in ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) of NO<sub>x</sub> conditions. The XRD, TG and N<sub>2</sub>-desorption results showed that the structures of the Cu-SAPO-34 and Cu-ZSM-5 remained intact after 750˚C hydrothermally aged, SO<sub>2</sub> and propene poisoned. After hydrothermal aging at 750˚C for 12 h, the NO reduction performance of Cu-ZSM-5 was significantly reduced at lower temperatures, while that of Cu-SAPO-34 was less affected. Moreover, Cu-SAPO-34 catalyst showed high NO conversion with SO<sub>2</sub> or propene compared to Cu-ZSM-5. However, Cu-ZSM-5 showed a larger drop in catalytic activity with SO<sub>2</sub> or propene compared to Cu-SAPO-34 catalyst. The H<sub>2</sub>-TPR results showed that Cu<sup>2 </sup> ions could be reduced to Cu<sup> </sup> and Cu<sup>0</sup> for Cu-ZSM-5, while no significant transformation of copper species was observed for Cu-SAPO-34. Meanwhile, the UV-vis DRS results showed that CuO species were formed in Cu-ZSM-5, while little changes were observed for the Cu-SAPO-34. Cu-SAPO-34 showed high sulfur and hydrocarbon poison resistance compared to Cu-ZSM-5. In summary, Cu-SAPO-34 with small-pore zeolite showed higher hydrothermal stability and better hydrocarbon and sulfur poison resistant than Cu-ZSM-5 with medium-pore.展开更多
ZSM-5 zeolites were directly synthesized on the surface of honeycomb cordierite substrates by hydrothermal method and certified by XRD and SEM techniques; the adhesion of ZSM-5 coatings was evaluated by ultrasonic vib...ZSM-5 zeolites were directly synthesized on the surface of honeycomb cordierite substrates by hydrothermal method and certified by XRD and SEM techniques; the adhesion of ZSM-5 coatings was evaluated by ultrasonic vibration. Cu-ZSM-5/cordierite monolithic catalyst was prepared by ion-exchange and impregnation method and applied for the selective catalytic reduction （SCR） of NO by NH3 using a simulated diesel exhaust. The results show that the cordierite surface is almost completely covered by ZSM-5 crystals and the crystallization time greatly impacts the loadings and adhesion of ZSM-5 coatings on substrate, the NOx removal rate over Cu-ZSM-5/cordierite is above 90% in a temperature range of 240-480℃. Moreover, Cu-ZSM-5/cordierite prepared by different methods shows a wide temperature window （240-540 ℃） with high NO removal activities.展开更多
Cu-ZSM-5 type molecular sieves were synthesized hydrothermally in weak acid medium in the presence of F- ions. The structures of these samples were investigated.Increasing the amount of copper in synthesized samples t...Cu-ZSM-5 type molecular sieves were synthesized hydrothermally in weak acid medium in the presence of F- ions. The structures of these samples were investigated.Increasing the amount of copper in synthesized samples the unit cell volumes of Cu-ZSM-5 zeolites increase, while the adsorption peaks of Cu-ZSM-5 shift to lower wavenumbers.These facts and the results of the electron probe micrograph and XPS analyese indicate that copper was introduced into the framework of molecular sieve.展开更多
文摘This study was aimed to investigate the effects of hydrothermal aging, propene and SO<sub>2</sub> poisoning on the ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) performance of both Cu-SAPO-34 and Cu-ZSM-5. The catalytic activities of fresh, aged and poisoned samples were tested in ammonia-selective catalytic reduction (NH<sub>3</sub>-SCR) of NO<sub>x</sub> conditions. The XRD, TG and N<sub>2</sub>-desorption results showed that the structures of the Cu-SAPO-34 and Cu-ZSM-5 remained intact after 750˚C hydrothermally aged, SO<sub>2</sub> and propene poisoned. After hydrothermal aging at 750˚C for 12 h, the NO reduction performance of Cu-ZSM-5 was significantly reduced at lower temperatures, while that of Cu-SAPO-34 was less affected. Moreover, Cu-SAPO-34 catalyst showed high NO conversion with SO<sub>2</sub> or propene compared to Cu-ZSM-5. However, Cu-ZSM-5 showed a larger drop in catalytic activity with SO<sub>2</sub> or propene compared to Cu-SAPO-34 catalyst. The H<sub>2</sub>-TPR results showed that Cu<sup>2 </sup> ions could be reduced to Cu<sup> </sup> and Cu<sup>0</sup> for Cu-ZSM-5, while no significant transformation of copper species was observed for Cu-SAPO-34. Meanwhile, the UV-vis DRS results showed that CuO species were formed in Cu-ZSM-5, while little changes were observed for the Cu-SAPO-34. Cu-SAPO-34 showed high sulfur and hydrocarbon poison resistance compared to Cu-ZSM-5. In summary, Cu-SAPO-34 with small-pore zeolite showed higher hydrothermal stability and better hydrocarbon and sulfur poison resistant than Cu-ZSM-5 with medium-pore.
基金Project (20906067) supported by the National Natural Science Foundation of China
文摘ZSM-5 zeolites were directly synthesized on the surface of honeycomb cordierite substrates by hydrothermal method and certified by XRD and SEM techniques; the adhesion of ZSM-5 coatings was evaluated by ultrasonic vibration. Cu-ZSM-5/cordierite monolithic catalyst was prepared by ion-exchange and impregnation method and applied for the selective catalytic reduction （SCR） of NO by NH3 using a simulated diesel exhaust. The results show that the cordierite surface is almost completely covered by ZSM-5 crystals and the crystallization time greatly impacts the loadings and adhesion of ZSM-5 coatings on substrate, the NOx removal rate over Cu-ZSM-5/cordierite is above 90% in a temperature range of 240-480℃. Moreover, Cu-ZSM-5/cordierite prepared by different methods shows a wide temperature window （240-540 ℃） with high NO removal activities.
文摘Cu-ZSM-5 type molecular sieves were synthesized hydrothermally in weak acid medium in the presence of F- ions. The structures of these samples were investigated.Increasing the amount of copper in synthesized samples the unit cell volumes of Cu-ZSM-5 zeolites increase, while the adsorption peaks of Cu-ZSM-5 shift to lower wavenumbers.These facts and the results of the electron probe micrograph and XPS analyese indicate that copper was introduced into the framework of molecular sieve.
