The Synthesis And NH₃-SCR Performance Of Cu-Ce-La-SSZ-13 Catalyst

NOx is one of the main air pollutants.NH3-SCR is one of the most effective method to remove NOx.Catalysts modified with rare earth metal have been widely studied due to its excellent catalytic properties and better water and sulfur resistance.In this paper,cerium and lanthanum-modified Cu-SSZ-13 were prepared by ion-exchange and one-step method.The structure,morphology and catalytic activity of the catalyst were also studied.The SSZ-13 catalyst was synthesized by hydrothermal method using N,N,N-trimethyl-1-adamantyl ammonium hydroxide as template,and then a series of Cu-Cex-Lay/SSZ-13 catalysts were prepared by ion exchange method.The structure,active species,redox ability,NH3 adsorption performance of the samples were studied by XRD,SEM,XPS,BET,TPR,TPD,BET and in situ DRFITS.The effects of GHSV,H2O and SO2 on NH3-SCR activity were studied in detail.The in situ DRIFTS were used to reveal the SCR reaction intermediates and processes on Cu/SSZ-13 and Cu-Ce0.016-La0.01/SSZ-13.XRD patterns show that the structure of zeolite Cu-Ce0.016-La0.01/SSZ-13 is the same as Cu/SSZ-13.The SEM images shows that morphologies of SSZ-13 and the modified Cu-Cex-Lay/SSZ-13 were both cubic and the average particle size was 700 nm.The BET results show that Cu-Ce0.016-La0.01/SSZ-13 had a larger specific surface area and smaller pore size than the corresponding Cu/SSZ-13.Cu-Ce0.016-La0.01/SSZ-13 exhibited excellent NH3-SCR catalytic activity due to the large specific surface area and small pore size.Which were in favor for the SCR reaction.The NO conversion was more than 90%between 210 and 480?.In addition,the catalyst demonstrated better water and sulfur resistance.The excellent properties of the catalyst can be attributed to the synergistic effects of Cu,Ce and La species.From the in situ-DRIFTS study,it was evident that the NH3-SCR path was similar on both catalysts.Compared with the Cu/SSZ-13 catalyst,Cu-Ce0.016-La0.01/SSZ-13 adsorbed more amount of NH3 and had a stronger NO oxidation ability.Therefore,the catalytic performance of Cu-Ce0.016-La0.01/SSZ-13 is better than that of Cu/SSZ-13.Cu-SSZ-13 and Cu-Ce-La-SSZ-13 were synthesized by one-step method using copper amine complex as an templating agent.XRD and SEM results showed that the growing directions of Cu-Ce-La-SSZ-13 and Cu-SSZ-13 were different,Cu-SSZ-13 was flaky accumulation,however,Cu-Ce-La-SSZ-13 was a flower-shaped structure.Cu-Ce-La-SSZ-13 showed better of NH3-SCR activity(The NO conversion was more than 90%between 210 and 480?).The catalyst demonstrated better water and sulfur resistance.From the in situ-DRIFTS spectra,it was evident that the NH3-SCR path was same on both catalysts.Compared with Cu/SSZ-13 catalyst,Cu-Ce0.016-La0.01/SSZ-13 adsorbed more amount of NH3 and had a stronger NO oxidation ability.