Superior Performance of Mesoporous TiO2–Al2O3 Supported NSR Catalysts with the Support Synthesized Using Nonionic and Cationic Surfactants as Co-Templates

Abstract

Mesoporous binary oxides TiO2–Al2O3 were prepared by citric acid complexation-organic template decomposition method using nonionic p-octyl polyethylene glycol phenyl ether (OP) and cationic cetyltrimethyl-ammonium bromide (CTAB) as co-templates; the corresponding NSR catalysts Pt/K/TiO2–Al2O3 were prepared by successive wetness impregnation. Multiple techniques including N2 physisorption, XRD, HR-TEM, NH3-TPD, H2-TPR and H2-chemisorption were employed for catalyst characterization. It is found that the support prepared using OP and CTAB as co-templates possesses much larger specific surface area (309 m2/g) than those prepared using CTAB as single template (275 m2/g) or using conventional co-precipitation (250 m2/g); meanwhile, this support exhibits the largest amount of surface acidic sites as indicated by NH3-TPD results, which makes its supported catalyst show the best sulfur-resistance performance among the catalysts with the support prepared by different methods. The results of H2-chemisorption and HR-TEM conformably indicate that this catalyst also possesses the highest dispersion of Pt, which determines its best NOx storage and reduction performance at lean/rich cycles, giving a mean NOx reduction percentage as high as 95 %.