Superior Performance of Mesoporous TiO2–Al2O3 Supported NSR Catalysts with the Support Synthesized Using Nonionic and Cationic Surfactants as Co-Templates
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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 %.
KeywordsCo-templates NOx storage and reduction Sulfur resistance Mesoporous TiO2–Al2O3
This work is financially supported by the National Natural Science Foundation of China (No. 21076146), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20090032110013) and the Program of New Century Excellent Talents in University of China (No. NCET–07–0599). The authors are also grateful to the financial support from the State Key Laboratory of Engines at Tianjin University (No. K2012-05).
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