Investigation of the effect of alumina binder addition to Pd/SO42− − ZrO2 Catalysts during sol−gel synthesis

2016-01-01
Sinha Majumdar, Sreshtha
Çelik, Gökhan
Ozkan, Umit
We have incorporated alumina into palladium catalysts supported on sulfated zirconia (Pd/SZ) during sol-gel synthesis for application in a washcoat for NOx emissions control in natural gas-fired lean-burn engines. In situ incorporation of the adhesivity-enhancing binder, alumina, during the sol-gel synthesis of the Pd/SZ catalyst demonstrated significantly improved NOx reduction activity of the previously reported dual-catalyst bed when compared to the conventional ex situ mode of binder addition in a slurry. The effects of alumina addition during sol-gel synthesis of Pd/SZ on the structural, textural, and chemical properties of the resulting catalyst were examined in this study. The evolution of the crystal phase of zirconia during calcination of the Pd/SZ catalyst with the binder incorporated during the sol-gel process was studied using in situ XRD during calcination under air. Comparison of the crystal phase composition of the binder-free and binder-incorporated samples calcined at 700 and 900 degrees C demonstrated a stabilizing effect on the tetragonal zirconia in the presence of alumina or boehmite dopants. N-2 adsorption experiments at 77 K indicated the presence of slit-shaped multimodal hierarchical pores as a result of sol-gel alumina addition. EPR spectra indicated that sol-gel alumina incorporation affected the nature of the Pd species on the resulting catalyst. Al-27 MAS NMR spectroscopy revealed a strong interaction of the alumina binder with the zirconia support. The possible formation of a zirconia-alumina solid solution was suggested and was further examined using laser Raman spectroscopy. The influence of the alumina dopant in the zirconia matrix on the chemical states of Zr, S, O, and Al was investigated using XPS. Ar+-ion-gun sputtering provided valuable insights into the nature of the alumina-support interaction due to in situ alumina incorporation during the sol-gel synthesis of Pd/SZ catalysts.
Industrial and Engineering Chemistry Research

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Citation Formats
S. Sinha Majumdar, G. Çelik, and U. Ozkan, “Investigation of the effect of alumina binder addition to Pd/SO42− − ZrO2 Catalysts during sol−gel synthesis,” Industrial and Engineering Chemistry Research, pp. 11445–11457, 2016, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/48907.