Efficient Synthesis of Gold-Alumina Catalyst by a Modified Impregnation Procedure: Effect of Promotion by Ceria on Activity and Stability of Catalyst
C.K. Banerjee, Z. Xu, J. Sankar
North Carolina A&T State University, US
gold catalyst, carbon monoxide, alumina, ceria
Ceria-promoted and unpromoted gold-alumina catalysts have been prepared by a modified impregnation procedure with a potential of easy-scale up. Both catalyst preparations showed high activity for oxidizing CO at room temperature and showed long-term stability under ambient conditions. Unlike other wet synthetic procedures, the modified impregnation procedure converts nearly 100% of the gold from its precursor compound to the final catalyst product and is suitable for depositing catalytically active gold nanoparticles on large granular or monolithic substrates. Activation and thermal stability of the preparations were studied by subjecting to heat treatment and subsequent measurement of catalytic activity and analysis by TEM and XRD. Gold–alumina preparation calcined at 200°C showed the maximum activity for CO oxidation. Catalytic activity decreased and size of gold nanoparticles increased simultaneously as the calcination temperature was raised above 200°C. Thus the catalytic activity may be related to the size of gold nanoparticles. XPS data demonstrate the presence of gold hydroxide and gold oxide along with metallic gold in the gold – alumina catalyst preparation calcined at 200°C. Effect of promotion by ceria on the catalytic activity in presence and absence of hydrogen along with thermal stability of the preparation will also be presented.
Nanotech 2008 Conference Program Abstract