The promotional effects of copper on Pt/Al2O3 and Pd/Al2O3 on n-butane dehydrogenation were investigated under atmospheric pressure and a reaction temperature of 500-550 degrees C. The addition of Cu to 1Pt/Al2O3 catalyst enhanced the stability and C-4 = selectivity of the catalyst, with the butane conversion remaining unchanged. In addition, the presence of Cu on Pd/Al2O3 catalyst significantly increased the conversion of n-butane. TEM images showed that Cu addition was able to disperse Pt and Pd particles well. However, H-2 chemisorption showed that the dispersion of Pt catalyst was decreased following Cu addition, but that of Pd was increased. This indicates that the Pt surface can be partly covered by Cu, whereas the Pd surface cannot. Therefore, the activity of just the Pd catalyst and not the Pt catalyst was enhanced by the addition of Cu. On the other hand, the alloy formation of Pt and Pd with Cu was confirmed using TPR, FTIR-CO chemisorptions and EDX-mapping studies. Cu effect on the stability and C-4 = selectivity of Pt and Pd catalysts can be enhanced by the alloy formation of Pt and Pd with Cu. (C) 2011 Elsevier B.V. All rights reserved.