Effects of tin on product distribution and catalyst stability in hydrodechlorination of CCl4 over Pt-Sn/γ-Al2O3

The Pt-Sn/gamma-Al2O3 catalyst with a moderate amount of tin showed an enhanced catalytic stability and selectivity to CHCl3 in hydrodechlorination of CCl4 compared to monometallic platinum catalyst. The tin added in consecutive order to 1.0wt%Pt/gamma-Al2O3 acted as a diluting component of platinum ensemble sites and resulted in reducing the formation of C-2 compounds and carbon deposition. Furthermore, tin addition modifies the electronic state of supported platinum particles by the electron transfer from tin to platinum, results in the reduction of the binding energy of intermediate species, and suppresses the complete hydrodechlorination activity of surface intermediates. Thus on Pt-Sn/gamma-Al2O3 catalysts, adsorbed CCl4 is readily desorbed as CHCl3 instead of residing too long on the surface until it is completely dechlorinated to form CH4. [GRAPHICS]