Effect of K-doping on 2-propanol adsorption, desorption and catalytic oxidation over vanadia-titania

The adsorption, desorption and catalytic oxidation of 2-propanol has been investigated over a vanadia-titania catalyst without and with potassium doping. 70 % yields in acetone can be obtained at 443 K over vanadia-titania, with propylene and carbon oxides as the main by-products. Potassium doping causes a slight reduction in activity but a significant increase of acetone selectivity. Acetone yields exceeding 85 % are obtained at 573 K. FT-IR and TPD data show that the key adsorbed intermediates are 2-propoxide groups that give propylene by elimination of an hydroxy- group, and acetone by oxidative dehydroge-nation. K-doping is found to decrease strongly the surface acidity. Consequently, the elimination reactions giving propylene is inhibited, while acetone adsorption is also weakened, making easier its desorption as such. Both these effects favour higher acetone selectivities. © 1994 Elsevier Science B.V. All rights reserved.