Effect of promoter Ce on silver-molybdenum-phosphate catalysts for selective oxidation of propane to acrolein

Abstract

Abstract A series of Me n Ag 0.3 Mo 0.5 P 0.3 O y (Me=Cu, Zn, Mn, W, Ce, Pr, Nd) and Ag 0.3 Mo 0.5 P 0.3 O x catalysts were prepared. The addition of Ce to Ag 0.3 Mo 0.5 P 0.3 O x catalysts improved the catalytic performance in selective oxidation of propane to acrolein, and Ce 0.1 Ag 0.3 Mo 0.5 P 0.3 O x catalysts showed the highest acrolein selectivity (28.7%) and yield (4.4%). The physicochemical properties of Ag 0.3 Mo 0.5 P 0.3 O x and Ce n Ag 0.3 Mo 0.5 P 0.3 O x ( n =0.1–0.5) catalysts have been comparatively characterized by BET, XRD, H 2 -TPR, XPS, EPR and C 3 H 8 (C 3 H 6 )-TPD. Significant differences in physicochemical properties between Ag 0.3 Mo 0.5 P 0.3 O x and Ce doped Ag 0.3 Mo 0.5 P 0.3 O x catalysts have been observed, which is due to the formation of the redox cycle (Ce 3+ +Mo 6+ ⇔Ce 4+ +Mo 5+ ) in the Ce n Ag 0.3 Mo 0.5 P 0.3 O y catalyst. Such effect modified the reducibility, the concentration of Mo 5+ , the activation of propane and the transformation of possible intermediate propene to acroelin, which in return greatly influenced the catalytic performance of Ce doped Ag 0.3 Mo 0.5 P 0.3 O x catalysts in selective oxidation of propane to acroelin. The proper addition of Ce to Ag 0.3 Mo 0.5 P 0.3 O x catalyst improved the acrolein selectivity and yield.