The catalytic properties of zeolite X containing transition metal ions: III. Propylene oxidation
Abstract The catalytic activity of X zeolites for the oxidation of 4.5% propylene in air in a flow system was enhanced by the exchange of ~20% of the sodium ions for transition metal ions. The major oxidation products were CO 2 and H 2 O; small quantities of acrolein, acetaldehyde, and formaldehyde were also detected. An activity series at 630 K showed that activity depended upon the acidity of the zeolite and the nature of the transition metal ion. The reaction was subsequently studied, using 2.3% propylene in air, on 22 catalysts in which controlled variations in the acidity and the extent of replacement of Na + by Cu 2+ had been made. First-order kinetics with respect to propylene were obeyed, and over the temperature range of the experiments, 434–623 K, the products were confined to CO 2 and H 2 O. The dependence of the activity at 500 K upon copper ion content and Bronsted acidity emphasizes the importance of the combination of these two factors in determining catalytic activity.