The effect of chromium exchange level on the cracking and dehydrocyclization of n‐Heptane on CrHNaY zeolite catalysts. Kinetic and spectroscopic study

The influence of the degree of chromium ion exchange on Y zeolites on the catalytic activity for cracking and dehydrocyclization of n‐heptane has been studied at 673, 723 and 748 K and atmospheric pressure in a continuous flow system. The kinetic rate constants and activation energy in absence of decay for the cracking of n‐heptane on the catalysts have been obtained. Measurements of the surface acidity of these catalysts by I.R. spectroscopy of adsorbed pyridine and by titration with n‐butylamine has been carried out. A good correlation between the activity cracking of n‐heptane and the concentration of stronger acid sites (pK a ≤ + 1.5) on the chromium‐exchanged Y zeolites has been found.