n-HEPTANE CRACKING ON USY ZEOLITE THE EFFECT OF REACTION TEMPERATURE ON ACTIVITY AND DEACTIVATION

n-Heptane cracking on a USY commercial zeolite at 350, 400 and 450ºC was studied. XRF, XRD, 27Al and 29Si-MAS-NMR were used for USY characterization. The nature of the coke was determined by 1H-NMR and infrared spectroscopy. It was observed that temperature influenced the nature of the coke formed, and that an increase in temperature led to a reduction in the solubility of coke in CH2Cl2 and an increase in its aromaticity. Despite these characteristics and the larger amount of coke formed, higher temperatures have less effect on the deactivation process than lower temperatures. Selectivity for C1-C6 fractions was hardly influenced by temperature, and it was that expected for the cracking mechanism of n-paraffins on acid catalysts