IULIEAN VASILE ASAFTEI, NECULAI CATALIN LUNGU, IOAN GABRIEL SANDU, ADRIAN FLORIN SPAC, MARIA IGNAT PERFORMANCE OF MFI ZEOLITE CATALYSTS IN N-HEPTANE CONVERSION REACTION TEST The aromatization of n-heptane, one of the main components of light naphtha, has been investigated over HZSM-5 (Si/Al = 33.9) and Zn-HZSM-5: Zn1-HZSM-5 (0.86% Zn); Zn2-HZSM-5 (1.35% Zn) and Zn3-HZSM-5 (2.89% Zn) catalysts prepared by the ion exchange with 10M aqueous solution of Zn(NO3)2. The catalytic activity measurement was performed by the chromatographic pulse method in the temperature range of 673 - 823K. The presence of zinc in Zn-HZSM-5 catalysts provided a significant increase in total aromatics selectivity due to the improvement of dehydrogenation activity by Zn incorporation. The Zn species facilitated the aromatization by converting paraffin’s into corresponding olefins which, in turn, were the aromatics precursors. Therefore, both acidity and zinc incorporation played important roles in the aromatization of n-heptane. Over 773 K the activity and selectivity of the Zn-HZSM-5 catalysts decrease very probably due to the loss of zinc ions.