Aromatization of C ₅ ‐rich Light Naphtha Feedstock over Tailored Zeolite Catalysts: Comparison with Model Compounds (n‐C ₅ ‐ n‐C ₇ )

Abstract

Abstract In this work, aromatization of C 5 ‐rich light naphtha as feedstock obtained from the refinery of Hindustan Petroleum Corporation Ltd. (HPCL) was studied along with n‐hexane (model compound for light naphtha) over non‐noble metal oxide based catalyst; ZnGa/ZSM‐5. Zeolite ZSM‐5 was modified with zinc and gallium by co‐impregnation method. High aromatic yields were obtained over modified ZSM‐5 catalysts due to dissociative chemisorption of alkanes resulting in dehydrogenation/ aromatization. The effect of acid sites on aromatization was studied by varying SiO 2 /Al 2 O 3 ratio (SAR) of ZSM‐5 and correlated with the temperature programmed desorption of ammonia (NH 3 ‐TPD) studies. Optimized catalyst composition was further used for aromatization of n ‐pentane, n ‐heptane and light naphtha from a refinery. The Zn‐Ga−H‐ZSM‐5 catalyst produced aromatics in high yields (64.8 % for light naphtha), especially high quantities of toluene with toluene/benzene ratio (T/B) ∼ 2. From the aromatization studies, it could be envisaged that a proper balance of acid sites with dehydrogenation function is required to achieve maximum aromatic yield. Nitrogen was found to be a better carrier gas compared to hydrogen for aromatization of light naphtha.