Enhanced Aromatization of Light Naphtha Using Ga and Zn-Modified Nano ZSM-11 Zeolites: Structural and Catalytic Insights

The aromatization of light naphtha has garnered significant attention in the petrochemical industry, as it offers a pathway to convert low-value streams into high-value aromatic hydrocarbons, delivering both economic and environmental advantages. This study investigates the synthesis, modification, and catalytic performance of nano ZSM-11 zeolites with varying SiO2/Al2O3 molar ratios (35 and 70) for the aromatization of light straight-run naphtha (LSRN). The nano ZSM-11 zeolites were synthesized hydrothermally and modified with gallium (Ga) and zinc (Zn) using the incipient wetness impregnation method to enhance their catalytic properties. The structural, textural, and acidic characteristics of the catalysts were analyzed using XRD, BET, NH₃-TPD, SEM, and TEM. XRD confirmed that the MEL topology of ZSM-11 remained intact after metal modifications, with GaZn/NZ11(70) displaying the highest crystallinity. BET analysis revealed that NZ11(70) exhibited a higher surface area (347 m²/g) than NZ11(35) (337 m²/g), while Ga incorporation led to a slight reduction in porosity due to partial pore blockage. NH3-TPD demonstrated that Ga/NZ11(70) had the highest total acidity (0.85 mmol NH3/g), significantly enhancing dehydrocyclization and selectivity toward aromatics. The catalytic evaluation showed that the unmodified zeolites achieved nearly complete conversion (~ 97–99%), with NZ11(70) offering superior aromatic selectivity due to its optimized pore structure and acidity. Zn/NZ11(70) increased BTEX selectivity to 67.8%, while Ga/NZ11(70) achieved the highest total aromatic yield (77.8%) by promoting dehydrocyclization. The bimetallic GaZn/NZ11(70) catalyst maintained complete conversion, but its aromatic yield was slightly lower than Ga/NZ11(70) alone, indicating limited additional synergy. SEM and TEM imaging confirmed distinct nanorod-like morphologies, with NZ11(70) displaying higher crystallinity and a more organized framework. These findings highlight the significant role of metal modifications in tailoring the acidity, pore structure, and catalytic activity of nano ZSM-11 zeolites for industrial applications in hydrocarbon conversion and aromatic production.