**3.1 Preparation of Co/NaZSM-5 and Co/HZSM-5 zeolite catalyst**

Co/NaZSM-5 h was prepared by incipient wetness impregnation method, in which 1 g of NaZSM-5 h was treated by 1.7 mL 0.2495 M Co2+ solution, stirred for 24 h at room temperature, and then calcined at 823 K for 3 h. Co/HZSM-5 h was prepared in a similar manner, using HZSM-5 h as starting material.
