Study on synergistic action between Zn component and H-ZSM-5 in the Zn/H-ZSM-5 catalyst for aromatization of light paraffins

Compared to Zn/H ZSM 5,lower aromatization activity and selectivity were obtained by the addition of Al_2O_3 to Zn/H ZSM 5 catalyst for n hexane aromatization, while the catalyst stability improved. The analytical results by TEM-EDS technique indicated that the effect of Al_2O_3 on the aromatization performance of Zn/H ZSM 5 was closely correlated with the zinc emigration from H ZSM 5 to Al_2O_3 after calcination and hydrothermal treatment. Especially, the aromatization on Al_2O_3 and Zn/Al_2O_3 and the effect of incorporation of Zn component or Zn/Al_2O_3 were studied. The experimental results showed that Al_2O_3 and Zn/Al_2O_3 had very weak aromatization activity and little effect on the catalytic properties of H ZSM 5. Therefore, it was concluded that it was only the zinc component on the surface of H ZSM 5 zeolite that could cooperate with H ZSM 5 and modify its catalytic performance, while the synergistic action couldn't take place between H ZSM 5 and zinc component on Al_2O_3.