The Influence Of Low Temperature Aromatization Of C₄ LPG By Fe Ion Modification

In this paper,we have firstly studied on the aromatization performance of different transitional-metals-modified nano-sized HZSM-5 catalyst.And then, Fe/HZSM-5 catalyst was chosen for its higher aromatization performance and C5+ liquid yield,moreover,the i-butane conversion in the beginning of the reaction is better. And it fully focuses on the aromatization performance of Fe/HZSM-5 prepared by different methods,such as normal impregnation methods including impregnating the extruded HZSM-5 with Fe3+ in hot solution and acidified hot solution, and impregnating the powdered HZSM-5 with Fe3+ in ambient temperature aqueous solution and ambient temperature ethanol solution,and solid-state ion-exchange method.The crystal structure of catalyst is characterized by XRD;The acidity of modified catalyst is characterized by NH3-TPD;The framework structure is characterized by FT-IR; The condition of HZSM-5 modified by Fe ion in the catalyst is characterized by Uv-Vis.The aromatizaton of C4 LPG to aromatics performance and the stability of the reaction are evaluated on small fixed-bed reactors.The result indicated that (1)HZSM-5 modified by Fe ion showes a higher aromatics yield, C5+ liquid yield and a better conversion of i-butane in the beginning than HZSM-5 modifid by Cu and Co ion in the aromatization reaction.(2) the reaction on extruded Fe/HZSM-5 and powdered Fe/HZSM-5 and can enhance i-butane conversion and the aromatics content in the liquid product. By contrast, Fe/HZSM-5 prepared by solid-state ion-exchange is more effective,such as higher i-butane conversion and more stable in the whole reaction (i-butane conversion can reach above 70%,and the aromatics content in the liquid product can reach above 50%) The modified nano-HZSM-5 catalysts with Fe ion can make some Fe3+ go into the framework of the zeolite. Compared with normal impregnation methods, the solid-state ion-exchange method can decrease the FexOy and it can help made more effective aromatization catalysts.(3)The influence of methanol in C4 LPG feedstock on the catalyst performance showed that methanol in C4 LPG feedstock can accelerates catalyst deactivation.In addition, the more methanol content in C4 LPG feedstock, the faster catalyst deactivated.