Study of the Performance of Zeolite -based Catalysts in n -Heptane Isomerization: Identification of the Best Catalysts for Industrial Applications

Zeolites are ideal catalyst supports due to their regular porous structure, high thermal stability, and acid regulation in refining processes, including n -heptane isomerization. In this study, the performance of five platinum catalysts, including Pt/MCM -۴۸-HZSM -۵, Pt/TiO ۲-HMS, Pt/YH, Pt/ZH, and Pt/XH in the n -heptane isomerization reaction was investigated and compared. These catalysts are a combination of zeolites HZSM -۵, HY, and X along with mesoporous supports such as MCM -۴۸ and HMS, which improve the surface and acidic properties. The presence of zeolite HZSM -۵ in Pt/MCM -۴۸-HZSM -۵, with its three-dimensional channel structure and high number of Bronsted acid sites, significantly increased the heptane conversion rate and improved the selectivity for multi-branched isomers. On the other hand, Pt/ZH, which includes zeolite X, showed high activity in isomerization due to the presence of Lewis acid sites and a more balanced Si/Al ratio and was the best catalyst in terms of selectivity (۹۰%). Zeolite HY in the Pt/YH combination also performed well in heptane conversion due to its high specific surface area and strong acid sites, but showed less stability against coke formation than Pt/MCM -۴۸-HZSM -۵ and Pt/ZH. In contrast, Pt/TiO ۲-HMS, which lacks a regular zeolite structure, had the weakest performance in terms of conversion and selectivity, which confirms the importance of the presence of zeolite in improving catalytic activity. Overall, the results of this study show that the combination of HZSM -۵, HY, and X zeolites with mesoporous supports such as MCM -۴۸ and HMS has a significant effect on improving the catalyst performance. This combination has increased the number of active sites, controlled the acidity distribution, and optimized the permeability. Based on the results of our research, Pt/MCM -۴۸-HZSM -۵ and Pt/ZH are suggested as the best catalyst options for industrial applications in heptane isomerization.

کلیدواژه ها:

Normal heptane isomerization ، platinum catalysts ، zeolite ، HZSM -۵