Hydroisomerization Of n-Paraffin Using Zeolytic Materials

Abstract

Hydroisomerization of n-paraffin is an important reaction in oil refining processes due to environmental considerations and it is integral part of refining processes for improving the quality of fuels and lube oils. Subsequently, hydroisomerization of n-paraffins had seen significant improvements both in terms of catalyst design and processes. Hydroisomerization of long chain paraffins to iso-paraffins, to obtain product with excellent cold flow properties and superior yields, had depicted an immense growth owing to the emergent demand for high quality fuel oils for automobile and industrial applications. Hydroisomerization for conventional diesel dewaxing and renewable diesel dewaxing had boosted the yields of diesel fuels to meet the ever rising demand. Isomerization reactions generally take place over bifunctional metal/acid catalysts. An ideal catalyst would be the one which provide a high yield of isomerization and should have shape-selectivity to react only with n-paraffins. To achieve these characteristics, the catalyst should have suitable compositional and structural characteristics, mainly: proper balance between metal and acid sites, medium pore size, high dispersion of metal on surface of catalyst, mild acidity, and strength distribution of acid sites. The scope of this thesis was to understand the effect of various zeolites with respect to Si/Al ratio, pore size and pore dimension on hydroisomerization of n-decane. In this study, Beta zeolite, Silica -alumina and ZSM-5 zeolite based materials were chosen for acid function and shaped into extrudate by adding Alumina as binder. The shaped extrudate were ion-exchanged with platinum using platinum tetraamine II chloride. The catalysts were characterized by XRD, SEM, BET surface area, and ammonia TPD methods. And the catalysts were evaluated in batch reactor using n-decane as a model compound for hydroisomerization reaction. Pt-Silica-Alumina showed low conversion and high selectivity compared to other zeolites. High performance of above catalysts might be due to low acidity, proper distribution of platinum across the mattix and necessary pore average diameter which facilitates ready diffusion of reactants.