Hydrocracking of C15-C18 hydrocarbons over Pt/HY catalysts for hydrotreated renewable jet fuel production

Abstract

Hydro treated renewable jet (HRJ) fuel has gained much attention as a replacement for conventional petroleum-based aviation fuels. In this research, the performance of hydro processing of different n-paraffin feed stocks present in hydrogenated biodiesel (n-C15, n-Cl6, n-Cl7, and n-Cl8) over a bifunctional 0.1 wt.% Pt/HY catalyst prepared by using two different methods—incipient wetness impregnation (IWI) and ion-exchange (IE) techniques—was investigated. The prepared catalysts were tested in a continuous flow packed-bed reactor at 310-320 °C, 490-510 psig, liquid hourly space velocity of 0.5-2.5 h-1, and H2/feed molar ratio of 30. The conversion of hydrocracking of different n-paraffin feed stocks over Pt/HY increased with increasing feedstock chain length. The higher conversion of the heavier n -paraffins could also be ascribed to stronger physisorption, which led to greater density on the catalyst surface and consequently to higher reaction rates. Considering product distribution, hydrocracking of octadecane gave the highest jet product yield of 47%. The reactivity on the IE catalysts was higher than that of the IWI catalysts, which might be due to Pt dispersion, resulting in a reduction of the diffusion limitation between the metallic and acidic sites. Moreover, different catalyst preparations gave the same reaction pathway but different in reaction rates.