Maximizing Gasoline Yield in Catalytic Cracking of VGO through Post-synthesis Modification of USY Zeolite

USY zeolite as a crucial component in FCC catalyst has been modified via post-synthesis acid treatment applying acetic acid, oxalic acid, and hydrochloric acid in order to increase mesoporosity and more pore accessibility. Acid leaching was performed under two different conditions including room temperature and reflux. Extra-framework Al atoms were removed which was confirmed through XRD, SEM, ICP-OES and N2 adsorption-desorption isotherm analyses. Elemental analysis showed increasing in SiO2 to Al2O3 ratio. Examining surface area and pore volume through BET-BJH and t-plot methods showed that total surface area, as well as mesoporous volume, were increased by acid-treating in all modified zeolites. The mesoporous surface was increased from 52.62 in primary zeolite to 115.09 m2/g in the sample which was acid leached through oxalic acid at room temperature. Moreover, the total surface area of the zeolite was increased from 684 to 743 m2/g. All modified zeolites were applied in the preparation of FCC catalyst. Catalytic cracking of VGO indicated a considerable increase in gasoline yield upon modified catalysts. Gasoline yield was increased from 18 wt.% over FCC to 40 wt.% in acetic acid-modified zeolite at room temperature.