Production and characterization of hierarchical zeolite Y catalyst for biodiesel production using waste cooking oil as a feedstock

Abstract

This study reports the production and characterization of hierarchical zeolite Y (HZY) catalyst from commercial zeolite Y (CZY) for biodiesel using waste cooking oil as feedstock. The hierarchical zeolite Y catalyst produce were characterized using X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Brunnauer, Emmeitt and Teller(BET) analysis. From the BET results of hierarchical Y zeolite produced shows that mole concentration of simultaneous desilication and mild dealumination determine the hierarchical factor of the produced hierarchical Y zeolite. Furthermore, this process was optimized by varying both the mole concentration aqueous solutions of Sodium Hydrides (NaOH) and Ethylenediaminetetraacetic acid (H₄EDTA). The two process variables NaOH and H₄EDTA were found to be statistically significant for high surface area, pore volume and pore size whereby, the value obtained for surface area are 193.83, 216.03, 212.34 and 218.33 m²/g while the hierarchy factor was calculated to be 0.0571, 0.1540, 0.1781 and 0.1042 respectively. The highest value of hierarchy factor (0.1781) of hierarchical zeolite Y sample (HZY-3) occur at 0.3 M of NaOH and 0.3 M of H₄EDTA with a pore volume of 0.3785 c m³/g and a pore size of 8.5512 nm, which represent the most suitable for optimum reactivity compared to others. The XRD of hierarchical zeolite Y shows a slight decrease in the peak intensity which is associated with partial extraction of Si and Al from the zeolite framework during alkaline-to-acid treatment. Some peaks were also formed which show that the level of crystallinity has increased while the SEM/EDX determined the crystallite size and the morphology. From the EDX, the hierarchical zeolite Y Si/Al ratio was calculated to be 15.0. HZY gave a biodiesel yield of 94.8% at 55 °C for 90 mins while CZY gave a yield of 62.00% at the same condition. A reusability test was also carried out and it was observed that at repeated 5th runs, biodiesel yield using the same HZY catalyst dropped to 83% which was still reasonable enough compared to the CZY catalyst which was observed to have dropped to 41%. This indicates that the hierarchy factor of the HZY catalyst produced decides the activity of solid catalysts in biodiesel production.

Keywords:

• Zeolite Y
• hierarchical zeolites Y
• biodiesel oil
• commercial zeolites Y
• cooking oil
• optimization
• mesopore

Disclosure statement

No potential conflict of interest was reported by the authors.