Durability Study of Low-Al Zeolite Beta through Steaming Process Modification As a Heterogeneous Catalyst for Biodiesel Production

In this study, sodium-modified Zeolite Beta was adopted to catalyze both transesterification of triglycerides and esterification of fatty acids for biodiesel production. Dealumination of Zeolite Beta by steaming process was conducted to give zeolites with different Si-to-Al atomic ratios. Subsequently, ion-exchange with Na⁺ was performed on as-obtained Zeolite Beta. Interestingly, Zeolite Beta with a higher atomic ratio of Si-to-Al possesses better catalytic durability. Coincidently, more defect sites where sodium could be stored were found on low-Al Zeolite Beta after the high temperature steaming treatment. Consequently, a biodiesel yield over 80% was resulted in less than 5 hours from transesterification of palm oil and triolein in thirteenth and eighth cycles, respectively, catalyzed by the sodium-modified Zeolite Beta. The results indicated sodium stored in defect sites are able to rapidly supply the surface reactivity of catalyst to effectively catalyze transesterification and esterification.