Reusable Catalyst of KF/Mg-Al Layered Double for Biodiesel Conversion and Optimization using Bohn-Behnken Design

Abstract

This work aimed to synthesize a reusable catalyst of KF/Mg-Al layered double hydroxide (KF/LDH) for a microwave-assisted biodiesel conversion from rice bran oil (RBO). The LDH was synthesized by co-precipitation method of Mg and Al precursors with additional surfactant of cetyl trimethyl ammonium followed by hydrothermal method, for furthermore, an impregnation procedure was applied to combine KF with LDH by using impregnation method. Instrumental analysis of materials was performed by XRD, gas sorption analysis, SEM-EDX, TEM and XPS method. Effect of KF loading onto LDH on the specific surface area and solid basicity was also studied. From the characterization by XRD, it can be concluded that the impregnation increased specific surface area of LDH without any structural destruction, which was also confirmed by the lattice fringe comparison by HRTEM analysis and surface analysis by XPS. The specific surface area enhancement is in line with the increasing solid basicity which directly enhanced the catalytic conversion of RBO into biodiesel. Statistical optimization of the use of KF/LDH was conducted by response surface methodology of Box-Behnken Design for the range of 2–4 g/100 mL of catalyst dose, 3–8 of the methanol to oil ratio, and 10–30 min of reaction time. It was revealed that all factors are significantly affect the yield. The KF/LDH catalyst is also reusable as it does not loss the activity until 5th cycles. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Keywords

• biodiesel
• microwave-assisted reaction
• layered double hydroxides
• basic catalyst