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Abstract

Layered double hydroxides (LDHs) serve as potential catalysts for biodiesel production through triglyceride (TAG) transesterification; nevertheless, mass transport limitations hinder their effectiveness, especially with larger TAG molecules. This study addresses this limitation by synthesizing macroporous MgAlLDH and ZnAlLDH using a polystyrene templating method. Thorough characterization reveals the successful formation of macroporous structures with significantly increased physicochemical properties and their structural design compared to conventional LDHs. X-ray Diffraction (XRD) confirmed the successful restoration of the LDH structure following calcination and rehydration, with enhanced crystallinity seen in the macroporous materials. The BET surface area analysis revealed a substantial increase (∼10x for MgAlLDH) in the macroporous framework. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images revealed a macroporous network with an average pore diameter of ∼300 nm, consistent with the dimensions of the polystyrene template. The X-ray Photoelectron Spectroscopy (XPS) analysis revealed slight changes in surface elemental composition and oxidation states, indicating the impact of the macroporous structure on surface properties. Catalytic testing with various TAGs (C4–C18) demonstrates a notable enhancement in catalytic activity, particularly for higher TAGs, due to improved mass transfer. The turnover frequencies of macroporous materials significantly exceed those of conventional LDHs, exceeding them by approximately 20 times for the MgAlLDH system and 15 times for the ZnAlLDH system. The findings highlight the efficacy of macroporous LDHs as very effective catalysts for biodiesel production, overcoming the inherent mass transfer limitations of conventional LDH catalysts.

Keywords

Biodiesel, Layered Double Hydroxides (LDH), Macroporous, Mass Transfer, Triglycerides

Article Type

Special Issue Article

First Page

1

Last Page

15

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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