Comparison of potassium catalysts on zeolite sodium A and X in transesterification of palm oil and active species specification

• Published in: Heliyon Vol. 10; no. 16; p. e35975
• Main Authors: Seejandee, Piyanat, Osakoo, Nattawut, Sereerattanakorn, Pakawan, Krukkratoke, Panot, Keawkumay, Chalermpan, Pansakdanon, Chaianun, Wittayakun, Jatuporn, Chanlek, Narong, Deekamwong, Krittanun, Prayoonpokarach, Sanchai
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 30.08.2024; Elsevier
• Subjects: Biodiesel; Palm oil; Potassium; Transesterification; Zeolite A; Zeolite X; Zeolite X; Zeolite A; Palm oil; Transesterification; Potassium; Biodiesel
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2024.e35975

Heterogeneous catalysts consisting of potassium supported on zeolites are active for transesterification, but the effect of zeolite properties is not clearly understood. This work compares catalysts containing 12 wt.% potassium on zeolite sodium A and X (12K/NaA and 12K/NaX) in terms of performance and physicochemical properties. Both catalysts were prepared by ultrasound-assisted impregnation with potassium acetate buffer. 12K/NaA is a better catalyst in transesterification of palm oil, giving a higher biodiesel yield than 12K/NaX in the first run (99.1 ± 0.3 % and 77.9 ± 2.2 %, respectively). From characterization by CO2-TPD, XRD, FTIR, XPS, and SEM-EDS, both catalysts have similar basicity but different dispersion of carbonates and interaction on the zeolites. The 12K/NaA has those species on external surfaces and more monodentate carbonate than 12K/NaX. Ion exchange occurs between potassium ions from the precursor and sodium ions from the zeolite. Moreover, 12K/NaA is more stable, providing higher biodiesel yields in the second and third catalytic cycles. •Potassium acetate buffer on NaA and NaX was converted to carbonates by calcination.•12 K/NaA gave more biodiesel yield than 12 K/NaX but they have similar basicity.•Carbonates on 12 K/NaA are on the external surface more than 12 K/NaX.•Potassium ions from precursor exchanged with sodium cations of zeolites.•In terms of stability and reusability, 12 K/NaA is better than 12 K/NaX.