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Acid-base bifunctional catalyst with coordinatively unsaturated cobalt-nitrogen sites for the simultaneous conversion of microalgal triglycerides and free fatty acids into biodiesel.
- Source :
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Bioresource technology [Bioresour Technol] 2022 Apr; Vol. 350, pp. 126862. Date of Electronic Publication: 2022 Feb 17. - Publication Year :
- 2022
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Abstract
- An acid-base bifunctional catacknalyst with coordinatively unsaturated cobalt-nitrogen active sites Co-N <subscript>x</subscript> (x < 4) was synthesized to convert microalgal lipids with high acid value into biodiesel. Pyrolysis destroyed Co-N <subscript>4</subscript> coordination structure in ZIF-67 and released coordinatively unsaturated Co-N <subscript>x</subscript> and uncoordinated N sites, which resulted in the Lewis/Brønsted acid ratio increasing from 0.1 to 11.45 and the basicity increasing from 0.96 to 6.05 mmol/g. According to DFT calculations, the adsorption energy of free fatty acid (FFA) on Co-N <subscript>2</subscript> site (-1.003 eV) exceeded that on Co-N <subscript>4</subscript> site (-0.271 eV). The strong interaction between Co-N <subscript>2</subscript> site and FFA increased electropositivity of carbonyl carbon atom in FFA from 1.379 to 1.529 eV and promoted esterification. The pyrolysis-induced defects generated more mesopores to promote the transportation of lipid molecules inside the catalyst. Therefore, the conversion efficiency of microalgal lipids into biodiesel over the ZC-450 catalyst (96.7%) was higher than that over the ZIF-67 catalyst (69.5%).<br /> (Copyright © 2022 Elsevier Ltd. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1873-2976
- Volume :
- 350
- Database :
- MEDLINE
- Journal :
- Bioresource technology
- Publication Type :
- Academic Journal
- Accession number :
- 35183722
- Full Text :
- https://doi.org/10.1016/j.biortech.2022.126862