Highly efficient sustainable heterogeneous catalyst derived from onion peels (Allium sepa L.) for the ecological biodiesel production using non-edible feedstock

• Published in: Energy conversion and management Vol. 315; p. 118801
• Main Authors: El yaakouby, Ichraq, Hlaibi, Miloudi, Kamil, Noureddine
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-09-2024
• Subjects: Allium sepa L; Biodiesel synthesis; Catalyst acid heterogeneous; Esterification reaction; Onion peel; Palm fatty acid distillate; FFA; OPACL > SO3H; Biodiesel synthesis; OPACL-(4.664)-SO3H; FT-IR; DLS; OPACL-(0.583)-SO3H; XRD; TGA/DTA; OPACL-(2h)-SO3H; OPACL-(x)-SO3H, Heterogeneous acid catalyst derived from onion peels; OPACL-(12h)-SO3H; OPACL; ASTM D−6751; Palm fatty acid distillate; Onion peel; AOAS Cd 3d-63; Allium sepa L; Catalyst acid heterogeneous; BET; SEM-EDX; FAME; AV; PFAD; OPACL-(OPT)-SO3H; Esterification reaction
• ISSN: 0196-8904
• DOI: 10.1016/j.enconman.2024.118801

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•A sustainable and low cost heterogeneous catalyst was developed from onion peels.•The maximum conversion of 98.9 % was obtained under optimized conditions.•The esterification reaction is endothermic, endergonic, and non-spontaneous.•The biodiesel properties are analyzed to reveal the main characteristics of FAME.•The catalyst was successfully recycled for four successive cycles.
In this study, a sustainable and economical acid heterogeneous catalyst derived from onion peels (Allium cepa L.) was developed through a direct sulfonation process to enhance sustainable biodiesel manufacturing via an esterification process using palm oil refining by-products as the primary feedstock. The developed catalyst OPACL-(OPT)-SO3H, was characterized using various analytical techniques, including XRD, SEM-EDX, FT-IR, TGA/DTA, DLS, BET, and Boehm titration. The results demonstrated an amorphous carbon structure with a high total acid density of 8.12 mmol/g, achieved under sulfonation conditions with 18.658 mol/l concentrated sulfuric acid at 70 °C for 8 h. Furthermore, under optimal esterification reaction conditions, the OPACL-(OPT)-SO3H catalyst exhibited excellent catalytic activity, achieving a maximum FFA conversion of 98.9 % after 3 h, with a catalyst amount of 5 wt% and a PFAD/methanol molar ratio of 1:15 at 80 °C. Moreover, the activation energy for the esterification reaction was determined to be 35.4 kJ/mol. Thermodynamically, the reaction was found to be endothermic and non-spontaneous. The catalyst demonstrated exceptional stability, capable of being regenerated in four consecutive cycles. An exhaustive analysis of the synthesized biodiesel’s physicochemical properties confirmed adherence to the internationally recognized ASTM D − 6751 standards. In conclusion, the acid catalyst derived from onion peels shows significant potential for use as a heterogeneous catalyst in biodiesel production.