DOI: https://doi.org/10.14710/jksa.29.9.581-589

Hydrothermal Conversion of Glycerol over Cu-Modified Acid-Activated Natural Zeolite: Effect of Cu Loading and Reaction Time on Catalytic Performance

Department of Chemical Engineering, Faculty of Engineering, Universitas Sebelas Maret, Jl. Ir. Sutami No.36A, Surakarta, 57126, Indonesia

Received: 10 Jun 2026; Revised: 2 Sep 2026; Accepted: 25 Sep 2026; Published: 30 Oct 2026.
Open Access Copyright 2026 Jurnal Kimia Sains dan Aplikasi under http://creativecommons.org/licenses/by-sa/4.0.

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Abstract

The conversion of glycerol into value-added chemicals represents an attractive approach for improving the economic sustainability of biodiesel production. In this study, Cu-modified acid-activated natural zeolite (Cu-ANZ) catalysts were prepared and evaluated for hydrothermal glycerol conversion, with particular attention to the formation of a product tentatively assigned to lactic acid based on its HPLC retention time relative to that of a lactic acid standard. Natural zeolite was activated using hydrochloric acid and subsequently modified by Cu impregnation at loadings of 2.5–15 wt%. The catalysts were characterized using FTIR, XRD, SEM-EDX, and BET analyses, while the reaction products were analyzed by HPLC after hydrothermal conversion of glycerol at 230°C in the presence of NaOH. FTIR and XRD analyses indicated that the modification treatments altered the physicochemical properties of the natural zeolite while preserving its fundamental structural features and crystallinity. SEM-EDX analysis confirmed the presence of Cu in the modified catalyst and showed a higher Si/Al ratio for Cu-ANZ than for the untreated natural zeolite. BET analysis showed that the surface area increased from 27.010 to 32.826 m2 g−1 after the overall modification process. The relative HPLC peak area (RHPA) increased with Cu loading up to 10 wt%, reaching its maximum, then decreased at higher Cu loadings. Investigation of reaction time showed an increase in the RHPA with longer reaction durations, with a pronounced increase observed between 100 and 180 min and the highest value observed at 300 min. These findings indicate that Cu loading and reaction time influence the relative HPLC response associated with the product tentatively assigned to lactic acid during hydrothermal glycerol conversion and provide insights into the potential application of Cu-modified acid-activated natural zeolite in this reaction.

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Keywords: Glycerol conversion; Lactic acid; Natural zeolite; Copper catalyst; Hydrothermal catalysis
Funding: GR-UNS research scheme under contract 228/UN27.22/PT.01.03/2023

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Section: Research Articles
Language : EN
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