Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications.

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The esterification of oleic acid with ethanol was studied in both batch and continuous conditions in a fixed-bed reactor over FAU-type zeolites prepared from shale rock. The addition of Co-Ni-Pt to the zeolite increased the catalyst activity over the entire reaction temperature range. Experiments confirmed that esterification follows pseudo first-order kinetics. Thermodynamic analysis and Thiele modulus calculations show that the reaction is kinetically controlled in batch conditions, while diffusional limitations occur at higher flow rates when conducted in continuous mode. The maximum oleic acid conversions were recorded as 93% for batch and 89% for continuous, which exceed those of any analogous studies.

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