Adsorption of Indole from Model Fuel onto Regenerated FCC Catalyst Waste: Kinetic, Equilibrium and Thermodynamic Evaluation
Adsorption of Indole from Model Fuel onto Regenerated FCC Catalyst Waste: Kinetic, Equilibrium and Thermodynamic Evaluation
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DOI: https://doi.org/10.22533/at.ed.1317672622066
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Palavras-chave: Adsorção de indol, catalisador de equilíbrio regenerado (ecat-R), desnitrogenação de combustível, termodinâmica da adsorção, valorização de resíduos.
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Keywords: Indole Adsorption, Regenerated equilibrium catalyst (ecat-R), Fuel denitrogenation, Adsorption thermodynamics, Waste valorization.
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Abstract: The removal of nitrogen-containing compounds from fuel streams remains an important challenge in petroleum refining due to their adverse effects on catalytic processes and fuel quality. In this study, the adsorption of indole, a representative neutral nitrogen- containing aromatic compound, onto regenerated FCC catalyst waste (ecat-R) was investigated. Batch adsorption experiments were conducted using model fuel under different temperature conditions (25, 40, and 55 °C). Adsorption kinetics, equilibrium behavior, activation energy, and thermodynamic parameters were evaluated. The adsorption process reached equilibrium within approximately 120 min for all investigated temperatures. Kinetic data were best described by the pseudo-second-order model, indicating a strong agreement between experimental and calculated adsorption capacities. Equilibrium studies showed favorable adsorption behavior, and the Langmuir model provided the best fit to the experimental data at 40 °C, yielding a maximum adsorption capacity of 6.62 mg g⁻¹. The activation energy was determined as 6.5 kJ mol⁻¹, suggesting a low energetic barrier for adsorption. Thermodynamic analysis revealed negative Gibbs free energy values, confirming the spontaneous nature of the process. The low enthalpy change and positive entropy change indicated limited temperature dependence and favorable adsorption conditions. The results demonstrate that regenerated FCC catalyst waste is a promising and sustainable adsorbent for indole removal from fuel streams, exhibiting rapid adsorption kinetics, favorable equilibrium characteristics, and stable performance over the investigated temperature range.
- Thamayne Valadares de Oliveira
- Nicole Salvador
- Iuri Ferreira Veiga
- Erik Nassif Barbosa
- Matheus Martins da Silveira
- Rafael Bruno Vieira