Organochlorine Liquid Adsorption Competitions in FAU-Modified Zeolites

1-Chloroheptane (C7Cl) removal from model pyrolysis oils was investigated using various exchanged FAU zeolites in batch adsorption experiments in the liquid phase. The influence of the zeolite acid–base properties and the solvent composition were analyzed. In paraffinic solvents, our findings align closely with results obtained in the gas phase. Solvent competition has a low impact on C7Cl adsorption, and a linear correlation is observed between the partial charge of framework oxygen atoms and the efficiency of C7Cl adsorption. In more complex mixtures containing short olefins and aromatic compounds, C7Cl removal is significantly reduced due to competitive adsorption and steric hindrances within the zeolite supercages. Despite this, Zn-X and K-X zeolites exhibit unexpected selectivity for C7Cl removal compared with Na-X. This behavior is attributed to cation location and size, as well as the higher affinity of Zn-X zeolites for olefins over aromatics. These findings highlight the potential of Zn-X and K-X zeolites as promising adsorbents for pyrolysis oil dechlorination in adsorption-based processes.