Preparation and selective adsorption performance of F‐modified <scp>ZSM</scp> ‐5 zeolite for m‐cresol and p‐cresol

Abstract M‐cresol and p‐cresol, typically produced as mixtures in industrial processes, are crucial chemical intermediates. However, their separation is challenging due to their similar structures and properties. ZSM‐5 zeolite has shown potential as an adsorbent for separation, while the performance is yet to be improved. In this study, ZSM‐5‐F(x) was synthesized via hydrothermal method, incorporating F − ions during the synthesis process. The adsorption behaviour of m‐cresol and p‐cresol on ZSM‐5‐F(x) was investigated through static experiments, with ZSM‐5‐F(8) demonstrating the highest selectivity (9.01). Both ZSM‐5‐F(0) and ZSM‐5‐F(8) were characterized using XRD, scanning electron microscopy (SEM), and Brunauer‐Emmett‐Teller (BET) techniques. In addition, the introduction of F − ions increased the material's electronegativity, as demonstrated by the change in zeta potential from 53.22 to −45.93 mV. Single‐component adsorption of m‐cresol or p‐cresol on ZSM‐5‐F(0) and ZSM‐5‐F(8) respectively were investigated in detail. The adsorption of m‐cresol on ZSM‐5‐F(8) showed a non‐monotonic phenomenon with a significant decrease after 0.06 mol/L. The thermodynamic parameters including Δ G , Δ H , and Δ S were calculated accordingly. All the values |Δ G |, |Δ H |, and |Δ S | of both components on ZSM‐5‐F(8) were greater than those on ZSM‐5‐F(0), suggesting that the introduction of F − ions facilitated the adsorption. Competitive adsorption experiments on both ZSM‐5‐F(0) and ZSM‐5‐F(8) were conducted at 298.2 K. The results indicated that the selectivity α p/m on ZSM‐5‐F(8) increased with increasing initial concentration and laid between 13 and 14. After seven consecutive regeneration cycles, the selectivity (α p/m ) only decreased to 13. This study suggests that ZSM‐5‐F(8) could be a promising adsorbent for m‐cresol and p‐cresol in industrial applications.