Structure‐Informed Regeneration of Spent Oil Refinery Molecular Sieves: Characterization and Multi‐Technique Treatment Assessment Toward Reuse

Spent molecular‐sieve adsorbents from petroleum refining constitute a recurring hazardous‐waste burden, yet no established criterion exists for determining which spent materials warrant regeneration. Three spent adsorbents recovered from refinery hydrocarbon‐dehydration service, designated MS‐BR, MS‐RR2, and MS‐RR2‐A, were characterized by X‐ray diffraction, X‐ray fluorescence, and scanning electron microscopy with energy‐dispersive spectroscopy, then regenerated by thermal treatment, hydrochloric acid treatment, and NaCl ion exchange. MS‐BR and MS‐RR2 retained identifiable Linde Type A (LTA) framework characteristics, with bulk Si/Al molar ratios of 1.46 and 1.70, respectively. In contrast, MS‐RR2‐A contained 90.11 wt% Al ₂ O ₃ and had a bulk Si/Al ratio of 0.079, consistent with severe structural degradation. Treatment mass recoveries ranged from 80.9% to 94.9%. Preliminary direct‐water screening showed that apparent gravimetric retention in MS‐BR and MS‐RR2 increased from 0.10–0.11 to 0.32–0.44 g g ⁻¹ after thermal or ion‐exchange treatment, compared with 0.41–0.49 g g ⁻¹ for fresh references, whilst treated MS‐RR2‐A remained at 0.01–0.07 g g ⁻¹ . Exploratory 16 h water–toluene batch‐contact testing showed stronger apparent responses after thermal treatment, followed by ion exchange, with limited chemical‐treatment effectiveness. These findings support structural characterization for identifying regeneration potential, with batch results representing comparative apparent retention rather than equilibrium adsorption capacities.