Study on the hydrothermal liquefaction of antibiotic residues with molecular sieve catalysts in the ethanol–water system: focus on product distribution and characterization

Abstract

In this study, the antibiotic residue was used as a raw material to catalyze hydrothermal liquefaction (HTL) in an ethanol–water system to prepare bio-oil. The study explored the effects of ethanol–water ratio and three kinds of molecular sieve catalysts (HZSM-5, MCM-41, and γ-Al₂O₃) on the yield and characterization of bio-oil. The experimental results showed that the highest bio-oil yield was obtained at the ethanol–water ratio of 1 : 1 and the three kinds of molecular sieve catalysts of 15%. GC-MS, ¹H NMR, TGA, and CHNS were used for the characterization of bio-oil. Higher carbon (up to 71.44%), hydrogen (up to 9.376%), and a high heating value (HHV, 34.714 MJ kg⁻¹) were observed for catalytically liquefied bio-oil compared to non-catalytically liquefied bio-oil. The analysis of aqueous phase products indicated the existence of valuable nutrients. Besides, the reusability of three kinds of molecular sieve catalysts indicated that catalysts could be successfully reused several times and continuously exhibited the catalyst effect.