Magnetically recyclable catalyst Ni/HZSM-5@SiO2@Fe3O4 for hydrodeoxygenation of 4-ethylphenol into high heat sink aviation fuel of ethylcyclohexane

Hydrodeoxygenation (HDO) of phenols has significant potential for the synthesis of cycloalkane. In this study, a Ni-based magnetic molecular sieve catalyst, Ni/HZSM-5@SiO2@Fe3O4, was carefully prepared and systematically characterized using various analytical methods. A screening of the HDO reaction conditions was carried out using a typical phenolic compound of 4-ethylphenol. Under the optimal reaction conditions (240 °C, 3 h) with n-dodecane as the solvent, the 6 % Ni/HZSM-5@SiO2@Fe3O4 catalyst showed excellent performance, achieving a 4-ethylphenol conversion of 59.3 % and an ethylcyclohexane selectivity of 85.1 %. In comparison to conventional Ni/HZSM-5, the magnetic micromesoporous molecular sieve catalyst exhibited superior catalytic activity, alkane selectivity and recyclability, with a catalyst recovery ratio of 95 %. Furthermore, the effect of liquid-solid mass transfer efficiency on the ethylcyclohexane selectivity considering of the stirring speed was studied, and the selectivity was increased from 81.6 to 85.1 % when the speed was increased from 400 to 600 rpm. This finding was further substantiated by Fluent numerical simulation. To elucidate the HDO pathway of 4-ethylphenol on Ni/HZSM-5@SiO2@Fe3O4, a comprehensive reaction pathway was proposed, providing insights into the catalytic mechanism.