Design synthesis of ZSM-5 zeolite with yolk-shell structure by Oswald ripening for aromatization of coal-oil co-refining oils

Aiming to improve the catalytic performance of HZSM-5 in the catalytic conversion of coal-oil co-refining oil, a range of zeolite catalysts (HZ5-xD) were prepared by adjusting the recrystallization times of dissolution–recrystallization of HZSM-5 basing on the Oswald ripening mechanism. The results show that HZ5-xD processes more easily accessible active sites and mixed microporous-mesoporous structures. Larger pore size and moderate acidity were beneficial for the generation of benzene, toluene, ethylbenzene and xylene (BTEX). The selectivity and yield of reached as high as 29.76 % and 236.83 mg·g−1 over HZ5-2D at 700 °C, respectively. Both HZSM-5 and HZ5-xD demonstrate high selectivity to C3 gaseous hydrocarbons, likely due to the obedience of the carbenium ion mechanism. HZ5-2D still demonstrated more excellent catalytic performance than HZSM-5 after five regenerations. Collectively, these finding illustrates the broad application potential of Oswald ripening in special morphologies of zeolite to improve the conversion efficiency of coal tar to BTEX.