Enhanced production of aromatics from syngas over CoMnAl oxides combined with b-axis thickness tailored HZSM-5

Abstract

The direct conversion of syngas to aromatics has a promising industrial future and can be achieved using bifunctional catalysts through olefin intermediates. However, the development of bifunctional catalysts with high aromatics yields remains a great challenge. In this work, we synthesized a series of HZSM-5 zeolites with different morphologies and pore structures and coupled them with CoMnAl oxides, which contain Co₂C nanoprisms as the active phase and are highly efficient syngas to olefin catalysts, for aromatics synthesis directly from syngas. We demonstrate that a decreasing b-axis thickness and an appropriate density of Brønsted acid sites of HZSM-5 favors the syngas conversion to aromatics via bifunctional catalysis. The bifunctional catalysts with the smallest b-axis thickness of HZSM-5 zeolite of approximately 37 nm achieve a CO conversion of more than 70% under mild reaction conditions of 280 °C and 2.0 MPa, with high stability. The selectivity toward aromatics is higher than 65% with 3.5% selectivity toward by-product CH₄ and the aromatics yield is up to 27.1%. This study provides an exemplary new strategy for the efficient synthesis of aromatic hydrocarbons from syngas.