Iron-Based Catalysts Integrated with Twinned HZSM-5 as Efficient Catalysts for Paraxylene Synthesis by CO₂ Hydrogenation

Optimization of zeolite geometries to break through the current selectivity limitations of CO2 hydrogenation for the synthesis of high-value paraxylene (PX) is a promising and challenging topic. Herein, twinned HZSM-5 (LZ5) with a high sinusoidal pore opening ratio was synthesized, and the tandem catalyst formed by coupling it with an iron-based catalyst could realize the highly selective production of PX by CO2 hydrogenation. Under industrially relevant conditions, the CO2 conversion was 31.5%, and the selectivies for PX in aromatics and in xylene (X) were as high as 34.0 and 90.0%, respectively. This good performance was attributed to the high sinusoidal pore opening ratio of the LZ5 in the tandem catalyst, improving its ability to screen xylene isomers. The particle size of LZ5 has a small effect on the selectivity of CO2 hydrogenation to PX. In addition, the proper proximity of the two components also played a crucial role in the continuous and cocatalytic conversion of CO2 to PX. The present work realized the improvement in the selective catalytic performance of zeolites through directional modulation of their pore structures and provided a new idea for the design of efficient catalysts in the hydrogenation of CO2 to PX.