The direct conversion of syngas (CO/H₂) to aromatics requires both high catalytic conversion and high selectivity, which is challenging to achieve. Bifunctional metal oxide-zeolite (OX-ZEO) catalysts have shown high selectivity to hydrocarbon products such as olefins and aromatics in the syngas conversion, but relatively low activity.

Zhen Huang, Fudan University, China, and colleagues have prepared an OX-ZEO bifunctional catalyst composed of the perovskite LaFeO₃ and the zeolite ZSM-5. The team synthesized a series of LaBO₃-type compounds (B = Fe, Co, Ni, Mn, Cr) and used them as the metal-oxide component of OX-ZEO catalysts. They found that LaFeO₃, LaMnO₃, and LaCrO₃ showed good performance for the conversion of syngas to aromatics, with the iron derivative performing best.

The developed LaFeO₃/ZSM-5 catalyst exhibited a superior catalytic performance with 82.0 % selectivity to aromatics and 28.5 % CO conversion at 420 °C and 3.6 MPa. The team found that syngas conversion over the La-based perovskites followed a formate-methoxy-oxygenates reaction pathway (pictured). This work, thus, presents new clues for designing highly selective bifunctional catalysts for the syngas-to-aromatics reaction with high conversion.

• La‐Based Perovskites Combined with HZSM‐5 for Selective Conversion of Syngas into Aromatics,
  Jinhao Wang, Zhen Huang, Yue Fang, Wei Shen, Hualong Xu,
  ChemistrySelect 2021.
  https://doi.org/10.1002/slct.202102689