Trace-level halogen blocks CO ₂ emission in Fischer-Tropsch synthesis for olefins production

This is the authors' abstract. We don't add key points for this paper.

Sustainable production of fuels and olefins from syngas (carbon monoxide and hydrogen) through the Fischer-Tropsch synthesis process requires catalysts that deliver high selectivity, industrial productivity, and minimal carbon dioxide (CO 2 ) emissions. Current industrial iron catalysts form substantial CO 2 by-product that limits carbon efficiency. We report that introducing trace amounts [parts per million (ppm) level] of halogen-containing compounds into the feed gas can suppress CO 2 formation using iron-based catalysts and boost olefin selectivity over paraffin and olefin productivity. Cofeeding 20 ppm bromomethane over an iron carbide catalyst decreased CO 2 selectivity to <1% and increased olefin selectivity to ~85% among all carbon-containing products. Surface-bound halogens modulated the catalyst surface structure and selectively inhibited pathways responsible for CO 2 generation and olefin hydrogenation. This strategy provides a simple, scalable, and broadly applicable route for carbon-efficient syngas conversion.