Cobalt carbide nanoprisms focus on light olefins

Prism-shaped cobalt carbide nanoparticles have been found to efficiently catalyze the Fischer-Tropsch to olefin (FTO) process—the conversion of syngas (CO + H₂) to light olefins—with high selectivity and at relatively low temperature (Nature 2016, DOI: 10.1038/nature19786). The discovery is surprising because spherical counterparts of cobalt carbide crystallites “are of little use in this reaction, and because spherical particles of cobalt metal produce a completely different product,” says catalysis specialist Michael Claeys of the University of Cape Town in an accompanying commentary. “This is a groundbreaking contribution that further unlocks the immense potential of the Fischer-Tropsch process for producing chemicals,” Claeys adds. The FTO process leads to industrially important light (C₂ to C₄) olefins that are used to make polymers. Iron carbide-catalyzed Fischer-Tropsch processes yield 24% light olefins at about 340 °C, and sulfur-modified iron-catalyzed FTO produces 60% light olefins at 325 °C. But both catalysts deactivate quickly at these temperatures. Liangshu Zhong and Yuhan Sun of Shanghai Advanced Research Institute and coworkers, who performed the new study, show that Co₂C nanoprism-catalyzed FTO produces about 61% light olefins. It also works at 250 °C, where the catalyst can be expected to be more stable, and produces lower quantities of undesired methane by-product.