Co–Co2C catalysts supported on carbon-coated ordered mesoporous silica with promoted CO insertion and C–C coupling for higher alcohol synthesis from syngas

Abstract

Higher alcohol synthesis (HAS) from syngas is a potential energy conversion route which has attracted extensive interest from both academia and industry. Co–Co₂C catalysts are promising candidates for HAS, but the yield of higher alcohols (HAs) and catalyst stability still need to be promoted. Here, a series of carbon-coated ordered mesoporous silica (OMS) supported cobalt catalysts were prepared with modulated carbon layer thicknesses. Co/10C/OMS with a carbon layer of 0.55 nm achieved an optimal ROH selectivity of 41.3%, space time yield (STY) towards a HA of 23.7 mmol g_cat⁻¹ h⁻¹ and stability over 300 h. As the carbon layer thickened, particle dispersion was facilitated and the metal-support interaction was modulated, which resulted in the volcanic variation of the surface Co₂C/Co⁰ ratio. In addition, compared to a carbon-coated amorphous SiO₂ supported sample, significant CO enrichment was observed inside the ordered mesopores in Co/xC/OMS, which enhanced the CO insertion and C–C coupling, boosting the selectivity of HA. This work may give insights into the use of carbon–silica composite supports and the design of high-performance Co–Co₂C catalysts for HAS.