Insight into the Formation of Co@Co₂C Catalysts for Direct Synthesis of Higher Alcohols and Olefins from Syngas

Citations Over TimeTop 10% of 2017 papers

Abstract

Cobalt carbide (Co2C) has recently been reported to be efficient for the conversion of syngas (CO+H2) to lower olefins (C2–C4) and higher alcohols (C2+ alcohols); however, its properties and formation conditions remain ambiguous. On the basis of our previous investigations concerning the formation of Co2C, the work herein was aimed at defining the mechanism by which the manganese promoter functions in the Co-based catalysts supported on activated carbon (CoxMn/AC). Experimental studies validated that Mn facilitates the dissociation and disproportionation of CO on the surface of catalyst and prohibits H2 adsorption to some extent, creating a relative C-rich and H-lean surface chemical environment. We advocate that the surface conditions result in the transformation from metallic Co to Co2C phase under realistic reaction conditions to form Co@Co2C nanoparticles, in which residual small Co0 ensembles (<6 nm) distribute on the surface of Co2C nanoparticles (∼20 nm). Compared with the Co/AC catalyst, where the active site is composed of Co2C phase on the surface of Co0 nanoparticles (Co2C@Co), the Mn-promoted catalysts (Co@Co2C) displayed much higher olefin selectivity (10% versus 40%), while the selectivity to alcohols over the two catalysts are similar (∼20%). The rationale behind the strong structure–performance relationship is twofold. On the one hand, Co–Co2C interfaces exist universally in the catalysts, where synergistic effects between metallic Co and Co2C phase occur and are responsible for the formation of alcohols. On the other hand, the relative C-rich and H-lean surface chemical environment created by Mn on the Co@Co2C catalysts facilitates the formation of olefins.

Related Papers

• → Catalytic investigation for Fischer–Tropsch synthesis from bio-mass derived syngas(2003)154 cited
• → Experimental microwave-assisted air gasification of biomass for syngas production(2022)37 cited
• → Methanol generation from bio-syngas: experimental analysis and modeling studies(2023)19 cited
• → Catalytic Conversion of Biomass-derived Syngas to Gasoline Range Hydrocarbons(2011)
• Assessment of the liquid phase methanol synthesis process: CO-rich vs. H{sub 2}-rich syngas(1994)