Carbon nanotube-supported bimetallic Cu-Fe catalysts for syngas conversion to higher alcohols

Abstract

Catalytic transformation of syngas into higher alcohols is a challenging theme in C1 chemistry. The formation of higher alcohols require the synergy between active sites with abilities for CO dissociative and non-dissociative adsorption. This work reports Cu-Fe bimetallic catalysts loaded on carbon nanotubes (CNTs) for the conversion of syngas to higher alcohols. The structure-performance relationship for the catalysts prepared by different methods including co-impregnation and immobilization of pre-fabricated bimetallic nanoparticles have been investigated to gain insights into the effect of proximity of active sites on the formation of higher alcohols. We found that the Cu-Fe/CNT-co-red-imm catalyst, which was prepared by immobilization of colloidal bimetallic nanoparticles pre-fabricated with a co-reduction method, showed the closest proximity of Cu and Fe domains. This catalyst demonstrates the highest selectivity of higher alcohols. Our DFT calculation suggests that the coupling of surface CHO and CHx intermediates to form CH3CHO is a rate-limiting step. The DFT calculation also shows that the closer proximity between Fe2C (Fe) and Cu species leads to a lower energy barrier for the formation of CH3CH2OH from syngas.