Direct Synthesis of Higher Alcohols from Syngas Over Al-Doped ZnO Semiconductor Catalysts

Graphical The Al-doped ZnO catalyst has a lower work function, which is conducive to promoting the dissociation of CH x O* to form CH x *; it also facilitates the generation of Zn x+ and oxygen vacancies, which further promotes the generation of C 2+ OH. The direct conversion of syngas into C 2+ OH has attracted significant attention as a potential pathway for energy conversion. However, this process typically requires the use of precious metals or the collaborative action of multi-component catalysts, making it relatively complex. In this paper, simple and economical Al-doped ZnO catalysts were employed for the synthesis of C 2+ OH. The results show that the work function, Zn x+, and the relative content of oxygen vacancies are linearly related to C 2+ OH/ROH. When the doping amount was 7 mol%, the catalyst had the highest C 2+ OH/ROH (82.6 wt%), corresponding to the lowest work function value, the highest Zn x+ content, and the relative content of oxygen vacancies. We reveal that the successful synthesis of C 2+ OH depends not only on the low work function of the Al-doped ZnO but also on the existence of the oxygen vacancies and Zn x+ sites. Specifically, the low work function induced by Al doping facilitates electron transfer in the reaction, facilitating the dissociation of CH x O* into CH x *. Meanwhile, the presence of oxygen vacancies enhances the dissociative adsorption capacity of CO and facilitates the formation of CH x * species. The Zn x+ sites serve as active centers for carbon chain growth, promoting C–C coupling through the insertion of CO or CH x O* into CH x *, thereby achieving chain elongation.