Higher alcohols (C2+alcohols) are important raw materials that have been used as intermediates in the production of valuable products. They are also widely used in the fuel, food, fine chemical, pharmaceutical and energy or syngas conversion industries. However, due to the coordination of CO dissociative and non-dissociative sites, the synthesis of higher alcohol via syngas remains difficult.

To address this, the researchers designed coexisting Ca-Fe catalysts to optimize active sites in CO hydrogenation and regulate product synthesis.

With the depletion of petroleum resources, direct synthesis of higher alcohols from syngas has emerged as a sustainable and potential process due to its abundant raw materials and high atomic utilization. However, its industrial application is limited due to the low yield of higher alcohols.

Direct synthesis of higher alcohols from syngas has been accomplished by a research team led by Professors SUN Jian and GE Qingjie from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) – highly selective production of higher alcohols from CO hydrogenation over synergistic iron carbide catalysts.

prof. SUN said: “The proposed Ca-Fe series synergistic catalysts could achieve an oxygenate selectivity of 69.7 wt% under mild conditions, in addition to the alcohol fraction of 86.4% in oxygenates. Overall selectivity for oxygenates and alcohols outperformed results from previously reported catalysts.”

According to the researchers, the Ca charge enabled the Ca-Fe catalyst to produce high surface area iron carbides with a proper Fe2C/(Fe5C2+Fe3C) ratio. To produce higher alcohols, the Fe5C2 and Fe3C as CO dissociative sites could benefit from a synergistic effect with Fe2C (CO non-dissociative sites).

As a result, the correct Fe2C/(Fe5C2+Fe3C) ratio helped to balance the dissociative and non-dissociative properties of CO and improved the cooperation of *CO and *CHx to CHx-CO species, which promoted higher alcohol formation.

prof. SUN said: “This study expands our understanding of the important role of Ca and provides a new strategy for catalyst design in the hydrogenation of CO to higher alcohols.”

Magazine reference:

  1. Xu, Zhang, Sun, J. Precisely synergistic synthesis of higher alcohols from syngas over iron carbides. Chemical catalysis. DOI: 10.1016/j.checat.2023.100584