Preparation of Co–Co9S8–MoS2 catalyst for efficient deoxygenation of lignin-derived aromatic oxy-compounds into arenes

The formidable challenge for the deoxygenation of lignin-derived aromatic oxy-compounds into arenes under mild conditions is how to engineer a robust catalyst. In this study, Co–Co9S8–MoS2 catalyst was prepared via thermal decomposition, in–situ sulfidation and following by H2 reduction, where Co was highly dispersed and mainly existed in the species of metallic Co and Co9S8. This catalyst exhibited high activity, allowing the reaction temperature for cleaving Caromatic–O bond lowered to 120 °C, which was attributed to that metallic Co accelerated the H2 dissociation and then enhanced the deoxygenation activity. Co–Co9S8–MoS2 also presented a high stability: both the conversion and product selectivity were unchanged after 8 continuous cycles, and the characterization results evidenced almost no structure change and sulfur loss during the deoxygenation reaction. In addition, other 20 aromatic oxy-compounds including acid, ester, guaiacol and dimer lignin linkages were also successfully deoxygenated, and the arenes selectivity could maintain higher than 98 %. This work offered a new strategy for constructing metal–sulfide–MoS2 type catalysts and provided an efficient route towards the practical application in bio-oil upgrading.