Hydrogenolysis Of Aryl Ether Bond Over Heterogeneous Cobalt-Based Catalyst

The development of efficient non-noble metal catalysts is of critical importance for conversion of lignin toward value-added chemicals. The trans-metal Co catalysts and the counterparts promoted with a small amount of Ru were found highly selective for hydrogenolysis of lignin-derived aromatic ethers in decalin at relatively mild conditions. The physical and chemical properties of the as-prepared catalysts were fully investigated by various characterization methods, and Co species was found well dispersed in the reduced catalysts. The experimental results showed that Co/CeO2 could selectively cleave the C-O bonds of diphenyl ether (DPE) to produce benzene and phenol, which can be further converted to cyclohexane and cyclohexanol. Upon 5Co/CeO2, 97% selectivity to those C-O bond ruptured products was achieved, while the direct hydrogenation products including dicyclohexyl ether and cyclohexyl account for only 3%. Moreover, benzene, featured as a typical intermediate product, could reach a maximum yield of 27.4% at around 80% conversion. The addition of a small amount of Ru (0.1 wt % and below) could significantly accelerate the hydrogenolysis reactivity but also result in the declined selectivity of benzene during the reaction due to the stronger hydrogenation ability.