Catalysis Letters, Vol.151, No.4, 932-939, 2021
Hydrodeoxygenation of Lignin-Derived Aromatic Oxygenates Over Pd-Fe Bimetallic Catalyst: A Mechanistic Study of Direct C-O Bond Cleavage and Direct Ring Hydrogenation
Hydrodeoxygenation of lignin-derived phenols could be achieved generally with three reaction pathways: tautomerization, direct ring hydrogenation and direct C-O bond cleavage. The former pathway has been extensively studied over Pd/Fe catalyst in liquid-phase reaction, however, the contribution of the latter two is yet subject to further investigations. In this report, a comparative study of direct C-O bond cleavage and direct ring hydrogenation reaction pathways is presented on Pd/Fe, Fe and Pd/C catalysts using diphenyl ether as modelling compound. Despite its much higher activation energy than direct ring hydrogenation, direct C-O bond cleavage is dominant over Pd/Fe with much higher rates than the monometallic analogues due to the synergic catalysis of Pd-Fe. Based on this study and our previous results, the detailed reaction network for HDO of diphenyl ether is proposed. [GRAPHICS] .