Co-self-assembly of lignin and tannin: A novel catalyst support for hydrogenation of lignin-derived aldehydes

Co-self-assembly of lignin oligomers together with other structurally similar molecules can provide composite particles with functional properties for specific applications. Herein, tannin was co-self-assembled for the first time with lignin oligomers into novel lignin–tannin particles (LxTy), induced by a dual driven force with π–π stacking interaction and hydrogen bonds. Abundant ortho-phenolic hydroxyl groups of tannin cause the efficient adsorption and partial reduction of Pd2+ ions (36.7%) by LxTy (>99%) to obtain Pd/LxTy with highly dispersed Pd nanoparticles, thereby avoiding the need for surfactants or reducing agents. Aldehyde groups of lignin-derived aldehydes could preferentially interact with phenolic hydroxyl groups on the hydrophilic shell of Pd/LxTy. Then, mitigated active hydrogen atoms on the LxTy support during the hydrogen spillover process induced a H-shift to C of −CO through a water bridge with low energy barrier and consequently selective hydrogenation to obtain lignin-derived alcohols at 30 °C.