High-Efficient and Recyclable Magnetic Separable Catalyst for Catalytic Hydrogenolysis of β-O-4 Linkage in Lignin.

Lignin is recognized as a good sustainable material because of its great abundance and potential applications. At present, lignin hydrogenolysis is considered as a potential but challenging way to produce low-molecular-mass aromatic chemicals. The most common linkage between the structural units of lignin polymer is the β-O-4 aryl ether, which are primary or even only target chemical bonds for many degradation processes. Herein, a Pd-Fe₃O₄ composite was synthesized for catalytic hydrogenolysis of β-O-4 bond in lignin. The synthesized catalyst was characterized by XRD, XPS, and SEM and the lignin depolymerization products were analyzed by GC-MS. The catalyst showed good catalytic performance during the hydrogenolysis process, lignin dimer was degraded into monomers completely and a high yield of monomers was obtained by the hydrogenolysis of bagasse lignin. More importantly, the magnetic catalyst was separated conveniently by magnet after reaction and remained highly catalytically efficient after being reused for five times. This work has demonstrated an efficient & recyclable catalyst for the cleavage of the β-O-4 bond in lignin providing an alternative way to make better use of lignins.