Selective depolymerization of lignosulfonate via hydrogen transfer enhanced in an emulsion microreactor

An efficient emulsion microreactor was constructed for selective conversion of lignosulfonate via hydrogen transfer reaction based on the self-surfactivity of this natural aromatic polymer. Industrial Raney Ni and isopropanol were used as catalyst and hydrogen donor, respectively. The results showed that the emulsion microreactor has a remarkable process intensification effect on the lignosulfonate depolymerization. Under mild condition of 473 K for 2.0 h, 116.1 mg g(-1) of volatile phenolic monomer can be obtained, which is twice of that from other investigated processes without emulsion of this work. In particular, 39.3 mg g(-1) of which is composed of 4-ethyl guaiacol, an important and versatile chemical currently from petrochemical industry. Furthermore, the solvent separates to two phases automatically after reaction due to the consumption of lignosulfonate, which makes handy products enrichment and separation. Additionally, the emulsion microreactor is significantly affected by hydrogen donor and is efficient for other lignin sources as well.