Lignin Pyrolysis with Sodium Formate for Stabilization of Pyrolytic Products

With the rapid commercialization of cellulosic ethanol in recent years, utilization of lignin byproduct to value-added products has received increasing attention. Depolymerizing lignin into phenolic monomers could provide valuable precursors for biofuels and other biobased products. Although fast pyrolysis process has the ability to thermal depolymerize lignin, it usually yields a very small amount of phenolic monomers and instead produces a large amount of phenolic oligomers that have limited applications. Repolymerization of reactive phenols could be responsible for the increasing molecular weight of pyrolysis products. Introducing hydrogen atoms during pyrolysis could promote stabilization of phenolic monomers thus prevents repolymerization of phenolic monomers to oligomers. In the present study, sodium formate is selected as a hydrogen donating agent and co-pyrolyzed with lignin in a micropyrolyzer. It is found that the presence of sodium formate promotes the production of simple or stable phenols such as phenol, syringle and ethylphenol, while reduces the yield of acetic acid. Deuterated sodium formate is also employed in the present study to investigate the mechanism of hydrogen transfer during pyrolysis.