Pyrolysis of LignoForceTM lignins for the production of valuable chemicals

Abstract

Brazil detains one of the hugest forestry activities worldwide that can fulfill several gaps regarding bioenergy and bioproduct generation. Forestry can provide clean energy through the use of natural polymers such as cellulose, hemicellulose, and lignin. Up to now, cellulose has been the most versatile woody product on Earth. By contrast, lignin is the most underutilized biopolymer. However, being a polyphenolic material, lignin offers several opportunities for the replacement of fossil fuels, additives, plastics, antioxidants, resins, and other carbon-based materials. Pulp and paper mills produce a massive amount of lignin daily (75,000 metric tons per year) and most of it is incinerated for energy and chemical recovery. Since lignin is overproduced in some of these industrial sites, it may be seen as a sustainable source of aromatic compounds and other platform chemicals. Besides, uncountable tons of lignin in residual materials could be used for the same purpose. In this work, lignin samples isolated from hardwood and softwood species by the LignoForce™ process were pyrolyzed at 550 °C to produce liquid small molecular weight compounds. The liquid products were separated into two phases and characterized by GC-MS, FTIR, acid index (AI), 31P NMR, and Karl-Fischer titration. Formic and acetic acids, besides a vast range of phenolics including chemicals such as catechol, pyrogallol, and guaiacol were identified in pyrolysis liquids. These monomers are important precursors for the synthesis of fuel additives, platform chemicals, and renewable hydrocarbons.