Techno-economic analysis of different integrated biorefinery scenarios using lignocellulosic waste streams as source for phenolic alcohols production

Abstract

The whole process of lignin extraction from a lignocellulosic waste streams (almond shell) by sulfur-free methods and its depolymerization by base catalyzed or solvolysis reactions have been addressed in this work. In addition, the influence of avoiding the lignin isolation stage prior to its depolymerization reaction has been studied based on the final product yields (phenolic monomers compounds, such as catechol derivatives), energy requirements and production costs. As summary, four different scenarios were approached using experimental data values from previous works and compared by the help of a simulation software (AspenTech®). The direct lignin depolymerization from black liquors equalized the phenolic monomer yields of the precipitated lignin depolymerization for the organosolv process (0.08 wt%), and increased in the soda process (0.05 wt% against 0.03 wt%). However, the bigger volume to be treated in the depolymerization reaction and downstream stages significantly increased the production costs (chemicals consumptions, energetic duties and waste stream disposal), as well as the investment cost. Regarding the depolymerization from the precipitated lignin, despite the loss of lignin during the isolation stage, the reduction of the volume to be treated led to hugely reduce the production costs and the environmental impact. Among these last two mentioned scenarios, the organosolv process presented better indicators. Even though the lignin extraction yield was poorer for the organosolv process, the depolymerization performance was improved in such level, that the most desirable product (phenolic oil) was obtained in higher amount.