Spent liquor reuse strategy applied to levulinic acid production

SOLEDAD GUTIERREZ; MARÍA EVANGELINA VALLEJOS; CLAUSER, NICOLÁS

Congreso; World Congress of Chemical Engineering; 2017

A process strategy is proposed in order to reduce hydrolysis, separation and recovery costs of valuable products in Ligno-cellulosic Bio-refinery (LCBR). In LCBR, the separation of valuable products from the reaction liquor is one of the most important contribution in processing costs, and for this reason the liquid to solid ratio has to be as little as possible. The following reuse of water is proposed in order to focus on reduce deconstruction and separation costs of valuable products from liquid extraction media. A sequential batch reaction mode is proposed instead of the currently considered batch mode process. In this way, a concentrated liquor is obtained and evaporation and heating costs are reduced. This strategy can be applied to pretreatment, hydrolysis, or reaction mixture, as long as the desired product is not degraded in a extend that negatively affect production costs.A techno-economic analysis was performed for Levulinic acid (LA) production from pine sawdust as an example. A comparison between conventional and proposed process is presented. For this, a sequence of alkaline pretreatment, followed by an acid hydrolysis [1] and separation method in which Furfural is used as solvent proposed by [2] was considered. Selected operating conditions and kinetic constants employed for yield calculations were extracted from [3]. For a solid to liquid ratio of 10, more than 30 % reduction in operating cost expressed in USD.kg-1 LA is obtained by reuse water once. Further reuse cycles also improves process economy. The optimum number of water reuse was 3, and the resulting reduction in operating cost was more than 50%.