Synthesis of novel ionic liquids and deep eutectic solvents from renewable sources for biomass chemical conversion

Author(s)

Gustavo Rodrigues Gomes

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2021-11-03

Examining board members

Júlio Cezar Pastre; Sarita Cândida Rabelo; Thiago de Melo Lima; Aline Carvalho da Costa; Airton Gonçalves Salles Junior

• Advisor: Júlio Cezar Pastre

Abstract

The integral use of renewable feedstocks to obtain energy, fuels and chemicals is a pivotal role to achieve environmentally friendly processes. In recent years, the use of non-conventional solvent systems for biomass pretreatment and/or chemical conversion has emerged, such as deep eutectic solvents and ionic liquids. In this Thesis, four projects related to the use of amino acid-based non-conventional systems applied to sugar conversion into value-added compounds are presented. In the first study, 5-(hydroxymethyl)-furfural (HMF) was produced from fructose-based carbohydrates using a NADES system composed of betaine hydrochloride (BHC) as the hydrogen bond acceptor (HBA), carboxylic acids as hydrogen bond donors (HBDs) and water as the third component of the mixture under microwave irradiation. Under optimized conditions, the NADES system composed of BHC/MA/H2O afforded HMF in 94% and 72% yield from fructose and sucrose, respectively. However, recycling experiments indicated that the reuse was hampered by thermal degradation of both HBA and HBD species, proved by thermogravimetric-mass spectrometry analysis (TG-MS). In the second study, a bio-based amino acid derivative, taurine hydrogen sulfate was applied as Brønsted-acid catalyst for the conversion of sugarcane molasses to ethyl levulinate (EL) under microwave irradiation, and the effect of the inorganic matter (ashes) on EL yields was also evaluated. When the molasses is treated with Dowex® 50WX2 resin, the ash content reduced by 97% in two percolations, providing a feedstock able to produce 82% of EL. The third study, EL was produced from lignocellulosic matrices mediated by a taurine-based imidazolium ionic liquid, under microwave irradiation. From the seven evaluated lignocellulosic biomass, sugarcane bagasse and straw; elephant grass leaves and stem; and corn biomass; sugarcane bagasse provided the best results on EL (59% EL yield). The EL mass yields from the evaluated biomass have a good linear correlation with the hemicellulosic content on the lignocellulosic materials, which means the higher hemicelluloses percentage the higher the EL yields. This correlation is advantageous because no pretreatment step is needed to achieve good EL yields from biomass mediated by [TauIm][HSO4]. The last study, furfural was produced from acid hydrolysates obtained from sugarcane bagasse pretreatment mediated by glycine-based imidazolium ionic liquid, under microwave irradiation. Excellent furfural yields (90%) could be obtained from the acid hydrolysates. Experiments with synthetic media showed that no matrix effect was observed, especially from the acid soluble lignin, on the hemicelluloses dehydration mediated by [GlyIm][HSO4] (AU)

• FAPESP's process: 18/09861-2 - Synthesis of novel ionic liquids from renewable sources and application on biomass conversion
• Grantee: Gustavo Rodrigues Gomes
• Support Opportunities: Scholarships in Brazil - Doctorate