Biorefinery concept with green solvents towards the phenolic valorization

The efficient separation, hydrolysis and conversion of principal components of lignocellulosic biomass allows to produce chemicals and value added compounds. Ionic liquids (ILs) have been used for the pre-treatment and fractionation of biomass.1-3 The pre-treatment reveals that phenolic compounds were found in the IL phase. This work was devoted for the extraction of phenolic compounds from the recovered IL liquid using several adsorption resins in small scale batch processes. Phenolic compounds, such as vanillin, catechol and flavonoids were identified in extraction samples and also quantified. Temperature, residence time and water amount were evaluated in order to find optimal extraction conditions of phenolic compounds from IL

Pretreatment and fractionation of wheat straw using various ionic liquids

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) is a promising and challenging process for an alternative method of biomass processing. The present work emphasizes the examination of wheat straw pretreatment using ILs, namely, 1-butyl-3-methylimidazolium hydrogensulfate ([bmim][HSO4]), 1-butyl-3-methylimidazolium thiocyanate ([bmim]-[SCN]), and 1-butyl-3-methylimidazolium dicyanamide ([bmim][N(CN)2]). Only [bmim][HSO4] was found to achieve a macroscopic complete dissolution of wheat straw during pretreatment. The fractionation process demonstrated to be dependent on the IL used. Using [bmim][SCN], a high-purity lignin-rich material was obtained. In contrast, [bmim][N(CN)2] was a good solvent to produce high-purity carbohydrate-rich fractions. When [bmim][HSO4] was used, a different behavior was observed, exhibiting similarities to an acid hydrolysis pretreatment, and no hemicellulose-rich material was recovered during fractionation. A capillary electrophoresis (CE) technique allowed for a better understanding of this phenomenon. Hydrolysis of carbohydrates was confirmed, although an extended degradation of monosaccharides to furfural and hydroxymethylfurfural (HMF) was observed

Pre-treatment of lignocellulosic biomass using ionic liquids: wheat straw fractionation

This work is devoted to study pre-treatment methodologies of wheat straw with 1-ethyl-3-methylimidazolium acetate ([emim][CH3COO]) and subsequent fractionation to cellulose, hemicellulose and lignin. The method developed and described here allows the separation into high purity carbohydrate and lignin fractions and permits an efficient IL recovery. A versatility of the established method was confirmed by the IL reuse. The fractionation of completely dissolved biomass led to cellulose-rich and hemicellulose-rich fractions. A high purity lignin was also achieved. To verify the potential further applicability of the obtained carbohydrate-rich fractions, and to evaluate the pre-treatment efficiency, the cellulose fraction resulting from the treatment with [emim][CH3COO] was subjected to enzymatic hydrolysis. Results showed a very high digestibility of the cellulose samples and confirmed a high glucose yield for the optimized pre-treatment methodology

The phase equilibrium phenomenon in model hydrogenation of oleic acid

Hydrogenation is one of the most commonly practised types of reaction in industry. The processing of low or null price feedstock to produce energy through hydrogenation is an interesting solution for waste valorisation. The hydrogenation in CO2 atmosphere offers a series of advantages and facilitates the process by the dramatic reduction of normally harsh reaction conditions. The hydrogenation of natural feedstock with complex matrix is a challenging task and the examination of the phase equilibrium of this system is crucial to understand the phenomena driving the kinetics of the hydrogenation reaction. High pressure phase equilibrium modelling is a key method to design and to analyse the obtained data and helps to understand the hydrogenation reaction outcome. The increase of H2 pressure does not translate to the increase of hydrogen solubility in the liquid phase due to the significant decrease of CO2 solubility in oleic acid. The obtained data confirm that both thermodynamics and kinetics play an important role in the hydrogenation of cattle fat in the presence of CO2

Ionic liquids’ cation and anion influence on aromatic amine solubility

he mutual solubility of aniline and a series of imidazolium based ionic liquids with bis(trifluoromethylsulfonyl)amide, chloride, dicyanamide, tetrafluoroborate, and hexafluorophospate anions were studied. The produced results show the potential in the new solvent systems which can be used in amine chemistry. The liquid–liquid equilibrium (LLE) and solid–liquid equilibrium (SLE) measurements were performed using a dynamic (synthetic) method. The mutual solubility of aniline in bis(trifluoromethylsulfonyl)amide and hexafluorophosphate ionic liquids was complete in the examined range of temperatures. The solubility of remaining studied ionic liquids decreases with the decrease of Kamlet–Taft basicity of ionic liquid anion. In other words, the solubility was the lowest for a chloride ionic liquid and increases for dicyanamide and for tetrafluoroborate ionic liquids. Additionally, the increase of the alkyl chain length of the IL cation effects negatively the solubility of aniline in the investigated ionic liquids