A kinetic study on the decomposition of 5-hydroxymethylfurfural into levulinic acid

Abstract

Levulinic acid (LA), accessible by the acid catalyzed degradation of biomass, is potentially a very versatile green intermediate chemical for the synthesis of various (bulk) chemicals for applications like fuel additives, polymers, and resin precursors. We report here a kinetic study on one of the key steps in the conversion of biomass to levulinic acid, i.e. the reaction of 5-hydroxymethylfurfural (HMF) to levulinic acid. The kinetic experiments were performed in a temperature window of 98-181 uC, acid concentrations between 0.05-1 M, and initial HMF concentrations between 0.1 and 1 M. The highest LA yield was 94% (mol/mol), obtained at an initial HMF concentration of 0.1 M and a sulfuric acid concentration of 1 M. The yield at full HMF conversion is independent of the temperature. An empirical rate expression for the main reaction as well as the side reaction to undesired humins was developed using the power law approach. Agreement between experimental and model data is good. The rate expressions were applied to gain insights into optimum process conditions for batch processing.

Microwave-assisted Liquefaction of Rape Straw for the Production of Bio-oils

“…Moreover, severe conditions (high temperature and/or long time) could induce the recondensation of the already liquefied lignin and hemicellulose fragments (Xie et al 2016a). Additionally, side reactions of the decomposed cellulose may yield insoluble substances (Girisuta et al 2006). Furthermore, the silica and silicates in the ashes may inhibit further liquefaction of the crop residues and cellulose (Xiao et al 2013).…”

“…This levulinate is an important chemical with numerous potential applications, such as a fuel additive used to improve petroleum stability, low-temperature fluidity, and flash point (Girisuta et al 2006). Hence, in this case, to obtain a high yield of levulinate ester, the liquefaction should be subjected to a severe reaction condition.…”

Pyrolysis Oil Stabilisation by Catalytic Hydrotreatment

“…Higher temperatures and the presence of acid catalysts (homogeneous and heterogeneous) increase the rate of D-glucose decomposition (Girisuta et al, 2006). Such reactions may also occur in the fast pyrolysis oil matrix.…”

“…As such, it is of interest to compare the reaction pathways provided in Figure 10 for pyrolysis oil with that of typical hydrogenation and thermal reactions occurring for carbohydrates at various process severities. Thermal decomposition of various monomeric sugars in aqueous media has been studies in detail and is known to lead to oligomerisation to soluble and subsequently to insoluble humins (Girisuta et al, 2006). As an example, Knezevic et al (2009) studied the thermal decomposition of D-glucose in hot compressed water at elevated temperatures (240-374 °C), giving solids (char, humins) and some gaseous components (primarily CO 2 ).…”

“…D-glucose, D-mannose) to temperatures up to 400 o C is well known. Thermal decomposition, either catalytic (mostly by acids) or non-catalytic, leads to solid products referred to as humins (Girisuta et al, 2006;Watanabe et al, 2005a;Watanabe et al, 2005b). The proposed reaction pathway consists of C-6 sugar conversion to 5-hydroxymethyl furfural (HMF) and subsequently levulinic acid (LA) and formic acid (FA).…”