Reaction mechanisms and kinetics of xylo‐oligosaccharide hydrolysis by dicarboxylic acids

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Hydrothermal pretreatment of lignocellulosic materials generates a liquid stream rich in pentose sugar oligomers. Cost-effective hydrolysis and utilization of these soluble sugar oligomers is an integral process of biofuel production. We report integrated rate equations for hydrolysis of xylo-oligomers derived from pretreated hardwood by dicarboxylic maleic and oxalic acids. The highest xylose yield observed with dicarboxylic acids was 96%, and compared to sulfuric acid, was 5-15% higher with less xylose degradation. Dicarboxylic acids showed an inverse correlation between xylose degradation rates and acid loadings unlike sulfuric acid for which less acid results in less xylose degradation to aldehydes and humic substances. A combination of high acid and low-temperature leads to xylose yield improvement. Hydrolysis time course data at three different acid concentrations and three temperatures between 140 and 180 C were used to develop a reaction model for the hydrolysis of xylo-oligosaccharides to xylose by dicarboxylic acids.

Xylan hydrolysis in Populus trichocarpa×P. deltoides and model substrates during hydrothermal pretreatment

“…Xylose and xylooligomers react to generate products such as furfural and pseudo-lignin (Kim et al, 2013;Saeman, 1945;Sannigrahi et al, 2011), and cooling results in product precipitation (Gray et al, 2007). In a fixed bed flowthrough reactor, soluble products are rapidly removed from the reactor after formation, thus improving the development of product profiles as a function of time (Liu and Wyman, 2003;Mok and Antal, 1992;Song et al, 2012).…”

“…Kobayashi and Sakai (1956) were the first to note that the initial rate of xylan hydrolysis was much faster compared to the rate later in pretreatment; they attributed this to the presence of fast reacting and slow reacting xylan fractions. Multiple kinetic models have since incorporated this biphasic behavior (Conner, 1984;Garrote et al, 1999;Kim et al, 2013;Maloney and Chapman, 1985;Zhu et al, 2012). The most frequently proposed cause for this behaviour is differences in intrinsic reactivity due to cell wall structure (Maloney and Chapmen, 1985), lignincarbohydrate bonds (Chen et al, 2010;Conner, 1984;Lee et al, 1999) and hemicellulose-cellulose interactions (Lee et al, 1999).…”

“…Some have concluded that hemicellulose removal is a key to increasing enzymatic digestibility (Kumar and Wyman, 2010;Leu and Zhu, 2013). Hydrothermal pretreatment with water at elevated temperatures removes hemicellulose through hydrolysis to oligomers and monomers (Kim et al, 2013). 4 The hemicellulose of Populus trichocarpa x P. deltoides wood, a promising North American biofuel feedstock, consists primarily of xylans (Sannigrahi et al, 2010).…”

Extraction of arabinoxylans from wheat bran using hydrothermal processes assisted by heterogeneous catalysts

“…below 100 ºC) is not able to break the cross-links between the WUAXs and the wall matrix (Izydorczyk & Biliaderis, 2007). In order to improve the AXs extraction yield from different biomass, several techniques, such as hydrothermal treatments (Bobleter, 1994;Buranov & Mazza, 2010;Carvalheiro, Garrote, Parajó, Pereira, & Gírio, 2005;Dien et al, 2006;Garrote, Domínguez, & Parajó, 1999;Garrote, Domínguez, & Parajó, 2001;Garrote, Domínguez, & Parajó, 2002;Kim, Hendrickson, Mosier, & Ladisch, 2009;Lavarack, Griffin, & Rodman, 2000;Li, Converse, & Wyman, 2003;Maes & Delcour, 2002;Mok & Antal, 1992;Nabarlatz, Farriol, & Montané, 2004;Negahdar, Delidovich, & Palkovits, 2016;Reisinger et al, 2013;Shen & Wyman, 2011;Tekin et al, 2014), chemical-solvent extractions (Adams et al, 1955;Aguedo, Fougnies, Dermience, & Richel, 2014;Bataillon, Mathaly, Nunes Cardinali, & Duchiron, 1998;Buranov & Mazza, 2010;Choteborská et al, 2004;Doner, Chau, Fishman, & Hicks, 1998;Höije, Gröndahl, TØmmeraas, & Gatenholm, 2005;Hollmann & Lindhauer, 2005;Kim, Kreke, & Ladisch, 2013;Kusema et al, 2011;Lavarack, Griffin, & Rodman, 2002;Maes & Delcour, 2002;Shen & Wyman, 2011;Swennen, Courtin, Lindemans, & Delcour, 2006;Xu et al, 2006;Yao, Nie, Yuan, Wang, & Qin, 2015;…”

Acidic Pretreatment

“…In addition, the pulping and paper industry utilized oxalic acid or diethyl oxalate to improve strength and brightness of products. Oxalic acid produces less inhibitory materials as maleic acid in pretreatment of lignocellulose [84,93]. Oxalic acid is a strong dicarboxylic acid with high pretreatment efficiency and is less toxic to microorganisms due to its lower pK a , which affects acid diffusion across the cellular membrane.…”