Obtaining xylitol by hydrolysis-hydrogenation of liquors derived from sugarcane bagasse

Abstract

This work presents the study of heterogeneous catalysis of sugarcane bagasse hydrothermal treatment spent liquors using a sulfonated resin. Besides, results were compared with those obtained by a conventional route using sulfuric acid as a homogeneous catalyst. Heterogeneous catalysis is suitable for the hydrolysis of sugarcane bagasse hydrothermal liquors under mild conditions (100 ?C and 6 h). The obtained maximum xylose yield was 82% due to furfural formation, which causes a xylose selectivity drop. The hydrogenation of this xylose-rich liquor at 100?C and 3 MPa of hydrogen pressure employing a supported Ni/?-Al2O3 produced the total conversion of xylose with a selectivity towards xylitol of 100% by using a catalyst to xylose mass ratio of 0.5. Heterogeneous catalysis in a two-step route (hydrolysis and hydrogenation) constitutes an outstanding alternative to produce xylitol from sugarcane bagasse hydrothermal spent liquors since materials can be easily separated and reused in several reaction cycles.

Modelling and dynamic simulation to produce fermentable sugars from lignocellulosic substrates through dilute acid hydrolysis

“…It is well-documented that prolonged exposure to elevated temperature can foster the conversion of xylose into diverse DP, such as acetic acid, glycerol, and furfural. [12,33] However, despite the advancements in hemicellulose removal and xylose production, the concentration of DP surged by 14.59%, as depicted in Figure 1C. This surge in DP concentration was noticeable under conditions of LSR below 4 v/w, C A surpassing 4% v/v, and durations surpassing 60 min.…”

“…This trend could be attributed to diminished molecular interactions between the substrate (SCB) and the catalyst under low LSR conditions, directly influencing the escalation of DP concentration. Furthermore, the tandem effects of elevated temperatures and reduced LSR can prompt the conversion of hemicellulose into acetic acid, [12] impacting process efficiency since acetic acid is formed by cleaving acetyl groups linked to hemicellulose molecules. [12,16,33] Therefore, considering DP concentration as a pivotal factor, the optimal operational conditions for the acid hydrolysis process were identified as follows: an C A of 2% v/v, an LSR of 4% w/v, and a 60-min duration.…”

“…[1][2][3][4][5][6] Among these sources, sugarcane bagasse (SCB), an abundant biomass, holds substantial promise for generating new renewable energy avenues and an array of value-added products due to its unique composition. [4,7] This biomass primarily comprises hemicellulose, lignin, and cellulose, [8][9][10][11][12] with hemicellulose and cellulose serving as key biopolymers within the SCB matrix. These biopolymers offer the potential to produce fermentable sugars, including xylose and glucose.…”

“…[13][14][15] Crucial to the conversion of these sugars is the stage of acid hydrolysis, employing dilute acids. [4,12] This process entails comminuting the biomass to reduce particle size through physical treatments and subjecting the SCB to acid steam, facilitating the solubilization of the hemicellulose and lignin fractions. [4,9,11,15] The primary objective of acid hydrolysis is to cleave polysaccharide chains into monosaccharides, such as glucose and xylose, while also yielding secondary products like acetic acid, furfural, 5-hydroxymethyl-furfural, and glycerol.…”

“…[4,9,11,15] The primary objective of acid hydrolysis is to cleave polysaccharide chains into monosaccharides, such as glucose and xylose, while also yielding secondary products like acetic acid, furfural, 5-hydroxymethyl-furfural, and glycerol. [12,16,17] However, the kinetics of lignocellulosic waste degradation are contingent on various physical factors such as biomass porosity, surface area, crystallinity of the cellulosic fraction, and hydrolysis reactor temperature, [18] which makes it difficult to model.…”