A Novel Method for the Pentosan Analysis Present in Jute Biomass and Its Conversion into Sugar Monomers Using Acidic Ionic Liquid

Summary

We present a protocol for the synthesis of C5 sugars (xylose and arabinose) from a renewable non-edible lignocellulosic biomass (i.e., jute) with the presence of Brønsted acidic ionic liquids (BAILs) as the catalyst in water. The BAILs catalyst exhibited better catalytic performance than conventional mineral acid catalysts (H₂SO₄ and HCl).

Abstract

Recently, ionic liquids (ILs) are used for biomass valorization into valuable chemicals because of their remarkable properties such as thermal stability, lower vapor pressure, non-flammability, higher heat capacity, and tunable solubility and acidity. Here, we demonstrate a method for the synthesis of C5 sugars (xylose and arabinose) from the pentosan present in jute biomass in a one-pot process by utilizing a catalytic amount of Brønsted acidic 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate IL. The acidic IL is synthesized in the lab and characterized using NMR spectroscopic techniques for understanding its purity. The various properties of BAIL are measured such as acid strength, thermal and hydrothermal stability, which showed that the catalyst is stable at a higher temperature (250 °C) and possesses very high acid strength (H_o 1.57). The acidic IL converts over 90% of pentosan into sugars and furfural. Hence, the presenting method in this study can also be employed for the evaluation of pentosan concentration in other kinds of lignocellulosic biomass.

Introduction

Biomass has great potential as a renewable energy and chemical source because it is sustainable, inexpensive, and equally distributed unlike fossil resources, which makes it one of the promising candidates to replace fossil feedstocks. The estimated production of lignocellulosic biomass is 146 billion metric tons per year¹. The lignocellulosic biomass is mainly comprised of lignin, cellulose, and hemicellulose as its three major constituents. Lignin is an aromatic polymer made from phenylpropanoid units; on the other hand, cellulose and hemicellulose are the polysaccharide parts of the lignocellulosic biomass. Cellulose is composed of glucose u....

Protocol

Several chemicals used in the presenting work are toxic and carcinogenic. Please use all appropriate safety practices when performing synthesis of IL and biomass processing.

1. Preparation of Acidic IL

1. Add 7.625 mmol of 1,3-propane sultone in a 50 mL round bottom flask and then close the flask with a rubber septum.
2. Add 7.625 mmol of 1-methylimidazole into 7.625 mmol of 1,3-propanesultone slowly (10 min) at 0 °C using a syringe (1 mL).
3. After the complete addition of 1-methylimidazole and 1,3-propanesultone, add 15 mL of dry toluene and reflux the mixture for 16 h at 120 °C to get the solid zwitterion.

Results

The exact amount of pentosan and lignin recovered from the biomass depends on the type of lignocellulosic biomass. Similar types of lignocellulosic biomass collected from different places can have different concentration of pentosan and lignin. The jute biomass used in this study contains 20 wt% pentosan and 14 wt% lignin.

Figure 1 shows the comparison of the catalytic activity of .......

Discussion

The pentosan present in jute biomass conversion into C5 sugar monomers is demonstrated using various homogeneous Brønsted acidic catalysts such as H₂SO₄, HCl, and acidic IL. Furthermore, the catalytic result of the acidic IL was compared with the IL without acidity (1-butyl-3-methylimidazolium chloride). All reactions were performed in a Parr autoclave at 160 °C in water. The usage of acidic IL showed the highest pentosan conversion when compared to homogeneous acids used in this work (min.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1-Methylimidazole	Sigma Aldrich	M50834
1,3-Propanesultone	Sigma Aldrich	P50706	Moisture sensitive
p-nitroaniline	Sigma Aldrich	185310
Toluene	J. T. Baker	9460-03
Sulfuric acid	Honeywell-Fluka	30743	Highly corrosive
Hydrochloric acid	Honeywell-Fluka	30719	Highly corrosive
1-butyl-3-methylimidazolium chloride	Sigma Aldrich	900856	Highly hygroscopic
D(+)-Xylose	Acros Organics	141001000
L(+)-Arabinose	Acros Organics	104981000
UV-Spectrometer	JASCO	V-670
Parr reactor	Parr USA	Seriese 4560
Parr reactor controller	Parr USA	Seriese 4848
High pressure liquid chromatography (HPLC)	JASCO	Seriese LC-2000
Digital hot plate stirrer	Thermo Scientific	SP142020-33Q Cimarec
Oven furnace	Thermal Scientific	FB1400 Thermolyne blast oven furnace