Subcritical CO2 shows no effect on liquid hot water pretreatment of poplar wood

Jose M (Chema) Jimenez-Gutierrez,Luuk A.M Van Der Wielen,Adrie J.J Straathof

doi:10.1016/j.biteb.2020.100442

Jose M (Chema) Jimenez-Gutierrez, Luuk A.M Van Der Wielen + Show 1 more

Open Access

https://doi.org/10.1016/j.biteb.2020.100442

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Abstract

Pretreatment of lignocellulosic biomass is required for many biorefinery processes. Previous studies have described hydrolysis of hemicelluloses by using liquid hot water (LHW) pretreatment. We evaluated the effect of carbonic acid originating from pressurized carbon dioxide during LHW pretreatment of poplar. The conditions applied covered temperatures from 120 to 200 °C, pretreatment times from 5 to 240 min and pressures from 1.0 to 2.2 MPa CO2 or N2. The pressure and the type of gas (CO2 or N2) did not have an effect on production of acetic acid, which functioned as a marker of progress of biomass hydrolysis. Results suggested that the presence of carbonic acid in the process does not significantly contribute to acidification. Deacetylation of lignocellulosic biomass can be achieved by LHW pretreatment irrespective of pressure and of gas type used, at the conditions tested.

Highlights

Considerable efforts have been made in the past decades towards investigating options to solve the fossil fuels depletion in combination with the increasing energy consumption and CO2 emissions by our society (Goldemberg, 2007)
Lignocellulosic biorefinery processes typically consist of four main parts: pretreatment, enzymatic hydrolysis, fermentation and purification
Due to the complex matrix and structure of lignocellulosic biomass, the pretreatment and enzymatic hydrolysis steps usually produce derived substances, apart from the desired and expected sugars, which could limit the activity of the microorganisms and reduces the efficiency during the fermentation (Liu et al, 2019)

Summary

Introduction

Considerable efforts have been made in the past decades towards investigating options to solve the fossil fuels depletion in combination with the increasing energy consumption and CO2 emissions by our society (Goldemberg, 2007). This situation has led to a path where biorefineries are promising options, picturing a scenario with industrial activities using bio-based sources and biological operations as main trend (Hassan et al, 2019). Due to the complex matrix and structure of lignocellulosic biomass, the pretreatment and enzymatic hydrolysis steps usually produce derived substances, apart from the desired and expected sugars, which could limit the activity of the microorganisms and reduces the efficiency during the fermentation (Liu et al, 2019)

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