Development of an integrated thermal and enzymatic hydrolysis for lignocellulosic biomass in fixed-bed reactors: 11th EWLP, Hamburg, Germany, August 16–19, 2010

Christian Kirsch; Carsten Zetzl; Irina Smirnova

doi:10.1515/hf.2011.061

Article

Development of an integrated thermal and enzymatic hydrolysis for lignocellulosic biomass in fixed-bed reactors

11^th EWLP, Hamburg, Germany, August 16–19, 2010

Christian Kirsch , Carsten Zetzl and Irina Smirnova

Published/Copyright: March 14, 2011

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From the journal Volume 65 Issue 4

Abstract

The limitations of the current biorefinery process utilizing stirred-tank reactors for the enzymatic step include poor mixing in the case of high biomass loadings, additional steps for the product separation, and a long reaction time. In this study the hydrothermal pretreatment and the enzymatic hydrolysis of the lignocellulosic biomass were combined in one fixed-bed reactor. The influence of the shear forces during recirculation and enzyme stability at elevated temperatures were investigated. It has been shown that the shear forces resulting from pumping have a negligible effect on enzyme activity. However, large pressure drops reduce the enzyme activity significantly. Furthermore, the enzyme stability was significantly increased at elevated temperatures (60°C) by applying static pressures up to 200 bar (56% residual activity at 60°C after 24 h). This is beneficial for the process as a higher temperature accelerates the reaction. Further improvement of the overall process efficiency was achieved by increasing the solid-to-water ratio and circulation of the enzyme solution. At a biomass content of 7%, a glucose concentration of 61 g l^-1 and a yield of 85% was achieved. The integrated process was first done on a laboratory scale (50 ml). At 100 bar, 60°C and 10% biomass loading an increased initial reaction rate was observed. However, this effect was followed by the stagnation of the glucose yield as one of the enzymes, Novozyme 188, showed no remarkable stabilization with pressure. Nevertheless, an overall glucose yield of 40% was achieved after 5.5 h, compared to 14 h under normal pressure and 50°C.

Keywords: Celluclast 1.5L; enzyme deactivation; enzymatic hydrolysis; enzyme pumping; enzyme stabilization; fixed-bed reactor; high pressure; hydrothermal treatment; integrated process; lignocellulose; lignocellulosic biomass; liquid hot water; Novozyme 188; shear deactivation; straw; thermal stability

Corresponding author. Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany Phone: +49(40)42878 2566 Fax: +49(40)42878 4072

Received: 2010-10-29

Accepted: 2011-2-3

Published Online: 2011-03-14

Published in Print: 2011-06-01

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https://doi.org/10.1515/hf.2011.061

Keywords for this article

Celluclast 1.5L; enzyme deactivation; enzymatic hydrolysis; enzyme pumping; enzyme stabilization; fixed-bed reactor; high pressure; hydrothermal treatment; integrated process; lignocellulose; lignocellulosic biomass; liquid hot water; Novozyme 188; shear deactivation; straw; thermal stability