Next Article in Journal
Genetically Fused T4L Acts as a Shield in Covalent Enzyme Immobilisation Enhancing the Rescued Activity
Previous Article in Journal
Catalytic Activity of Sulfated and Phosphated Catalysts towards the Synthesis of Substituted Coumarin
Previous Article in Special Issue
Advances in Base-Free Oxidation of Bio-Based Compounds on Supported Gold Catalysts
Article Menu
Issue 1 (January) cover image

Export Article

Open AccessArticle
Catalysts 2018, 8(1), 39; doi:10.3390/catal8010039

Kinetic Modelling and Experimental Studies for the Effects of Fe2+ Ions on Xylan Hydrolysis with Dilute-Acid Pretreatment and Subsequent Enzymatic Hydrolysis

1
Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
2
National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
3
Chemical Engineering Department, University of North Dakota, 241 Centennial Drive, Grand Forks, ND 58202, USA
4
Chemistry Department, University of North Dakota, 241 Centennial Drive, Grand Forks, ND 58202, USA
*
Author to whom correspondence should be addressed.
Received: 1 December 2017 / Revised: 9 January 2018 / Accepted: 16 January 2018 / Published: 20 January 2018
(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)
View Full-Text   |   Download PDF [2015 KB, uploaded 20 January 2018]   |  

Abstract

High-temperature (150–170 °C) pretreatment of lignocellulosic biomass with mineral acids is well established for xylan breakdown. Fe2+ is known to be a cocatalyst of this process although kinetics of its action remains unknown. The present work addresses the effect of ferrous ion concentration on sugar yield and degradation product formation from corn stover for the entire two-step treatment, including the subsequent enzymatic cellulose hydrolysis. The feedstock was impregnated with 0.5% acid and 0.75 mM iron cocatalyst, which was found to be optimal in preliminary experiments. The detailed kinetic data of acid pretreatment, with and without iron, was satisfactorily modelled with a four-step linear sequence of first-order irreversible reactions accounting for the formation of xylooligomers, xylose and furfural as intermediates to provide the values of Arrhenius activation energy. Based on this kinetic modelling, Fe2+ turned out to accelerate all four reactions, with a significant alteration of the last two steps, that is, xylose degradation. Consistent with this model, the greatest xylan conversion occurred at the highest severity tested under 170 °C/30 min with 0.75 mM Fe2+, with a total of 8% xylan remaining in the pretreated solids, whereas the operational conditions leading to the highest xylose monomer yield, 63%, were milder, 150 °C with 0.75 mM Fe2+ for 20 min. Furthermore, the subsequent enzymatic hydrolysis with the prior addition of 0.75 mM of iron(II) increased the glucose production to 56.3% from 46.3% in the control (iron-free acid). The detailed analysis indicated that conducting the process at lower temperatures yet long residence times benefits the yield of sugars. The above kinetic modelling results of Fe2+ accelerating all four reactions are in line with our previous mechanistic research showing that the pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C–O–C and C–H bonds in cellulose, resulting in enhanced sugar solubilization and digestibility. View Full-Text
Keywords: pretreatment; enzymatic hydrolysis; bio-ethanol; Lewis acid; iron cocatalyst; kinetics pretreatment; enzymatic hydrolysis; bio-ethanol; Lewis acid; iron cocatalyst; kinetics
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Wei, H.; Chen, X.; Shekiro, J.; Kuhn, E.; Wang, W.; Ji, Y.; Kozliak, E.; Himmel, M.E.; Tucker, M.P. Kinetic Modelling and Experimental Studies for the Effects of Fe2+ Ions on Xylan Hydrolysis with Dilute-Acid Pretreatment and Subsequent Enzymatic Hydrolysis. Catalysts 2018, 8, 39.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Catalysts EISSN 2073-4344 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top