Although ionic liquids have only been studied in depth during the last decades, the field is now maturing to such a degree that the focus is on larger scale applications for use in real processes such as catalysis. Current information is scattered across the literature and Catalysis in Ionic Liquids provides a critical analysis of the research published to date on ionic solvents in all areas of the catalytic science. The book covers both catalyst synthesis using ionic liquids as solvents and green syntheses using both ionic liquids as well as mixtures of ionic liquids and carbon dioxide (as a subcritical and supercritical liquid), including enzymatic, homogeneous, and heterogeneous catalysis, electrocatalysis and organocatalysis. As well as the catalysis community, the book will also be of interest to postgraduates, postdoctoral workers and researchers in academia and industry working in organic synthesis, new materials synthesis, renewable sources of energy and electrochemistry. Written by leading experts in the field, this is the reference source to find about catalysis in ionic liquids.

Chris Hardacre

Catalysis in Ionic Liquids

From Catalyst Synthesis to Application

By Chris Hardacre, Vasile Parvulescu

The Royal Society of Chemistry

Copyright © 2014 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-1-84973-603-9

Contents

Chapter 1 Catalytic Conversion of Biomass in Ionic Liquids Hui Wang, Leah E. Block and Robin D. Rogers,
Chapter 2 Biocatalysis in Ionic Liquids Roger A. Sheldon,
Chapter 3 Homogeneous Catalysis in Ionic Liquids Simon Doherty,
Chapter 4 Catalysis in Ionic Liquid–Supercritical CO2 Systems Mark J. Muldoon,
Chapter 5 Heterogeneous Catalysis in Ionic Liquids Peter Goodrich, Christopher Hardacre and Vasile I. Parvulescu,
Chapter 6 Modification of Supports and Heterogeneous Catalysts by Ionic Liquids: SILP and SCILL Systems Peter Claus and Frederick Schwab,
Chapter 7 SILP and SCILL Catalysis Marco Haumann and Peter Wasserscheid,
Chapter 8 Electrocatalysis in Ionic Liquids Leigh Aldous, Asim Khan, Md. Mokarrom Hossain and Chuan Zhao,
Chapter 9 Photochemistry in Ionic Liquids Hermenegildo Garcia and Sergio Navalon,
Chapter 10 Ionothermal Synthesis F. H. Aidoudi and R. E. Morris,
Chapter 11 Metal Nanoparticle Synthesis in Ionic Liquids Christoph Janiak,
Subject Index,

CHAPTER 1

Catalytic Conversion of Biomass in Ionic Liquids

HUI WANG, LEAH E. BLOCK AND ROBIN D. ROGERS

1.1 Introduction

The fossil fuel-based economy is facing several problems and challenges, which involve the increasing emissions of CO2, decreasing reserves, and increasing energy prices. These challenges have driven the search for new transportation fuels and bioproducts to substitute the fossil carbon-based materials. Biomass is defined as organic matter available on a renewable basis, and it includes forest and mill residues, agricultural crops and wastes, wood and wood wastes, animal wastes, livestock operation residues, aquatic plants, and municipal and industrial wastes. Biomass is deemed a sustainable and green feedstock for the production of fuels and fine chemicals, although perhaps not always in the way they are proposed to be used.

A major source of biomass is lignocellulosic biomass, which is particularly well suited for energy applications because of its large-scale availability, low cost, and environmentally benign production. Lignocelluloses are composed of cellulose, hemicellulose, lignin, extractives, and several inorganic materials, of which the first three biopolymers are the main components. The cellulose microfibrils that are present in the hemicellulose–lignin matrix are often associated in the form of bundles or macrofibrils. The structure of these naturally occurring cellulose fibrils is mostly crystalline in nature and highly resistant to attack by enzymes. In addition, the presence of lignin also impedes enzymatic hydrolysis, as enzymes bind onto the surface of lignin and hence do not act on the cellulose chains.

Usually, conversion of lignocellulosic biomass is carried out in the presence of catalysts, such as strong liquid and solid acids. Various types of lignocellulosic biomass, such as wood chips, sawdust, corncobs, and walnut shells, have been tentatively processed by liquid acid-catalyzed hydrolysis with H2SO4, HCl, H3PO4, etc. Despite the relatively high catalytic activity of these liquid acids in the hydrolysis of cellulosic materials, by and large their uses are still uneconomical because the process suffers from severe corrosion, a requirement for special reactors, and costly separation and neutralization of waste acids.