Teresa de Diego, Arturo Manjon, and Jose Luis Iborra

Abstract This chapter focuses on the application of enzyme technology in non-aqueous green solvents as ionic liquids (ILs) to transform biomass, mainly non-edible biomass (e. g. cellulose, lignocellulose, wood, forest residues, etc.), into fermentable monomeric compounds, and low cost vegetable oils or animal fats in biodiesel. This review aims to identify the key parameters that determine the biocompatibility of ionic liquids with enzymes for the rational design of ionic liquid-based formulations in biocatalysis for biofuel production.

Keywords Biofuels • Ionic liquids • Enzymatic-saccharification • Enzymatic- transesterification • Biodiesel • Bioethanol

Abbreviations

T. de Diego • A. Manjon • J. L. Iborra (*)

Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, P. O. Box 4021, E-30100 Murcia, Spain e-mail: jliborra@um. es

Z. Fang et al. (eds.), Production of Biofuels and Chemicals with Ionic Liquids, Biofuels and Biorefineries 1, DOI 10.1007/978-94-007-7711-8_11,

© Springer Science+Business Media Dordrecht 2014

[(MeO)2PO2] Dimethylphosphate

[Ac] Acetate

[TFA] Trifluoroacetate

[DMP] Dimethylphosphate

[MeSO4] Methylsulfate

[TfO] Trifluoromethylsulfonate

[NTf2] Bis[(trifluoromethyl)sulfonyl] amide

[SCN] Thiocyanate

[SbF6] Hexafluoroantimonate

Cations

1-Methyl-3-methylimidazolium

1-Ethyl-3-methylimidazolium

1-Butyl-3-methylimidazolium

1-Octyl-3-methylimidazolium

1-Butyl-1-methylpyrrolidinium

Triethyl-3-methylimidazolium

1-Hexadecyl-3-methylimidazolium

1- Octadecyl-methylimidazolium Methyl trioctylammonium Butyl trimethylammonium

Ethyloctadecanoyl oligoethyleneglycol ammonium Ethyloctadecanoyl oligoethyleneglycol ammonium

2- Hydroxy-N, N,N-trimethylethanammonium

11.1 Introduction

Increasing energy demands inevitably lead to an increase in crude oil prices, directly affecting global economic activity [1]. The progressive depletion of con­ventional fossil fuels with increasing energy consumption and gas emissions have led to a move towards alternative, renewable, sustainable, efficient, and cost — effective energy sources with lower emissions. Biomass appears to be the most feasible feedstock for current routes towards the production of biofuels since it is renewable, cheap, has low sulphur content and involves no net release of carbon dioxide, meaning that it has a high potential to become economically feasible at the present time [2].

Bioethanol is a major biofuel on the market worldwide. In 2011, total fuel bioethanol production worldwide was 28.94 billion gallons (109.4 billion litres)

[3] . It is estimated that bioethanol production could reach more than 227.4 billion litres of bioethanol thereby displacing a substantial portion of the fossil fuel currently consumed by the transportation sector [4]. Bioethanol is used to partially replace gasoline to make gasoline-ethanol mixtures, E15 (15 % ethanol and 85 % gasoline) and E85 (85 % ethanol and 15 % gasoline). The current commercial fuel
ethanol is produced mainly from sugarcane and corn, depending on the climatic conditions of the producers’ locations. The feedstock used for fuel ethanol produc­tion is mainly sugarcane in tropical areas such as Brazil and Colombia, while it is predominantly corn in other areas such as the United States, the European Union and China [2].

However, the production of these raw materials is competing for the limited arable land available for food and feed production. Therefore, it is critical to investigate advanced or second generation biofuel production technologies. Bioethanol can also be produced from lignocellulosic materials, which is com­monly called second generation bioethanol [5]. The feedstocks for the second generation bioethanol include agricultural residues, grasses, and forestry and wood residues [6].

Biodiesel which is produced using vegetable oil, plant oil and animal fat is another major biofuel. Nigam and Singh [7] consider biodiesel as a “carbon neutral” fuel, as any carbon dioxide released from its burning was previously captured from the atmosphere during the growth of the vegetative crop that was used for its production. Obviously, biodiesel is an alternative fuel for diesel, and most diesel engines can use 100 % biodiesel. The main feedstock currently used for biodiesel production includes soy bean, canola seed or rapeseed, sunflower and palm oil. There are going research activities into using alternative oils such as waste oils from kitchens and restaurants and microalgal oils for biodiesel production. However, these biofuels represent a tiny portion (<4 %) of the total fuels consumed because it is not feasible to greatly increase biofuel production using the current technologies available [7].