New generation of high energy density biofuels: ‘Furanics’

Fuels with superior economics and properties in comparison to current biofuels

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The recently patented biofuels are based on 5-hydroxymethylfurfural (HMF) derivatives, in particular 5-alkoxymethylfurfural ethers manufactured by reacting a glucose-containing starting material with an alcohol in the presence of a catalytic or sub-stoichiometric amount of acid catalyst. The catalysts can be heterogeneous or homogenous and may be employed in a continuous flow fixed bed or catalytic distillation reactor. The resulting ethers can be used as a fuel and as starting material for the synthesis of monomers for polymerisation reactions.

The conversion of sugars or sugar (hexoses) containing biomass into more economically useful compounds is of increasing interest. Current fuel activities are mainly directed towards ethanol from sugar/glucose. Typically, sucrose and glucose are fermented into ethanol. One glucose molecule is converted into two molecules of ethanol and two molecules of CO2. This conversion has drawbacks especially in view of atom economy, the low energy density of ethanol (7.7 kWh/kg or 6.1 kWh/L) and its relative low boiling point (78,4 degrees Celsius).

Another application area of interest of both the scientific and industrial community involves the conversion of sugars such as fructose into hydroxymethyl furfural (HMF) in the presence of an acid catalyst. HMF is then obtained as a potential starting material for obtaining bio-based monomer such as furandicarboxylic acid which can be used for bioplastics (polyethylene terephthalate (PET) type polyesters). However, when under these conditions sucrose or glucose was used as a feed, no conversion to HMF is observed, which is a distinct disadvantage given the low price and abundant availability of sucrose and glucose. Only in the presence of ionic liquids or in a sub- and supercritical mixture of acetone and water reasonable HMF yields from starting materials other than fructose can be obtained.

Fructose as feed is undesirable given its high price compared to glucose and/or sucrose. Therefore, so far, no process for the synthesis of HMF has been developed on an industrial scale.

In short, current methods for the synthesis of HMF mostly start from fructose and typically do not give a high yield, partly attributable to the instability of HMF under the acidic reaction conditions. In most acid-catalysed water-based reactions, the further reaction to levulinic acid and humins has been reported, making this a less attractive alternative.

Avantium has overcome these disadvantages. Its researchers have found that the conversion of glucose-containing starting material that may be derived from biomass in the presence of a catalytic or sub-stoichiometric amount of acid in the presence of an alcohol with or without the presence of one or more additional diluents leads to the formation of the corresponding HMF-ether in good yield and selectivity.

Avantium’s HMF chemistry prevents the occurrence of the onward and undesired reaction towards levulinic acid and humins, thus leading to an efficient procedure for the conversion of glucose-containing material into HMF derivatives.

High energy density
The energy density of ethoxymethylfurfural (EMF, a Furanics example) is 8.7 kWh/L. This is as good as regular gasoline (8.8 kWh/L), nearly as good diesel (9.7 kWh/L) and significantly higher than ethanol (6.1 kWh/L). This means that with a full tank of Furanics you can drive almost as far as as with a full tank of traditional fuels. The high energy density of EMF, the fact that these HMF derivatives can now be obtained in high yields, in one step, from very cheap hexose or hexose containing starting materials such as sucrose and glucose, and as these ethers are, in contrast to HMF, liquids at room temperature, make these very interesting biofuels.

The acid catalyst in the production method can be selected from amongst organic acids, inorganic acids, salts, Lewis acids, ion exchange resins and zeolites or combinations and/or mixtures thereof.

The glucose-containing feedstock can be obtained from a wide variety of biomass sources. In general any feed with a sufficient high glucose content can be used. It is preferred that the glucose-containing starting material is selected from the group of starch, amylose, galactose, cellulose, hemi-cellulose, glucose-containing disaccharides such as sucrose, maltose, cellobiose, lactose, preferably glucose-containing disaccharides, more preferably sucrose or glucose.

Engine tests
The company successfully completed engine tests to demonstrate the potential of these novel biofuels. The tests were carried out by Intertek, in Geleen, The Netherlands, an independent test center. Using a Citroën Berlingo with a regular diesel engine, Avantium tested a wide range of blends of Furanics with regular diesel. The test yielded positive results for all blends tested. The engine ran smoothly for several hours. Exhaust analysis uncovered a significant reduction of soot (fine particulates). On top of this, Furanics do not contain any sulphur, a significant environmental benefit compared to oil-based fuels.

The significant reduction of soot in the car exhaust is encouraging, as soot emmissions are considered a major disadvantage of using diesel today, because of its adverse environmental and health effects. We are developing a next generation biofuel that has superior fuel properties and process economics compared to existing biofuels. The production process of Furanics has an excellent fit with existing chemical process technology and infrastructure. Ultimately our ambition is to develop biofuels that are competitive with fossil based fuels. – Tom van Aken, Chief Executive Officer of Avantium

The company plans to undertake an additional, comprehensive engine tests in 2008 to study engine performance and long terms effects of Furanics.

Avantium also announced the filing of over a dozen patent applications on the production and use of Furanics as part of the
company’s strategy to build an extensive patent portfolio for its biofuels program. In September 2007, the first two key patents were published, that claim amongst others the use of furanics as a biofuel and its production routes from sugars.

The company recently appointed Dr. Ed de Jong, a well-known and highly respected biomass expert. Previously, he worked at Wageningen University & Research Centre.

Given that Avantium’s Furanics are products derived from carbohydrates such as sugars, the company stands to benefit from the efficiencies of an existing market for these feedstocks. Carbohydrates are globally the most abundantly available biomass feedstock.

Avantium is a leading technology company in the area of advanced high-throughput R&D operating in the energy, chemicals and pharmaceutical industries. The company develops products and processes in the area of biofuels, bio-based chemicals and novel crystal forms of existing drugs by applying its proprietary, high-throughput R&D technology. Avantium has demonstrated the potential of this technology by providing R&D services and tools to more than 70 companies worldwide, including many of the world’s largest energy, chemicals and pharmaceutical companies. Avantium has approximately 100 employees; its offices and head quarters are based in Amsterdam, the Netherlands.

Image: sucrose, a disaccharide consisting of two monosaccharides (glucose and fructose), is one of the carbohydrates that can be converted into the high energy density Furanics.

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