EU-Funded Project Targets Sustainable Production of Ethyl Levulinate from Biomass as Diesel Miscibile Biofuel

31 October 2009

Representation of DIBANET processes, products and linkages. Source: Carbolea. Click to enlarge.

An EU-funded research project is seeking to develop new technologies that will enable the sustainable production of diesel miscible biofuels (DMB) from cellulosic biomass wastes in Europe and Latin America.

Specifically, the DIBANET (Development of Integrated Biomass Approaches Network) project will advance the art in the production of ethyl levulinate from organic wastes and residues. Ethyl levulinate (EL) is a novel diesel miscible biofuel (DMB) produced by esterifying ethanol with levulinic acid. The project will also use fast pyrolysis to convert the residue left over from biofuel production to bio-oil for subsequent upgrading to DMB.

EL has an oxygen content of 33%; a blend of 20% EL, 70% petroleum diesel and 1% co-additive has a 6.9% oxygen content, resulting in a significantly cleaner burning diesel fuel. The fuel has high lubricity, reduced sulfur content, meets all the ASTM D-975 diesel fuel specifications, and experiences no significant losses in fuel economy, according to Prof. Michael Hayes of the Carbolea Research Group at the University of Limerick in Ireland, the DIBANET co-ordinator.

The DIBANET project has received €3.73 million (US$5.5 million) under the Energy Theme of the EU’s Seventh Framework Programme (FP7). In addition to the Carbolea Research Group, the DIBANET consortium comprises partners from Argentina, Brazil, Chile, Denmark, Greece, Hungary and the UK.

DIBANET aims to:

• Optimize the yields of levulinic acid from the conversion of biomass.

• Improve the energy balance and the total biofuel yields possible from a feedstock by sustainably utilizing the residues in pyrolysis processes to produce a bio-oil that will be upgraded to a DMB.

• Reduce the energy and chemical costs involved in producing ethyl levulinate from levulinic acid and ethanol.

• Select key biomass feedstocks for conversion to levulinic acid, analyse these, and develop rapid analytical methods that can be used in an online process.

• Analyze the DMBs produced for their compliance to EN590 requirements and, if non-compliant, suggest means to achieve compliance.

The envisioned production process for the optimized production of DMBs entails six main steps (see diagram above):

1. Optimization of the sourcing, selection and preparation of the feedstock.

2. The hydrolysis and subsequent degradation of biomass. This can produce (i) levulinic acid, (ii) furfural (which can be converted to levulinic acid via hydrogenation), (iii) formic acid, and (iii) solid residues (SR).

3. The esterification of levulinic acid with (sustainable) ethanol to produce the DMB ethyl-levulinate.

4. Pyrolysis of some or all of the SR to produce a bio-oil and a biochar. Pyrolysis can be enhanced by using the formic acid produced in (2) as a co-feed.

5. Catalytic upgrading of the bio-oil to produce an upgraded bio-oil (UBO) that is miscible with diesel.

6. Utilization of the biochar as a soil-amender for plant-growth promotion or to fuel the processes. (The Carbolea Group suggests that a configuration of the DIBANET process chain may provide a means for obtaining carbon negative biofuels through using biochar as a soil amender.)

Levulinic acid (LA) can also be used to produce methyltetrahydrofuran (MTHF), an oxygenated fuel extender for gasoline. Produced via the hydrogenation of LA, MTHF has an octane value of ~87, and a low Reid Vapor Pressure. It is hydrophobic, and has a LHV of 32 MJ/kg—somewhat higher than that of ethanol. Gasoline has an LHV of about 44 MJ/kg.

Resources

• DIBANET (Michael H.B. Hayes, Carbolea Research Group, University of Limerick)

• The New Generation of Biofuels: How Europe and Latin America can Work Together