Biofuel containing levoglucosone and its production process from cellulose or starch using as a solvent a mixture of an ionic liquid and an alkyl alcohol

Description

1. FIELD OF INVENTION

Liquid biofuels from cellulose, ionic liquids, renewable energy, solvent extraction from ionic liquids

2. BACKGROUND OF THE INVENTION

The world production of cellulose on land is 40 billion ton per year and the stock of cellulose is 700 billion ton.

The world consumption of fossil fuels was in 2007, according to the International Energy Agency, 10 billion ton per year, which is 4 times less than the production of cellulose.

The food production in the world is 3 billion ton per year, which is 13 times less than the production of cellulose.

From these 3 numbers we conclude that, to take out from food, materials to produce bio ethanol or vegetable oils for biodiesel would not solve the problem of substituting fossil fuels, and would cause hunger.

On the other side, there are large surfaces of arable land, which are not cultivated or which can only produce crops not suitable for food. In these surfaces, the production of cellulose from trees, sugar cane or bush is possible. On the other side, cellulose containing biomass is a side product of many food crops. This biomass is also a raw material for biocell.

Sugar cane, has yields of 80-100 ton per hectar. In one ton of sugar cane there are about 80 kg of sugar, which may be converted to 50 kg of bioethanol. Besides sugar there are 250 kg of cellulose and hemicellulose, which is not converted to liquid fuels. There are also about 80 kg lignin, which may become a useful energy source in the conversion of cellulose to liquid biofuels.

Cellulose, hemicellulose and starch have been studied in the past as possible sources of raw materials for liquid fuels and chemicals.

Wood itself is since thousands of years an energy source. Biomass is used today to produce electricity less than 1% of electricity, and electricity represents only 17% of final energy consumption.

It is therefore important to find a process to convert cellulose in liquid fuels, suitable for energy supply to transportation and industry, which represent 95% of the consumption of crude oil.

The use of electricity for transportation is being made since a long time with electric trains, fork lifts and cars, but its economy for most transports and the electricity availability are not competing with biofuels from cellulose.

The substitution of fossil fuels is also important because of the carbon dioxide which they produce by burning. Although cellulose also produces carbon dioxide by burning, the same quantity of carbon dioxide was taken before out of the atmosphere by photosynthesis in plants to produce cellulose.

Although the carbon dioxide content on earth was up to 6000 ppm 100 million years ago, it decreased to 250 ppm in the nineteen century and increased again up to 380 ppm. These sharp increase in the last century is caused by burning fossil fuels and causes dramatic climate changes due to the greenhouse effect.

As a consequence, to convert cellulose into a liquid fuel is since decades a challenge for scientists, because the existing cars and trucks could drive with such a liquid biofuel without major changes in the motor.

The exhausting oil reserves and the political dependency on unstable countries producing oil is also a major problem today.

Producing electricity from nuclear or from renewable sources like wind, waves, rivers or photovoltaic, represents only 32% of electricity production. The rest is produced from fossil fuels. The substitution of liquid fuels by electricity for transports creates a major problem of storage and transportation of electricity, which is technically possible, but far more expensive than the cellulose biofuels (Biocell).

Because cellulose is renewable, abundant and not producing carbon dioxide by burning if photosynthesis is considered, there has been recent scientific work on following subjects (Bibliography 1 to 13):

• • dissolution of cellulose in ionic liquids instead of traditional processes using water and organic solvents
  • hydrolysis of cellulose in ionic liquids
  • dehydration of fructose in ionic liquids to hydroxyl methyl furfural
  • hydrogenation in organic solvents of hydroxymethyl furfural to dimethyl tetrahydrofuran
  • isomerisation of glucose to fructose
  • In our previous work (PCT WO 2008 053284, PCT IB 2008 03313, U.S. Pat. No. 1,235,6643, U.S. Pat. No. 1,247,6402) we found that the hydrolysis of cellulose to glucose in N methyl imidazol hydrochloride was always followed by dehydration of glucose and the production of oligomers of glucose both by incomplete hydrolysis of cellulose and by intermolecular dehydration of glucose.
  • In our previous work we found that the dehydration intermediates obtained from glucose easily react to oligomers by intermolecular dehydration. These oligomers can not be easily extracted with organic solvents.
  • from the ionic liquid phase we tried extraction with 3-pentanone, diethylether, disopropylether, buthanol. The best solvent was butanol but it also extracted considerable quantities of N.Alkyl imidazole.
  • In our U.S. Pat. No. 1,274,8425 application we filed for an ionic liquid immiscible with water, which is trioctylamine hydrochloride. However, the solubility of cellulose is very poor.

2. DETAILED DESCRIPTION OF THE INVENTION

According to our previous experiments, we decided to use:

• • As an ionic liquid N-alkyl imidazole hydrochloride as it is by far the best solvent for cellulose
  • We added a small amount of hydrochloric acid 37% in order to catalyse the hydrolysis of cellulose to glucose
  • We also added a small amount of an alkylalcohol in order to react with hydroxyl groups of glucose and by this way avoid the oligomerisation by intermolecular dehydration between hydroxyls of two different glucose molecules.
  • We found that by adding an alkyl alcohol the temperature could be raised without any carbonisation of glucose. This means that we stopped effectively the intermolecular dehydration.
  • The best solvent for extraction is in fact n-butanol, however it has the inconvenient to extract also N-alkyl imidazole (boiling temperature 198° C.), which in the GC-MS overlapps with levoglucosone (boiling temperature 203° C.) and has a similar boiling temperature. We solved the problem by washing out the butanol extract with 37% hydrochloric acid, which takes out the N-methyl imidazole.

Example

In a round bottom flask with reflux condenser were introduced:

N.methyl imidazole—41.5 g (0.50 mole)

Hydrochloric acid 37%—50.0 ml=60 g (0.60 mole)

The water was removed by vacuum destillation.

We added:

This mixture was heated to 80-90° C. during 1 hour. After cooling, we added 50 g of water to reduce viscosity and improve the immiscibility of butanol in the ionic liquid phase.

We then extracted with 3 portions of 50 ml butanol. The butanol extract was extracted with two portions of 50 ml of hydrochloric acid 37% to remove N-alkyl imidazole from the butanol extract.

The residue was checked by NMR, FT-IR and elemental analysis. The yield was 87% of stechiometry. The stechiometry is 126 g of levoglucosone from 168 g of cellulose.

The residue was found to be a levoglucosone almost pure:

BIBLIOGRAPHY

• 1. Jaroslaw Lewkowski, Synthesis, Chemistry and Applications of 5-Hydroxymethyl-furfural and its derivatives, Arkivoc, 2001, 17-54
• 2. Claude Moreau, Annie Finiels, Laurent Vanoye, Dehydration of fructose and sucrose into 5-hydroxymethylfurfural in the presence of 1-H-3-methyl imidazolium chloride acting both as solvent and catalyst, journal of Molecular Catalysis A, 2006, 165-169
• 3. Fred Shafizedh, Saccharification of lignocellulosic materials, Pure and Appl. Chem., vol 55, No 4 pp 705-720, 1983
• 4. Khavinet Lourvanij and Gregory Rorrer, Reaction rates for the partial dehydration of glucose to organic acids in solid-acid molecular sieving catalyst powders J. Chem. Tech. Biotechnol., 1997, 69, 35-44
• 5. Yuri. Roman Leshkov, Christopher Barrett, Zehn Y. Liu, James A. Dumesic, Production of dimethylfuran for liquid fuels from biomass derived carbohydrates, Nature, Vol 447, 21 Jun. 2007, 982
• 6. Acid in ionic liquid: an efficient system for hydrolysis of lignincellulose, Changzhi Li et al. Green Chemistry, 17 Dec. 2007
• 7. Cataklytic conversion of cellulose into Sugar alcohols Atsushi Fukuoka et al. Angewandte Chemie, 2006, 45, 5161-5163
• 8. Pyranone by pyrolysis of cellulose, Fred Shafizadeh, Pure & Applied Chem, 1983, 55-4, 705-720
• 9. Dissolution of cellulose with ionic liquids and its application—a minireview, Shengdong Zhu et al, Green Chemistry, 2006, 8, 325-327
• 10. WO 2008/053284 A1—Liquid biofuels containing dihydroxymethyl furan, Pedro Correia, priority date 9 Mar. 2007.
• 11. PCT IB 2008 03313, Liquid biofuels containing 2 methyl tetrahydro pyran, Pedro Correia
• 12. U.S. patent application Ser. No. 12/356,6643—Liquid biofuels from cellulose, Pedro Correia
• 13. U.S. patent application Ser. No. 12/748,425—Liquid biofuels from cellulose using trioctylamine hydrochloride, Pedro Correia
• 14. Simple chemical transformation of lignocellulosic biomass into furan for fuel and chemicals, J. A.m. Chem. Soc. 2009, 131, (5), 1979-1985, Joseph Binder, Ronald Raines