Technical field

The present invention relates to a molecule for use as fuel, or more specifically as biofuel for a combustion engine and a method for production and synthesis of the same.

Background

In light of the current need to reduce the greenhouse gas (GHG) emissions in the world, and reduce or eradicated the dependency on fossil fuels there is a need to provide alternative fuel resources.

There are a number of different fuels used in combustion engines in for instance the automotive sector, such as petrol, ethanol and diesel. Where petrol and diesel have conventionally been manufactured from petroleumbased sources, i.e. through the refinement of crude oil, there are currently a number of other sources, such as biological material, biomass from the forest i.e. biofuel, and methods for production of these fuels. The use of biofuels is also debated for many reasons, such as that they are not as efficient or actually even as renewable as necessary to cut the GHG emissions.

Ethanol is a simple alcohol and can be easily produced from different types of biomass and can be further manipulated for the employment as biofuel, either directly or through refinement or synthesis into other molecules.

Even though biofuels generally are aimed at mimicking the characteristics of conventional fossil fuels, i.e. with regards to efficiency and function in the engine, there is an increased need to find new types of high value liquid fuels with even more improved qualities.

Summary

It is in view of the above considerations and others that the embodiments described in this disclosure have been made.

This disclosure recognizes the fact that there is a need for new and improved molecules for use as biofuel. It is an object of the present disclosure, to provide a molecule for use as biofuel and a method for producing the biofuel. The object is wholly achieved by the molecule and inventive method for synthesis of the molecule. The invention is defined by the appended independent claims. Embodiments are set forth in the appended dependent claims and in the following description.

According to a first aspect there is provided a molecule having a general formula 7 for use as a fuel in a combustion engine: and wherein said molecule is a di(2-ethylhexy I) ether.

The di(2-ethylhexyl) ether, with alternative name: bis(2-ethylhexyl) ether: IIIPAC: 3-(((2-ethylhexyl)oxy)methyl)heptane, CAS: 10143-60-9, has previously been used for instance as a lubricant. The invention lies in the surprising finding the di(2-ethylhexyl) ether according to the formula 7 is suitable for use as a fuel in a combustion engine, i.e. as a biofuel molecule.

According to the first aspect the fuel is diesel. The molecule may thus be used as a standalone diesel fuel, i.e. as a higher value liquid fuel.

According to the first aspect the fuel may optionally comprise an additive such as a lubricant.

Further, the fuel according to the first aspect may have a density at 15°C according to EN ISO 12185 in the range of 800 to 845 kg/m ³ or a density at 15°C according to EN ISO 12185 in the range of 810 to 820 kg/m ³ , or more preferably a density at 15°C according to EN ISO 12185 of 814.0 kg/m ³ .

According to the first aspect the molecule for use as fuel as claimed in any may be mixed with a fossil diesel fuel. Since the biofuel molecule has properties matching a conventional fuel the biofuel molecule may be mixed with a fossil diesel to lower the carbon footprint of the fossil fuel.

According to a second aspect there is provided a one-pot method for producing an intermediary product of the di(2-ethy lhexy I) ether according to formula 7, wherein said intermediary product is a branched Cs aldehyde according to the general formula 5, wherein said method comprises an integrated catalytic conversion of a C4 croton aldehyde having the general formula 2: and wherein said method comprises acid catalyzed etherification of a branched Cs alcohol having the general formula 6: through the reaction scheme 2:

in which system a Ni(0) metal catalyst is used.

According to the method of the second aspect there is thus provided a one-pot production method for the di(2-ethylhexyl) ether according to formula 7. In the first step, i.e. the synthesis of the branched alcohol according to formula 6, and by using the Ni(0) metal catalyst, a high ratio of the branched aldehyde according to formula 5 is obtained, which is essential for the subsequent reduction into the intermediate product, i.e. the branched alcohol 6. The desired final product C16 ether is then obtained through an acid catalyzed etherification of branched alcohol 6.

According to a third aspect there is provided a method for the production of a di(2-ethylhexyl) ether according to the formula 7, wherein said is di(2-ethylhexyl) ether is synthesized through an acid catalyzed etherification reaction of the branched Cs alcohol as obtained through the reaction according to claim 6, according to any one of the reactions in reaction scheme 6:

99% total conversion According to a fourth aspect there is provide a biofuel molecule obtained through the method of the thirds, and second aspect, having the general formula 7: wherein said biofuel molecule is a diesel, and wherein said fuel further has a density at 15°C according to EN ISO 12185 in the range of 810 to 820 kg/m ³ or wherein said fuel has a density at 15°C according to EN ISO 12185 of 814 kg/m ³ .

According to a fifth aspect there is provided the use of a molecule having a formula (7) as a fuel in a combustion engine: and wherein said molecule is a di(2-ethylhexyl) ether, wherein the fuel has a density at 15°C according to EN ISO 12185 in the range of 800 to 845 kg/m3has a density at 15°C according to EN ISO 12185 of 814 kg/m ³ . The fuel may have a density at 15°C according to EN ISO 12185 in the range of 810 to 820 kg/m ³ , or density at 15°C according to EN ISO 12185 of 814.0 kg/m ³ .

According to a sixth aspect there is provided a one-pot method for producing an intermediary product, comprising an integrated catalytic conversion of a C4 croton aldehyde as starting material having the general formula 2, under 10 bar H2, at 100 to 120°C, during 4 hours in a solvent: wherein said intermediary product is a branched Cs aldehyde according to the general formula 5, with 100 % conversion rate of the starting material based on GC-MS analysis, and subsequently reduction of said branched Cs aldehyde according to the general formula 5, into the branched alcohol having formula 6: andwherein said method comprises acid catalyzed etherification of branched Cs alcohol having the general formula 6: in which reaction a Ni(0) metal or a Pd(0) catalyst is utilized.

According to a seventh aspect there is provided a method for the production of a di(2-ethylhexyl) ether according to the formula 7, wherein said is di(2-ethylhexyl) ether is synthesized through an acid catalyzed etherification reaction of the branched Cs alcohol according to formula 6 as a starting material: and as obtained through the reaction according to the sixth aspect, according to any one of the following reactions: reacting compound 6 with 4 wt.-% H2SO4 solid on silica at 180°C for 12h, neat, wherein water is removed, resulting in an 80:20 ratio of compound 7 and compound 13 having formula: and 99% conversion of said starting material; and/or reacting compound 6 with 4 wt.% H2SO4 in a liquid at 180°C for 12h, neat, wherein water is removed, resulting in a 90:10 ratio of compound 7 and compound 13 and a 99% conversion of said starting material.

According to an eight aspect there is provided the use of a molecule having a formula (7) obtained by the method according to the seventh aspect as a fuel in a combustion engine: and wherein said molecule is a di(2-ethylhexyl) ether, wherein the fuel has a density at 15°C according to EN ISO 12185 in the range of 800 to 845 kg/m ³ has a density at 15°C according to EN ISO 12185 of 814 kg/m ³ .

Description of Embodiments

The C16 ether, i.e. the di(2-ethylhexyl) ether for use as liquid fuel for a combustion engine, or more specifically as diesel fuel, with the alternative name: Bis(2-ethylhexyl) ether: IIIPAC: 3-(((2-ethylhexyl)oxy)methyl)heptane, CAS: 10143-60-9, was synthesized according to a two-step synthesis, where a first step is preferably performed in a so called one-pot method, with a subsequent acid catalyzed etherification in a separate and final step, and will be described in more detail below.

The starting material for the inventive biofuel is preferably a bioethanol, produced from conventional sources, such as biomass. The bioethanol may further be oxidized through conventional methods to acetaldehyde, or converted or croton aldehyde.

A branched Cs alcohol according to formula 6 below, was in a first step prepared by integrated catalytic system from a simple C2 acetaldehyde according to the general formula 1 below or from a C4 croton aldehyde according to the general formula 2 below in a one-pot method. Preferably, the C4 croton aldehyde according to the general formula 2, is used as feedstock and is catalytically transformed into branched saturated aldehyde according to the general formula 5 below, and subsequently reduced into the branched alcohol having formula 6. By using the C4 croton aldehyde a more precis control of the reaction is achieved, i.e. providing the highest yield of the Cs alcohol.

In a final step, an acid catalyzed etherification of the Cs alcohol into desired final product C16 ether is performed according to the overall reaction Scheme

Scheme 1 . Overall integrated catalysis pathway for the conversion of simple aldehyde to higher value liquid fuel. The key intermediate in the process the branched Cs aldehyde according to formula 5 below and controlling the formation thereof.

A one-pot conversion of acetaldehyde 1 , or more preferably a croton aldehyde 2, into a branched valuable Cs aldehyde according to formula 4 below and 5, is accomplished by a hydrogenation-condensation- hydrogenation in domino sequential reaction, according to reaction Scheme 2 below, via the in situ formation of intermediate butanal according to formula 3 below, followed by an additional cascade hydrogenation to form the branched Cs alcohol 6.

Reaction scheme 2. One-pot cascade reaction for the formation of Cs alcohol.

According to the invention an essential step in the inventive process is controlling the outcome products, i.e. the intermediary products, of the condensation reaction of croton aldehyde 2.

Therefore, in the inventive method croton aldehyde 2, is used as feedstock in the one-pot heterogeneous metal catalyzed synthesis of branched Cs aldehyde 5 and branched alcohols 6 to achieve a high yield.

Transition metals such as Pd, Ni, Pt, Mo and Cu supported on aluminum and silica as heterogeneous catalysts were investigated for the catalytic conversion of acetaldehyde 1 and croton aldehyde 2 into Cs branched alcohols 4.

Experiments

In initial experiments, an autoclave batch reactor was used as a reaction vessel to conduct this transformation and toluene were chosen as solvent for the one-pot experiments at different temperatures, according to reaction Scheme 3 below. The reaction conditions as disclosed in Scheme 3 were as follows 750 mmol/ 61 mL of croton aldehyde in 180 mL of solvent, C= 4M, under indicated H2 gas pressure and indicated temperature and time. The yields are based on GC-MS analysis.

Reaction scheme 3. Suggested catalytic conversion of croton aldehyde 2

Furthermore, utilizing a Pd(0) metal as catalyst instead of the Ni(0) afford the branched aldehyde 5 as major product in one pot starting from the croton aldehyde 2, as feedstock, which is disclosed in reaction Scheme 4 below, where the reaction conditions were as follows: 750 mmol/ 61 mL of croton aldehyde in 180 mL of solvent, C= 4M, under indicated H2 gas pressure and indicated temperature and time. The yields based on GC-MS analysis.

Reaction scheme 4. Using Pd(0) catalyst

It was found that in order to sufficiently reduce the Cs, branched aldehyde 5, to branched alcohol 6 a Ni(0) based catalyst (catalyst TK-49 provided by HALDOR TOPSOE) preferably may be utilized.

In the second and separate step the target Ci6 ether 7, is synthesized by an acid catalyzed etherification reaction.

As disclosed in reaction scheme 6 a sulfuric acid both as liquid and as heterogeneous supported on silica were applied successfully, utilizing a dean-stark equipment to remove the formed water as by product. The reaction conditions for the below reaction were: neat condition. The yields are based on GC-MS analysis.

99% total conversion

99% total conversion

Reaction scheme 6. Acid catalyzed etherification reaction

Fuel analysis The di-(2-ethylhexyl) ether according to formula 7, was analyzed by Saybolt Sweden AB with regards to its properties as diesel fuel (with interpretation of test results as defined in ASTM D3244, EN 590, IP 367, ISO 4259 or GOST 33701 ). The test results showed that the di-(2-ethylhexyl) ether according to formula 7 is suitable for use as diesel, since the density at 15°C according to EN ISO 12185 was analyzed to be in the range of 800 to 845 kg/m ³ , or more specifically in the range of 810 and 820 kg/m ³ , and even more specifically to be 814.0 kg/m ³ . The analysis showed that the fuel product does however need further additives such as a lubricity improver to function properly in a combustion engine. The test results are disclosed in Table 1 , below. The analysis discloses that the high value liquid fuel product may also be suitable for mixing with a fossil based diesel, since it has the same properties as a fossil fuel, e.g. with regards to density. It may also be useful for mixing with so called FAME products.

Table 1 . Analysis of di(2-ethylhexyl) ether according to formula 7 as diesel

Modifications and other variants of the described embodiments will come to mind to one skilled in the art having benefit of the teachings presented in the foregoing description and associated drawings. Therefore, it is to be understood that the embodiments are not limited to the specific example embodiments described in this disclosure and that modifications and other variants are intended to be included within the scope of this disclosure. Furthermore, although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Therefore, a person skilled in the art would recognize numerous variations to the described embodiments that would still fall within the scope of the appended claims. As used herein, the terms “comprise/comprises” or “include/includes” do not exclude the presence of other elements or steps. Furthermore, although individual features may be included in different claims (or embodiments), these may possibly advantageously be combined, and the inclusion of different claims (or embodiments) does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Finally, reference signs in the claims are provided merely as a clarifying example and should not be construed as limiting the scope of the claims in any way.