WO2015072911A1

WO2015072911A1 - Method for preparing an ethanol fuel composition

Info

Publication number: WO2015072911A1
Application number: PCT/SE2014/051317
Authority: WO
Inventors: Roger Mattebo; Martin Karlsson; Gunder HÄGGSTRÖM
Original assignee: Sekab Biofuels & Chemicals Ab
Priority date: 2013-11-12
Filing date: 2014-11-06
Publication date: 2015-05-21
Also published as: SE538634C2; EP3068524A4; EP3068524A1; SE1351329A1

Abstract

The invention relates to a method for preparing an ethanol fuel composition, comprising the following steps: a) providing a first amount of ethanol to a vessel b) addition of an amount of ethoxylated oleyl amine and an amount of ignition improver to the ethanol provided in step a) such that a first mixture is obtained wherein: the concentration of ethanol in the first mixture is 35-55 % (w/w); the ratio (w/w) of ethoxylated oleyl amine to ethanol in the first mixture is in the range 1:4 – 1:15, preferably in the range 1:6 – 1:10, and the ratio (w/w) of ignition improver to ethanol in the first mixture is in the range 1:1 – 1:3, preferably in the range 1:1.2 – 1:2 c) blending the first mixture by using vertical circulation and/or stirring such that a blended first mixture is obtained; d) combining the blended first mixture obtained in step c) with a second amount of ethanol such that a second mixture is obtained; e) blending of the second mixture obtained in step d) to obtain the ethanol fuel wherein the ethanol fuel obtained in step e) comprises: 20 80-90 % (w/w), preferably 84-88 % (w/w) ethanol 0.1-2 % (w/w), preferably 0.5-1.5 % (w/w) ethoxylated oleyl amine 3-10 % (w/w), preferably 4-6 % (w/w) ignitionimprover and wherein the ignition improver added in step b) is a water soluble adduct of 25 polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide and wherein the molecular weight of the aduct is 350 to 2000 Da, preferably 600-1000 Da;

Description

METHOD FOR PREPARING AN ETHANOL FUEL COMPOSITION

Technical field

The present invention relates to the field of preparation of ethanol fuel compositions. In particular the invention relates to methods which reduces or avoids precipitation of components of the ethanol fuel compositions during the preparation.

Background

Global warming, petroleum depletion and energy security have been the main driving forces for the development of renewable fuels that can replace the petroleum-derived fuels, such as gasoline and diesel. Ethanol is currently the most commonly used renewable automobile fuel. It is largely produced by fermentation of sugar- or starch-containing feedstocks, such as cane sugar, corn and wheat. Also, it may be produced from lignocellulose, which is a less expensive raw material. Other benefits of lignocellulose are that it is not considered a human food resource and that ethanol may be produced from it with a relatively high net energy gain and a high renewable CO₂-efficiency, i.e. the amount of fossil CO₂ generated throughout the production chain when producing ethanol from lignocellulose is comparatively low. The use of ethanol in traditional gasoline or diesel engines is associated with a number of problems. To overcome these problems, various ethanol fuel compositions that are adapted for such use have been developed over the past years. Many of these fuel compositions comprise various additives, and it may be problematic to achieve a sufficient mixing of the ethanol and such additives, especially in large scale production of the fuel compositions.

Summary of the present disclosure

ED95 is an ethanol based fuel comprising an ignition improver consisting of an adduct of a polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide; a surface active agent consisting of ethoxylated oleyl amine, a corrosion inhibitor, denaturants and a colorant. Even though the said ignition improver and the said surface active agent are soluble in ethanol, efficient preparation of the fuel has been challenging due to precipitation of the ignition improver and the surface active agent. It is an object of the present invention to provide a method for the preparation of an ethanol fuel composition, comprising such ignition improver and such surface active agent, which reduces or even eliminates the precipitation of the ignition improver and the surface active agent.

The present inventors have developed a method of preparing such ethanol fuels which surprisingly overcomes the problem described above by reducing or even eliminating precipitation of the ignition improver and the surface active agent in the preparation of the fuel.

Therefore a first aspect of the present invention relates to a method for preparing an ethanol fuel composition, comprising the following steps:

a) providing a first amount of ethanol to a vessel

b) addition of an amount of ethoxylated oleyl amine and an amount of ignition improver to the ethanol provided in step a) such that a first mixture is obtained wherein:

the concentration of ethanol in the first mixture is 35-55 % (w/w);

the ratio (w/w) of ethoxylated oleyl amine to ethanol in the first mixture is in the range 1 :4 - 1 :15, preferably in the range 1 :6 - 1 :10 , and

the ratio (w/w) of ignition improver to ethanol in the first mixture is in the range 1 :1 - 1 :3, preferably in the range 1 :1 .2 - 1 :2

c) blending the first mixture by using vertical circulation and/or stirring such that a blended first mixture is obtained;

d) combining the blended first mixture obtained in step c) with a second amount of ethanol such that a second mixture is obtained;

e) blending of the second mixture obtained in step d) to obtain the ethanol fuel

wherein the ethanol fuel obtained in step e) comprises: 80-90 % (w/w), preferably 84-88 % (w/w) ethanol

0.1 -2 % (w/w), preferably 0.5-1 .5 % (w/w) ethoxylated oleyl amine

3-10 % (w/w), preferably 4-6 % (w/w) ignitionimprover

and

wherein the ignition improver added in step b) is a water soluble adduct of polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide and wherein the molecular weight of the aduct is 350 to 2000 Da , preferably 600-1000 Da; Detailed description

Ethanol based fuels comprising 80-90 % (w/w) ethanol, a surface active agent, consisting of ethoxylated oleyl amine, and of an ignition improver, consisting of an adduct of a polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide, are presently used as fuel for busses and lorries. A drawback with these kinds of fuels is that it is hard to mix the fuel in an efficient way since the ignition improver and the surface active agent easily precipitates. This is problematic since the precipitates are hard to dissolve and non-dissolved precipitates will affect the concentration of ignition improver and surface active agent in the final fuel. The present inventors have realized that there is a need for improved methods of blending ethanol based fuels comprising such surface active agent and such ignition improvers.

The present inventors have found that it is possible to vastly reduce or even prevent the precipitation of ignition improver and surface active agent by making an initial premix of ethanol, ignition improver and surface active agent in a premixing step. The present inventors have further found that the concentration of ethanol, the ratio of ethanol to ignition improver and the ratio of ethanol to surface active agent, in the premixing step, are critical for the level of precipitation. In particularly, if the ethanol concentration in the premixing step is 35-55 % (w/w); the present inventors have discovered that precipitation of the ignition improver is surprisingly low if the ratio of ethanol to ignition improver is in the range 1 :1 - 1 :3. Even better results are achieved if the ratio of ethanol to ignition improver is in the range 1 :1 .2 - 1 :2. The present inventors have further discovered that the precipitation of the surface active agent can be vastly reduced if the ratio of ethanol to surface active agent is in the range 1 :4— 1 :15. Even better results are achieved if the ratio of ethanol to surface active agent is in the range 1 :6— 1 :10. The present inventors have further discovered that the ignition improver and the surface active agent preferably should be added to the ethanol and not the other way around. If the ethanol is added to a vessel comprising the ignition improver and/or the surface active agent, the present inventors have discovered that the levels of precipitated ignition improver and/or the surface active agent will be higher. The present inventors have discovered that vertical circulation and/or stirring of such a premix is a suitable way of blending the premix. One advantage with vertical circulation is that less costly equipment can be used compared to if for example a stirred tank reactor is used for the blending of the premix. After the premix is prepared, the final fuel can be prepared from the premix by addition of ethanol up to the desired concentration, i.e 80-90 % (w/w), followed by blending of the obtained mixture by stirring, preferably in a stirred tank reactor. In the context of the present disclosure, "blending" refers to mixing at least two constituents such that these become less separated from eachother. In the present disclosure the term "vertical circulation" shall be interpreted as that liquid in a container is pumped from a first position in the container to a second position in the container which is located higher than the first. Typically in vertical circulation, liquid is pumped from the bottom of the container to a position near the liquid surface The present invention is at least partly based on the discoveries, insights and findings which are described above, and thus a first aspect of the invention relates to a method for preparing an ethanol fuel composition, comprising the following steps:

a) providing a first amount of ethanol to a vessel

the concentration of ethanol in the first mixture is 35-55 % (w/w); the ratio (w/w) of ethoxylated oleyl amine to ethanol in the first mixture is in the range 1 :4 - 1 :15, preferably in the range 1 :6 - 1 :10 , and

wherein the ethanol fuel obtained in step e) comprises:

80-90 % (w/w), preferably 84-88 % (w/w) ethanol

0.1 -2 % (w/w), preferably 0.5-1 .5 % (w/w) ethoxylated oleyl amine

3-10 % (w/w), preferably 4-6 % (w/w) ignitionimprover

and

wherein the ignition improver added in step b) is a water soluble adduct of polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide and wherein the molecular weight of the aduct is 350 to 2000 Da , preferably 600-1000 Da

Since the the self ignition temperature of ethanol is relatively high, a traditional diesel engine does not run well on pure ethanol. Therefore, an ignition improver is added. In the context of the present disclosure, an

"ignition improver" refers to an agent which improves the ignition properties of a fuel into which it has been blended. Examples of suitable ignition improvers for the fuels prepared according to the present invention have been described previously, see WO9505437, and are also commercially available and sold under the trade name Beraid (Akzo Nobel). Suitable ethoxylated oleyl amine includes tertiary amine ethoxylate, based on a primary oleyl amine. A preferred ethoxylated oleyl amine is bis-(2-hydroxyethyl)-oleyl amine. One example of a suitable ethoxylated oleyl amine is Ethomeen Ο/12 (Akzo Nobel). To prevent precipitation of the ignition improver it is important that the temperature of the ignition improver is not to low. Therefore, in one

embodiment the temperature of the ignition improver added in step b) is at least 15 °C such as at least 20 °C .

Usually denaturing agents are added to ethanol fuel compositions, to prevent consumption of the fuel composition. Such denaturing agents should preferably have one or more, preferably all, of the following properties:

unpleasant smell; disagreeable taste; solubility in ethanol; and compatibility with the ignition improver. Further it is beneficial if the denaturing agent(s) is/are not harmful to fuel systems and engines and is/are not easily separated from the fuel composition by distillation or other methods. Examples of suitable denaturating agents includes butanol and C1 -3 alkyl-tert-butyleter, such as metyl-tert-butyleter (MTBE) and etyl-tert-butyleter (ETBE). For example the commercially available fuel ED95 comprises Iso-butanol and MTBE. The present inventors have discovered that the denaturing agents (at least in the case of iso-butanol, MTBE and ETBE) can be added at any of the steps a)-e). However, the present inventors have discovered that the blending is more efficient if the denaturating components are added to the ethanol provided in step a) together with the ethoxylated oleyl amine and the ignition improver.

Thus in one embodiment the method further comprises a step of adding butanol prior to and/or during any of the steps a)-e) such that the ethanol fuel obtained in step e) comprises 0.2-1 .5 % (w/w) butanol. In one embodiment at least part of the butanol is added during step b) to the ethanol provided in step a). In one embodiment the butanol is n-butanol and/or iso-butanol. In a preferred embodiment the butanol is iso-butanol. In one embodiment the method further comprises a step of adding MTBE and/or ETBE prior to and/or during any of the steps a)-e) such that the ethanol fuel obtained in step e) comprises 1 -3 % (w/w) MTBE and/or ETBE. In one embodiment at least part of the MTBE and/or ETBE is added during step b) to the ethanol provided in step a). In one embodiment the ethanol fuel composition is ED95. In one embodiment the method further comprises addition of a colourant prior to and/or during any of the steps a)-e).

Engines, such as diesel engines, running on ethanol fuel are particularly susceptible to corrosion. Therefore, a corrosion inhibitor may be added to the fuel composition. The inventors have found that morpholin is a particularly suitable corrosion inhibitor for this purpose. Consequently, in one

embodiment of the invention, the corrosion inhibitor may be morpholin or derivatives thereof. Furthermore, in one embodiments of the invention, the corrosion inhibitor is added in an amount corresponding to 5-500 ppm, preferably 30-300 ppm, more preferably 50-150 ppm of the total weight of the ethanol fuel composition, i.e. the ethanol fuel composition obtained in step e). The ranges are particularly relevant if the corrosion inhibitor is morpholin. In embodiments of the invention, the corrosion inhibitor is added together with the ignition improver in step b). For example, the corrosion inhibitor may be pre-mixed with the ignition improver added in step b).

As described above the blending of the first mixture in step c) is performed at least partly by using vertical circulation and/or stirring. In step e) vertical circulation is less suitable since the volume in step e) is much larger than in step c). Vertical circulation is less practical and demands more energy and expensive equipment when the volumes are larger.

Therefore, in one embodiment the blending in step e) is at least partly mediated by stirring of the second mixture obtained in step d). In one embodiment the total weight of the first mixture obtained in step b) is between 100 and 1000 tons preferably 200-600 tons such as 300-500 tons. In one embodiment the total weight of the second mixture obtained in step d) is between 540 and 5400 tons preferably 1 100-3200 tons such as 1600-2700 tons.

Step d) can preferably be performed by transferring the blended first mixture obtained in step c) to a second vessel comprising the second amount of ethanol. The present inventors have realized that this is benificial for the blending in step e). Thus, in one embodiment the blending of the first mixture in step c) is performed in a first vessel comprising means for vertical circulation and step d) comprises transferring the blended first mixture obtained in step c) to a second vessel. In one embodiment the second vessel is comprising the second amount of ethanol and the blending of the second mixture in step e) is performed in the second vessel. In one embodiment the second vessel is a stirred tank reactor. The present inventors have realized that a lot of benefits can be achieved if the second vessel is a tank on a motor vehicle designed to carry liquefied loads. Such motor vehicles are well known to the skilled person and are commonly referred to as tank trucks, tanker trucks or petrol tankers. One advantage with this solution is that the second mixture is, at least to som extent, blended by the movement of the second mixture within the tank, mediated by the movement generated when the motor vehicle is driving. Another advantage is that it eliminates the needs for a large stirred tank reactor for the blending of the second mixture. A third advantage is that the fuel can be produced on demand from a premixed solution, directly in a vehicle for transportation of the fuel. The present inventors have realized that this is particularly suitable if the first mixture and the second amount of ethanol are mixed inline prior to introduction of the obtained second mixture in the tank. For example, blended first mixture can be withdrawn from the first vessel via a first pipe and the second amount of ethanol can be withdrawn from a container containing ethanol via a second pipe. Both the first pipe and the second pipe can lead to a third pipe such that the first blended mixture is mixed with the second amount of ethanol in the said third pipe to obtain the second mixture within the third pipe. The third pipe can lead to the tank on the motor vehicle, such that the second mixture is transferred to the said tank via the third pipe. The inline mixing can be mediated by an inline mixing device which can be present in the third pipe. Such inline mixing devices are well known to the skilled person. For example the inline mixing device can be a static mixer. Such static mixers can comprise geometric mixing elements fixed within a pipe, and which use the energy of a flow stream to create mixing between two or more fluids. For example, a static mixer can be arranged in the third pipe to facilitate blending of the first mixture obtained in step c) with the second amount of ethanol prior to introduction of the second mixture in the tank on the motor vehicle designed to carry liquefied loads.

Thus, in one embodiment the second vessel is a tank on a motor vehicle designed to carry liquefied loads. In one embodiment, the blending of the second mixture in step e) is at least partly achieved by the motion created when the motor vehicle is driving. In a preferred embodiment the blended first mixture obtained in step c) is inline mixed with the second amount of ethanol such that the second mixture is formed inline prior to introduction of the second mixture in the tank on the motor vehicle designed to carry liquefied loads. In one embodiment, the inline mixing is at least partly mediated by an inline mixing device. In one embodiment the inline mixing device is a static mixer

Alternatively, the second amount of ethanol can be added to the blended first mixture obtained in step c). An advantage with this is that only one vessel is needed for the preparation of the fuel but a draw back is that the blending in step e) is less effective. Thus, in an alternative embodiment the blending of the first mixture in step c) is performed in a first vessel, preferably comprising means for vertical circulation, and step d) comprises adding the second amount of ethanol to the first vessel and the blending of the second mixture in step e) is performed in the first vessel. In one embodiment the first vessel is a stirred tank reactor, preferably comprising means for vertical circulation.

The inventors have realized that blending in step e) preferably shall be performed until the density difference between the liquid by the liquid surface and the liquid by the bottom of the vessel is 2 % or less, such as 1 % or less. Preferably, the density difference is 0.5 % or less, more preferably 0.2 % or less. Under given circumstances, the person skilled in the art understands what "by the liquid surface" and "by the bottom of the vessel" refer to. Typically, "by the bottom" is within 0.5 m of the bottom, and "by the liquid surface" is within 0.5 m of the surface. However, this depends on the size of the vessel. Further, equipment for density measurements is well known and commercially available, and the person skilled in the art understands how to perform the density measurements.

Also in the blending in step c) it is important that the density difference between the liquid by the liquid surface and the liquid by the bottom of the vessel is low. Thus in one embodiment the density difference between the liquid by the liquid surface and the liquid by the bottom of a vessel of the first mixture obtained in step c) is 5 % or less, such as 2 % or less, such as 1 % or less. Preferably, the density difference is 0.5 % or less, more preferably 0.2 % or less. Such a low density difference may preferably be achieved by means of vertical circulation of the total volume of the first mixture obtained in step b) at least 1 time, such as at least 1 .15 times, such as at least 1 .5 times, such as at least 2 times. The number of times the total volume is circulated is calculated as the capacity of the pump by means of which the circulation is performed multiplied by the duration of the pumping divided by the total volume. For example, if the total volume is 500 m³, the capacity of the pump is 60 m³/h and pumping is performed during 10 h, the total volume is circulated 60^*10/500 = 1 .2 times.

Detailed description of an example embodiment

200 tonnes ethanol liquid comprising about 93 % ethanol (w/w) and 7 % water (w/w) is pumped to a tank comprising means for vertical circulation.

Thereafter 120 tonnes of ignition improver, (Beraid from Akzo Nobel), 10. 3 tonnes of Isobutanol, 51 . 4 tonnes of MTBE, 24 tonnes of ethoxylated oleyl amine (Ethomeen from Akzo Nobel) and 4.8 kg of the red colorant

Basonylbasic Red (BASF) is pumped to the tank during vertical circulation of the liquid in the tank. This circulation is performed at a rate of 60 m³/h. After all the components have been added, the liquid in the tank is vertically circulated for 10 h at a rate of 60 m³/h to obtain a first mixture. Thereafter the first mixture is pumped into a stirred tank reactor comprising 800 tonnes of ethanol ( 93% w/w) during stirring of the stirred tank reactor. Thereafter 1 190 tonnes of ethanol (93 % w/w) is added during stirring, followed by stirring of the solution for about 1 -5 days to obtain the ethanol fuel.

Claims

1 ) Method for preparing an ethanol fuel composition, comprising the following steps:

a) providing a first amount of ethanol to a vessel

the concentration of ethanol in the first mixture is 35-55 % (w/w);

the ratio (w/w) of ethoxylated oleyl amine to ethanol in the first mixture is in the range 1 :4— 1 :15, preferably in the range 1 :6— 1 :10, and

the ratio (w/w) of ignition improver to ethanol in the first mixture is in the range 1 :1 - 1 :3, preferably in the range 1 :1 .2— 1 :2

wherein the ethanol fuel obtained in step e) comprises:

80-90 % (w/w), preferably 84-88 % (w/w) ethanol

0.1 -2 % (w/w), preferably 0.5-1 .5 % (w/w) ethoxylated oleyl amine

3-10 % (w/w), preferably 4-6 % (w/w) ignitionimprover

and

wherein the ignition improver added in step b) is a water soluble adduct of polyol having 3-10 hydroxyl groups and ethylene oxide and/or propylene oxide and wherein the molecular weight of the aduct is 350 to 2000 Da, preferably 600-1000 Da; 2) Method according to claim 1 wherein the ethoxylated oleyl amine is bis-(2- hydroxyethyl)-oleyl amine 3) Method according to any of the previous claims wherein the method further comprises a step of adding butanol prior to and/or during any of the steps a)- e) such that the ethanol fuel obtained in step e) comprises 0.2-1 .5 % (w/w) butanol

4) Method according to claim 3 wherein at least part of the butanol is added during step b) to the ethanol provided in step a)

5) Method according to any of the previous claims wherein the method further comprises a step of adding MTBE and/or ETBE prior to and/or during any of the steps a)-e) such that the ethanol fuel obtained in step e) comprises 1 -3 % (w/w) MTBE and/or ETBE

6) Method according to claim 5 wherein at least part of the MTBE and/or ETBE is added during step b) to the ethanol provided in step a)

7) Method according to any of the previous claims wherein the blending in step e) at least partly is mediated by stirring of the second mixture obtained in step d)

8) Method according to any of the previous claims wherein the total weight of the first mixture obtained in step b) is between 100 and 1000 tons preferably 200-600 tons such as 300-500 tons 9) Method according to any of the previous claims wherein the total weight of the second mixture obtained in step d) is between 540 and 5400 tons preferably 1 100-3200 tons such as 1600-2700 tons

10) Method according to any of the previous claims wherein the temperature of the ignition improver added in step b) is at least 15 °C such as at least 20

°C 1 1 ) Method according to any of the previous claims wherein the blending of the first mixture in step c) is performed in a first vessel and wherein step d) comprises transferring the blended first mixture obtained in step c) to a second vessel

12) Method according to claim 1 1 wherein the second vessel is comprising the second amount of ethanol and wherein the blending of the second mixture in step e) is performed in the second vessel 13) Method according to claim 12 wherein the second vessel is a stirred tank reactor

14) Method according to claim 1 1 wherein the second vessel is a tank on a motor vehicle designed to carry liquefied loads

15) Method according to claim 14 wherein the blended first mixture obtained in step c) is inline mixed with the second amount of ethanol such that the second mixture is formed inline prior to introduction of the second mixture in the tank on the motor vehicle designed to carry liquefied loads