GB2528041A - Enhanced fuels, methods of producing enhanced fuels, and additives for enhanced fuels - Google Patents

Abstract

An additive for fuels is provided, wherein the additive is a PEG (poly-ethylene glycol) trinitrate derivative. The additive is operable to function as a cetane enhancer when mixed with a fuel and combusted within a combustion engine. The additive has a chemical formula: CH2-(O-CH2-CH2)n -ONO2 CH-(O-CH2-CH2)m -ONO2 CH2-(O-CH2-CH2)p -ONO2 wherein n, m, p are integers which represent the number of basic monomers in an ethoxylate chain in the additive. Optionally, the additive is chosen from compounds with n, m and p varying in a range of 1 to 5.

Description

ENHANCED FUELS, METHODS OF PRODUCING ENHANCED FUELS, AND

ADDITIVES FOR ENHANCED FUELS

Technical Field

The present disclosure relates to enhanced fuels suitable for use in internal combustion engines, for example to cetane-enhanced alcohol-based fuels suitable for use in internal combustion engines, for example cetane-enhanced methanol-based fuel suitable for use in internal compression-ignition combustion engines. Moreover, the present disclosure is also concerned with methods of producing such enhanced fuels, for example with methods of producing cetane-enhanced alcohol-based fuels, for example with methods of producing cetane-enhanced methanol-based fuels.

Furthermore, the present disclosure is also concerned with compounds for enhancing fuels, for example with compounds which can be added to alcohol-based fuels, for example methanol-based fuels, to enhance their cetane properties.

Background

Combustion systems such as internal combustion engines are well known. In such combustion systems, combustible hydrocarbon fuels are oxidized by air to generate hot gases that are used to generate mechanical power, for example for transportation purposes. However, such combustion in air generates as by-products carbonaceous soot particles and Nitrogen oxides (NOx). Several innovations have been devised in recent years to reduce and/or filter such soot particles and Nitrogen oxides (NO) in exhaust gases from combustion systems.

Contemporary combustion fuels are derived, namely manufactured, from geological fossil reserves. Such fossil reserves are of finite capacity and are being gradually exhausted, as the present World consumption of oil is in an order of 100 millions barrels of oil per day. More recently, there is a growing interest in biofuels derived from contemporary biota. The use of biofuel as a motor fuel has been studied in detail already since the 20th Century. In a recent period, alternative fuels, in contradistinction to conventional fossil-reserve-derived fuels, is used as a motor fuel, or an addition to basic fuel, in many countries, such as Brazil, Germany, Sweden and USA [1].

Technologies have been developed for producing motor fuels including plain ethanol, as well as its blends with regular gasoline and diesel fuel to be used in internal combustion engines. Significant innovations relating to alternative fuels are described in patent documents W02009/1 06647, US5, 628, 805 and DE10339355.

In a European patent document EPO1 16197B1 (proprietor: AECI Ltd.; inventor Stiff), there is described a fuel additive comprising a mixture of a first component A, and second component B, wherein the first component A is at least one alcohol with a molecular weight of less than 160, and wherein the second component B is at least one organic compound of the formula N02-O-(CH2CH2-O-)rNO2 Eq. 1 wherein x = an integer greater than 3, and wherein the average molecular weight of the at least one compound of formula N02-O-(CH2CH2-O-)x-N02 Eq. 2 is a range of 260 and about 390, with a proviso that no other compounds of formula N02-O-(CH2CH2-O-)x-N02 Eq. 3 are present. Optionally, the fuel additive is added to a fuel such as ethanol and/or methanol to provide a mixture which can be combusted in combustion engines, for example cylinder-based internal combustion engines. The additive is capable of improving fuel ignition in cylinder-based internal combustion engines, for example at lower temperatures when such engines are started and their respective engine blocks are cold.

Over recent years, many different fuel additives have been developed. An example is a contemporary fuel additive known as ELAvocetJ ELAvocet is a trademark.

In mid 1980's, a South African chemicals group, AECI, introduced a "green innovation" in the area of fuels, namely "Encetal"; "Encetal" is a trademark. Encetal was developed for purposes of seeking to increase a local consumption of methanol produced from local coal feedstock, which could be used as an alternative to imported oil for fuels.

"Encetal", the name of the fuel mixture of Methanol and Avocet, burns cleanly, producing low amounts of pollutant gases (Nitrous Oxide and Carbon Monoxide) and particulates in a vehicle's exhaust. Moreover, Avocet is an ignition improver to allow methanol fuel to be used in diesel engines, requiring a minimum of engine modifications to accommodate its use.

Avocet has been employed in several tests using alcohols as biofuels, to substitute for fossil-reserve-derived diesel fuel in private and public transportation vehicles. In the mid-i 990s, ethanol containing 4% Avocet as an ignition enhancer was tested in a small controlled group of public transport vehicles [i]. Theory predicts a significantly higher volume consumption of ethanol, in comparison to diesel fuel, but the exact higher volume has to be calculated for each case, since it depends on the specific characteristics of the vehicle (e.g. operation temperature) and the detailed composition of the fuel itself. It was found from the tests that the use of ethanol-Avocet fuel consumed 84% more per volume, which both negatively compensated for an initial economic argument as well as presented a new significant logistic challenge of transporting 84% more fuel by volume.

Moreover, the use of alcohols in existing diesel engines also requires some modifications to be made to engine components to prevent chemical degradation due to exposure to alcohols. Further improvements in engine operation, temperature and catalysts are needed in preparation for the use of ethanol and other alcohols as a replacement for diesel fuel. As far as economic arguments are concerned, a reduction in the use of Avocet, which represents a significant proportion of the costs, potentially makes combustion systems cheaper, potentially sufficiently to compensate for the comparative ratio Alcohol/diesel; as above, ethanol is taken as the reference, ethanol/diesel = i.84.

An initial economic argument for using the avocet-enhanced methanol fuel as a diesel replacement was based on an average 25% cost savings when comparing the same volume of methanol to diesel fuel. Meanwhile, environmental arguments pointed out less particulate emissions and less smokiness of such avocet-enhanced methanol fuel.

However, in early 1990's, the use of Avocet as an ignition improver or as a fuel enhancer has been deemed impractical and/or expensive for regular automobiles and other road vehicles by the parent company ICI-UK (Imperial Chemical Industries UK was the holding company of the group that owned AECI). This conclusion was reached, in part, due to the lack of commercial drive for environmentally friendly fuels when the additive has been introduced in early 1980s. Since then, there has been little activity in this area of work.

Although the composition of Avocet is proprietary, and may have varied overtime, the composition of the original Avocet additive includes following components as provided inlablel: Table 1: Original Avocet composition Component part Percentage composition PEG (PolyEthyleneGlycol) dinitrate 80% Methanol 18% Lubricity additive 1.5% Antioxidant 0.1% In a European patent document EPO08O314 Al (AECI Ltd.), there is described an organic nitrate-compound of the general formula (I) Xrn(Rf) [(OA)nX]t-m (I) Eq. 4 wherein: (i) a radical Rf is an organic residue containing three or more carbon atoms derived from a base polyhydroxy compound of formula R(OH)f by removal of OH, wherein f denotes the number of hydroxyl functions on the molecule; (H) one or more of X are nitrate groups (-ONO2); (H) a remainder in the formula (Eq. 4) are hydroxyl (-OH), wherein n is an integer between 1 and 100, and may vary in a particular compound where f-m is greater than 1; and (iv) OA is an oxyalkylene unit derived from ethylene oxide or propylene oxide, wherein m is an integer in a range of 0 to f-i, and wherein f is an integer in a range of 2 to 10, and is always equal to or less than the number of carbon atoms in the radical R. The compounds as defined in the formula (Eq. 4) can be used as additives to fuels, alcohols, combustion fluids and similar, for example for use in compression-ignition internal combustion engines.

The compound proposed in the aforementioned patent document EPOOBO31 4 Al, as defined by the equation (Eq. 4) is too general and as such can include thousands of other compositions. However, when the compound of the formula (Eq. 4) is used as a cetane enhancement of methanol, or ethanol, the value of n needs to be in a very small range, for example in a range of 1 to 5; the patent document EP0080314 Al defines 1< n <100, and does not disclose, or even appreciate, the use of the above compound to address a major problem to which the present disclosure provides an at least partial solution. For instance, values of n above 6 or 7, let alone remotely close to 100, makes the use of this additive proposed in the aforementioned patent document EP0080314 Alcompletely impractical due to its extremely high viscosity and most importantly, complete incapacity of improving the ignition of alcohols.

It has been proposed to use PEG dinitrate as an additive for alcohols, for example methanol, when employed as a fuel in combustion engines.

Additives are also employed in exhaust systems of vehicles, for example for reducing emissions of NOx components in exhaust gases emitted from exhaust systems associated with internal combustion engines. A well known contemporary additive for this purpose of reducing NOx emissions is "AdB/ue", which is the registered trademark for AUS32, or Aqueous Urea Solution 32.5% that is used with the Selective Catalytic Reduction system (5CR) to reduce emissions of oxides of nitrogen from the exhaust of UK diesel vehicles. AdBlue is a 32.5% solution of high-purity urea in de-mineralized water that is clear, non-toxic and safe to handle. It is non-explosive, non-flammable, nor harmful to the environment. AdBlue is classified under a minimum risk category of transportable fluids. However, Adblue is not a fuel, nor a fuel additive, and needs to be supplied from a dedicated tank in heavy-duty vehicles, for example trucks and buses.

The dedicated tank is replenished with AdBlue in a similar manner to refuelling diesel into heavy-duty vehicles. In an event that AdBlue is accidently spilt on human skin, it can simple washed off with water, and presents no great hazard.

However, as aforementioned, Avocet is a fuel additive and is prohibitively expensive for use in many contemporary combustion systems, which has unfortunately limited its general use. There is therefore a need for alternative additives which, when added to fuel, is able to enhance combustion properties of the fuel, for example to enhance its cetane properties at reasonable cost.

Summary

The present disclosure seeks to provide an enhanced fuel, for example an enhanced which has cetane-enhanced properties.

Moreover, the present disclosure seeks to provide an improved method of producing the aforesaid enhanced fuel.

Furthermore, the present disclosure seeks to provide additives for fuels, which, when added to the fuels, is capable of enhancing the fuels, for example for increasing their cetane properties.

According to a first aspect, there is provided an additive for fuels as claimed in appended claim 1: there is provided an additive for fuels, characterized in that the additive is a PEG (poly-ethylene glycol) trinitrate derivative.

The present invention is of advantage in that the additive is capable of enhancing cetane characteristics of fuels in a highly beneficial manner, for use in internal combustion engines, for example compression ignition combustion engines.

Optionally, the additive is operable to function as a cetane enhancer when mixed with a fuel and combusted within a combustion engine.

Optionally, the additive has a chemical formula: CI-(2-(O-CH2-GH2)n -0N02 CH-(O-CH2-CH2)ni -0N02

I

CH2(0CH2CH2)p 0N02 wherein n, m, p are integers which represent the number of basic monomers in an ethoxylate chain in the additive.

Optionally, the additive is chosen from compounds with n, m and p varying in a range of 1 to 5.

Optionally, the additive is blendable with an alcohol-based fuel. More optionally, the additive is blendable with an alcohol-based fuel including methanol and/or ethanol.

According to a second aspect, there is provide a method of producing a cetane-enhanced fuel, characterized in that the method includes blending an additive pursuant to the first aspect with a fuel.

Optionally, in the method, the additive is blended with the fuel in a volumetric concentration in a range of 0.5% to 10%, more optionally in a range of 1% to 7%.

Optionally, in the method, the additive is blended with the fuel in a ratio which enhances a cetane characteristic of the fuel.

According to a third aspect, there is provided a cetane-enhanced fuel as produced by a method pursuant to the second aspect.

Optionally, the cetane-enhanced fuel includes ethanol and/or methanol.

Optionally the cetane-enhanced fuel is useable as a diesel fuel substitute.

It will be appreciated that features of the invention are susceptible to being combined in various combinations without departing from the scope of the invention as defined by the appended claims.

Description of the diagrams

Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein: FIG. 1 is a graphical illustration of a chemical structure of a cetane-enhancing

additive pursuant to the present disclosure.

In the accompanying diagrams, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

Description of embodiments of the disclosure

In overview, the present disclosure is concerned with economical and environmental benefits of using Avocet and alcohols as a substitute for diesel fuel. Avocet is based upon PEG, wherein an approximate Avocet composition is provided in aforementioned Table 1. Pursuant to the present disclosure, there are cost benefits of adding Avocet in-situ or in-engine rather than pre-mixing with fuels. A major reason is that Avocet accounts for a significant cost of the fuel, when included in the fuel. In part, these high costs are also related to other components present in Avocet, such as HITEC 414.

As an example economic computation, assuming fuel methanol is available at a cost of 20 pence/litre (wherein 100 pence = 1 GBP), two scenarios are envisaged as follows: Scenario 1: a diesel truck running 350 kilometres (200 miles) consumes 1 litre methanol fuel with 5% Avocet, wherein following costs pertain per 1.6 km (per mile): Methanol cost GBP 40.00 Avocet cost GBP 20.00 Total fuel cost GBP 60.00 Scenario 2: the same diesel truck with Avocet injection: First 5 miles with 5% Avocet injection: GBP 0.50 Second 5 miles with 2% Avocet injection GBP 0.20 Final 190 miles with 1% Avocet injection: GBP 3.80 litres methanol GBP 40.00 Total fuel cost GBP 44.50 In the present disclosure, there is proposed an alternative additive as a substitute for PEG-based and/or Avocet additives that allows alcohols to be used in existing compression ignition engines.

The use of PEG dinitrate in combination with methanol and other additives as an alternative to diesel fuel was well-established by AEGI in the early 1980's. Such an approach was tested in practical situations, wherein the introduction of a fuel additive branded as an ignition impro vef. The additive was called "Avocet", as aforementioned.

However, this additive has since not been able to capture main stream markets, in part due to a lack of perceived commercial benefits from contemporary the fuel producers and, especially, from vehicle manufacturers who need to impart changes in the existing engines.

In recent years, current environmental laws and society pressure have placed less emphasis on economics of fuels, and more on environmental gains. Nevertheless, an additive that costs less, and makes an overall combustion process in internal combustion engines more efficient will increase economic benefits, which associated to intrinsic environmental gains, makes alcohol once more an attractive alternative to diesel fuel from a commercial perspective.

Embodiments of the present disclosure are concerned with an introduction of a new additive which increases the efficiency of a given fuel, for example methanol-based fuel, by acting as a cetane enhancer. The new additive provides at least one of following benefits: (a) the new additive allows methanol to act a direct replacement to diesel fuel; (b) the new additive is more efficient than aforementioned Avocet in lowering the compression rate of an alcohol-based fuel, for example methanol or ethanol; (c) the new additive potentially increases the lifetime of engines by providing better lubricity to lubrication systems of the engines; (d) the new additive Is non-explosive, and this less hazardous in use; and (e) the new additive has a potential for application in petrol engines.

The new additive is of the family of PEG (poly-ethylene glycol) Trinitrate derivatives having a chemical formula as graphically depicted as: CI-(2-(O-CH2-GH2)n -ONO2 CH-(O-CH2-CH2)ni -0N02

I

CH2(0CH2CH2)p 0N02 Eq. 5 wherein n, m, p are integers which represent the number of units in an ethoxylate chain (namely, the number of basic monomers) in the new additive.

A representation of the new additive is also provided in FIG. 1, and indicated generally by 10. The new additive 10 includes a first chemical group 20A, a second chemical group 20B and a third chemical group 20C, wherein the groups 20A, 20B, 20C are mutually joined in sequence via their CH2-molecular groups.

Optionally, the new additive is chosen from compounds with n, m and p varying in a range of 1 to 5.

Optionally, the new additive is chemically stable, for example in ambient conditions and storage conditions in which fuels are used. Optionally, the new additive is non-explosive, namely is resistant to shock and resistant to impact. Thus, unlike most organic nitrates which have hitherto been used as fuel additive, this new additive pursuant to the present disclosure is not detonable, and hence can be treated as a simple fuel, particularly when blended with methanol and/or ethanol.

"Cetane" is a measure of an ignition quality of a diesel fuel. The higher the cetane measure of a given diesel fuel, the easier it is to start a standard (direct injection) diesel engine using the given diesel fuel. The cetane measure is defined by a percentage, by volume, of cetane, with a chemical name hexadecanc" in a combustion mixture, containing cetane and 1 -methylnapthalene, whose ignition characteristics match those of a given diesel fuel being tested. Comparisons with other additives and fuels can be made by way of equivalent cetane measure", for example as employed when

describing embodiments of the present disclosure.

Modifications to embodiments of the invention described in the foregoing are possible without departing from the scope of the invention as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", consisting of", "have", "is" used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.

Reference literature [1] Gaouyer, J. P.: " What has happened in Europe in the Biofuels Domain over the last two years?" Proceedings 2nd European Motor Biofuels Forum, Graz, p.37-41,1996. -12-

Claims (12)

1. CLAIMSWe claim: 1. An additive (10) for fuels, characterized in that the additive is a PEG (poly-ethylene glycol) trinitrate derivative.
2. 2. An additive (10) as claimed in claim 1, characterized in that the additive is operable to function as a cetane enhancer when mixed with a fuel and cam busted within a combustion engine.
3. 3. An additive (10) as claimed in claim 1, characterized in that the additive has a chemical formula: CI-(2-(O-CH2-CH2)n -0N02 CH-(O-CH2-CH2)ni -0N02 CH2-(O-CH2-CH2)p -0N02 wherein n, m, p are integers which represent the number of basic monomers in an ethoxylate chain in the additive.
4. 4. An additive (10) as claimed in claim 3, characterized in that the additive is chosen from compounds with n, m and p varying in a range of 1 to 5.
5. 5. An additive (10) as claimed in claim 1, characterized in that the additive is blendable with an alcohol-based fuel.
6. 6. An additive (10) as claimed in claim 5, characterized in that the additive is blendable with an alcohol-based fuel including methanol and/or ethanol.
7. 7. A method of producing a cetane-enhanced fuel, characterized in that the method includes blending an additive as claimed in claim 1 with a fuel.
8. 8. A method as claimed in claim 7, characterized in that the additive is blended with the fuel in a volumetric concentration in a range of 0.5% to 10%, more optionally in a range of 1%to 7%.
9. 9. A method as claimed in claim 7, characterized in that the additive is blended with the fuel in a ratio which enhances a cetane characteristic of the fuel.
10. 10. A cetane-enhanced fuel as produced by a method as claimed in claim 7.
11. 11. A cetane-enhanced fuel as claimed in claim 10, characterized in that the cetane-enhanced fuel includes ethanol and/or methanol.
12. 12. A cetane-enhanced fuel as claimed in claim 10, characterized in that the cetane-enhanced fuel is useable as a diesel fuel substitute.