JP2011511870A - Use of alcohol in fuels for spark ignition engines. - Google Patents

Abstract

The use of at least one C ₄ alcohol to increase the vapor pressure of the fuel for spark ignition engines comprising base fuel and ethanol, at least one C ₄ alcohol, is added to the fuel comprising base fuel and ethanol , 15-50% by volume base fuel, used to produce the synthetic fuel mixture containing 15 to 65% by volume of ethanol and 15 to 50 volume% _{C 4} alcohol. This synthetic fuel mixture exhibits, for example, a sufficiently high vapor pressure that meets the specifications, and also exhibits good start-up behavior even at winter temperatures.

Description

The present invention relates to the use of alcohol in fuels for spark ignition engines and the production of fuels for spark ignition engines. These fuels, in addition to ethanol, also containing C ₄ alcohol.

The fuel for the spark ignition engine is a suitable engine fuel for an engine with spark ignition. They usually comprise a mixture of different hydrocarbons with different boiling points, typically in the range of 26 ° C. to 210 ° C. at atmospheric pressure. However, this range is not specifically defined and may depend on the actual composition of hydrocarbons, additives and other components, and environmental conditions. Typically, the hydrocarbon component of the fuel comprises C ₄ to C ₁₀ hydrocarbons.

  The requirements for spark ignition fuel that must be met in their manufacture are multifaceted. Requirements are the result of their use in laws and regulations, distribution chains and institutions. These add to the drive-specific conditions and various drive concepts that require the spark ignition fuel to be separated into different types. In Germany, minimum requirements are imposed by instructions in the form of DIN Standards. They must be identifiable at the gas station with appropriate identification information. The Fuel Quality Decree, introduced in 1993 and updated in 2004 and 2006, now only approves fuels that meet all the requirements of DIN Standard EN228. In the United States, the corresponding standard is imposed by ASTM 4814.

  In order to achieve optimal drive conditions, the fuel must meet a variety of different requirements of the vehicle. Specifically, this is: “After a long cold night, the engine is just as easy as in summer, ie a fully heated engine restarts after a short break. Means "must start up". The engine must not stall when idling and must not operate irregularly under high loads. Even under unfavorable conditions, there must be no interfering residues in the intake system, combustion chamber or sump.

  The fuel must be adapted to these different and partially conflicting requirements so that it is trouble-free, reliable, and capable of interactive interaction. Therefore, the German manufacturer in Germany mixes so-called “mineral oil substitutes” such as alcohols and ethers in a limited proportion with the base fuel together with up to 0.5 weight percent of chemically active substances.

  Specific requirements are specified for fuels having an alcohol content of 0 to 85% by volume of ethanol for use in what are called flex fuel vehicles. For what is referred to as E85 fuel containing 70 to 85 vol% ethanol, the vapor pressure for the cold start behavior is particularly important. Fuels with high alcohol content such as ethanol or a mixture of different alcohols are known. Examples include Patent Documents 1, 2, 3, and 4.

  It is also known to mix a standard refinery “Super Benzine” or gasoline with a summer or winter quality research octane number of 95 (also called RON) and 70-85 vol% bioethanol. In May 2005, draft standards CWA 15293 and Draft Standard E DIN 51625 (October 2007, Beth Verlag) by CEN Worksshop Agrément recommend a minimum vapor pressure of 35 kPa for summer months (Class A). A minimum vapor pressure of 50 kPa is recommended for the month (Class B). Depending on the vapor pressure of the basic superbenzine or gasoline fuel, the vapor pressure of the gasoline / ethanol mixture cannot meet the draft standard. In such cases, the ethanol concentration in the mixture must be adjusted downward. This is undesirable.

Application HK 106,428 Specification US Patent Application Publication No. 2006/0137243 US Patent Application Publication No. 2004/0107634 US Patent Application Publication No. 2004/123518

  Accordingly, it is an object of the present invention to provide a fuel with a high alcohol concentration that exhibits a sufficiently high vapor pressure, for example, a pressure that meets specifications. This aims to improve the cold start behavior, for example to ensure that the fuel exhibits good cold start behavior even under winter temperatures.

This object is solved by the use of at least one C ₄ alcohol according to claim 1.

  The base fuel is conventional gasoline, for example unleaded gasoline, for example unleaded gasoline supplied by 95 RON elsewhere in Germany and Europe.

  The minimum standard for unleaded gasoline that has been offered at gas stations as Normal since 1984, as Euro-Super since 1985, and as SuperPlus since 1989 was specified in 1993 in the European Standard DIN EN 228. The composition of spark-ignition fuel from German refineries of normal, super and super-plus quality is, for example, German Scientific Association for Mineral Oil, Natural Gas, and Coals, also called DGMK Research Report 502-1 (DG) To be found. In this analysis, the main components of the fuel were specifically identified as average values and ranges. The basis for this analysis was the winter product of the winter of 2001/2002. This report is explicitly referred to herein. Specifically, the contents for 50 hydrocarbons having 3 to 6 carbon atoms, 51 aromatic compounds and 3 oxygen-containing compounds were confirmed. In addition, all typical total contents of the same carbon content in each case were measured for paraffins, naphthenes, cyclic and acyclic olefins and aromatics. The contents of 10 diolefins and 15 polycyclic aromatics were tested individually. The spark ignition fuels listed are obtained from 14 different refineries.

  The synthetic fuel according to the present invention comprises 15-50% by volume of the basic fuel.

  The tendency of gasoline to evaporate, ie its volatility, is a central prerequisite for use as a spark ignition fuel as well as an essential quality feature. Because gasoline is a mixture of many hydrocarbons, it does not have a clear boiling point and usually has a boiling range between 30 ° C and 200 ° C.

Fuel according to the invention comprises 15 to 65 volume% of ethanol and 15 to 50 volume% _{C 4} alcohol. Inevitably, overall, the total is always 100% by volume, including any other components present.

  Basically, due to the high alcohol content, the characteristics of the fuel are modified compared to normal fuel. The characteristic is, for example, volatile.

  Volatility is characterized by a boiling curve and vapor pressure in the temperature range of 30 to 200 ° C in most cases and up to 26 to 210 ° C. The boiling curve shows the ratio of evaporated fluid at different temperatures. Vapor pressure is the result of the fuel component changing from a liquid phase to a vapor phase at different temperatures in a closed vessel.

  The “evaporated gasoline fraction / temperature” function gives what is called a boiling curve, and its location and characteristics allow one skilled in the art to draw conclusions about the behavior of the fuel in the engine. Basically, the volatility of the spark ignition fuel must be set so that the ignitable fuel-air mixture is available in the combustion chamber under all conditions. For example, under certain operating conditions, such as using a particularly cold engine or a particularly hot engine, it becomes difficult to satisfy this precondition so that quality differences in the fuel can be identified to this criterion.

  The ignitability of the mixture is influenced not only by the fuel but also by the engine concept. That is, it depends on whether the engine is driven with a “rich” or a “lean” mixture.

  For winter operation, the volatility of the spark ignition fuel is generally adapted to lower ambient temperatures. For reliable cold start, the fuel should be as volatile as possible. If the volatility is too low, insufficient evaporation will dilute the mixture and excess fuel will condense on the intake manifold walls, so lower boiling curves and higher vapor pressures in the lower range will cause engine startup and warming. Promote machine operation.

  The requirements for gasoline used in high temperature engines are exactly the opposite. Under unfavorable conditions, too much of the fuel evaporate (“vapor phase formation” in the fuel pump) evaporates from the float chamber of the vaporizer, or the components of the fuel system become so hot that they form a vapor cushion in the injection system. Can be. As a result, fuel delivery is interrupted and the mixture is over-rich, resulting in a negative impact on drive behavior. These obstacles occur more frequently as the fuel system (pump, carburetor and fuel injection system) gets hotter and as the fuel delivery volume and system pressure decreases. On the fuel side, it is obvious that excessively high volatility leads to adverse effects. High atmospheric temperatures in summer increase the probability of failure. For this reason, fuel manufacturers blend their summer quality fuels with higher boiling curves and lower vapor pressures in the lower range compared to winter quality fuels. However, this adjustment should not be done so as to cause problems with cold start.

  In particular, base fuels containing a mixture of fuels with a high ethanol content cannot maintain the minimum vapor pressure that should be maintained according to draft standards, especially for winter products. As a result, the ethanol content must be reduced to achieve the lowest vapor pressure.

Surprisingly, by mixing basic gasoline and ethanol (eg, E85) with at least one C ₄ alcohol, such as may be present in other fuels having high concentrations of C ₄ alcohol, for example, It has been found that an increase in the mixed vapor pressure higher than that of the fuel can be achieved. In the laboratory, the vapor pressure (according to EN 13016-1) of various different ethanol and butanol mixtures in super gasoline was tested.

  The results are shown in Tables 1 and 2. The number after the letter characterizing the individual combination in each case indicates the content of this combination in volume% units.

  The requirements presented so far are met by the fuel according to the invention, in particular the cold start-up characteristics are improved.

Basically, when using a mixture of base fuel and a relatively high proportion of ethanol, at least one C ₄ alcohol is added to this mixture so that its content in the synthetic fuel mixture is at least 15% by volume. It can be confirmed that an unusual increase in vapor pressure occurs. This increase in vapor pressure is unpredictable by those skilled in the art. The effect after mixing, 15 to 50 volume% of the base fuel are prominent among the fuel containing 15 to 65% by volume of ethanol and 15 to 50 volume% _{C 4} alcohol. The effect after mixing, while the fuel containing 20 to 46% by volume of base fuel, 20-60% by volume of ethanol and 20 to 50 volume% _{C 4} alcohol, in particular, after mixing from 19.5 to 44 volume% basic fuel, which is particularly pronounced among the fuel containing 21 to 59.5% by volume of ethanol and 21 to 49 volume% _{C 4} alcohol. This effect, C ₄ alcohol (also called 1-butanol) n- butanol, secondary butanol (2-butanol also called) or isobutanol (also called 2-methyl-1-propanol), or at least of those butanol This is especially true when it is a mixture of two butanols.

  From the analysis of boiling behavior (distillation according to EN ISO 3405), a positive effect was confirmed when a fuel containing ethanol and a fuel containing butanol were mixed. The distillation curve leveling in the range of about 20 to 90% evaporation capacity shows a trajectory similar to that of the spark-ignited fuel because it shows a constant rise in the mixture according to the invention.

Mentioned are that effect, the vapor pressure, and optionally C ₄ alcohol is isobutanol are particularly preferred for the boiling behavior.

When ethanol is included in the fuel according to the invention, basically the source from which it comes is not important for the fuel properties. Preferably, however, ethanol of natural origin, such as biomass, should be used, at least in large part because it generates carbon dioxide that is environmentally neutral upon combustion. For the same reason, it is preferred most similar C ₄ alcohol used also has a natural origin.

  The total alcohol content of the fuel according to the invention is at least 50% by volume, but preferably at least 70% by volume.

  As already mentioned, the basic fuel is, for example, a fuel such as unleaded gasoline that is commercially available at the present time. This is a mixture of hydrocarbons having mainly 4 to 12 carbon atoms. Its main components are mainly paraffins, naphthenes, olefins and aromatic compounds. In addition, the base fuel can include components that include oxygen. In this situation, ether is preferred. The ether content is preferably up to 15% by volume relative to the base fuel. As ethers, tertiary butyl methyl ether (also called MTBE) as well as tertiary butyl ethyl ether (also called ETBE) or mixtures thereof are very suitable.

  The invention further relates to a process for the production of a synthetic fuel according to the invention, as well as its use as a fuel for a spark ignition engine, in particular in a motor vehicle.

Preferably, the synthetic fuel according to the invention is produced from an existing fuel mixture. One of these mixtures is the previously described E85 fuel (mixture (I)) with ethanol in a proportion of 70-85% by volume and base fuel in a ratio of 15-30% by volume. Other mixture comprises 30 to 50 volume% of the base fuel and 50 to 70 volume% _{C 4} alcohol (mixture (II)). A suitable mixing ratio of mixture I: II is 1: 1. Mixture I may be E70 or E85 gasoline and Mixture II may be B50 or B70 gasoline. Mixture having a 70 volume% ethanol (I) and 50 volume% C ₄ alcohols, especially mixtures with isobutanol mixture of (II) are preferred. Preferably, the ratio of mixture (I) to mixture (II) ranges from 40:60 to 60:40, in particular 50:50 or 1: 1 respectively. However, mixture (I) comprises ethanol up to 85% by volume, mixture (II) may comprise a _{C 4} alcohol of up to 70 volume%.

Basically, however, as noted, the C ₄ alcohol is not only added to the base fuel mixture with a high content of ethanol as a mixture with the base fuel, but also the C ₄ alcohol (100% It is also possible to add to the latter mixture at high concentrations (up to). In the final analysis, the concentration ratio in the synthesis mixture is decisive. Accordingly, the present invention further provides a use of at least one C ₄ alcohol to increase the vapor pressure of the fuel for spark ignition engines comprising base fuel and ethanol, at least one C ₄ alcohol, and a basic fuel It was added to the fuel comprising ethanol, 15 to 50% by volume of base fuel, to the use of producing synthetic fuel mixture containing 15 to 65% by volume of ethanol and 15 to 50 volume% _{C 4} alcohol. The volume% data relates to the synthetic fuel mixture in each case.

  The synthetic fuel mixture preferably has a water concentration of less than 800 ppm by weight, for example in the range of 100 to 400 ppm by weight.

  The invention will now be described by way of example only with reference to the data in Tables 1 and 2. Vapor pressures measured in the laboratory according to EN 13016-1 for various different ethanol and butanol mixtures in super gasoline are measured and shown in Tables 1 and 2.

The difference between the estimated vapor pressure calculated according to the relative capacity of each component and the measured vapor pressure is also shown. Estimated vapor pressure was calculated according to the relative proportion of each component. For example, the estimated vapor pressure of a 70 vol% iB50 / 30 vol% E70 mixture was calculated as 70% iB50 vapor pressure + 30% E70 vapor pressure. The data in the table, the use of at least one C ₄ alcohol, the vapor pressure of the fuel containing the basic fuel and ethanol, to a total of various gasoline / ethanol and gasoline / butanol mixture ratio corresponding to their amounts It shows that the vapor pressure estimated by is exceeded. Thus, for example, 1B50 has a vapor pressure of 56.1 kPa, 2B50 has a vapor pressure of 55.7 kPa, iB50 has a vapor pressure of 55.6 kPa, and iB70 has a vapor pressure of 40.7 kPa. E70 has a vapor pressure of 56.1 kPa and E85 has a vapor pressure of 40.0 kPa. The vapor pressures of various 50:50 (volume / volume) mixtures of these butanol and ethanol mixtures were measured and found to be greater than the average of the vapor pressures of the component mixtures. Thus, the C ₄ alcohol, the vapor pressure of the fuel mixture rose.

  Tables 1 and 2 also show the difference between the estimated and measured vapor pressures for various ratios of E70 / iB50 and E85 / iB70 mixtures, and the estimated values are the relative volume ratios of the two mixtures. Is calculated according to

Shown in Table elevated brought vapor pressure by C ₄ alcohol.

Claims (19)

The use of at least one C ₄ alcohol to increase the vapor pressure of the fuel for spark ignition engines comprising base fuel and ethanol, at least one C ₄ alcohol, is added to the fuel comprising base fuel and ethanol , 15-50% by volume base fuel, used to produce the synthetic fuel mixture containing 15 to 65% by volume of ethanol and 15 to 50 volume% _{C 4} alcohol. Synthetic fuel mixture
20-46% by volume basic fuel,
20-60 volume% of ethanol, and the use of claim 1 containing 20 to 50 volume% _{C 4} alcohol. Synthetic fuel mixture
19.5 to 44% by volume basic fuel,
21 to 59.5% by volume of ethanol, and the use according to claim 1 or 2 containing 21 to 49 volume% _{C 4} alcohol. C ₄ alcohol, n- butanol, Use according to one or claim 1 further in which the secondary butanol and isobutanol. C ₄ alcohols are used according to any one of claims 1 to 3 is isobutanol.   Use according to any one of claims 1 to 5, wherein ethanol is predominantly of natural origin. C ₄ alcohols are used according to any one of claims 1 to 5 mostly of natural origin.   8. Use according to any one of the preceding claims, wherein the basic fuel mainly comprises a mixture of hydrocarbons having mainly 4 to 12 carbon atoms.   Use according to claim 8, wherein the mixture of hydrocarbons mainly comprises paraffins, naphthenes and aromatics.   Use according to claim 8 or claim 9, wherein the base fuel comprises 0 to 15% by volume of ether.   Use according to claim 10, wherein the ether is tertiary butyl methyl ether and / or tertiary butyl ethyl ether.   12. Use according to any one of the preceding claims, wherein the alcohol content of the synthetic fuel mixture is at least 50% by volume.   Use according to claim 12, wherein the alcohol content of the synthetic fuel mixture is at least 70% by volume. A mixture I containing 15-30% by volume base fuel and 70 to 85 volume% of ethanol, by mixing a mixture II containing 30 to 50% by volume of base fuel and 50 to 70 volume% _{C 4} alcohol 14. Use according to any one of the preceding claims comprising producing a fuel.   15. Use according to claim 14, wherein the mixture I and the mixture II are mixed in a volume ratio of 1: 1.   16. Use according to claim 14 or claim 15, wherein mixture I is E70 or E80 gasoline and mixture II is B50 or B70 gasoline. A method for producing a fuel that is a synthetic fuel mixture according to any one of claims 1 to 13, comprising a mixture I comprising 15 to 30% by volume of basic fuel and 70 to 85% by volume of ethanol, 30 which comprises mixing a mixture II comprising 50% by volume of base fuel and 50 to 70 volume% _{C 4} alcohol.   The process according to claim 17, wherein the mixture I and the mixture II are mixed in a volume ratio of 1: 1.   19. A process according to claim 17 or claim 18, wherein mixture I is E70 or E80 gasoline and mixture II is B50 or B70 gasoline.