GASOLINE COMPOSITION ENABLING REDUCED PARTICULATE EMISSIONS

Abstract

 The present invention relates to the use of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms in a gasoline composition to reduce the particulate emissions. The present invention also relates to the gasoline composition comprising at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms.

Description

[0001] The present invention relates to gasoline compositions especially to gasoline compositions suitable as automobile fuels and associated with low particulate emissions, the present invention also relates to the use of alcohols chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms, for example isopropanol, in gasoline compositions to reduce particulate emissions.

[0002] On-road vehicles are an important source of particulate matter emissions. Especially, particulate matter emissions from motor vehicles are of particular importance in urban areas where emissions occur in close proximity to populations. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.

[0003] Particulates are generated in the combustion chamber and then emitted through the exhaust system. Norm Euro6C of the European Union requires that gasoline engines emit less than 4.5 mg/km of particulate matter in mass and less than 6.10¹¹ per km in number. Reducing particulate emissions is thus of great interest.

[0004] The reduction of the particulate emission can be addressed by the engine-fuel system or through the exhaust system. Three ways of reducing particulate matter emissions are available:

(i) Engine design;

(ii) Fuel composition;

(iii) Exhaust system (depollution).

[0005] Up to now, developments have been mainly concentrated on engine design and depollution at the exhaust system (catalytic conversion, particulate filters, etc).

[0006] There is thus a need to develop new fuel composition enabling to reduce particulate emissions.

[0007] It is known, especially from EP2568033 and Westphal et al, Toxicology, 2010, 268, 198-203, that oxygenate compounds (for example ethanol and ethyl tertiary butyl ether (ETBE)) can be used in gasoline compositions to reduce particulate emissions. However, the addition of oxygenates in gasoline is limited due to the oxygen limit of 3.7% in mass fixed by EN228 norm. Therefore, the maximum reduction in particulate matter emissions in mass and in number can only be achieved by identifying the oxygenate compounds which have the highest effect on particulate emissions.

[0008] There is thus a need to find alternative solutions to the use of ethanol and ETBE as oxygenates for gasoline and to identify new oxygenate compounds enabling to reach a higher particulate emissions reduction when added in gasoline composition.

[0009] A second challenge is also to obtain the maximum reduction of particulate emissions while achieving the highest greenhouse gases emissions reduction in terms of CO₂ equivalents through the incorporation of a maximum amount of biobased gasoline components.

[0010] An object of the invention is thus to provide a gasoline composition enabling to reduce particulate emissions.

[0011] Another objective of the invention is to provide such gasoline composition comprising a maximum amount of biobased components.

[0012] Another objective of the invention is also to provide a gasoline composition in conformation with norm Euro6C (2009) and EN228 (2008).

[0013] Other objectives will be disclosed in the description of the invention which follows.

[0014] These objectives are obtained by the present invention which relates to a gasoline composition comprising hydrocarbons mixture with 13% to 99.5%, preferably from 13% to 95%, more preferably 30% to 95%, preferably 30 to 90%, by volume of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms, for example isopropanol, and preferably from 0.5 to 87%, preferably 5 to 70%, preferably 10 to 70%, by volume of hydrocarbon and oxygenated compounds.

[0015] Preferably, the gasoline composition of the invention comprises from 13% to 99.5%, preferably 30% to 95%, preferably 30 to 90%, by volume of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms, for example isopropanol.

[0016] Preferably, the secondary alcohol is biobased. A biobased secondary alcohol, such as isopropanol, can be obtained by fermentation of renewable resources. The biobased isopropanol can be produced by fermentation for example according to the process disclosed in WO2013007786, WO201514447 or PCT/EP2015/061391.

[0017] According to the present invention, "biobased compounds" refers to compounds obtained from bioresources for example by use of renewable resources (such as agricultural resources). A compound is considered fully biobased when it is produced using only renewable resources. A compound is considered partially biobased when it is produced from compounds issued from renewables resources and compounds which are not issued from renewable resources. The biobased content can be tested using ASTM D6866 - 16 (Standard test methods for determining the biobased content of solid, liquid, and gaseous samples using radiocarbon analysis).

[0018] The compounds comprising oxygen can also be named oxygenates, there are organic compounds (i.e. compounds comprising carbon and hydrogen) comprising at least one oxygen atom. In the present invention, any oxygenate that increases the weight percentage of oxygen in the gasoline composition can be used. Oxygenates are generally combustible liquids comprising carbon, hydrogen and oxygen. Preferably, oxygenates are chosen among alcohols other than the secondary alcohols as mentioned above or ether compounds. Preferably, oxygenates are chosen among tertiary alkyl ether such as ethyl tertiary butyl ether (ETBE), methyl tertiary butyl ether (MTBE), ethanol, tertiary-amyl methyl ether (TAME) or mixtures thereof. Preferably, the oxygenate is ETBE.

[0019] The composition of the invention can comprise combination of different oxygenates.

[0020] Preferably, in the composition according to the invention, the oxygenate, or the combination of oxygenates, is present in an amount comprised between 0.5 and 87% by volume, preferably between 5 and 30% by volume, more preferably between 10 and 30% by volume.

[0021] Preferably, oxygenates used in the compound according to the invention are totally or partially biobased oxygenates, for example ethanol from bioresources (also called bioethanol), ether obtained by etherification between an alcohol from bioresources and alkanes from bioressources. For example, ETBE can be obtained by etherification of ethanol obtained from bioressources and isobutene obtained from bioresources for example according to the process disclosed above.

[0022] Secondary alcohols are defined as organic chemical compounds with a hydroxy group bound to a secondary carbon atom. A secondary carbon is defined as a carbon atom bound to two other carbon atoms. According to the invention, the secondary alcohols are linear or branched. They may be represented by the formula (R)(R')CH-OH, R and R', identical or different, being linear or branched (C₂-C₆)alkyl groups, and wherein the total of carbon atoms of the R and R' groups being comprised between 2 and 6. Preferably, the secondary alcohols according to the invention are branched secondary alcohols. Isopropanol (propan-2-ol), butan-2-ol, pentan-2-ol, pentan-3-ol, 3-methylbutan-2-ol, hexan-2-ol, hexan-3-ol, 3-methylpentan-2-ol, 4-methylpentan-2-ol, 2-methylpentan-3-ol, 3,3-dimethylbutan-2-ol, heptan-2-ol, heptan-3-ol, heptan-4-ol, 3-methylhexan-2-ol, 4-methylhexan-2-ol, 5-methylhexan-2-ol, 4-methylhexan-3-ol, 5-methylhexan-3-ol, 2-methylhexan-3-ol, 2,4-dimethylpentan-3-ol, 3,3-dimethylpentan-2-ol, 4,4-dimethylpentan-2-ol, 2,2-dimethylpentan-3-ol and 3-ethylpentan-2-ol, are examples of secondary alcohols according to the invention.

[0023] Mixtures of secondary alcohols according to the invention could be for example a mixture of isopropanol and butan-2-ol, or a mixture of 3-methylbutan-2-ol and pentan-3-ol.

[0024] In the present invention, the following expressions have the following definitions:

"Particulate matter", or "particulate" or "particle": a complex mixture of extremely small particles and liquid droplets that get into the air. These particles are composed of a carbon core upon which high-molecular weight organic chemical components and heavy metals deposit.

"Research Octane Number" (RON) : the octane number of a fuel determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane. RON can be measured according to ASTM D 2699.

"Motor Octane Number" (MON) : the octane number of a fuel determined by running the fuel through a similar test engine to the one used in RON but with a preheated fuel mixture, a higher engine speed and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline is generally about 8 to 10 points lower than the RON. MON can be measured according to ASTM D 2700.

"Vapor pressure" or "Reid vapor pressure" of a gasoline is a measure of the vapor pressure of the gasoline in pounds per square inch at 1000 °F (537,8°C). It is an indication of the volatility of the gasoline. Reid vapor pressure of a gasoline can be measured according to ASTM D5191.

"Petroleum based fuel" means a fuel that includes a fractional distillate of petroleum.

"Fuel additive" refers to chemical components added to fuels to alter the properties of the fuel, e.g. to improve engine performance, fuel handling, fuel stability or for contaminant control. Types of additives include, but are not limited to, antioxidants, thermal stability improvers, cetane improvers, stabilizers, cold flow improvers, combustion improvers, antifoams, anti-haze additives, corrosion inhibitors, lubricity improvers, icing inhibitors, injector cleanliness additives, smoke suppressants, drag reducing additives, metal deactivators, dispersants, detergents, demulsifiers, dyes, markers, static dissipaters, biocides and combinations thereof.

[0025] In the description, all numbers disclosed herein are approximate values, regardless whether the word "about" or "approximate" is used in connection therewith.
In the description, the range from xxx to yyy, without any other information, includes the values xxx and xxx.

[0026] The gasoline composition according to the invention is any petroleum-derived composition comprising organic compounds generally obtained by the fractional distillation of petroleum. The gasoline composition of the invention can be a conventional mix of straight chain alkanes, branched and cyclic, comprising from 5 to 12 carbon atoms, with 13% to 99.5%, preferably 30% to 95%, preferably 30 to 90% by volume of at least one alcohol chosen among linear or branched secondary alcohols according to the invention, along with some aromatic compounds. Preferably, the maximum concentration of aromatics in the gasoline composition is 35% by volume. Preferably, the gasoline composition has properties complying to EN228 norm or can be blended with an additional component, such as an oxygenate, and the resulting blend is compliant to the EN228 norm.

[0027] The present invention also relates to the use of at least one secondary alcohol as defined in the invention as a gasoline composition or in a gasoline composition to reduce particulate emissions.

[0028] The present invention also relates to the use of 4% to 100 vol%, preferably 10% to 99.5% vol%, preferably 30 to 95 vol%, more preferably 30 to 90 vol%, of at least one secondary alcohol according to the invention, in a gasoline composition to reduce the particulate emissions.

[0029] The gasoline composition, the alcohol and the oxygenates are as disclosed above.

[0030] The present invention also relates to a method for reducing the particulate emissions of an engine car comprising the use of at least one secondary alcohol as defined in the invention as gasoline composition or in a gasoline composition. Preferably, the secondary alcohol is used in a proportion from 4% to 100 vol%, preferably 10% to 99.5% vol%, preferably 30 to 95 vol%, more preferably 30 to 90 vol%The present invention also relates to a method for reducing the particulate emissions of an engine car comprising the use of a gasoline composition comprising from 4% to 100 vol%, preferably 10% to 99.5% vol%, preferably 30 to 95 vol%, more preferably 30 to 90 vol%, at least one alcohol according to the invention.

[0031] The present invention also relates to a method for reducing the particulate emissions of an engine car comprising the use of a gasoline composition according to the invention and as disclosed above.

[0032] The use of at least one secondary alcohol according to the invention enables a huge reduction of the particulate emissions, especially a reduction up to 99% in particle number, preferably up to 77% in particle number, compared with a gasoline composition without such additives, of the particulate emissions.

[0033] The use of a secondary alcohol according to the invention is compliant with EN228 up to 12% in volume. It

Figure 1 represents the particle number in function to the particle size emitted by the use of different gasoline compositions. A higher incorporation of isopropanol than 12% by volume in gasoline has not been tested due to the price of the component compared to gasoline.

Figure 2 represents the total number of particles emitted by the use of different gasoline compositions.

[0034] The present invention will now be described thanks to the following non-limiting examples.

[0035] Tests were carried out in a one-cylinder engine such as descried above. All equipment used for the measures meets the specification of the DIN EN 228 norm.

1. Description of the gasoline composition used in the tests

[0036] The tests have been carried out on:

• a base fuel composition from a refinery having a RON of 91 and no ethanol (named "Base fuel RON91E0");
• a blend A comprising RON91E0 and 10,0 vol% of Ethanol;
• a blend B comprising RON91E0 and 20.0 vol% of ETBE; and
• a blend C comprising RON91E0 and 12.0 vol% isopropanol;

[0037] The compositions of the different fuel compositions are given in table 1 below.

Table 1

	Composition in vol%
Blend	Isopropanol	Ethanol	ETBE	RON91E0
Blend A	0	10	0	90
Blend B	0	0	20	80
Blend C	12	0	0	88

[0038] The different compositions were analyzed with respect to DIN EN 228, the results are given in table 2 below.

Table 2

Fuel properties (unit)	Base fuel RON91E0	Blend A	Blend B	Blend C
Density at 15°c (kg/m3)	730.2	735.4	733.8	735.8
% vaporized at 70°C (vol%)	34.1	55.1	34.3	52.4
% vaporized at 100°C (vol%)	62.2	66.7	70.8	68.4
Final boiling point (°C)	189	185.3	185.0	187.4
Vapor pressure DVPE, 37.8°C (KPa)	47.4	55.8	48.0	51.1
Oxygen content (% m/m)	0.0	3.61	3.06	3.41
Ethanol (about 1.6% in ETBE) (% vol/vol)	0.0	10	0	0
ETBE (% vol/vol)	0.0	0	20	0
Isopropanol (% vol/vol)	0	0	0	12
RON/MON	91/84	95.9/85.9	97.8/87.2	95.2/86.4

Engine tests

[0039] The tests were carried out on a single cylinder engine. The configuration parameters are given in table 3 below. A pre-optimization of engine parameters in proposed engine load points was performed with the RON95E10composition. The composition ratio was chosen to be 10.8, at upper level of series production engines, which enables a good evaluation of knock tendency.

Table 3 - engine configuration

	Unit	Value
Bore	mm	75
Stroke	mm	90.5
Displacement	cm3	400
Max. cylinder peak pressure	bar	170
Compression ratio	1	10.8
Inlet and exhaust CVVT	°CA	55
Intake/exhaust event length (1 mm)	°CA	186
Direct injection (central, solenoid)		6-hole
	bar	200
	cm3/s	13.5

[0040] The engine tests performed were catalyst heating. Intention of catalyst heating load point is to increase exhaust temperature/heat flow at cold engine operation: fast light-off of three-way-catalyst (TWC). Catalyst heating load point was selected for fuel comparison due to its challenging boundary conditions for mixture formation, combustion and particulate emissions. Double injection (2^nd ignition coupled injection) was investigated. For ignition coupled injection (5°CA after spark timing) is initiated. 2^nd injection results in a stabilizing diffusive combustion allowing for later combustion at same combustion facility.

[0041] Table 4 below gives the parameters for catalyst heating tests.

Table 4

	Unit	Value
nENG	min-1	1200
IMEP	bar	3
Compression ratio		10.76
EVC	° CA BTDC	10
IVO	° CA ATDC	10
PFuel	bar	200
SOI Main	° CA BTDC	250
SOI Ignition	° CA	ST+5
Air compression ratio		1.05
TOil	°C	30
Tcoolant	°C	30
Tintake	°C	25
Spark Timing (ST)	° CA BTDC	-15

nENG refers to the engine speed expressed in rotations per minute. IMEP, indicated mean effective pressure, is the mean effective pressure calculated with indicated power. The mean effective pressure can be regarded as an average pressure in the cylinder for a complete engine cycle. EVC refers to exhaust valve closing. IVO refers to inlet valve opening. SOI refers to start of injection. °CA refers to the Crank angle. The top dead centre (TDC) is the position of a piston in which it is farthest from the crankshaft. °CA BTDC refers to Crank angle before top dead center. °CA ATDC refers to Crank angle after top dead center.

[0042] The results of these tests are presented in figures 1 and 2.

[0043] Figures 1 and 2 enable to show the particle emissions reduction in number depending on the oxygenate compound incorporated in gasoline. Compared to the base fuel RON91E0, blend A shows a reduction of particle emissions of 55% in number, blend B shows a reduction of particle emissions of 46% in number and Blend C shows a reduction of particle emissions of 77% in number.

[0044] The results thus show that secondary alcohols enable to reach a higher level of reduction of particulate emissions in number, compared to ethers or primary alcohols.

Claims

1. Gasoline composition comprising hydrocarbons mixture with from 13% to 99.5% by volume of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms.

2. Gasoline composition according to claim 1 comprising from 30% to 95% by volume of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms.

3. Gasoline composition according to claim 1 or 2, further comprising 0.5% to 87% by volume of isooctane and 0.5% to 87% by volume of oxygenated compounds different from the at least one secondary alcohol.

4. Gasoline composition according to any one of claims 1 to 3, wherein the alcohol is isopropanol.

5. Gasoline composition according to any one of claims 1 to 4, wherein the alcohol comes from renewable resources.

6. Use of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms, as a gasoline composition or in a gasoline composition to reduce particulate emission.

7. Use according to claim 6, wherein the amount of alcohol is from 4 to 100 vol%, preferably from 10 to 100 vol%.

8. A method for reducing the particulate emissions of an engine car comprising the use of at least one alcohol chosen among linear or branched secondary alcohols comprising 3 to 7 carbon atoms, as gasoline composition or in the gasoline composition used in the engine.

9. A method for reducing the particulate emissions of an engine car comprising the use of a gasoline composition according to anyone of claims 1 to 5.

Drawing