JPH04227990A - Fuel composition - Google Patents

Abstract

PURPOSE: To obtain a fuel compsn. which can reduce the amt. of pollutants emitted by a diesel engine by incorporating a small amt. of an org. nitrate combustion improver into a fuel mainly comprising a hydrocarbonaceous middle distillate fuel having a low sulfur content.

CONSTITUTION: This compsn. mainly comprises a hydrocarbonaceous middle distillate fuel having a low sulfur content and contains a minor combustion- improving amt. of at least one org. nitrate combustion improver dissolved therein. An esp. suitable example of this compsn. is a hydrocarbonaceous middle distillate fuel which has a sulfur content not higher than 500 ppm. esp. pref. up to 60 ppm, and a 10% b.p. (ASTM D-86) in a range of about 154-230°C and contains a minor combustion-improving amt. of at least one org. nitrate combustion improver soluble therein. The amts. of NO_x and CO emitted into the air during running an engine or other combustion apparatus operated with a middle distillate fuel can be decreased by using this fuel compsn.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

[0001] The present invention relates to environmental conservation. More particularly, the present invention relates to fuel compositions and methods for reducing air pollution normally caused by operating engines or combustion devices with mesophilate fuels.

The importance and desirability of reducing the release of pollutants into the atmosphere is well recognized. Among the pollutants that are desired to be reduced are nitrogen oxides ("NOx"), carbon monoxide, unburned hydrocarbons, and particulate matter.

The present invention provides, among other things, that the amount of NOx, CO, or unburned hydrocarbons emitted to the atmosphere during operation of an engine or other combustion device operated on medium-temperature distillate fuel is 500 p.p.
with a sulfur content of less than pm and a combustion improvement amount of at least 1
This includes the discovery that the reduction can be achieved by using as a fuel a mesophilate fuel having an organic nitrate combustion improver dissolved therein. In fact, by using such fuel compositions, it is possible to reduce the amount of two and in some cases all three such pollutants (NOx, CO and unburned hydrocarbons) emitted by diesel engines. It was discovered that it is possible. Moreover, this important and highly desirable objective is and can be achieved without incurring an undesirable increase in particulate emissions. This is because current experimental evidence and mechanistic theory of combustion
This is a unique discovery because it suggests that reducing x increases the amount of particulate matter, and vice versa.

[0004] Accordingly, the present invention in one embodiment comprises a hydrocarbonaceous medium-temperature distillate fuel having a sulfur content of less than 500 ppm (preferably 100 ppm or less, most preferably at most 60 ppm). The present invention also provides a fuel composition in which the fuel contains a small combustion improving amount of at least one organic nitrate ester combustion improver dissolved therein. "Hydrocarbonaceous" as used herein and in the claims consists of fuels whose mesophilic fraction fuels are derived either primarily or entirely from petroleum, either by conventional processing operations. The final fuel may also contain small amounts of non-hydrocarbon fuels or mixtures of substances such as alcohols, dialkyl ethers, and/or small amounts of tar sands, shale oil, etc.
Alternatively, it may contain a suitably desulfurized auxiliary liquid fuel of a suitable boiling range (i.e., from about 160 to about 370°C) derived from coal. When using such a mixture of desulfurized auxiliary liquid fuel and hydrocarbonaceous intermediate distillate fuel, the sulfur content of the total mixture must be maintained below 500 ppm.

In another embodiment, the present invention provides an improved combustion process in which hydrocarbonaceous intermediate distillate fuels are subjected to combustion in the presence of air. Such modifications include hydrocarbonaceous medium-temperature materials having a sulfur content of 500 ppm (preferably 100 ppm or less, most preferably at most 60 ppm) and having a small combustion improving amount of at least one organic nitrate combustion modifier. providing a distillate fuel as a fuel for use in such combustion methods.

Still other embodiments of the present invention provide improvements in the production of hydrocarbonaceous intermediate distillate fuels. Such modifications control or reduce the sulfur content of the fuel to 500 ppm or less (preferably 100 ppm or less, most preferably no more than 60 ppm), and the organic nitrate combustion improver is added to the resulting sulfur content. and mixing with reduced fuel.

Further embodiments of the invention include improvements in the operation of motor vehicles and aircraft operated on mesophilate fuels. These improvements are 500ppm (preferably 100ppm)
A hydrocarbonaceous medium-temperature distillate fuel having a sulfur content of 60 ppm or less, most preferably at most 60 ppm) and a small combustion improving amount of at least one organic nitrate combustion modifier is used to fuel a motor vehicle or aircraft. including driving.

According to a particularly preferred embodiment of the invention, 50
a 10% boiling point (A
A hydrocarbonaceous medium temperature distillate fuel having a combustion modifier of at least one fuel-soluble organic nitrate combustion improver is provided. Such fuel compositions tend to emit particularly low amounts of NOx upon combustion. While not wishing to be bound by theoretical considerations, the explanation for such highly desirable performance is that fuels with higher 10% boiling points have higher peak temperatures resulting in a lag in the progression of combustion, resulting in increased NOx production. It means inducing.

According to another particularly preferred embodiment of the invention:
having a sulfur content of no more than 500 ppm (preferably 100 ppm or less, most preferably no more than 60 ppm) and a 90% boiling point (ASTM D-86) in the range of about 260 to about 320°C; A hydrocarbonaceous intermediate temperature distillate fuel is provided that contains a combustion-improving amount of at least one fuel-soluble organic nitrate combustion improver. Such fuel compositions tend to emit particularly low amounts of particulates upon combustion.

These and other embodiments are set forth in the following description and claims.

In the accompanying drawings, FIG. 1 is a least squares plot of NOx emissions versus 10% boiling point for a fuel having a nominal cetane number of about 50; and FIG. 1 is a least squares plot of particulate emissions versus 90% boiling point for a fuel with a specific temperature.

The hydrocarbonaceous fuel utilized in the practice of this invention generally consists of a mixture of hydrocarbons falling within the distillation range of about 160°C to about 370°C. Such fuels are called ``mid-distillate fuels'' because they contain a fraction that distills out after gasoline.
dle-distillation-fuels). Such fuels include diesel fuel, burner fuel, kerosene, intermediate oil, jet fuel, and gas turbine engine fuel.

[0013] Suitable mesophilate fuels are those characterized by the following distillation tendency:
°F °C
IBP 250
-500 121-260
10% 310-500
154-288 50%
350-600 177-
316 90% 400-7
00 204-371 EP
450-750
Diesel oils having a 232-399 clear cetane number (ie, cetane number without cetane improvers such as organic nitrates) in the range of 30 to 60 are preferred. Those having an additive-free cetane number in the range of 40 to 50 are particularly suitable.

Organic nitrate combustion improvers (often known as ignition improvers) comprise nitrate esters of substituted or unsubstituted aliphatic or cycloaliphatic alcohols which may be monovalent or polyvalent. The preferred organic nitrate has about 10 carbon atoms.
and preferably substituted or unsubstituted alkyl or cycloalkyl nitrate having 2 to 10 carbon atoms. The alkyl group may be straight chain or branched (or a mixture of straight and branched alkyl groups). Specific examples of nitrate compounds suitable for use in the present invention include, but are not limited to:
but not limited to: methyl nitrate, ethyl nitrate, n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butyl nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, n-amyl nitrate, nitric acid isoamyl, 2-amyl nitrate, 3-amyl nitrate, ter nitrate
t-amyl, n-hexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, 2-ethylhexyl nitrate, sec-octyl nitrate, n-nonyl nitrate,
n-decyl nitrate, cyclopentyl nitrate, cyclohexyl nitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, etc. Additionally, nitric esters of alkoxy-substituted aliphatic alcohols such as 2-ethoxyethyl nitrate, 2-(2-ethoxyethoxy)ethyl nitrate, 1-methoxypropyl-2-nitrate, and 4-ethoxybutyl nitrate, and diol nitrates such as 1 , 6-hexamethylene dinitrate are also suitable. Preferred are alkyl nitrates having 5 to 10 carbon atoms, most especially mixtures of primary amyl nitrates, mixtures of primary hexyl nitrates, and octyl nitrates such as 2-ethylhexyl nitrate.

As is well known, nitrate esters are commonly prepared by mixed acid nitration of appropriate alcohols or diols. A mixture of nitric acid and sulfuric acid is generally used for this purpose. Other methods of making nitrate esters include reacting alkyl or cycloalkyl halides with silver nitrate.

The concentration of nitrate ester in the fuel can be varied within a relatively wide range, provided that the amount used is at least sufficient to induce a reduction in emissions. Generally speaking, the amount used is about 250 to 10 parts per million parts by weight of fuel.
000 parts by weight. Suitable concentrations typically fall within the range of 1000 to 5000 parts per million parts of fuel.

The fuel compositions of the present invention may contain other additives provided they do not adversely affect the reduction in exhaust emissions achievable by practicing the present invention. Thus, substances such as organic peroxides and hydroperoxides, corrosion inhibitors, antioxidants, rust inhibitors, detergents and dispersants, friction reducers, defoamers, dyes, inert diluents, etc. are added. Good too.

The advantages that can be achieved by implementing the invention are:
Demonstrated in a series of engine tests using a Detroit Diesel 11.1 liter Series 60 engine mounted on an engine dynamometer. This system is defined as Code of Federal Regulations (7-1-86), Volume 40, Part 86,
EPA Engine Dynamometer for High Performance Diesel Engines as shown on pages 810-819 of Appendix I.
I drove according to the schedule. In these tests, the first of five consecutive tests had a nominal sulfur content of 2
The engine was run on conventional DF-2-diesel fuel ranging from 0.000 to 4000 ppm. This test served as one of two baselines. In the next exam,
The engine was operated using low sulfur diesel fuel with the following characteristics:

In the third and fourth tests, which demonstrate the practice of the invention, the same low sulfur fuel as described above was used, except that the fuel was mixed with a diesel ignition improver consisting of 2-ethylhexyl nitrate. did. In the third test, the concentration of organic nitrate was 2000 ppm. In the fourth test, the fuel contained 5000 ppm of organic nitrate. Fifth
, the last test included another baseline run using the first conventional DF-2 diesel fuel. In all cases, the amounts of NOx, unburned hydrocarbons ("HC"), carbon monoxide ("CO") and particulates emitted by the engine were measured and integrated. The results of these tests are summarized in the table below. The values shown herein for NOx, HC, CO, and particulates are given in g/brake horsepower/hour. Therefore, the lower the value, the lower the rate and amount of release.

[0020]

[Table 1] Test number NOx
HC CO granules
1 4.641
0.086 1.414
0.227 2
4.345 0.068 1
．． 490 0.165
3 4.173 0.0
51 1.312 0.164
4 4.208
0.073 1.324
0.165 5
4.623 0.078
1.525 0.223 In particularly preferred embodiments of the invention, the use of fuels with certain boiling point characteristics as well as low sulfur content further reduces either NOx or particulate emissions. thus meeting the low sulfur parameters mentioned above and further 154-230
By using a fuel with a 10% boiling point (ASTM D-86) in the range of 0.degree. C., NOx emissions can be reduced to very low amounts. Similarly, a 90°C temperature range that meets the low sulfur parameters mentioned above
% boiling point (ASTM D-86), particulate emissions tend to be reduced to particularly low amounts. For illustration purposes, see Detroit Diesel Co.
it・Diesel・Corp. ) Series 60 engine of 11.1 liter type and nominally rated at 1800 rpm and 320 horsepower was used in a series of emissions tests. The engine was installed in a high performance transient emission chamber equipped with a constant volume sampling system (CVS). The use of a dilution tunnel allowed measurements of HC, CO, NOx, and particulate matter using the EPA transient emission cycle method.

For each test, the engine was started and warmed up. It was then run for 20 minutes at rated speed and load. Enabled rated horsepower. He also performed horsepower tests and plotted the engine's torque against speed. These parameters are EPA transient
Required as part of the cycle method. Get this information,
Two 20 minute EPA transient cycles were then performed and the engine controls were adjusted to meet the statistical operating limits previously noted for the test. I stopped the engine and let it soak for 20 minutes. At the end of this soak period, a hot start EPA transient cycle was performed and NOx, CO, and particulate emissions were measured. A second release evaluation was performed after another 2 minute soak. The results for the two hot transient cycles were averaged for the final reported value. Every time I changed fuel, I introduced new fuel into the fuel system, installed a new fuel filter, and cleaned out the fuel lines.

Each fuel (A-D) was evaluated using the same hot start EPA transient emission cycle method. Fuels A, B, and C contained sufficient 2-ethylhexyl nitrate to raise the cetane number of each fuel to a nominal value of 50. Fuel D had a natural cetane number of 49.8 and was tested without additives.

The physical and chemical properties for unadded fuels A to D are shown in the table below:

[0024]

[Table 2]
Surface fuel properties
A B
C D Hydrocarbon composition, volume % Aromatic 3
6.5 28.5 37.6
39.4 Olefin
1.2 1.1
2.2 2.9 Saturated compounds 62.3
70.4 60.2
57.7 carbon, wt%
86.35 86.49 86.
12 87.32 Hydrogen, wt%
13.15 13.25
12.89 13.35 Nitrogen,
ppm 5.3
285 356
152 Sulfur, ppm <
1 225 219
476 aniline point, ℃
70.1 60.0
65.4 69.4 Diene content, weight %
<0.1 0.2
<0.1 <0.1 viscosity, c
st @ 40℃ 2
．． 99 2.20 3.10
3.53 @ 100℃
1.22 0.97
1.23 1.34 Heat of combustion
BTU/lb 19,593
19,840 19,543 19,
672 boiling range, °C IBP 17
0 172 202
218 10%
217 211
234 252 20%
233
222 246 2
62 30%
249 230 257
271 40%
262 237
267 278 50%
274
244 276
284 60%
288 253 2
86 291 70%
300 263
294 298 8
0% 314
276 306
306 90%
331 297
322 317 95%
344 3
19 338 329
FBP 352
334 353
341 Recovery rate, %
98.7 98.9
98.6 98.9 specific gravity, API degree
34.9 36
．． 1 34.6 34.5 specific gravity
0.850 0.844 0.8
52 0.852 Calculated Cetane Number Index
48.1 44.0
48.9 51.7 Cetane number index
48.5 43
．． 8 48.3 49.7 Cetane number 45.
3 39.6 47.7
49.8 In the table above, the following test method was used:
Hydrocarbon composition - ASTM D-1319
Carbon - Carlo-Erba
ba) 1106 Hydrogen - Carlo-Erba 1106 Nitrogen - ASTM D-
4629 Sulfur - ASTM D-31
20 Aniline Point - ASTM D-6
11 Diene content - UOP 326
Viscosity - ASTM D-445
Heat of Combustion - ASTM D-2382 Boiling Point Range - ASTM D-86 Specific Gravity
- ASTM D-287 Calculated Cetane Number Index - ASTM D-4737
Cetane number index - ASTM D-976
Cetane Number - ASTM D-613 Figure 1 graphically shows the results of NOx emissions versus 10% boiling points for four fuels. It can be seen that fuels with 10% boiling points below 230°C exhibit the lowest NOx emissions.

The measurement results of particulate matter are shown graphically in the figure. In this case, the results are shown as a function of the 90% boiling point of the base fuel. The tendency for fuels with 90% boiling points in the range of 260-320°C to have low particulate emissions is significant.

Methods for reducing the sulfur content of hydrocarbonaceous intermediate distillate fuels or their precursors have been reported in the literature and are otherwise well known to those skilled in the art. Such methods include solvent extraction using agents such as sulfur dioxide or furfural, sulfuric acid treatment, and hydrodesulfurization. Hydrodesulfurization processes are, of course, generally preferred and include many special methods and operating conditions to suit various feedstocks. For example, hydrotreating or hydroprocessing of naphtha or medium oils is generally carried out under mild or moderately harsh conditions. On the other hand, sulfur removal by hydrocracking, as applied to distillation feedstocks, is usually carried out under more severe operating conditions. Vacuum distillation of bottoms from atmospheric distillation is another method for controlling or reducing the sulfur content of hydrocarbon feedstocks used in the production of hydrocarbonaceous intermediate distillate fuels. Further information on such methods can be found in Kirk-Othmer, Dictionary of Chemical Technology, 2nd edition, Interscience Publishers (In.
terscience・Publishers), 1st
Volume 1, 432-445 (Copyright 1966) and references cited therein; Ibid., Volume 15, pages 1-77 and references cited therein; and Kirk-Othmer, Dictionary of Chemical Technology, Volume 17. Volume, 3rd edition, Wiley-Interscience, 1
See pages 83-256 (Copyright 1982) and references cited therein. All such publications and citations are incorporated herein by reference with respect to methods of controlling or reducing the sulfur content of hydrocarbon intermediate distillate fuels or precursor feedstocks thereof.

Other methods that may be used include treatment of the hydrocarbonaceous intermediate distillate fuel with a metal desulfurization agent such as sodium metal or a mixture of sodium and calcium metals.

In summary, the present invention may present many embodiments, some of which are listed below: A. A fuel composition comprising primarily a hydrocarbonaceous medium-temperature distillate fuel having a sulfur content of 500 ppm or less, and wherein the fuel contains a small amount of a dissolved combustion-improving amount of at least one organic nitrate ester combustion modifier. thing.

B. Base fuel sulfur content is 100ppm
or less.

C. The composition of A, which is a diesel fuel, is further characterized in that the base fuel has an additive-free cetane number of 30-60.

D. The composition of A, wherein the base fuel has a sulfur content of 100 ppm or less and an unadded cetane number in the range of 30-60.

E. Base fuel is the next distillation trend
°F
℃
IBP 250-500
121-260 10%
310-550
154-288 50% 3
50-600 177-316
90% 400-700
204-371 EP
450-750 2
32-399.

F. The base fuel has a sulfur content of 100 ppm or less and a distillation tendency of
°F °C
IBP 250
-500 121-260
10% 310-550
154-288 50%
350-600 177-
316 90% 400-7
00 204-371 EP
450-750
Composition of A with 232-399.

G. Base fuel has an unadded cetane number in the range of 30-60 and the following distillation tendency
°F °C
IBP 250
-500 121-260
10% 310-550
154-288 50%
350-600 177-
316 90% 400-7
00 204-371 EP
450-750
Composition of A with 232-399.

H. The base fuel has a sulfur content of 100 ppm or less, an unadded cetane number in the range of 30 to 60, and a distillation tendency of
°F °C
IBP 250
-500 121-260
10% 310-550
154-288 50%
350-600 177-
316 90% 400-7
00 204-371 EP
450-750
Composition of A with 232-399.

I. The composition of A, wherein the base fuel has a sulfur content of 100 ppm or less and an unadded cetane number in the range of 40-50.

[0037]J. The composition of any of A to I, wherein the organic nitrate combustion modifier consists essentially of a nitrate ester of an aliphatic or alicyclic alcohol.

[0038]K. The composition of any one of A to I, wherein the organic nitrate combustion improver consists essentially of a nitrate ester of at least one primary alcohol having 5 to 10 carbon atoms in the molecule.

[0039]L. Organic nitrate combustion improver is nitric acid 2
- Any of the compositions A to I consisting essentially of a mixture of ethylhexyl.

[0040]M. the organic nitrate combustion improver consists essentially of a nitrate ester of at least one primary alkanol having from 5 to 10 carbon atoms in the molecule, and the mesophilate fuel has a % boiling point (A
STM D-86).

[0041]N. the organic nitrate combustion improver consists essentially of a nitrate ester of at least one primary alkanol having from 5 to 10 carbon atoms in the molecule, and the mesophilate fuel is % boiling point (A
STM D-86).

[0042]O. 2 per million parts by weight of the fuel
Any of the compositions A to I comprising an amount of the organic nitrate ranging from 50 to 10,000 parts by weight.

[0043]P. The composition of any one of A to I, wherein the fuel contains at least one nitric ester of an aliphatic or alicyclic alcohol in an amount of 1000 to 5000 parts by weight per million parts by weight of the fuel.

Q. A to I, wherein the fuel contains 1000 to 5000 parts by weight of at least one nitric ester of at least one primary alcohol having 5 to 10 carbon atoms in the molecule;
Any composition of.

[0045]S. When burning intermediate temperature distillate fuel in the presence of air, 500
A method of combustion of a hydrocarbonaceous intermediate temperature distillate fuel having a sulfur content of less than ppm and having a small combustion improving amount of at least one organic nitrate combustion improver dissolved therein.

[0046]T. (i) a major proportion of a hydrocarbon medium distillate fuel having a sulfur content of 100 ppm or less and an additive-free cetane number in the range 30 to 60; and (ii) a minor proportion of at least one aliphatic or cycloaliphatic alcohol. S improvements for combustion in the combustion chamber of a compression ignition engine operating on a diesel fuel composition comprising a small combustion-improving amount of one nitrate ester.

[0047]U. An improvement in T in which the organic nitrate combustion improver consists essentially of a nitrate ester of at least one primary alkanol having 5 to 10 carbon atoms in the molecule.

[0048]V. Organic nitrate combustion improver is nitric acid 2
- Modification of T consisting essentially of ethylhexyl.

W. In producing a hydrocarbonaceous intermediate distillate fuel, the sulfur content of the fuel is adjusted to an amount of 500 ppm or less and an organic nitrate combustion modifier is mixed with the resulting reduced sulfur content fuel. The method for producing the hydrocarbon medium-temperature distillate fuel, comprising:

X. For operation of motor vehicles operated on medium-temperature distillate fuels, hydrocarbon medium-temperature distillate fuels having a sulfur content of not more than 500 ppm and containing a small amount of dissolved combustion-improving amount of at least one organic nitrate combustion improver. A method of driving a motor vehicle comprising operating the motor vehicle.

Y. For the operation of aircraft operating on medium-temperature distillate fuels, hydrocarbon medium-temperature distillate fuels having a sulfur content of not more than 500 ppm and containing a small amount of dissolved combustion-improving amount of at least one organic nitrate combustion modifier. A method of operating an aircraft comprising operating the aircraft.

Z. Medium temperature distillate fuel is about 154 to about 230℃
10% boiling point (ASTM D-86) in the range of and about 2
90% boiling point (ASTM D
-86).

Other similar embodiments of the invention will readily occur to those skilled in the art in view of the above disclosure.

Features and aspects of the present invention are as follows.

1. The fuel comprises primarily a hydrocarbonaceous medium distillate fuel having a sulfur content of not more than 500 ppm, and the fuel has dissolved therein a small amount of at least one organic nitrate ester combustion modifier. A fuel composition containing

2. The composition of 1 above, wherein the base fuel has a 10% boiling point (ASTMD-86) in the range of 154-230°C.

3. The composition of 1 or 2 above, wherein the base fuel has a 90% boiling point (ASTM) in the range of 260-320°C.

4. 4. The composition of any of the preceding claims, wherein the base fuel has a sulfur content of 100 ppm or less and an additive-free cetane number in the range of 30 to 60.

5. 4. The composition of any one of 1 to 3 above, which is a diesel fuel, further characterized in that the base fuel has an additive-free cetane number of 30 to 60.

6. 6. The composition according to any one of 1 to 5 above, wherein the organic nitrate combustion improver consists essentially of a nitrate ester of at least one primary alkanol having 5 to 10 carbon atoms in the molecule.

7. When burning intermediate temperature distillate fuel in the presence of air, 500
A method of combustion of a hydrocarbonaceous intermediate temperature distillate fuel having a sulfur content of less than ppm and having a small combustion improving amount of at least one organic nitrate combustion improver dissolved therein.

8. In producing a hydrocarbonaceous intermediate distillate fuel, the sulfur content of the fuel is adjusted to an amount of 500 ppm or less and an organic nitrate combustion modifier is mixed with the resulting reduced sulfur content fuel. The method for producing the hydrocarbon medium-temperature distillate fuel, comprising:

9. For operation of motor vehicles operated on medium-temperature distillate fuels, hydrocarbon medium-temperature distillate fuels having a sulfur content of not more than 500 ppm and containing a small amount of dissolved combustion-improving amount of at least one organic nitrate combustion improver. A method of driving a motor vehicle comprising operating the motor vehicle.

10. For the operation of aircraft operating on medium-temperature distillate fuels, hydrocarbon medium-temperature distillate fuels having a sulfur content of not more than 500 ppm and containing a small amount of dissolved combustion-improving amount of at least one organic nitrate combustion modifier. A method of operating an aircraft comprising operating the aircraft.

[Brief explanation of the drawing]

FIG. 1: NO of a fuel with a nominal cetane number of approximately 50.
Figure 2 is a least squares plot of x emission versus 10% boiling point.

FIG. 2 is a least squares plot of particulate emissions versus 90% boiling point for a fuel having a nominal cetane number of about 50.

Claims (5)

[Claims] 1. A fuel comprising primarily a hydrocarbonaceous medium distillate fuel having a sulfur content of not more than 500 ppm, the fuel dissolving a small amount of at least one organic nitrate ester combustion modifier. A fuel composition containing [Claim 2] When a medium temperature distillate fuel is combusted in the presence of air, 500
A method of combustion of a hydrocarbonaceous intermediate temperature distillate fuel having a sulfur content of less than ppm and having a small combustion improving amount of at least one organic nitrate combustion improver dissolved therein. 3. In producing a hydrocarbonaceous intermediate distillate fuel, the sulfur content of the fuel is adjusted to an amount of 500 ppm or less, and an organic nitrate combustion improver is added to reduce the resulting sulfur content. A method of producing a hydrocarbonaceous medium-temperature distillate fuel comprising mixing the hydrocarbonaceous medium-temperature distillate fuel with 4. A hydrocarbon having a sulfur content of not more than 500 ppm and containing a small amount of a combustion-improving amount of at least one organic nitrate combustion improver dissolved therein, for use in the operation of motor vehicles operated on mesophilate fuels. A method of operating a motor vehicle comprising operating the motor vehicle on a mesophilate fuel. 5. A hydrocarbon having a sulfur content of not more than 500 ppm and containing a small amount of a combustion-improving amount of at least one organic nitrate combustion improver dissolved therein, for the operation of an aircraft operating on medium-temperature distillate fuels. A method of operating an aircraft comprising operating the aircraft on mesophilate fuel.