IE53445B1

IE53445B1 - Diesel fuel

Info

Publication number: IE53445B1
Application number: IE2442/82A
Authority: IE
Original assignee: Veba Oel Ag
Priority date: 1981-10-10
Filing date: 1982-10-08
Publication date: 1988-11-09
Also published as: FI823426L; EP0077027A3; PT75662A; JPH036958B2; FI823426A0; PT75662B; DK153225C; BR8205904A; DK446182A; DE3270279D1; NO823376L; MX162435A; ES516382A0; IE822442L; CA1180895A; ES8307886A1; FI75592C; TR22309A; DK153225B; ATE18919T1

Abstract

1. Diesel fuel composed of hydrocarbons and optionally containing alcohols, characterized in that it contains one or more ethers of the general formula R1 -O-C(CH3 )2 -R2 , wherein R1 and R2 are a methyl, ethyl, 1-propyl, 2-propyl, 1-butyl or 2-butyl group.

Description

ORGANISED UNDER THE LAWS OF THE FEDERAL REPUBLIC OF GERMANY QF 4660 GELSENKIRCHEN-BUER, FEDERAL REPUBLIC OF GERMANY.

Price 90p 3 4 -j 5 Frequently, the exhaust emissions from diesel powered engines contain unacceptable concentrations of smoke and soot. The tendency for smoke and soot formation can be reduced by utilizing fuels blended with ethers and metal salts of organic acids. The salts are prepared from Group IX metals, in particular barium.

The ethers include mono- and dialkyl ethers of glycols, particularly mono- and dimethyl ether of ethylene glycol. However, such admixtures are very expensive and their effectiveness in soot reduction is relatively small. An objectionable feature *0 of the fuels blended with the salts is that exhaust emissions containing the metals are environmentally unacceptable.

Diesel motors have also been successfully operated on diesel fuel mixed with alcohols and ethers (WO-A-8 100 721). Alcohols include methanol, ethanol, n-propanol and n-butanol. The greatest advantage is obtained from fuels blended with dimethyl ether and methanol. Since blends containing the above alcohols in concentrations great enough to achieve desired results are immiscible, it is necessary to inject the blend components and diesel separetly, e.g. in the intake air and by the usual injection pumps. Disadvantages are that the 2θ calorific value of the blending components is less than half that of the diesel plus the cetane number of such mixtures is strongly reduced or even inadequate for running a commercial diesel motor smoothly.

The present invention avoids the difficulties and disadvantages of the conventional diesel fuels containing the above additives and is outstanding for its improved combustion characteristics of diesel fuels. As a result, mechanical efficiency is improved and the emission of noxious material in the exhaust gases is greatly reduced.

According to the invention, these advantages as well as others are-achieved by adding to the diesel fuel one or more ethers of the general formula R1-0-C(CHj)2R2' where Ri and represent a methyl-, ethyl-, η-propyl-, 2-propyl-, 1-butylor 2-butyi group. I(1 and R2 may or may nor be the same. Particularly useful arc .«cunyl-tert.-butyl ether (2-methoxy-2-methyl-propane), methyl-tert.-amyl ether (2-methoxy-2-methyl butane), isopropyl-tert.-butyl ether (2-(21propoxy)-2-methyl propane), sec.-butyl-tert.-butyl ether (2-(2‘butoxy)-2-methyl propane), methyl-tert.-2,3-dimethylbutyl ether (2-methoxy-2,3-dimethyl butane) and methyl-tert.-2-methylpentyl ether (2-methoxy-2-methyl pentane). Mixtures which contain up to 90 % by volume of one of the above ethers are prefered. Of particular interest are mixtures containing 5 - 50 % by volume methyl-tert.-butyl ether, 5 - 50 % by volume methyl-tert.-amyl ether, 5 - 50 % by volume isopropyl-tert.-butyl ether, 5-50 % by volume sec.-butyl-tert.-butyl ether, 5 - 50 % by volume methyl-tert.-2,3-dimethylbutyl ether, and 5 - 50 % by volume methyl-tert.-2-methylpentyl ether.

Although blends of gasoline and the above ethers, particularly methyl-tert.-butyl ether, have been successfully used in car20 buretor engines, their usefulness in upgrading diesel fuels has not been apparent. For example, on one hand the antiknock property required for gasoline is not essential for diesel fuel, while on the other hand, an acceptable self ignition characteristic as well as a defined rate of evaporation and good solutizing properties are required for diesel fuels.

The favourable effects on diesel properties can already be shown for ether concentrations as low as 2 % by volume, whereas the prefered minimum concentration of the ether in the diesel fuel mixture is 5 % by volume. The ethers can be produced by simple methods 3q from hydrocarbons, which are highly volatile under standard conditions. These hydrocarbons are available in large quantities and are obtained from such sources as oil and from crude oil and gas processing. The produced diesel fuels can contain up to 40 % by volume ether, preferably up to 25 % by volume ether.

Conventional diesel fuel is a mixture of hydrocarbons boiling within a prescribed range. The many types of compounds that make-up diesel can be grouped into four broad classes; paraffinic, naphthenic, olefinic and aromatic. An asthetic problem asso5 ciated with the use of diesel motors is the soot contained in the exhaust emissions, the soot being produced from cycloparaffins, and polynuclear aromatics. The amount of smoke and soot can be decreased with an increase in air to fuel ratio.

However, since the volume of the combustion chambers are fixed, an increase in air ratio requires a corresponding reduction in fuel rate and, thus, results in a reduction in energy output.

Ether addition according to the invention greatly reduces soot formation, thus enabling the quantitiy of excess air to be minimized. This in turn results in increased energy output. As a result of the reduced air ratio total amount of exhaust emissions are reduced, resulting in a reduction of ΝΟχ as well as soot. Additionally, markedly lower concentrations of carcinogen polycyclic aromatics have been observed.

Since the ethers are essentially sulphur-free, the sulphur con20 tent of the blended diesel fuel is decreased. The lower tendency to form smoke coupled with the lower sulphur content result in less motor oil fouling and thus in an extended service life of the motor oil.

When added to diesel fuel, the ether mixtures produced in accor25 dance with the invention also serve as solutizers for alcohols, in particular for methanol and ethanol. Alcohols with 1 to 4 carbon atoms, i.e. methanol, ethanol, isopropanol, butanol, sec.butanol and tert.-butanol, can be added as pure components or as mixtures to the diesel fuel, in concentrations of from 2 to 40, preferably 5 to 25 % by volume. Since the above alcohols are miscible in diesel only in low concentrations, addition of ethers to the diesel fuel permits utilization of greater amounts of the above mentioned alcohols as diesel fuel components. When producing blends of ethers-alcohols-diesel fuel, the quantity of ether plus alcohol should not be greater than 60 % by volume of the blended diesel. The prefered blend contains more than 50 % diesel fuel.

Although used successfully to produce diesel fuels containing alcohols, solutizers, which are produced by complex processes, are not readily available in large quantities. In addition, the solutizers used do not effect the combustion characteristics of diesel fuel. In the same favourable way as the ethers according to the invention do.

Examples Specifications for the commercial diesel fuel used as the base for blended fuels are shown in Table 1.

Table 1 density (g/ml) 0,830 flash point (°C) 80 viscosity (mm2/s) 4,46 sulphur (%-wt.) 0,23 calorific value (MJ/kg) 42,9 initial/final boiling point (°C) 199 - 353 residue after distillation (%-vol.) 1,5 cetane number 56,5 Eight diesel blends containing various amounts of ethers and/or alcohols were prepared. Compositions and analyses of these samples are shown in Table 2. 534 15 Table 2 Ex- am- ple Fuel composition Density (g/ml, Sul- phur (%-wt) Visco- sity Calori- fic value h2 (tu/kg) Cetane nuitoer 1 50 DK + 50 B1 0,793 0,12 1,53 39,87 40* 2 43 DK + 32 B1 + 29 M 0,798 0,10 1,69 35,24 - 3 50 DK + 25 B1 + 25 E 0,804 0,12 2,05 37,19 45* 4 90 DK + 10 Ba 0,821 0,21 3,43 42,46 49,5 5 78,5 DK + 16,5 B1 + 5 M 0,815 0,18 2,70 40,91 41,0 6 81 DK + 14 B1 + 5 E 0,817 0,19 2,94 41,11 42,0 7 50 DK + 50 B2 0,778 0,11 1,78 40,43 45* 8 90 DK + 10 B2 0,822 0,21 3,50 42,38 49,5 Legend: DK Basic component as per Table 1 B1 Mixture of 90 % by volume methyl-tert.-butyl ether, isopropyl-tert.-butyl ether, sec.-butyl-tert.-butyl ether (volume ratio 1 : 1 : 1), plus % by volume methanol, isopropanol, sec.-butanol (volume ratio 1 :1 :1) b2 sec.-butyl-tert.-butyl ether M Methanol E Ethanol * To accelerate ignition, di-sec.-butyl-para-phenyl-diamine was added to three examples. The examples and amount added to each are: 0,5 % weight to example 1, 3,5 % weight to example 3 and 2,0 % weight to example 7.

The test runs comparing the invented diesel fuel with commercial fuels were carried out with commercial diesel motors; Daimler Benz Type 240 D and VW Type Golf D. For all tests, the motors were operated at fixed rotational speeds of 4400 rpm for the Daimler Benz 240 D and 4800 rpm for the VW Golf D. Motor operation was adjusted such that the performance for each test was equivalent to that of the motors operating on commercial diesel fuel.

The exhaust gas blackness and specific energy consumption were determined using a Daimler Benz motor Type 240 D operating at 4400 rpm and 47,3 kW. The blackness is reported as Bosch-Zahl (BZ) or Bosch number. Table 3 shows the Bosch number and speci10 fic energy requirements determined in tests using commercial diesel, example 0, and blends, example 1 through 8. The composition of examples 1 through 8 are shown in Table 2.

Table 3 Example BZ Specific energy consumption (MJ/kWh) 0 2,1 15,98 1 1,2 16,00 2 0,8 15,06 3 0,8 15,22 4 1,3 15,73 5 1,4 15,80 6 1,1 15,30 7 0,9 15,54 i 8 I 1,4 15,88 Table 3 reveals that soot formation from the blended fuels 25 according to the invention is much less than that from commercial diesel fuel. As shown, the reduction in soot formation ranges from 32 % to 62 %. Also, as shown by example 4, which is % by volume diesel, small amounts of ether-alcohol greatly reduce soot formation. In example 4, soot formation has been reduced by 38 %.

Irrespective of the lower calorific value of the mixtures des5 cribed by the invention, it can be seen that the specific energy consumption is of the same level or in most cases even lower than when using the basic diesel fuel.

A commercial VW type Golf D motor operating at 31,4 kW and a speed of 4800 rpm was used to evaluate the effect of ether10 alcohol blends on the concentration of NO in the exhaust x emissions. The results of these tests are shown in Table 4.

Table 4 Fuel Ν0χ (ppm) 0 500 1 370* 2 440* 3 430* 4 470 5 410 6 450 7 380 8 500 *To accelerate ignition, di-sec.-butyl-para-phenyldiamine was added to examples 1, 2 and 3. The amounts added were 0.1% by volume to example 1, 2.5% by volume to example 2, and 1.5% by volume to example 3.

As shown in Table 4, the diesel blends according to the invention reduce the Ν0χ concentrations in the exhaust gases up to 26% in comparison with conventional diesel fuel.

Claims

1. Diesel fuel composed of hydrocarbons and optionally containing alcohols, comprising one or more ethers of the general formula R.j-0-C(CH 3 ) 2 -R 2 , wherein R 1 and R g are a methyl-, ethyl-, Ι-propyl-, 2-propyl-, 1-butyl- or 2-butyl group.

2. Diesel fuel as claimed in Claim 1, comprising 2 to 50% by volume of a material consisting of 0 to 90% by volume methyl-tert.-butyl ether 0 to 9o% by volume methyl-tert.-amyl ether 0 to 90% by volume isopropyl-tert.-butyl ether 0 to 90% by volume sec.-butyl-tert.-butyl ether 0 to 90% by volume methyl-tert.-2,3-d1methylbutyl ether 0 to 90% by volume methyl-tert.-2-methylpentyl ether.

3. Diesel fuel as claimed in Claim 1 or Claim 2, comprising 5 to 25% by volume of the ether mixture.

4. Diesel fuel as claimed in one of Claims 1 to 3, wherein the added material consists of 5 to 50% by volume methyl-tert.-butyl ether. 5. Sec.-butyl-tert.-butyl ether approximately in a volume ratio 1:1:1. 11. Diesel fuel as claimed in one of Claims 1 to 10, comprising 2 to 40% by volume alcohols having 1 to 4 carbon atoms per molecule. 12. Diesel fuel as claimed in Claim 11, comprising 5 to 25% by volume alcohol.

5. Diesel fuel as claimed in one of Claims 1 to 4, wherein the added material consists of 5 to 50% by volume methyl-tert.-amyl ether.

6. Diesel fuel as claimed in one of Claims 1 to 5, wherein the added material consists of 5 to 50% by volume isopropyl-tert.-butyl ether.

7. Diesel fuel as claimed 1n one of Claims 1 to 6, wherein the added material consists of 5 to 50% by volume sec.-butyl-tert.-butyl ether.

8. Diesel fuel as claimed in one of Claims 1 to 7, wherein the added material consists of 5 to 50% by volume methyl-tert.-2,3-dimethylbutyl ether.

9. Diesel fuel as claimed in one of Claims 1 to 8, wherein the added material consists of 5 to 50% by volume methyl-tert.-2-methylpentyl ether. 10. Diesel fuel as claimed in one of Claims 1 to 9, wherein the added material contains methyl-tert.-butyl ether, isopropyl-tert.-butyl ether and 9.

10. 13. Diesel fuel substantially as described herein with reference to Example 1 to 8.