GB1591398A

GB1591398A - Use of methanol-based composition as diesel fuel

Info

Publication number: GB1591398A
Application number: GB4946877A
Authority: GB
Original assignee: Berol Kemi AB
Current assignee: Nouryon Surface Chemistry AB
Priority date: 1976-11-29
Filing date: 1977-11-28
Publication date: 1981-06-24
Also published as: NL7713095A; SE7613355L; DE2753027A1; JPS5381504A; ES464891A1; SE404702B; BR7707906A; IT1091508B; JPS6140717B2; FR2372224A1; FR2372224B1; CA1098699A

Description

(54) USE OF METHANOL-BASED COMPOSITION AS DIESEL FUEL (71) We, BEROL KEMI AB, a Swedish Joint Stock Company of S-444 01, Stenungsund 1, Sweden, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a method of operating a diesel-type engine using a diesel fuel based on methanol and containing a cetane number improver.

The shortage of oil products latterly has considerably increased the interest in other kinds of liquid fuel. Particularly great expectations have been set upon short-chained alcohols, such as methanol, ethanol and propanol. One of many fields of use contemplated is the use as fuel for diesel type engines.

The cetane number of said short-chained alcohols, which cetane number is a measure of the ignitibility of the fuel is, however, too low for the alcohols in question to be used as fuel in diesel engines with no special measures taken. The ignitibility of the diesel engine can be increased by preheating the inlet air. In the case of methanol this means that the temperature of the inlet air has to be increased up to no less than about 1300C for the diesel engine to ignite.

A way of increasing the ignitibility of the short-chained alcohols and consequently reducing the demans for preheating comprises the addition of an alkyl nitrate, e.g. hexyl nitrate. Even if the alkyl nitrates have a very positive effect on the cetane number, it has been shown that the alkyl nitrates easily hydrolyze to form acidic compounds causing a strong corrosion.

Further, the presence of nitrogen will increase the content of nitrogen-containing exhaust gases.

According to the present invention there is provided a method of operating a diesel type engine which comprises using as fuel a methanol-based composition of which at least 50%by weight is methanol and which contains, per 100 parts by weight of methanol, 2 to 40, preferably 5 to 25, parts by weight of a methanol-soluble polyether containing 4 to 400, preferably 6 to 100, oxyalkylene units derived from ethylene oxide and/or propylene oxide, the oxyalkylene units being at least 40%, preferably at least 60% by weight of the total polyether, and the composition being substantially free from hydrocarbon fuels.

Particularly preferred is the use of polyethers wherein at least 4 oxyalkylene units from a coherent chain. The polyethers can suitably be obtained by adding, in a manner knownper se, ethylene oxide and/or propylene oxide to water, hydrogen sulphide or ammonia or to organic compounds containing the reactive grouping -N-H, -C-OH, -S-H or -COOH. If desired, within the scope of the invention, the alkylene oxide adducts obtained can be further reacted, e.g. by etherification or esterification to carboxylate, sulphate or phosphate. If groups reactive towards ethylene oxide or propylene oxide are then formed, said groups can be further alkoxylated.

The composition used in the method of the invention contains at least 50% by weight, preferably at least 70%by weight, of methanol.

Another aspect of the present invention comprises the provision of a composition as hereinbefore defined, for use as a complete diesel fuel, specifically one containing other additives commonly used in diesel fuels, such as corrosion inhibitors, lubricants, combustion promoting agents, stabilizers, agents for preventing the precipitation of combustion residues and/or agents for reducing the amount of impurities in the exhaust gases. So, for example, a smaller amount of water, suitably 2 to 10% calculated on the weight of methanol, can be added to reduce the proportion of nitrogen oxide in the exhaust gases.However, the addition of water will not increase the ignitibility of the fuel but rather has the opposite effect. (Insofar as such compositions containing additives are covered per se in the present invention, as opposed to their use in operating a diesel type engine they do not contain boric acid).

The diesel fuel used in the invention has a substantially decreased ignition temperature compared to a pure methanol fuel and causes low corrosion compared with methanol fuel to which alkyl nitrate has been added. It shows good stability when subjected to temperature and pressure changes as well as to mechanical stress. In addition, the polyether has a lubricating effect and promotes a regular running of the engine even when the exhaust gases contain a high proportion of non-combusted organic compounds.

Examples of polyethers which may be present in the compositions used in the present invention are alkylene oxide adducts obtained by hydroxyalkylation of ammonia and by hydroxyalkylation of mono- or polyamines containing one or more primary or secondary nitrogen atoms. Particularly preferred such compounds are compounds of formula

whercin each of Rl and R2 independently is an alkyl group containing 1 to 24 carbon atoms or, preferably, a group (A)nH, and each A independently is an oxyalkylene group derived from ethylene oxide or propylene oxide and n is an interger from 4 to 40 inclusive.

Other examples of compounds that can advantageously be used according to the invention are hydroxyalkylated mercaptans or hydroxyalkylated hydrogen sulphide. Particularly preferred such compounds are compounds of formula R3- S-(A)nH B wherein R3 is a hydrocarbon group containing 1 to 24 carbon atoms or, preferably, a group (A)nH and each A independently is an oxyalkylene group derived from ethylene oxide or propylene oxide and n is an integer from 4 to 40 inclusive.

Preferred polyethers for use in the present invention are formula R4 [O(A)nHj1n C wherein R4 is hydrogen or the residue of an organic compound which compound contains hydrogen, carbon and optionally oxygen and contains 1 to 12 hydrogen atoms reactive towards ethylene oxide or propylene oxide, each A independently is an oxyalkylene group derived from ethylene oxide or propylene oxide m is an integer from 1 to 12 inclusive and n has a value such that the total number of units derived from ethylene oxide and/or propylene oxide is 4 to 400, preferably 6 to 100. In addition to the above-mentioned advantages, the use of the latter compounds in conjunction with methanol provides the further advantage that the fuel will contain only oxygen, hydrogen and carbon so that the fuel will comply with heavy environmcntal demands.

The polyethers of formula C can be polyalkyleneglycols obtained, in a manner known per se, by polymerization of ethylene oxide or propylene oxide or mixtures of said alkylene oxides. In case of a polyether containing both ethylene oxide and propylene oxide the alkylene oxides can be polymerized each per se in one or several steps or can be polymerized in a process being a combination of the above-stated methods.

Other examples of compounds of formula C are reaction products between the alkylene oxides in question and acyclic or isocyclic, mono- or polyfunctional hydroxyl or carboxyl compounds containing 1 to 40 carbon atoms. Examples of suitable monofunctional hydroxyl and carboxyl compounds are methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, acetic acid, propionic acid, butanoic acid, hexanoic acid and 2-ethylhexanoic acid. Examples of polyfunctional hydroxyl and carboxyl compounds are glycerol, trimethylolpropane, butyleneglycol, butanetriol, hexanetriol, pentaerythritol, sorbitol, sorbitan, saccharides such as sucrose, glucose, arabinose, fructose, mannose, dextrose, lactose, and maltose, succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, dodecanedicarboxylic acid and resorcinol.

Preferred polyethers for use in the diesel fuel of the invention are polyethyleneglycols having a molecular weight within the range 400 to 4,000 and surface active polyethers within the defined scope, as well as mixtures of the same. The weight ratio between the polyethyleneglycol and the surface active compound in such mixtures can vary within broad limits but usually is within the range of from 9:1 to 1:9, preferably from 9:1 to 1:1.

Polyethyleneglycol having a mplecular weight below 400 provides a relatively small temperature reduction whereas polyethyleneglycol having a molecular weight above 4,000 has disadvantageous physical properties, such as low melting point and poor solubility in methanol.

Surface active compounds refer to compounds imparting to water a surface tension of below 50 dynes/cm at a concentration of 1 %by weight at a temperature of 25 C. The surface active compounds usually are compounds of formula C wherein R4 is a hydrocarbon or acyl group containing 8 to 30 carbon atoms, at least 50% by weight of each A group consists of groups derived from ethylene oxide, m is 1 and n is an integer from 4 to 40 inclusive, preferably from 6 to 25 inclusive.Examples of suitable surface active compounds are an ethylene oxide adduct with decyl alcohol, lauryl alcohol, myristy alcohol, cetyl alcohol, stearyl alcohol, eicosyl alcohol, oleyl alcohol, cyclooctanol, cyclododecanol, cyclohexadecanol, octyl phenol, nonyl phenol, dodecyl phenol, hexadecyl phenol, dibutyl phenol, dioctyl phenol, dinonyl phenol, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and arachidic acid. If desired, nonionic compounds of formula C upon alkoxylation can be phosphated or sulphated to the corresponding anionic surface active compounds.

The Examples below will further illustrate the invention.

Examples A number of polyether compounds were tested with regard to their ability to reduce the ignition temperature of methanol. The tests were carried out using a two-cylinder diesel engine having an effect of 10 HP. The fuel was introduced whereupon the temperature of the inlet air was increased to such an extent that the engine ran smoothly and gave a stable proportion of organic compounds in the exhaust gases. Thereupon the temperature was decreased successively and was recorded when the proportion or organic compounds in the exhaust gases was 3,000 ppm measured according to SAE J 215. The temperature of the inlet air when this occurs is a measure of the ignitibility of the fuel, i.e. the cetane number.

The compound added, the amount thereof calculated on the amount of methanol and the temperature decrease obtained are shown in the table below. The margin of error has been calculated tomaximally + 3"C.

Exp. Amountin So Temperature nr. Compound of methanol decrease in "C 1 Ethyleneglycol 5 0 2 Polyethyleneglycol, mol.weight 200 5 7 3 Polyethyleneglycol, mol.weight 300 5 13 4 Polyethyleneglycol, mol.weight400 5 17 5 Polyethyleneglycol, mol.-weight 600 5 21 6 Polyethyleneglycol, mol. weight 600 10 26 7 Polyethyleneglycol, mol. weight 600 15 42 8 Polyethyleneglycol, mol.-weight 600 20 70 9 Polyethyleneglycol, m6l.weight 600 25 76 10 Polyethyleneglycol, mol.weight 1 000 5 20 1-1 Polyethyleneglycol, mol.weight 1 500 5 19 12 Polyethyleneglycol, mol.weight 2000 5 23 13 P6lyethyleneglycol, mol. weight 4000 5 18 14 Propyleneglycol ' 5 0 15 Polypropyleneglycol, mol.weight 400 5 6 16 Polypropyleneglycol, mol;;weight-1 200 5 14 17 Polypropyleneglycol, mol.weight 1 800 5 11 18 Polypropyleneglycol, mol.weight 2000 5 6 19 Polypropyleneglycol, mol .weight 4000 5 4 20 Sorbitanemonooleate + 18EO 5 14 21 Sorbitanetrioleate + 20EO 5 12 22 Sucrose + 9 EO 5 11 23 Sorbitol + 7 PO 5 14 24 Dinonylphenol + 16EO 5 17 Exp. md Amountin % Temperature nr.Compound | or ofmethanol decrease in C 25 Dinonylphenol + 30EO 5 17 26 Nonylphenol + 20 EO 5 12 27 Nonylphenol + 40EO 5 15 28 Propropyleneglycol (mol.weight 1 200) + 5EO 29 Polypropyleneglycol (mol.weight 1 800) 13 +4EO 30 Polypropyleneglycol (mol.weight 1 800) 13 + 16EO 31 2-ethylhexanol + 20EO 5 15 32 Lauricacid+15EO 5 14 33 Polyethyleneglycol, mol.weight 600, and 10 56 dinonylphenol + 16 EO 5 34 Polyethyleneglycol, mol.weight 600, and 5 58 dinonylphenol + 16 EO 5 35 Cocofattyamine + 15 EO 5 21 36 NH3+23EO 5 23 37 Oleylamine + 20 EO 5 22 38 Cetylmercaptane + 20 EO 5 20 39 SH2+20EO 5 22 40 Lauryltetra (oxyethylene)phosphateester 5 16 + 2EO 41 Lauryltetra (oxyethylene)sulphate 5 15 From Experiments 2-13, 15-19 and 28-30, it is evident that the addition of polyalkyleneglycols to methanol makes it possible to reduce strongly the temperature of the inlet air whereas ethyleneglycol and propyleneglycol (Experiments 1 and 14, respectively) have no demonstrable effect. A particularly great temperature decrease is shown by polyethyleneglycol having a molecular weight of 400-4,000.Experiments 5-9 show that the temperature decrease is dependent on the amount of additive within a broad range. Different kinds of alkylene oxide adducts have been tested in Experiments 20-27, 31-32 and 35-41 and they have all been shown to provide essential temperature decreases. Experiments 33 and 34 illustrate mixtures of a polyethyleneglycol and a surface active compound. In said Experiments the temperature decrease is essentially greater than could be expected from the results obtained for the individual compounds contained in-the mixture.

WHAT WE CLAIM IS: 1. A method of operating a diesel type engine which comprises using as fuel a methanol-based composition of which at least 50% by weight is methanol and which contains, per 100 parts by weight of methanol, 2 to 40 parts by weight of a methanol soluble polyether containing 4 to 400 oxyalkylene units derived from ethylene oxide and/or propylene oxide, the oxyalkylene units being at least 40% by weight of the polyether, and the composition being substantially free from hydrocarbon fuels.

2. A method according to claim 1 in which the methanol-soluble polyether contains 6 to 100 oxyalkylene units derived from ethylene oxide and/or propylene oxide.

3. A method according to claim 1 or 2, in which the composition contains the polyether in an amount of 5 to 25 parts by weight per 100 parts by weight of methanol.

4. A method according to claim 1, 2 or 3 in which at least 70% by weight of the composition is methanol.

5. A method according to any one of the preceding claims in which the oxyalkylene units in the polyether have been introduced by the addition of ethylene oxide and/or propylene oxide to water, hydrogen sulphide or ammonia or to an organic compound containing the grouping -N-H, -C-OH, -S-H or -COOH.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

Exp. md Amountin % Temperature nr. Compound | or ofmethanol decrease in C

25 Dinonylphenol + 30EO 5 17

26 Nonylphenol + 20 EO 5 12

27 Nonylphenol + 40EO 5 15

28 Propropyleneglycol (mol.weight 1 200) + 5EO

29 Polypropyleneglycol (mol.weight 1 800) 13 +4EO

30 Polypropyleneglycol (mol.weight 1 800) 13 + 16EO

31 2-ethylhexanol + 20EO 5 15

32 Lauricacid+15EO 5 14

33 Polyethyleneglycol, mol.weight 600, and 10 56 dinonylphenol + 16 EO 5

34 Polyethyleneglycol, mol.weight 600, and 5 58 dinonylphenol + 16 EO 5

35 Cocofattyamine + 15 EO 5 21

36 NH3+23EO 5 23

37 Oleylamine + 20 EO 5 22

38 Cetylmercaptane + 20 EO 5 20

39 SH2+20EO 5 22

40 Lauryltetra (oxyethylene)phosphateester 5 16 + 2EO

41 Lauryltetra (oxyethylene)sulphate 5 15 From Experiments 2-13, 15-19 and 28-30, it is evident that the addition of polyalkyleneglycols to methanol makes it possible to reduce strongly the temperature of the inlet air whereas ethyleneglycol and propyleneglycol (Experiments 1 and 14, respectively) have no demonstrable effect. A particularly great temperature decrease is shown by polyethyleneglycol having a molecular weight of 400-4,000.Experiments 5-9 show that the temperature decrease is dependent on the amount of additive within a broad range. Different kinds of alkylene oxide adducts have been tested in Experiments 20-27, 31-32 and 35-41 and they have all been shown to provide essential temperature decreases. Experiments 33 and 34 illustrate mixtures of a polyethyleneglycol and a surface active compound. In said Experiments the temperature decrease is essentially greater than could be expected from the results obtained for the individual compounds contained in-the mixture.

WHAT WE CLAIM IS: 1. A method of operating a diesel type engine which comprises using as fuel a methanol-based composition of which at least 50% by weight is methanol and which contains, per 100 parts by weight of methanol, 2 to 40 parts by weight of a methanol soluble polyether containing 4 to 400 oxyalkylene units derived from ethylene oxide and/or propylene oxide, the oxyalkylene units being at least 40% by weight of the polyether, and the composition being substantially free from hydrocarbon fuels.
2. A method according to claim 1 in which the methanol-soluble polyether contains 6 to 100 oxyalkylene units derived from ethylene oxide and/or propylene oxide.
3. A method according to claim 1 or 2, in which the composition contains the polyether in an amount of 5 to 25 parts by weight per 100 parts by weight of methanol.
4. A method according to claim 1, 2 or 3 in which at least 70% by weight of the composition is methanol.
5. A method according to any one of the preceding claims in which the oxyalkylene units in the polyether have been introduced by the addition of ethylene oxide and/or propylene oxide to water, hydrogen sulphide or ammonia or to an organic compound containing the grouping -N-H, -C-OH, -S-H or -COOH.
6. A method according to any one of-the preceding claims in which the oxyalkylene units

are at least 60%byweight of the polyethe,r and at least 4 oxyalkylene units form a chain.
7. A method according to any one of the preceding claims in which the polyether is of formula

wherein each of R l and R2 independently is an alkyl group containing 1 to 24 carbon atoms or a group (A)nH, and each A independently is an oxyalkylene group derived from ethylen eoxide or propylene oxide and n is an integer from 4 to 40.
8. A method according to any one of claims 1 to 6 in which the polyetheris of formula R3-S-(A)nH wherein R3 is a hydrocarbon group containing 1 to 24 carbon atoms or a group (A)nH, and each A independently is an oxyalkylene group derived from ethylene oxide or propylene oxide andn is an integer from 4 to 40.
9. A method according to any one of claims 1 to 6 in which the polyether is of formula R4- tO(A)nH]rn wherein R4 is hydrogen or the residue of an organic compound, which compound contains hydrogen, carbon and optionally oxygen and contains 1 to 12 hydrogen atoms reactive towards ethylene oxide or propylene oxide, each A independently is an oxyalkylene group derived from ethylene oxide or propylene oxide, m is an integer from 1 to 12 and n has a value such that the total number of units derived from ethylene oxide and/or propylene oxide is as specified in claim 1 or 2.
10. A method according to claim 9 in which the polyether is a polyalkyleneglycol.
11. A method according to claim 10 in which the polyalkyleneglycol is a polyethyleneglycol having a molecular weight of 400 to 4,000.
12. A method according to claim 9 in which the polyether is a reaction product between ethylene oxide or propylene oxide and an acyclic or isocyclic, mono- or polyfunctional hydroxyl or carboxyl compound containing 1 to 40 carbon atoms.
13. A method according to claim 12 in which the polyether is surface active.
14. A method according to claim 9 in which the polyether is a mixture of a polyethyleneglycol having a molecular weight of 400 to 4,000 and a polyether as defined in claim 13, the weight ratio of the polyethyleneglycol to the surface active polyether being from 9:1 to 1:9.
15. A method according to claim 14 in which the weight ratio of the polyethyleneglycol to the surface active polyether is from 9:1 to 1:1.
16. A method according to claim 13, 14 or 15 in which the surface active polyether is a compound as defined in claim 9 wherein R4 is a hydrocarbon or an acyl group containing 8 to 30 carbon atoms, at least 50% by weight of each A group consists of groups derived from ethylene oxide, m is 1 and n is an integer from 4 to 40.
17. A method according to claim 16 in whichn is a number from 6 to 25.
18. A method according to any one of the preceding claims in which the composition contains a corrosion inhibitor, a lubricant, a stabilizer or an agent for promoting combustion, preventing the precipitation of combustion residues or for reducing the amount of impurities in an exhaust gas formed by igniting the composition.
19. A method according to claim 1 substantially as described in any one of the Examples.
20. A methanol-based composition suitable for use as a diesel fuel of which at least 50% by weight is methanol and which contains, per 100 parts by weight of methanol, 2 to 40 parts by weight of a methanol-soluble polyether containing 4 to 400 oxyalkylene units derived from ethylene oxide and/or propylene oxide, the oxyalkylene units being at least 40% by weight of the polyether, the composition containing an additive which is a corrosion inhibitor, a lubricant, a stabilizer or an agent for promoting combustion, preventing the precipitation of combustion residues or for reducing the amount of impurities in an exhaust gas formed by igniting the composition, the additive being other than boric acid, the composition being substantially free from hydrocarbon fuels.