2. Description of the Prior Art : Fuels for the internal combustion engines and turbines damage the environment due to, among other factors, the incomplete combustion in the engines, of hydrocarbons, carbon monoxides and nitrogen oxides. Metal-ceramic catalytic converters are known to reduce this damage by means of catalytic afterburning of the engine exhausts. The combustion energy released thereby cannot be used, however, for the primary process of energy production in the engine. Also, the efficiency of the catalytic converter can decrease over time leading to increased polluant emission levels. The addition of a fuel additive, prior to the combustion stage, would have distinct advantages over, or in addition to the traditional methods for handling exhaust emissions.

The amelioration of fuel qualities by the addition of diverse substances is a familiar technique in the prior art. Thus, e. g., according to DE-PS 582 718, heavy metal salts, namely, cooper, nickel, cobalt, zinc and chromium salts, as well as the condensation products of amines with compounds which contain one or more oxygen groups in addition to a carbonyl group, are added to the fuel in order to improve its knock resistance. In DE-PS 448 620 and DE-PS 455 525, fuels are described which have a content of iron carbonyl or nickel, cobalt and/or molybdenum carbonyl. However, these techniques have not become popular, because the use of metal carbonyis causes a metal oxide deposit in the combustion chamber of the vehicle and are toxic. DE-PS 801 865 teaches the use of fuel additives, which can be toluene, benzene, acetone, trichlorethylene or isobutyl alcohol, besides the metal carbonyls, although the fundamental drawback of metal oxide deposits in the combustion chamber remains the same. DE-AS 1 221 488 describes fuel additives consisting of methylcyclopentadienyl manganese tricarbonyl, lead tetraethyl or other organometallic compounds and organic compounds having two ester groups. The following organic fuel additives are also recognised as constituting a part of the state-of-the-art : a mixture of an aromatic amine and a polyalkyl phenol, as shown in DE-PS 845 286 ; tretaarylhydrazine, diarylnitrosamine and triarylmethyl derivatives from DE-PS 505 928 ; aldehydes, quinones and ketones from DE-PS 612 073 ; ketones of formula R--CO--R', wherein R represents a ring radical and R'an aliphatic radical with at least 6 C-atoms, from United States Patent No. 2, 100, 287 ; hydroquinone in a benzene solution from DE-PS 486 609 ; ether derivatives from DE-PS 703 030 ; alcools from DE-PS 843 328 ; condensation products of alkylene oxides and alkylphenols from DE-PS 19 37 000 ; anthracene derivatives from Unites States Patent No. 1, 885, 190 and 1. 4-dialkyl- arylamino-anthraquinone from EP 09 095 975 B1.

United States Patent No. 1, 973, 475 describes a method for oxidation of fuels with air or oxygen at elevated temperatures, possible in the presence of a catalyst. DE-PS 699 273 discloses a method of dehydrogenation of non-flammable oils from the boiling range of diesel oils in inflammable oils with oxidising agents such as air or oxygen, ozone, peroxides, chromic acid or nitric acid at 150°-350°C, possibly at elevated pressure and preferably in presence of a catalyst. The ozonization of fuels is also described in DE-PS 324 294 and DE-PS 553 943. According to DE-PS 324 294, ozonides such as ethylene ozonide, or a mixture of one of the conventional fuels with an ozonide, are added to the internal combustion engine. The drawback of the method is the instability of the ozonides, so that when kept for a lengthy time the availability of oxygen carriers is necessarily variable, apart from the problems of environmental pollution, which were not known at the time. According to DE-PS 553 943, a mixture of hydrocarbons is ozonized under pressure in the presence of an oxygen carrier, such as turpentine oil, and slight amounts of ignition-promoting substances.

The procedures described in the patents above are not commercialized. The described substances are partially toxic, carcinogenic or the procedures are too expensive. They do not add any value in the petrochemical market.

In DE 1144971 there is shown the use of leadtetraethyl in addition to monocarbonic acids, to achieve boosting of the octane number. In DE 1271455 diketons are patented in combination with leadtetraethyl as antiknock-substances. Aliphatic polyethers with the general formula R- (O-X) n-O-R') are described in the United States Patent No.

2, 655, 440 as additives increasing the cetyl number. DE 19527423 A1 describes the ozonisation of gasoline containing benzene, wherein together with other oxidation products glyoxal is formed. This process has the disadvantage, that ozonisation apparats in a refinery are unusual and expensive.

SUMMARY OF THE INVENTION The present invention has as its object the reduction of the emission of polluants and the consumption of fossil fuels and their derivatives. The pollution of environment by the incomplete combustion sequence in combustion engines with expulsion of carbon monoxide, unburned hydrocarbons, as well as nitrogen oxide is sufficiently well known.

Subsequent use of catalytic converters, and the like, are a stop gap measure, at best.

Thus, preference should be given to an optimization of the combustion process in the immediate energy-supplying step.

The present invention accomplishes this purpose in a fundamental, technically feasible and effective mode and manner.

In the present invention, polluant emissions from combustion engines are reduced by the addition of glyoxal and glyoxal derivatives and adducts in aqueous solution to the fuel supply to the combustion engine. Preferably, different acetals and hemiacetals or a mixture thereof obtained by the acetalization of glyoxal are added to the fuel.

Additional objects, features and advantages will be apparent in the written description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of the reduction in emission of CO achieved through the use of the additives of the invention with the engine at idle ; Figure 2 is a similar graph of the reduction in emission of HC at idle ; Figure 3 is a similar graph of the reduction in emission of CO at increased idle ; Figure 4 is a similar graph of the reduction in emission of HC at increased idle ; Figure 5 is a graph of diesel emission of carbon particles with time showing the effects of the additives of the invention in reducing such emissions ; and Figure 6 is a graph of the reduction in emission of NOX with time showing the effects of the additives of the invention in reducing such emissions.

DETAILED DESCRIPTION OF THE INVENTION Applicant's EP94/02052, now issued as United States Patent No. 5, 762, 655, describes a technique for optimizing the combustion process in internal combustion engines. In that process, the ozonization products of gasoline and diesel fuels provide a catalytic effect on the combustion process with the result that unburned hydrocarbons and carbon monoxide are reduced drastically. On one hand, this technique has the advantage that it is highly effective. On the other hand, however, it has the disadvantage that it is relatively costly since an ozonization system has to be integrated into the respective refinery plants supplying the combustion fuel.

The present invention has as its object to provide the same benefits achieved with the previously described ozonization process, but without the attendant expense.

In the present invention, glyoxal in aqueouss solution is used as a basic product for fuel additives in order to obtain a reduction of polluant emission. Glyoxal is obtained by oxidation from glycol in aqueous solution in industrial scale techniques. Here, glyoxal can be added to the fuel either together with flammable emulsifiers or in a chemical compound as described below. Compare to previous suggestions, this technique has the advantage that, here, a product can be used which is produced on an industrial scale and, therefore, economically and easily available ; furthermore, the substances described herein are relatively stable in storage compared to the oxides which arose in the ozonization process of previous techniques and which drastically reduced the storage stability.

One factor to be considered in the practice of the present invention is the relative solubility of glyoxal in water when it is added to gasoline. It has been discovered, however, that a usual 40% glyoxal solution, together with a usual emulsifier consisting of esterified aliphatic compounds, can be mixed surprisingly well with gasoline if polyethyleneglycol is added. Thus, for example, 10 milliliters of a 40% glyoxal solution plus 10 milliliters of a standard, off the shelf emulsifier based on esterified aliphats (i. e.

"Ecocool-ACC"of the firm Fuchs Ole), as well as 10 milliliters polyethyleneglycol can easily be mixed with 500 milliliters gasoline. Here, after thorough mixing for some time, a slightly cloudy gasoline-additive-emulsion is obtained. If 10 milliliters methyltertiarybutylether are added hereto, the mixture becomes completely clear afterwards. It is, however, very important here that, first, the glyoxal in aqueous solution, the emulsifier and the polyethyleneglycol are very thoroughly homogeneously mixed and then, the mixture added to the gasoline. The gasoline-additive-emulsion obtained by this process is quite stable in storage. In high gasoline quantities, there is no longer any separation of phases. Aqueous glyoxal solution or concentrated glyoxal can also be added to"Aquazole" (trade name of ELF Aquitaine) as it is described in Focus 22/1999, page 188-189.

In the practice of the method of the invention, the addition of 500 milliliters of the gasoline-additive-emulsion to 40 liters gasoline has been found sufficient to obtain a reduction of unburned hydrocarbons of 95% in vehicles with catalytic converters at increased idle and at idle after the cars have been driven five kilometers in urban driving. Usually, carbon monoxide can no longer be identified under these conditions.

Also a reduction of the emission of nitrogen oxides (NOX) of approximately 90 % has been obtained.

The tables that follow provide the results of a statistical survey on the results of tests with gasoline to which the above-described additive was added. As only 4 grams glyoxal were mixed into 40 liters of gasoline, it can be calculated that glyoxal shows its effectiveness as a homogeneous catalyst at the ppm-level. Furthermore, the quantity of water of 10 milliliters per 40 liter gasoline is so low that there is no danger of corrosion for the engine. Any and all components of the described additive are flammable and nontoxic so that toxic side effects can be excluded.

In diesel fuel, the aqueous glyoxal solution as described above is even more easily soluble than in gasoline. Here, a milky cloudy fuel mixture is obtained, the phase mixture of which is considerably more stable. Fuels to which this additive have been added produce in diesel engine vehicles at idle and at increased idle (10 % according to ECE-standard) an average reduction of the particulate emission or coke deposit of 30 to 40% and of nitrogen oxides of 20%.

Tables I and II below as well as the graphs shown in Figures 1-5 provide the results of emissions tests using the glyoxal solution additive of the invention : TABLE I Reduction in emission through glyoxal emulsion in gasoline (at idle) n=22 Date CO before CO after HC before HC after 07. 03. 1998 0, 01 0 34 5 07. 03. 1998 0 0 34 5 07. 03. 1998 0, 01 0 79 2 07. 03. 1998 0 0 8 7 06. 26. 1998 0, 01 0 6 3 06. 26. 1998 0 0 21 10 06. 26. 1998 0 0 5 7 06. 26. 1998 0 0 6 9 05. 22. 1998 0 0 5 3 05. 22. 1998 0 0 9 3 05. 22. 1998 0, 02 54 10 05. 22. 1998 0, 02 0, 01 20 11 04. 08. 1998 0, 1 0 111 6 03. 25. 198 0 0 22 29 03. 25. 1998 0 0 6 4 03. 23. 1998 0 0 6 2 03. 23. 1998 0,01 0 16 0 03. 23. 1998 0 0 4 4 03. 18. 1998 0, 07 0, 09 34 13 03. 05. 1998 0, 04 0 42 1 03. 05. 1998 0, 04 0 57 7 without date 0, 02 0, 01 15 9 average value 0, 02 0, 01 27, 00 6, 82 standard deviation 0, 03 0, 02 27, 67 6, 06 Table 11 Reduction in emission through glyoxal emission in gasoline (at increased idle) n=22 Date CO before CO after HC before HC after 07. 03. 1998 0,26 0 99 9 07. 03. 1998 0, 02 0 56 5 07. 03. 1998 0, 06 27 5 07. 03. 1998 0 0 14 11 06. 26. 1998 0 0 5 2 06. 24. 1998 0 0 10 12 06. 24. 1998 0 0,1 10 15 06. 24. 1998 0, 03 0, 01 8 9 05. 22. 1998 0 0 5 2 05. 22. 1998 0 0 12 2 05. 22. 1998 0, 03 0 13 7 05. 05. 1998 0 0 10 12 04. 08. 1998 0,12 0 41 6 03. 25. 1998 0, 03 0, 01 17 13 03. 25. 1998 0, 01 0, 02 8 5 03. 23. 1998 0 0 8 5 03. 23. 1998 0, 1 0 27 0 03. 23. 1998 0 0 11 6 03. 18. 1998 0, 29 0, 05 13 17 03. 05. 1998 0, 13 0 24 3 03. 05. 1998 0,01 0 16 8 without date 0,05 0,04 9 5 average value 0, 05 0, 01 20, 14 7, 23 standard deviation 0, 08 0, 02 21, 49 4, 56 Conditions : All cars were BMW Type 5 (525 or 528) measuring equipment : Digas AVL Type 465 (Graz, Austria) Sensor AVL Type 1554 The Figures 1 to 4 graphically present the average pollution emission values of a stationary engine (BMW Type 5 (525 or 528)) of tables I and 11 that is operated with a conventional gasoline before and after application of a glyoxal mulsion according to the present invention.

Fig. 1 shows the carbon monoxide (CO) values in % vol at idle. After application of an aqueous glyoxal emulsion, containing 4 g glyoxal in 10 ml water to 40 I gasoline fuel, which corresponds to a ratio additive to fuel 1 : 10000, i. e. 0, 1 % ovol a reduction of 50 % from 0, 02 % vol to 0, 01 % vol CO is obtained. Fig. 2 shows the emission values of hydrocarbons (HC) in % vol, ppm under equal conditions. Here after the application of the additive a reduction of nearly 75 % from 27, 00 % vol, ppm to 6, 82 % vol, ppm is obtained.

Fig. 3 shows the carbon monoxide value at increased idle (10 % according to ECE- standard) under the same quantitative conditions, concerning the ratio additive to fuel.

With conventional gasoline fuel a value of 0, 05 % vol is measured. After adding the additive this value decreases to 0, 01 % vol, which is a reduction of 80 %. Also the hydrocarbon value, shown in Fig. 4, decreases from 20, 14 % vol, ppm to 7, 23 % vol, ppm at increased idle.

The reduction of the emission of carbon particles with time of a diesel fuel engine, type AUDI diesel 5 cylinder, 140 hp (no oxidationkat) after the application of an additive, according to the present invention is shown in Fig. 5. Said additive comprising 5, 0 ml 1, 1, 2, 2-tetraethoxyethane on 10, 31 diesel fuel, which is a ration of additive to fuel of 1 : 2060, i. e. 0, 485 % o. After adding the additive the value of emitted carbon particles decreases rapidly from 27, 56 carbon particles m~1 to 3, 78 carbon particles m~ within 21 min, a reduction of 86, 3 %. After another 91 min the value reaches 0, 82 carbon particles m~1, which is a total reduction of emitted carbon particles of 97 %.

Finally Fig. 6 shows the reduction of emitted nitrogen oxides (NOX) in % vol, ppm with time in the exhaust gas of an gasoline engine, type Ford Van V6 (1996), at increased idle with 1300 to 1370 RPM. Without the aditive, according to the invention a value of 340 % vol, ppm is measured. After the application of 0, 86 % o (= 50, 0 ml) 1, 1, 2, 2- tetramethoxyethane (TME) the value decreases after approximately 25 min to 135 % vol, ppm and after another 15 min the value drops to 37 % vol, ppm, which is a overall reduction of nearly 90 %.

In an especially preferred embodiment of the present invention, instead of glyoxal in aqueous solution, acetals and hemiacetals of glyoxal are added to the fuel mixture.

Acetal formation is a well known process in organic chemistry and is described, e. g., in "Organic Chemistry", Morrison and Boyd, 2nd Ed., 0969, page 633 et seq., and is used to describe compounds of the general type RCH (OR') 2. For example, in simples terms, acetaldehyde reacted with methanol in the presence of HCI yields acetaldehyde diethyl acetal (Acetal). Similarly, alcohols will be added to aldehydes to produce"hemiacetals" in a reaction catalyzed by both acids and bases. A hemiacetal in the presence of an alcohol and an acid catalyst is converted to an acetal. See also,"Organic Chemistry", Holt, Rinehart and Winston, 1964, pages 308-310.

Such acetals and hemiacetals can be prepared according to the state-of-the-art as described above. A particular way to manufacture this products is described as follow : 660 grams of molecular sieves 4 A is placed in a column reactor. A mixture of 600 grams glyoxal trimmer hydrated and 180 grams of amberlist 15 (ion-exchange resin) is filled on top of the molecular sieve in that column. The content of the column is heated up to 80°C. Then for example methanol or ethanol is pumped through the ion exchange resin as a catalyst and through the molecular sieve (water scavenger). The ratio of methanol to glyoxal is 4 mol, in the case of ethanol 12 mol.

During 16 hours the desired compound is obtained. The purification and the separation of the desired compound from the solvent occurs by distillation. Methanol and ethanol are removed at 40°C and 22 torr. The purification occurs at 58°C and 20 torr.

The acetals and hemiacetals used in the present invention are obtained by the acetalization of glyoxal with linear and/or branched alcools having Cl-Cl6 carbons such as methanol, ethanol, propanol, butanol, isopropanol, isobutanol, amylalcohol, with diols such as ethane diol, propane diol, butane diol, octane diol, neopentylglycol as well as triols such as glycerol. Furthermore mixtures of such mono-, di-, and trialcohols can be applied. Thus, the acetals and hemiacetals used in the present invention can have various alkoxy groups at the-CH2-CH2- ; unit of glyoxal. Thus different physical properties of the acetals and hemiacetals can be adjusted by the variation of the alkoxy groups.

While the invention has been shown in only two of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit thereof.