WO2007022962A1

WO2007022962A1 - Lubricant

Info

Publication number: WO2007022962A1
Application number: PCT/EP2006/008266
Authority: WO
Inventors: Bo Kylberg
Original assignee: Svenska Statoil Ab
Priority date: 2005-08-25
Filing date: 2006-08-23
Publication date: 2007-03-01
Also published as: BRPI0614886B1; EP1917332B1; BRPI0614886A2; EA018857B1; UA93382C2; EP1917332A1; EA200800541A1

Abstract

A lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb, and Bi.

Description

Lubricant

This invention relates to engine lubricant oils, in particular diesel engine lubricant oils, which are formed using at least two combustion enhancers which contain different metal ions. Preferably the combustion enhancers contain cerium ions and iron ions respectively.

Emissions from vehicles such as cars, lorries and buses, diesel railway engines, but especially older buses and lorries, often comprise a substantial amount of soot and non-combusted or partially combusted hydrocarbons, oxides of nitrogen (NOx), sulphur (SOx and sulphur salts) and metals like calcium (oxides and salts).

Most of the smog in urban areas comes from these vehicles, especially lorries and buses, both from motor oil smoke as well as smoke from the fuel itself. This problem is most acute in large metropolitan areas where older buses and trucks are used, such as in Central America and South America and many areas of the developing World. All over the World, but in particular in developing cities, there is a demand for cleaner air to alleviate the problems of smog.

Many inventors have tried to produce vehicles with lower emissions. Governments in the West now force vehicle and fuel manufacturers to make vehicles and fuels which give rise to very low levels of emissions. Modern engine technology combined with modern fuel preparation enables this to occur. It is most common therefore, for inventors to reduce emissions through the use of a highly efficient engine or using an ultra modern fuel.

Emissions are also reduced however, through the addition of additives to the fuel. US 2004/0261313 describes a fuel comprising an iron and/or a cerium compound which is used in connection with a gel. US 4474580 describes the use of a mixture of iron enolate and cerium enolate as a additive for fuel. US 4568360 describes further fuel additive compositions formed from mixed organometallic compositions. US 6096104 describes a mixture of at least three different metal compounds as fuel additives. US 2005/0160663 describes a cleaner burning diesel fuel employing a fuel borne metal catalyst.

The problem with adding these materials to fuels is that vehicles use a lot of fuel. Even at very low concentrations therefore, vehicles are still using very significant amounts of the additive to the fuel.

The above ways of reducing emissions rely heavily however on modern technology. In the Developing World, such technology is often too expensive to be used so the present inventors have sought ways to reduce emissions in older engines used throughout the Developing World which might run on lower quality fuel. It would be greatly beneficial therefore if emissions could be reduced without recourse to new engines, fuel additives or high grade fuel.

The present inventors have surprisingly realised that emissions reduction and numerous other benefits can be achieved by adding certain combustion enhancers to the engine lubricant oil as opposed to fuel. Since engines use much less lubricant oil than fuel, the amounts of additive which a vehicle uses are massively reduced. Moreover, the addition of the combustion enhancing package of the invention has been found to improve emissions in older vehicles making it ideal for use in the developing world.

There are of course, numerous patent applications filed for lubricating oils for vehicle engines. US 2149856 describes a lubricating oil which contains a mixture of beta diketone metal salts to prevent the formation of hard carbon deposits which can block valves and cause loss of compression. Some inventors have looked to reducing emissions by adding material to the lubricant in an engine. In DE 3926817, lubricating oils comprising cerium or cerium alloys for reducing pollutant content in exhaust gases are disclosed. EP-A-334248 describes an engine lubricating oil containing an iron compound such a ferrocene to help prolong the service life of the diesel particle filter. It is clearly desirable to be able to provide an engine lubricant that reduces emissions, in particular small particulates such as soot, partially combusted hydrocarbons and non-combusted hydrocarbons which contribute to engine smoke. Moreover, it would also be desirable for a lubricant to enhance the service life of an engine and maintain the valves of the engine clean. The inventors have surprisingly found that a lubricant oil comprising a particular mixture of combustion enhancers has the ability not only to reduce emissions but also to clean the engine in a vehicle. Summary of the invention

Thus, viewed from one aspect the invention provides a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb and Bi.

More specifically, the invention provides a lubricant oil comprising a first combustion enhancer comprising cerium ions; and a second combustion enhancer comprising iron ions. Viewed from another aspect there is provided the use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb and Bi; to reduce emissions, in particular smoke emissions from an engine. Viewed from another aspect the invention provides the use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi; to clean an engine, e.g. to reduce carbonaceous deposits within an engine. Viewed from another aspect the invention provides the use of a lubricant oil comprising at least two combustion enhancers to both clean the engine and reduce emissions from the engine wherein each combustion enhancer independently comprises a metal ion selected from the lanthanides or actinides, transition metals, Sn, Pb, Sb and Bi.

Viewed from another aspect the invention provides the use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi; to increase the service life of an engine, e.g. to increase the distance travelled by a vehicle running the engine between services.

Viewed from a further aspect the invention provides a method of reducing the emissions of an engine, in particular smoke emissions, comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb, and Bi.

In particular, the invention provides a method of reducing the smoke emissions from an engine by at least 5 % comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb and Bi.

Viewed from a further aspect the invention provides a method for cleaning an engine, e.g. removing carbonaceous deposits from an engine comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi.

Viewed from a further aspect the invention provides a method increasing the service life of a vehicle comprising running said engine in said vehicle using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi. Viewed from another aspect the invention provides a method for reducing lubricant oil consumption in an engine comprising running said engine in said vehicle using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi.

Viewed from a further aspect the invention provides the use of cerium and iron ions as an additive to a lubricant oil for cleaning an engine or reducing emissions therefrom.

Detailed description of the invention

The expression "lubricant oil" embraces any lubricant oil useful in a combustion engine such as a four-stroke or two-stroke engine, especially a diesel engine. The lubricant oil may be a synthetic or a mineral lubricant such as mineral HDDO (Heavy Duty Diesel Oil). The actual nature of the motor oil used is not itself critical. Engine oils are typically formed from a vacuum gas oil fraction of crude oil. A suitable oil for use in this invention is Statoil's PowerWay 15W-40.

By "reducing emissions from an engine" is meant that at least one of the undesirable components of the engine exhaust is reduced relative to an engine operating in the absence of a lubricant oil containing the additives of the invention (i.e. one operating with the lubricant oil but no additives). Thus for example, the NOx, particulates and/or smoke emitted by the engine during operation is reduced relative to an engine operating in the absence of a lubricant containing the additives oil of the invention. In particular, the lubricant oil with the combustion enhancing additives of the invention reduces smoke emissions from an engine.

By cleaning the engine is meant that carbonaceous deposits which form during engine operation, e.g. on the valve covers or crankcase, are prevented, reduced or eliminated relative to an engine operating in the absence of a lubricating oil with the additives of the invention (i.e. one operating with the lubricant oil but no additives).

By "increasing the service life of an engine/vehicle" is meant that the distance travelled by a vehicle, or the number of hours of operation of the vehicle, between services is increased relative to an engine operating in the absence of a lubricating oil of the invention (i.e. one operating with the lubricant oil but no additives).

By "reducing lubricant oil consumption" is meant that an engine using the lubricant oil of the invention uses less lubricant oil than one operating in the absence of a lubricating oil of the invention (i.e. one operating with the lubricant oil but no additives).

The lubricant oil of the invention comprises a mixture of combustion enhancers comprising metal ions selected from transition metals, actinides, lanthanides or Sn, Pb, Sb, and Bi. The composition therefore comprises at least a first combustion enhancer and a second combustion enhancer. The first combustion enhancer preferably comprises at least one metal ion selected from lanthanides or actinides. Whilst the first combustion enhancer can comprise a mixture of metal ions, preferably the first combustion enhancer comprises a single metal ion (i.e. cerium ions only as opposed to a mixture of cerium and europium ions for example). It is preferred if this first combustion enhancer comprises a metal ion which has various stable oxidation states, e.g. two or three stable oxidation states. Suitable metal ions therefore particularly include those from the lanthanide series. Highly preferred metal ions include Ce or Eu ions, especially Ce³⁺. Ce can take the 3⁺ or 4⁺ oxidation state and is the most preferred metal ion of use in the first combustion enhancer.

It is also highly preferable that the metal ion is present in the combustion enhancer in a form which is readily soluble or dispersible in the lubricant oil. The metal ions may therefore be in a molecular or particulate form which is soluble or dispersible in lubrication oil. The combustion enhancer is preferably a salt or a complex. Preferred counter ions to the metal ion therefore include alkyl sulphonates (e.g. ethyl sulphonate ), alkylbenzene sulphonates and phenates. Alternatively, the ion may be coordinated as part of a complex such as a metallocene, an enolate, carboxylates or acetylacetonato and other such ligands. Most preferably the first combustion enhancer is a cerium alkylbenzene sulphonate. It has been surprisingly found that the first combustion enhancer operates most effectively within the cylinder area of an engine.

The second combustion enhancer comprises a metal ion preferably selected from transition metals, Sn, Pb, Sb and Bi. Whilst the second combustion enhancer can comprise a mixture of metal ions, preferably the second combustion enhancer comprises a single metal ion (e.g. iron ions only as opposed to a mixture of iron and vanadium ions for example). It is preferred if this second combustion enhancer comprises a metal ion which has various stable oxidation states, e.g. two or three stable oxidation states. Suitable metal ions therefore particularly include those from the first transition series (Sc to Zn), in particular those of the first row of transition elements and those of groups 8 and 10. Especially preferred are compounds of vanadium (V), manganese (Mn) and nickel (Ni), palladium (Pd), platinum (Pt) and compounds from Group 8: iron (Fe), ruthenium ( Ru) and osmium (Os). Most preferably the second combustion enhancer comprises iron ions, especially Fe²⁺ ions.

Again, it is highly preferred if the second combustion enhancer is in a form which is soluble or dispersible in the lubricant oil. Preferred counter ions therefore include sulphonates, alkyl sulphonates, alkylbenzene sulphonates, naphthenates, hydroxides and carbonates. Alternatively, the ion may be coordinated as part of a complex such as a metallocene like ferrocene, enolate, carboxylates, alkyl carboxylates, acetylacetonato, or bipyridine. Most preferably the second combustion enhancer is an iron alkylcarboxylate or ferrocene.

It has been surprisingly found that the second combustion enhancer operates most effectively within the crankcase ventilation system of an engine.

Suitable additives containing, for example, cerium ions or iron irons are available commercially from suppliers. The combustion-enhancing additives of use in the lubricant oil act as pro- catalysts. When the engine is in operation, the combustion enhancers combust at the intended site, e.g. in the crankcase ventilation chamber or the cylinders of the engine, generating the active catalyst.

The active catalyst is thus typically a metal, e.g. iron or cerium, oxide, e.g. Fe₂O₃, CeO₂, Ce₂O₃. This could be in molecular, nano-particulate, particulate or in any other form of aggregated metal oxide. Ideally however, the catalyst generated from the combustion enhancing additives of the invention is nanoparticulate, e.g. less than 500 nm in particle size, especially less than 250 nra in particle size.

The reaction catalysed by the metal oxide is the formation of carbon dioxide (CO₂) and/or carbon monoxide (CO) by the catalyst-assisted combustion of heavy hydrocarbon and/or coke residues originating from incompletely combusted fuel and/ or lubricant base oil, thus eliminating all forms of carbon-based or carbon- containing smoke-generating particles, aggregates, aerosols etc.

The weight ratio of the combustion enhancers to each other may vary from 1 :1000 to 1000:1 by weight, preferably 1 :100 to 100:1, more preferably 1 :50 to 50:1, especially 1 :25 to 25:1, most especially 1 :10 to 10:1. It is preferred if the second combustion enhancer is present in excess compared to the first combustion enhancer. The most preferred weight ratios are therefore first enhancer: second enhancer 1 : 100 to 1 : 1 , preferably 1 :50 to 1 :5, more preferably 1 :25, to 1 :8, e.g. 1 :10.

The amount of each combustion enhancer employed (in weight terms) in the lubricant oil may be in the range 0.1 to 2000 ppm, e.g. 1 to 1000 ppm, preferably 1 to 100 ppm with respect to the metal ion in question.

According to a preferred embodiment of the first aspect of the present invention there is provided a lubricant wherein the first combustion enhancer, preferably operating from the cylinder area of an engine, is present in a concentration of from 0.1 to 1000 ppm, preferably from 1 to 100 ppm, more preferably 2 to 50, most preferably from 5 to 12 ppm with respect to the metal ion in question.

Preferably the second combustion enhancer, ideally operating from the crankcase ventilation of an engine, is present in a concentration of from 0.1 to 2000 ppm, preferably from 1 to 1000 ppm, more preferably from 2 to 200 ppm, especially 5 to 150 ppm, most especially from 10 to 120 ppm with respect to the metal ion in question.

The lubricant oil of the invention may contain other standard lubrication oil additives in addition to the combustion enhancers herein described. According to a preferred embodiment of the invention, there is provided a lubricant oil additionally comprising a noise reduction agent, preferably a pour point depressant (PPD). Said PPD is preferably a short chained poly(alkyl-methacrylate) (PAMA). Most preferably said PPD is added so that a relatively high concentration is obtained, e.g. 1 to 5 % approximately 3% by weight in the oil. Without wishing to be limited by theory, it is believed that the addition of these high amounts of noise reduction agent make the oil more tacky whilst also serving to reduce noise.

Viewed from another aspect therefore the invention provides the use of a pour point depressant as a noise reducing additive. The fuel in the engine where the lubricant according to the invention may be used may be any fuel used for engines in vehicles, and may preferably be a liquid hydrocarbon fuel which may be a hydrocarbonaceous petroleum distillate fuel such as motor gasoline as defined by ASTM Specification D481 or diesel fuel or fuel oil as defined by ASTM Specification D975. Normally liquid hydrocarbon fuels comprising non-hydrocarbonaceous materials such as alcohols, ethers, organo- nitro compounds and the like (e. g., methanol, ethanol, diethyl ether, dimethyl ether, methyl ethyl ether, methyl tert-butyl ether, nitromethane) are also included as are liquid fuels derived from vegetable or mineral sources such as corn, alfalfa, shale and coal. Normally liquid hydrocarbon fuels, which are mixtures of one or more hydrocarbonaceous fuels and one or more non-hydrocarbonaceous materials, are also included. Examples of such mixtures are combination of gasoline and ethanol, diesel fuel and ether, diesel fuel and methyl esters of vegetable or animal oils. Included are fuels known as gas-to-liquid fuels, GTL. The fuel may also be lead containing or lead free. The fuel may also be an emulsified fuel, either a macro- emulsion, a micro-emulsion or combinations thereof.

It will be appreciated that when an engine is operating there will be a degree of mixing between the lubricant oil and the fuel. If the fuel containing combustion enhancing additives as described herein, these could therefore accidentally be mixed with the lubricant oil. Such a mixture of fuel and lubricant oil does not constitute a lubricant oil of the invention. The invention requires that the additives are present in the lubricant oil added to the vehicle not in the fuel added to the vehicle. The invention therefore covers a lubricant oil as hereinbefore described when not in the engine, e.g. packaged in a container. The lubricant oil of the invention can be used in conjunction with any internal combustion engine, e.g. four-stroke engines but also two-stroke engines, especially a diesel engine. The vehicle may be a road or railroad vehicle, ship/boat or aircraft, especially a bus. The lubricant oil of the invention is of particular utility with older engines, e.g. pre 2000 engines, preferably pre 1997 engines, more preferably pre 1995 engines, especially pre 1993 engines.

It will be appreciated that an old engine will undergo reconditioning and repair however, this does not detract from the fact that the engine is still old. The date of the engine for the above purposes therefore is the date on which it first came into service, e.g. as evidenced by the serial number on the engine.

Alternatively viewed, the engine is one which has done a large mileage, e.g. at least 75,000 km, preferably at least 100,000 km preferably at least 125,000 km. Such engines are used in vehicles throughout the Developing World. It is especially preferred if the lubricant oil is employed in a large diesel engine vehicle such as a bus or lorry or an agricultural vehicle, or a railroad engine

Viewed from another aspect therefore the invention provides an engine comprising the lubricant oil of the invention. It has been surprisingly found that when the lubricant oil of the invention is employed in an engine, especially an old engine, remarkable improvements are observed. Firstly, the engine emissions, in particular smoke emissions are greatly reduced. In addition, the engine cleanliness is markedly improved. Thus, where previously sludge deposits built up, no such deposits are formed, hi fact, the examples show that the lubricant oil of the invention can actually enable removal or reduction in sludge deposits from an engine. When applied in newer engines, cleanliness is improved as to allow the usage of fuels of a wider specification and/or poorer quality.

As noted below, this leads to many consequential advantages such as improved fuel economy, less servicing, fewer oil changes, less down time, less labour to maintain a fleet of vehicles and so on.

The reduction in smoke emissions, measured as described in example 7 using a smoke meter, can be at least 3%, e.g. at least 5 %, e.g. at least 10 %, preferably at least 20% relative to an engine run on an otherwise identical lubricant oil without the combustion enhancers of the invention. The smoke eliminated by the invention may derive from the incomplete combustion of the oil itself or from the fuel. Reduction of smoke from fuel is particularly effective in engines using a closed crankcase ventilation system.

The additives of the present invention can reduce lubricant oil consumption by at least 3%, e.g. at least 5 %, e.g. at least 10 %, preferably at least 20% relative to an engine run on an otherwise identical lubricant oil without the combustion enhancers of the invention.

The additives of the present invention can increase service life of an engine by at least 3%, e.g. at least 5 %, e.g. at least 10 %, preferably at least 20% relative to an engine run on an otherwise identical lubricant oil without the combustion enhancers of the invention. The additives of the present invention can reduce carbonaceous deposits within an engine, e.g. carbonaceous deposits on a cylinder by at least 3%, e.g. at least 5 %, e.g. at least 10 %, preferably at least 20% relative to an engine run on an otherwise identical lubricant oil without the combustion enhancers of the invention.

The additives of the present invention can increase the distance travelled by a vehicle between oil changes by at least 3%, e.g. at least 5 %, e.g. at least 10 %, preferably at least 20% relative to an engine run on an otherwise identical lubricant oil without the combustion enhancers of the invention.

The lubricant of the invention can be manufactured simply be adding the combustion enhancers of the invention in appropriate amounts to a motor oil. The market is replete with appropriate motor oils such as PowerWay 15 W-40 sold by Statoil.

It is also within the scope of some aspects of the invention for the combustion enhancing additives to be sold in a form ready for addition by the user to a standard motor oil, e.g. a diesel oil. Thus viewed from another aspect the invention provides a kit comprising a source of cerium ions and a separate source of iron ions with instructions for how much of each to add to a fixed amount of motor oil, e.g. to achieve a concentration of 10 ppm Ce ions and 100 ppm Fe ions.

The invention is further described in the following non-limiting examples in conjunction with the appended figures.

Brief description of the figures

Fig. 1 shows the setup of the primary test set out in example 1. Fig. 2 - 7 show results from the test set out in example 5. More specifically, Figures 2 to 4 describe CO, CO₂, smoke and hydrocarbon contents for closed crankcase ventilation for lubricant oils of the invention in comparison to an oil without the additives. Figures 5 to 7 describe CO, CO₂, smoke and hydrocarbon contents for closed crankcase ventilation for lubricant oils of the invention in comparison to an oil without the additives.

Figs 8 to 18 are photographs of various parts of the engine of the buses used in the tests in Example 6 before, during and after the tests. More specifically, Figures 8a and 8b show the valve cover of Bus 05178 before the use of the lubricant oil of the invention (called Cityway in the figures). Sludge was present to a depth of 15 mm.

Figures 9a and 9b show the cylinder head of Bus 05178 before the use of the lubricant oil of the invention. As is clear, cylinder head features are not visible. Figure 10 shows the valve cover of Bus 05178 after 28,000 km using the lubricant oil of the invention.

Figures 11a and 1 Ib show the cylinder head of Bus 05178 after 28,000 km using the lubricant oil of the invention. Cylinder head features are now visible.

Figure 12 shows the valve cover of Bus 05178 after 33,000 km using the lubricant oil of the invention.

Figures 13a and 13b show the cylinder head of Bus 05178 after 33,000 km using the lubricant oil of the invention. Cylinder head features are now visible.

Figures 14 a-c show a side by side comparison of the valve cover before, after

28,000 km and after 33,000 km using the lubricant oil of the invention. Figure 15a, 15b, 16a and 16b show the valve cover of Bus 01801 after 13,000 km and 26,000km using the lubricant oil of the invention.

Figure 17 shows the cylinder head of bus 01801 after 13,000 km using the lubricant oil of the invention.

Figures 18a and 18b show the cylinder head of bus 01801 after 13,000 km and 26,000 km using the lubricant oil of the invention

Figs 19 to 31 show the emission results from Example 7 in graphical form. More specifically, Figure 19 shows CO emissions from the 60 km/h test.

Figure 20 shows CO emissions from the Braunschweig test.

Figure 21 shows hydrocarbon emissions from the 60 km/h test.

Figure 22 shows hydrocarbon emissions from the Braunschweig test. Figure 23 shows NOx emissions from the 60 km/h test.

Figure 24 shows NOx emissions from the Braunschweig test.

Figure 25 shows particle emissions from the 60 km/h test.

Figure 26 shows particle emissions from the Braunschweig test.

Figure 27 shows fuel consumption from the 60 km/h test. Figure 28 shows fuel consumption from the Braunschweig test.

Figure 29 shows particle number and size distribution from the 60 km/h test.

Figure 30 shows particle number and size distribution from the Braunschweig test.

Figure 31 shows smoke measurement from the 60 km/h test.

Figure 32 shows the Braunschweig bus test cycle

Examples

Example 1

Primary tests were run at a bus dismantling company in Sweden. The bus dismantling company provided 3 buses which were ready for scrap having reclined Volvo motors. A test method especially adapted for heating oil was used, with a minor modification. The oil is burnt in a heating oil furnace (1) and samples taken from the exhaust thereof (2) using a True Spot smoke tester (3). 15 pump strokes were used for sampling, (see Figure 1). The exhaust gas is drawn across a filter membrane by the pumping action. This filter is then checked for colour changes and/or the appearance of particles. Any particles found may be counted and sized by optical microscopy. The test output is a pass/fail rating. Additives were added to the engine oil in different concentrations and the effect upon smoke generation was observed.

In a first screening test, one additive was used as listed below: Bus No. Registration number: Stock solution for test containing:

1 MMT 082 Ferrocene, 150 ppm Fe ions

2 DHA 422 Cerium (III) alkylbenzene sulphonate, 30 ppm Ce ions

3 OSA 091 PIB (poly iso-butylene) + detergent

In this first test, it was found that both ferrocene and cerium compound had a positive effect on the suppression of smoke, but PIB and detergent gave no effect (Bus 3).

Example 2

In a second screening test, various additives were tested in various concentrations and it was found that the combination of cerium and ferrous additives worked best. Smoke generation was suppressed as a function of increasing cerium ion concentration until a plateau was reached and the effect levelled off. The cerium additive used was cerium alkylbenzene sulphonate. The effect of added iron additive was similar to that of cerium, with the addition of a second phase effect where the iron additive started to affect the fuel-generated smoke (i.e. another mechanism). This effect could be turned on and off by opening and closing the crankcase ventilation. The iron additive used was ferrocene. It was observed that smoke from the fuel was significantly lowered. This seemed to be related to the crankcase ventilation into the inlet system. A possible relation was observed involving that the cerium additive worked in the fluid phase in the cylinders and inlet valves and the ferrous additive worked in the mist phase in the crankcase ventilation and influenced the combustion of fuel in a positive way.

Example 3

A third set of tests was performed on buses 1 and 2. The buses were started and run warm by idling for approx. 40 minutes whereupon a first smoke sample was drawn from the exhaust pipe and at the same time a first dose was added with respective additive directly into the lubricant tank of the bus. The additive was a premix of approx. 1 dl engine oil with cerium and iron additives (same components as in Example 1 and 2) giving a final concentration in the engine oil (approx 18 liter of oil in the engine) of 4 ppm cerium ions and 10 ppm Fe ions. After a further approx. 70 minutes a second smoke sample was taken out in the same manner as above and a further dose of the same additive was added, resulting in a concentration in the engine oil of approx. 8 ppm cerium ions and 20 ppm iron ions.

Approx. 35 minutes later a third and last smoke sample was taken out and the bus engines were stopped.

The tests on the two buses showed markedly enhanced results. After the addition of the second dose, the smoke had disappeared and thus the problem of visual smoke was eliminated.

A separate oxidation test was performed on an engine oil with these additives. The engine oil PowerWay 15 W-40 with these additives was tested regarding RBOT (Rotary Bomb Oxidation Test) and flash point without any measurable changes.

Example 4 Progression of cylinder wear during oil combustion.

The test was performed on a Lister Petter diesel engine, model 4X90, performing a running cycle simulating city bus traffic, for 536 h. The engine was a new engine that had only about 10Oh running time before the test. The test oil was the new oil claimed in the invention, in a formulation containing cerium alkylbenzene sulphonate (10 ppm cerium (III) ions) and iron (II) alkylcarboxylate (100 ppm iron ions) added to a standard motor oil PowerWay 15W-40. . The test oil was put into the crankcase. The test fuel contained 440 ppm sulphur.

As can be seen from Table 1 below showing wear, no wear incurred during the test.

Table 1. Wear test in a Lister Petter diesel engine after 536 h running with a cycle simulating bus in city traffic. Cylinder measurings on the Lister Petter engine in connection with lubricant test.

The hypothesis investigated in this test was a concern that the lubricating film would disappear and that this would result in increased wear on the cylinders. This hypothesis was thus falsified.

Example 5 Exhaust Gas Analysis

Using the engine of Example 4, analysis of the exhaust gases was made by using a special instrument for emissions analysis provided by Boo Instrument AB in Nacka, Sweden, a so-called multi-instrument. The test oil was identical to the oil utilized in Example 4, and was tested under the name "PowerWay Low Smoke" (abbreviated LS)

The characteristics of PowerWay Low Smoke 15W-40 are given below, in Table 2. PowerWay is a trademark owned by Statoil. In the test there was a concentration of 10 ppm of the cerium ions and 100 ppm of the iron ions in said PowerWay Low Smoke 15W-40.

The following engine oil products/diesel fuel product qualities were used during the test;

1 PowerWay LS, 440 ppm S, with closed crankcase ventilation

2 PowerWay LS, 440 ppm S, without closed crankcase ventilation

3 PowerWay LS, 919 ppm S, with closed crankcase ventilation

4 PowerWay LS, 919 ppm S, without closed crankcase ventilation

5 PowerWay Standard, 440 ppm S, with closed crankcase ventilation

6 PowerWay Standard, 440 ppm S, without closed crankcase ventilation

Products 1, 2, 3 and 4 correspond to an oil (PowerWay) with low smoke additives according to the present invention, in combination with two different diesel qualities containing 440 ppm sulphur (S) and 919 ppm sulphur, respectively. The additives used in PowerWay were 10 ppm cerium ions as the alkylbenzene sulphonate, and 100 ppm iron ions as the alkylcarboxylate. Products 5 and 6 represent standard HDDO oil without any additives of the invention.

The test results in Table 2, with closed crankcase ventilation, are also illustrated in Figures 2-4. The test results in Table 2, with open crankcase ventilation, are illustrated in Figures 5-7. In these figures the following abbreviations are used:

PW Standard PowerWay 15 W-40

PW LS 1 PowerWay Low Smoke and 440 ppm Sulphur fuel

PW LS 2 PowerWay Low Smoke and 919 ppm Sulphur fuel

The results from the exhaust gas test show that the smoke was influenced in a positive direction. The results in Table 2 demonstrate improved fuel economy since the concentration of CO and CO₂ is lower when additives are used than without additives. NOx and HC concentrations are also reduced, resulting in emissions that are less harmful to the environment. It is also known and can be seen from Table 2, that the smoke index will increase when the amount of sulphur in the fuel decreases.

These results are obtained using a new modern engine. For older, worn engines benefits from the invention are likely to be much higher. Thus, it can be concluded that the present invention can make a substantial contribution to solving the problem of smelly and unhealthy exhaust gases and soot in big cities and densely populated areas, in particular where the vehicles are of an older date and therefore the problems with air pollution are substantive.

Example 6

Moscow Bus Test - Engine Cleanliness

The lubricant oil of the invention was used in tests on Mosgortrans buses. Mosgotrans Depot No. 5 bus reference 05178 had completed 135,600 km before the trial began. The lubricant oil was changed for the oil of the Invention (PowerWay

15W-40 with 10 ppm cerium ions as the alkylbenzene sulphonate and 100 ppm iron ions as the alkyl carboxylate. After 8000 km the oil was changed due to defective injectors. After 33,000 km the state of engine was reviewed. The photographs in Figures 8 to 13 show various parts of the engine before the use of the oil of the invention and after 28,000 km and 33,000 km. The removal of engine sludge is clearly shown.

A similar test was conducted on Mosgotrans Depot 18 Bus No. 18101. After changing to the lubricant oil of the invention and a further oil change after 13,000 km, results are presented after 26,000 km and are shown in Figures 14 to 18.

The striking engine cleaning capabilities of the lubricant oil of the invention make it a very attractive oil for use by bus companies and the like. A cleaner engine means an engine that may use less fuel and one which has significantly lower emissions. A clean engine means longer engine life, the use of fewer spare parts, less servicing and consequent reduction in servicing manpower. Due to the clean engine, lubricating oil actually needs to be changed less frequently than with conventional oils meaning less lubricant oil used and less labour for oil changing.

Fewer oil changes means less down time for a vehicle and hence the possibility of maintaining a smaller fleet.

Example 7

Emissions from Old Bus A Volvo B10M-70 Bus was used in this test along with Commercial diesel fuel with 500 ppm sulphur. Three different lubricant oils were tested.

1 PowerWay 15W-40 2. PowerWay 15W-40 with 10 ppm Ce ions (as the alkylbenzene sulphonate) and 100 ppm Fe ions (as the alkylcarboxylate) 3. PowerWay 15W-40 combined with 20 ppm Ce ions (as the alkylbenzene sulphonate) and 200 ppm Fe ions (as the iron alkylcarboxylate).

The vehicle specification is given in Table 4.

Table 4

Chassis dynamometer

The bus was tested on a cradle dynamometer with 515 mm roller diameters at ambient temperature 22 °C. The setting of dynamometer was done by simulating of an overloaded vehicle road conditions (using typical vehicle inertia and road load curve).

Driving cycle

Steady state test and transient test were carried out in this project. The steady state test was performed with the vehicle at 60 km/h for 10 minutes. The transient test was done using a Braunschweig bus test cycle. The transient Braunschweig vehicle cycle simulates realistic road load conditions as shown in Figure 32. Exhaust emission sampling and measurement

Emissions of CO, CO₂, HC, NO_x, particle mass (PM), particle number and size distribution and smoke were measured. Smoke measurement was performed only on the 60 km/h constant speed tests.

The measurement of smoke was performed via direct sampling of the raw exhaust gas stream. The measurement of CO, CO₂, HC, NO_x, particle mass (PM), particle number and size distribution are carried out using a diluted sampling method.

The diluted sampling method is based on a full flow dilution system, i.e. the total exhaust is diluted using Constant Volume Sample (CVS) concept. The total volume of the mixture of exhaust and dilution air is measured by a Critical Flow Venturi (CFV) system.

Horiba Mexa 9000 series (9400D) was used for CO, HC, NO_x and CO_x analysis. The fuel consumption was calculated using a carbon balance method. AVL Smoke Meter 415 S was used for smoke measurement. The particle number and size- distribution measurements were carried using an Electrical Low-Pressure Impactor (ELPI) (Dekati). The instrument provides a particle size resolution of 7 ran to 6 μm.

The measurement principles for the different components are given in Table 5 below.

Table 5: Measurement principles

Test program

The testing of lubricant oil was carried according to the following steps:

1. PowerWay l5W-40

2. PowerWay 15W-40 plus 100 ppm iron ions (as the alkyl carboxylate) and 10 ppm cerium ions (as the alkylsulphonate). (In this test the oil was called Cityway in the figures) 3. PowerWay 15 W-40

4. PowerWay 15W-40 plus 200 ppm iron ions (as the alkyl carboxylate)and 20 ppm cerium ions ( as the alkylbenzene sulphonate) (Called SL 06-306 in the figures)

5. PowerWay 15 W-40

For each step a test programme was performed according to the following procedure:

1. Change oil (drain-flush-drain-refill)

2. Conditioning vehicle at 60 km/h for 30 minutes 3. Emission test at 60 km/h for 10 minutes

4. Emission test using Braunschweig bus test cycle

Results

The emission results from the constant speed tests and Braunschweig bus cycle tests are illustrated in Figures 19-31 and Tables 6-9. For the PowerWay 15W-40 triple tests have been performed, thus the standard deviations are illustrated in the figures.

Table 6: CO, HC, NO_x, CO₂ PM emissions, fuel consumption and smoke from 60 km/h tests.

Table 7: Particle number and size distribution from 60 km/h tests.

Table 8: CO, HC, NO_x, CO₂ PM emissions, fuel consumption from Braunschweig tests.

Table 9: Particle number and size distribution from Braunschweig tests.

Claims

1. A lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb, and Bi.

2. A lubricant according to claim 1 , wherein the first combustion enhancer comprises a cerium compound.

3. A lubricant according to claim 1 or 2 wherein the second combustion enhancer comprises an iron compound.

4. A lubricant according to claim 1 to 3, wherein the metal ions of the first combustion enhancer are present in a concentration of from 0.1 to 1000 ppm.

5. A lubricant according to claim 4, wherein the metal ions of the first combustion enhancer are present in a concentration of from 1 to 20 ppm.

6. A lubricant according to claim 1 to 5, wherein the metal ions of the second combustion enhancer are present in a concentration of from 0.1 to 2000 ppm.

7. A lubricant according to claim 6, wherein the metal ions of the first combustion enhancer are present in a concentration of from 1 to 200 ppm.

8. A lubricant according to claim 2 to 7, wherein the cerium compound is a cerium salt.

9. A lubricant according to claim 2 to 8, wherein the cerium compound is a cerium alkylbenzene sulphonate.

10. A lubricant according to claim 3 to 9, wherein the iron compound is a complex of iron.

11. A lubricant as claimed in claim 10 wherein the complex is ferrocene or an iron carboxylate.

12. A combustion engine comprising a lubricant according to any one of claims 1 to 11.

13. Use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb and Bi; to reduce emissions, in particular smoke emissions from an engine.

14. Use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi; to clean an engine, e.g. to reduce carbonaceous deposits within an engine.

15. Use of a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi; to increase the service life of an engine, e.g. to increase the distance travelled by a vehicle running the engine between services.

16. A method of reducing the emissions of an engine, in particular smoke emissions, comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb, and Bi.

17. A method of reducing the smoke emissions from an engine by at least 5 % comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion different from the first combustion enhancer selected from the transition metals, Sn, Pb, Sb and Bi.

18. A method for cleaning an engine, e.g. removing carbonaceous deposits from an engine, comprising running said engine using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi.

19. A method increasing the service life of a vehicle comprising running said engine in said vehicle using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi.

20. A method for reducing lubricant oil consumption in an engine comprising running said engine in said vehicle using a lubricant oil comprising a first combustion enhancer comprising at least one metal ion selected from the lanthanides or actinides; and a second combustion enhancer comprising at least one metal ion selected from the transition metals, Sn, Pb, Sb, and Bi.

21. Use of cerium and iron ions as an additive to a lubricant oil for cleaning an engine or reducing emissions therefrom.

22. A kit comprising a source of cerium ions and a separate source of iron ions with instructions for how much of each to add to a fixed amount of motor oil.

23. Use of a lubricant oil comprising at least two combustion enhancers to both clean the engine and reduce emissions from the engine wherein each combustion enhancer independently comprises a metal ion selected from the lanthanides or actinides, transition metals, Sn, Pb, Sb and Bi.