How to commission an exhaust particulate filter

Abstract

To provide a method of commissioning a particulate filter for an exhaust system of an internal combustion engine.SOLUTION: Following steps are provided as a method of improving filtration efficiency of a particulate filter. The method includes: (i) a step of making a gas flow pass through an uncarbonized new particulate filter or decarbonized readjusted particulate filter; (ii) a step of releasing the flow of metallic oxide particles to the gas flow at an upstream side of the particulate filter during a single discharge period sufficient to accumulate the metallic oxide particles on the uncarbonized or decarbonized surface of a channel of the filter exposed to the gas flow; and (iii) a step of operating the particulate filter by an exhaust gas discharged from an internal combustion engine of a device in operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to improving the control of hydrocarbon particulate emissions from devices powered in whole or in part by internal combustion engines operating on gaseous or preferably liquid hydrocarbon fuels, particularly spark-ignited internal combustion engines operating on gasoline fuel. In particular, the present invention provides for improving the operating efficiency of particulate filters installed in the exhaust systems of such devices by a commissioning method for such filters that results in a measurable increase in filtration efficiency for hydrocarbon particulate emissions. This commissioning method allows such filters to reach higher filtration efficiencies sooner after installation, with a low associated exhaust backpressure build-up that, if not reduced, can adversely affect engine operation during service. [Background technology]

[0002] The use of particulate filters in the exhaust system of diesel engines is a well-known hardware strategy for controlling tailpipe hydrocarbon particulate emissions. For many years, diesel engines have been widely known as a source of hydrocarbon particulates, in part due to the inherent characteristics of compression ignition combustion, and in part due to engine design strategies that favor lower peak combustion temperatures to reduce harmful nitrogen oxides in exhaust gas emissions. This emission balance effect has meant that engine exhaust particulate levels have increased due to the NOx particulate trade-off, resulting in the need for exhaust aftertreatment to subsequently reduce tailpipe particulate emissions to acceptable levels. Legislation of increasingly stringent emission limits for hydrocarbon particulate emissions has also prompted the adoption of diesel particulate filters.

[0003] Diesel particulate filters are essentially fine sieves for the hydrocarbon particulates entrained in the exhaust gas mixture emitted from the engine. Commercially available filters are typically ceramic monoliths or metal wire structures that provide a series of fine channels through which the exhaust gas mixture passes. The hydrocarbon particulates fed into the flowing gas stream are bound to the surfaces of the filter channels. Over time, the hydrocarbon particulates that build up on the filter in this way must be removed to maintain effective filter operation, and removal is typically accomplished by a secondary combustion method of the filter called regeneration. In regeneration, the collected particulates, which are hydrocarbonaceous (sometimes called carbonized deposits, or "soot"), are burned with oxygen in the flowing exhaust gas stream. Conditions favorable for this combustion are created by post-injecting fuel into the exhaust gas stream, or by using heaters around the particulate filter to raise the exhaust gas temperature to autoignition levels of the collected hydrocarbonaceous material (around 600° C. or higher), or by using catalytic materials that are either incorporated into the filter or fed via the fuel or into the exhaust gas stream. This cyclical method of carbonization (due to particulate accumulation) and regeneration is a long-term feature of particulate filter use, and various hardware and engine systems have been developed to effectively manage it. However, in-situ regeneration of the vehicle typically does not completely decarbonize the filter, leaving some residual carbonization. Filters can be periodically removed from the vehicle and reconditioned to return them to a decarbonized state. Given the high cost of new filters, reconditioned filters can also be utilized as spare parts.

[0004] While particulate emission control has typically focused on diesel engines, more recently the use of direct injection gasoline engines and interest in ever stricter emissions legislation has called into question the levels of hydrocarbon particulate emissions from other clean fuel engines such as gasoline and gas engines. Particulate filters are now also being designed for use in such engines, and the highly adaptable nature of exhaust aftertreatment has highlighted particulate filters as a primary emissions control strategy across a range of internal combustion engine types.

[0005] In addition to carbonization during use, particulate filters are also susceptible to the gradual accumulation of "ash" deposits. These deposits are in the form of metal oxides and other salts resulting from the steady combustion of small amounts of metal-based lubricant additives, such as surfactants. These metal-based additives are typically salts of alkali or alkaline earth metals found in the lubricating oil that coat combustion chamber surfaces, such as cylinder walls, and are gradually consumed in small amounts during engine operation. In addition, metal residues from engine wear contribute to ash deposits. This long-term ash buildup has the effect of clogging the particulate filter channels and reducing the effective filter volume, which in turn builds up higher exhaust backpressure, thus affecting gas flow through the particulate filter and engine operation.

[0006] A fundamental design consequence of long-term carbon residue and ash buildup in particulate filters is the need to build tolerances into the as-manufactured filter channel dimensions to allow for this deposit to build up over time during operation. In doing so, manufacturers face another operational design trade-off. A filter manufactured with finer channel dimensions will have higher filtration efficiency when new, allowing vehicle manufacturers to meet lower tailpipe particulate emissions when the filter is fresh from the factory. However, it will also be more susceptible to filter clogging, and long-term buildup of carbon residue and ash will narrow the channels to the point where exhaust gas flow through the filter is seriously impeded, thereby adversely affecting engine operation over time as exhaust backpressure increases unacceptably. This can result in long periods of unscheduled maintenance and customer dissatisfaction. As a result, manufacturers generally account for the effects of long-term deposits by producing filters with as-manufactured channel dimensions that are designed to accommodate some degree of ash buildup over long-term operation. While this reduces the risk of long term problems developing, the resulting factory filter may have a lower filtration efficiency and provide a less significant initial contribution to tailpipe emissions control or may even fail required emissions certification.

[0007] Thus, there is a need in the art for a strategy to improve out-of-the-box filtration efficiency to more aggressively control hydrocarbon particulate emissions without creating an initial backpressure increase that can adversely affect exhaust gas flow and engine operation, particularly at higher speeds and loads where higher levels of hydrocarbon particulates are generated, while allowing particulate filters designed with tolerances in channel dimensions to accommodate long-term residual deposits.

[0008] A paper published by the Society of automotive Engineers on October 17, 2016 (cited as Shae, H., Lam, W., Remias, J., et al., "Effect of Lubricant Oil Properties on the Performance of Gasoline Particulate Filter (GPF)," SAE Int. J. Fuels Lubr. 9(3):650-658, 2016, https: / / doi.org / 10.4271 / 2016-01-2287) proposes introducing a high percentage (around 2% by weight) of lubricant oil treated with a metal-containing lubricant additive into the engine fuel to accelerate the natural deposition of lubricant-derived ash deposits and thereby increase filtration efficiency. However, such an approach has several drawbacks.

[0009] First, the introduction of lubricating oil introduces a significant amount of base hydrocarbon-based oil of lubricating viscosity into the fuel. This is a heavier organic fraction that is less volatile and flammable than base hydrocarbon-based fuel, and therefore cannot be practically fed into the engine with gaseous fuel, does not burn as cleanly as liquid fuel, and is counter to the basic objective of reducing particulate and other emissions. Also, because the base lubricating oil is less volatile and has a different chemical composition, it is more susceptible to the formation of sticky, carbonaceous deposits on critical surfaces of the fuel system, such as fuel injection nozzles, which are themselves manufactured with small operating tolerances. The accumulation of deposits in this area impairs fuel flow and combustion efficiency. Also, the heavier components in the lubricating oil are more likely to separate from the fuel and lead to filterability problems in the fuel system. Thus, the introduction of lubricating oil into the fuel, especially in the recommended amount, brings about a number of associated operating concerns.

[0010] Secondly, typical additives used in lubricating oils include metal surfactants and other ash-forming additives, and also contain elements such as sulfur and phosphorus. The oxidation products of sulfur and phosphorus that inevitably form in the combustion chamber are themselves detrimental to emission control, as they are acidic and toxic to platinum or other precious metal-based catalysts that are placed elsewhere in the exhaust system to control gas emissions. In addition to small amounts being entrained in the oil consumed, the net increase in these elements delivered to the combustion chamber by adding them to the fuel results in increased acidity and potential catalyst poisoning. Also, the typical lubricant metal content that ends up deposited as ash in the particulate filter leads to an increase in exhaust system back pressure over time.

[0011] Third, the use of 2% by mass of lubricating oil in the fuel increases fuel costs. Finally, such use of lubricating oil derived additives only serves as an attempt to "mimic" the natural accumulation of lubricant ash, and in effect accelerates the known long-term build-up problem of particulate filters for short-term gain. It is not an attempt to improve ash build-up properties, and does not provide a standalone solution to the need to improve hydrocarbon particulate filtration efficiency at the time of fresh manufacture or installation. [Prior art documents] [Non-patent literature]

[0012] [Non-Patent Document 1] Shae, H., Lam, W., Remias, J. et al., "Effect of Lubricant Oil Properties on the Performance of Gasoline Particulate Filter (GPF)," SAE Int. J. Fuel Lubr. Vol. 9(No. 3): pp. 650-658, 2016, https: / / doi.org / 10.4271 / 2016-01-2287 Summary of the Invention [Problem to be solved by the invention]

[0013] There remains a need in the art for an independent solution to improve the filtration efficiency of freshly manufactured or newly installed hydrocarbonaceous particulate filters designed for long term operation without generating an initial back pressure increase that can adversely affect exhaust gas flow and engine operation, especially at higher speeds and loads. [Means for solving the problem]

[0014] The present invention first provides a method for commissioning a new or freshly reconditioned particulate filter, improving its initial filtration efficiency while generating less backpressure increase than the prior art use of lubricating oil in the fuel, especially at higher speed and higher load engine conditions. The method of the present invention has the further advantage that it can be performed on the filter before it is installed on the vehicle, and therefore does not rely on engine operation or consume expensive lubricating oil even when performed on an in-situ filter on the vehicle, and other drawbacks of adding lubricating oil to the fuel are avoided. The method of the present invention can be equally deployed on uncarbonized new particulate filters and decarbonized reconditioned particulate filters, providing a solution applicable for use on both gas and liquid fueled engines.

[0015] Accordingly, in a first aspect, the present invention provides a method for commissioning a particulate filter for an exhaust system of a machine powered in whole or in part by an internal combustion engine fuelled by either a liquid or gaseous hydrocarbon-based fuel that is not treated with a lubricating oil, comprising the steps of: (i) passing the gas stream through an uncarbonized new particulate filter or a decarbonized reconditioned particulate filter; (ii) discharging a flow of metal oxide particles into the gas stream upstream of the particulate filter during a single discharging period sufficient to deposit the metal oxide particles on uncarbonized or decarbonized surfaces of the channels of the filter exposed to the gas stream, thereby providing a measurable increase in filtration efficiency for hydrocarbon particulate emissions; and (iii) operating the particulate filter on exhaust gases emitted from the internal combustion engine of the device in operation; The present invention provides a method comprising:

[0016] In a second aspect of the invention, the invention provides a commissioned particulate filter obtainable, and preferably obtained, by the method of the first aspect of the invention. Other aspects and advantages of the present invention are described in detail below. The invention is further illustrated in the following figures. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 shows the vehicle measurement cycle used in this example to measure the filtration efficiency of the installed particulate filter for hydrocarbon-based particles. [Diagram 2] FIG. 1 compares filtration efficiency results of gasoline particulate filters ("GPF") commissioned in accordance with the present invention and the prior art. [Diagram 3] FIG. 3 is a magnified view of the results of FIG. 2 for an engine operating point of 5500 rpm and 300 Nm torque. [Figure 4] FIG. 4 shows the average filtration efficiency and average pressure difference before and after GPF, compared with FIG. 3 . [Diagram 5] FIG. 1 shows an X-ray of a gasoline particulate filter (GPF) after commissioning according to the method of the present invention. [Figure 6] FIG. 6 shows the X-ray depth profile along the length of the filter channel of a filter commissioned according to the invention of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The method of the first aspect of the invention relates to the commissioning of a particulate filter. This commissioning is carried out on a new uncarbonized particulate filter or a decarbonized reconditioned particulate filter, i.e. a particulate filter that has substantially, preferably no, carbonized deposits in its interior. This lack of carbonized deposits allows metal oxide particles to have direct access to the surfaces of the filter's channels exposed to the gas flow passing through it, and the resulting metal oxide deposits are associated with an advantageous increase in filtration efficiency. The concept of commissioning is well known to practicing engineers, but in this context it is a step that makes the relevant equipment ready for operation, i.e. for long-term normal use, at which point it can be put into operation for long-term normal use. The first aspect of the invention provides an improved method for commissioning a new or reconditioned particulate filter, which allows the filter to start operating at a higher filtration efficiency, providing the invention with other advantages as described above.

[0019] Without wishing to be bound by theory, and with reference to the experiments presented herein, it is believed that the commissioning method of the present invention results in the deposition of metal oxide particles in the particulate filter, the nature and / or distribution of which is surprisingly more advantageous than the lubricant treatment of fuels proposed in the prior art for increasing initial filtration efficiency without increasing exhaust backpressure. This advantageous effect is achieved before the filter becomes significantly carbonized, and is therefore independent of the known catalytic effect of metal oxides on hydrocarbon deposits in carbonized filters.

[0020] Filtration efficiency can be determined as follows, using a particle counter deployed to record particle counts (two separate measurements, both in units of 1 / s) before and after the gasoline particulate filter, allowing calculation of the efficiency of the GPF for particulate filtration: TIFF0007660369000001.tif15116

[0021] Thus, in non-limiting examples, a measurable increase in filtration efficiency for hydrocarbon-based particles and the like, as determined by the methods described above, may be an increase of at least 0.01%, at least 0.1%, at least 0.5%, at least 1%, at least 2%, at least 3%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, or at least 30%. Without attempting to approach the limits of measurability, selected upper limits of filtration efficiency increase (each of which may be independently combined with each of the lower limits described above), as determined by the methods described above, may be 1000% or less, 500% or less, 200% or less, 100% or less, 80% or less, 75% or less, 60% or less, 50% or less, and 40% or less.

[0022] In one embodiment of the method of the first aspect of the invention, the commissioning steps (i) and (ii) may be carried out with the particulate filter installed in its operational position in the exhaust system of the apparatus of step (iii). In this embodiment of the invention, the gas stream in the commissioning step (i) is the exhaust gas stream discharged from the internal combustion engine of the device during the first run after installation of the particulate filter, and the metal oxide particles used in the commissioning step (ii) are (a) adding a metal oxide or a precursor thereof to an engine fuel in such a form that upon combustion of the fuel, the metal oxide particles are released into the exhaust gas stream exiting the combustion chamber; or (b) Emission of metal oxide particles directly into the exhaust gas stream into the exhaust gas stream upstream of the particulate filter. In an alternative embodiment of the first aspect, commissioning steps (i) and (ii) are performed on the particulate filter prior to it being installed in its operational position in the exhaust system of an apparatus for use in step (iii). In this embodiment, it is preferred to first attach the particulate filter to a gas line downstream of a source of the gas flow remote from the apparatus, and then step (i) is performed on a gas flow other than the engine exhaust gas from the apparatus, and the metal oxide particles used in step (ii) are discharged directly into this gas flow upstream of the particulate filter, and in step (iii) the particulate filter is removed from the remote gas line and operatively positioned in the exhaust system of the apparatus.

[0023] The method of the first aspect preferably relates to commissioning a particulate filter of an apparatus which is a vehicle or vessel or a stationary generator or plant. Preferably, the method relates to commissioning a particulate filter for a vehicle, more preferably a road vehicle, even more preferably a passenger road vehicle, in particular a passenger road vehicle powered wholly or partly by a spark ignition internal combustion engine. The method of the first aspect also relates to commissioning a particulate filter for a device powered by an internal combustion engine fueled by a liquid hydrocarbon-based fuel that is preferably not treated with lubricating oil. The absence of any lubricating oil treatment avoids both the addition of heavier hydrocarbon species derived from the lubricating base oil to the liquid fuel and the addition of additives that are deployed in the lubricating oil. An essential feature of the present invention is that the liquid fuel is not treated by adding lubricating oil and / or lubricating oil additives derived therefrom according to the prior art before being fed to the engine (which leads to the disadvantages of the prior art where deliberate addition of lubricating oil to the fuel is used before being fed to the engine). Reference to "liquid hydrocarbon-based fuel is not treated with lubricating oil" should be understood to explicitly exclude the treatment of the fuel by adding lubricating oil containing a lubricating oil base stock and / or additives derived therefrom that improve oil properties or performance to the fuel before the fuel reaches the engine.

[0024] Preferably, the internal combustion engine is fuelled with a liquid hydrocarbonaceous fuel which is diesel or gasoline petroleum fuel, or a biofuel, or a mixture thereof, more preferably, the internal combustion engine is fuelled with gasoline fuel or a biofuel, or a mixture thereof, most preferably, the internal combustion engine is fuelled with gasoline fuel, most particularly, it is a spark ignition internal combustion engine fuelled with gasoline fuel.

[0025] The method of the first aspect (and preferably its embodiment in which the internal combustion engine is fuelled with gasoline or biofuel or a mixture thereof, most preferably gasoline) preferably relates to commissioning a particulate filter for a device powered by a hybrid power source including an internal combustion engine and one or more electric drive motors. In this aspect, the hybrid power source may preferentially include either (i) an internal combustion engine providing a direct drive connection to the wheels of the vehicle, with one or more battery-powered electric motors available to power the vehicle under non-engine conditions, or (ii) an internal combustion engine operated to generate charge via a battery or other charge storage device to power the wheels of the vehicle by the electric drive motor. In such hybrid embodiments, the method of the invention is particularly advantageous in that the commissioning of the particulate filter according to the invention results in improved filtering efficiency, especially at higher speeds and higher load operation where engine operation would preferentially occur, while electric operation of the vehicle with charge storage is advantageous at lower speeds and lower loads such as typical "city" driving. As such, the commissioning method of the first aspect has been found to be particularly well suited to such hybrid vehicles, allowing particulate emission control to be targeted to areas of the engine operating map that are most relevant to such hybrids.

[0026] Particulate filters suitable for commissioning by the method of the first aspect include filters known in the art, most notably filters based on ceramic or wire structures. However, the method is particularly advantageous for particulate filters based on ceramic monoliths. Such filters include a monolith with a plurality of adjacent, often parallel, channels, and the exhaust gas path through the monolith is typically constructed to exhibit countercurrent flow between adjacent channels. This directed flow within the monolith drives the exhaust gas alternately up and down successive channels, exposing the gas to a large filtration surface area. Each channel of the monolith is sealed at its ends by a plug that prevents the exhaust gas from simply leaking out, instead creating a resistance that propels the gas through the porous walls of the channel to the holes of the next channel, thereby filtering carbon-based particulates.

[0027] It has been found that the method of the first aspect of the invention is particularly advantageous in that the particulate filter of step (i) comprises a ceramic monolith, and the deposition of metal oxide of step (ii) is observed on at least a portion of the uncarbonized or decarbonized surface of the end plugs of the monolithic filter channels exposed to the gas flow. Without being bound by theory, it is believed that the accumulation of metal oxide particles on the end plugs of the filter channels leads to a more effective sealing of the channel ends and, as a result, a more effective lateral filtration action through the channel walls. Also, the partial deposition of metal oxide on the end plugs accordingly reduces the proportion of metal oxide that accumulates on the side walls of the channels, thereby limiting the reduction in flow through the uncarbonized or decarbonized channel walls that may be due to metal oxide blockage, increasing its overall filtration efficiency and providing a new or reconditioned ceramic monolith filter with a distribution of metal oxide deposits that provide the advantageous effects of the invention.

[0028] The method of the first aspect of the invention therefore provides a preferred embodiment in which the particulate filter of step (i) comprises a ceramic monolith and the metal oxide deposits formed in step (ii) accumulate on at least a portion of the uncarbonized or decarbonized surfaces of the end plugs of the channels of the monolithic filter exposed to the gas flow. This preferred embodiment is particularly advantageous in combination with devices powered by an internal combustion engine fueled by gasoline fuel or biofuel or a mixture thereof, more particularly by a gasoline fueled engine, and especially with devices powered by a hybrid power source including an engine and one or more electric drive motors.

[0029] Thus, in a second aspect of the invention, the invention provides a commissioned particulate filter obtainable and preferably obtained by the method of the first aspect of the invention. Without wishing to be bound by theory, the commissioned particulate filter can be described as comprising a metal oxide on the surface of the end plugs of the channels of the filter, which is preferably a ceramic monolithic filter. Thus, in an embodiment of the second aspect of the invention, the commissioned particulate filter comprises a ceramic monolith comprising one or more accumulations of metal oxide deposits on at least a portion of the surface of the end plugs of the channels of the monolithic filter. Preferably, the surface of the end plugs of the channels of the monolithic filter is uncarbonized or decarbonized. In steps (i) and (ii) of the method of the first aspect, a gas stream is passed through the uncarbonized new particulate filter or the decarbonized reconditioned particulate filter to be commissioned and a flow of metal oxide particles is released thereinto, the gas stream following a flow path through the filter to be constructed by the engine exhaust gases when the filter and device are in operation, and the metal oxide particles are released into the gas stream upstream of the filter.

[0030] In a first embodiment of the first aspect, the commissioning steps (i) and (ii) are carried out with the particulate filter installed in its operational position in the exhaust system of the apparatus of step (iii), again any suitable gas flows and flow rates can be used as an initial commissioning procedure, the gas flows being connected and disconnected for this purpose prior to normal operation of the apparatus in operation. However, in this first embodiment, the gas stream for the commissioning steps (i) and (ii) is preferably the exhaust gas stream discharged from the internal combustion engine of the device during the first run after installation of the particulate filter. In this latter embodiment, the metal oxide particles used in the commissioning step (ii) are (a) adding a metal oxide or a precursor thereof to an engine fuel in such a form that upon combustion of the fuel, the metal oxide particles are released into the exhaust gas stream exiting the combustion chamber; or (b) Emission of metal oxide particles directly into the exhaust gas stream More preferably, the particulate matter is discharged into the exhaust gas stream upstream of the particulate filter by either

[0031] In option (a) of the above embodiment, where the engine fuel is a liquid hydrocarbon-based fuel that has not been treated with a lubricating oil, the metal oxide or precursor thereof is preferably added to a single quantity of the fuel in the form of a fuel additive that disperses the metal oxide or precursor in the liquid fuel. The fuel additive can be added to the liquid fuel in various ways. In a first embodiment, the fuel additive is added to the liquid fuel before it enters the fuel system of the device to form a commissioning fuel composition. This fuel composition can then be placed in the fuel tank of the device, or placed or pumped into the fuel line between the tank and the engine to prepare for the start of commissioning. In a second embodiment, the fuel additive can be added to the fuel tank of the device in the form of a liquid dispersion or a tablet that disperses in the liquid fuel contained therein to form the commissioning fuel composition in situ in the fuel tank. Such ways for constructing the fuel composition are known in the art and typically include blending or mixing by stirring.

[0032] In option (a), the fuel additive preferably comprises a metal oxide or precursor stabilized by one or more organic compounds in the form of a dispersion in a hydrocarbon diluent, and the fuel additive does not contain any lubricating oil or other heavier petroleum fractions or additives derived therefrom. In such an embodiment of option (a), after installation of the particulate filter, the internal combustion engine is first operated with a single amount of fuel containing the fuel additive, which constitutes the commissioning steps (i) and (ii) of the method, and then operated with fuel not containing the fuel additive, so that the filter is operated with exhaust gas that does not contain metal oxide particles derived from the fuel. Thus, the present specification may alternatively state that the particulate filter is operated with exhaust gas emitted from the internal combustion engine of the device in operation. The initial operation of the internal combustion engine, whether the engine is operated on one continuous occasion or multiple occasions to consume a single amount of fuel containing the fuel additive, both represent a single period of emission according to the present invention, although the single period of emission is preferably one continuous operation of the internal combustion engine. In such an embodiment, the single amount of fuel is preferably equal to or less than the amount required to fill the device's on-board fuel tank. Thus, the present invention serves to provide a commissioning method that can be implemented using a single tank's worth of fuel (or less), where a commissioning fuel composition containing a fuel additive is first run on the device to commission the particulate filter, and then a regular operating fuel without the same fuel additive is used. This commissioning fuel composition can be added to the device at the time of manufacture, and the commissioning method is performed before distribution, or during its initial distribution, or before sale, or during its first run after sale, with no additional measures required. The device and its particulate filter are then ready for long-term operation.

[0033] In option (b) of the above embodiment, the metal oxide particles can be directly released into the exhaust gas stream via delivery from a remotely mounted particle reservoir. This reservoir may be permanently connected or attached to the vehicle, or may be attached for commissioning purposes and then removed. The metal oxide particles are preferably delivered into the exhaust gas stream by an injection device mounted on the wall of the exhaust system, the injection device being preferably fed from the particle reservoir by a mechanical or electronic pump or suction device. The metal oxide particles may be delivered either in discrete solid form or dissolved or suspended in a solvent that evaporates upon exposure to the exhaust gas to release the particles in discrete solid form. More preferably, in embodiment option (b) above, the metal oxide particles are released directly into the exhaust gas stream from a particulate reservoir mounted in the exhaust system upstream of the particulate filter and opening into a bore in the exhaust system. In this embodiment, the particulate reservoir preferably takes the form of a container mounted proximate the upstream end of the particulate filter. In operation, the container is pre-loaded with metal oxide particles and release is achieved by initiating commissioning, which may occur before the vehicle leaves the factory or work site.

[0034] In a second embodiment of the first aspect, the commissioning steps (i) and (ii) are performed on the particulate filter before it is installed in its working position in the exhaust system of the device, and the gas flow serves as a transport medium for entraining the metal oxide particles and transporting them to the filter during commissioning, and may be any gas flow suitable in the art for entraining such solid particles. Suitable examples of gases include air, nitrogen, and inert gases such as helium. The flow rate of such gas flow will be selected by the skilled technician as a flow rate sufficient to transport the selected solid particulate matter to the particulate filter, and may advantageously correspond to a flow rate typical for spray coating or substrate impregnation, or alternatively may correspond to a flow rate typical of exhaust gas passing through the particulate filter during operation, and may be adjusted by the skilled technician depending on the circumstances.

[0035] In this embodiment, the metal oxide particles may be released into the gas stream from a storage container or device (referred to herein as a "particle reservoir") that may be located directly in the gas line feeding the particulate filter or in communication therewith via intermediate equipment. The metal oxide particles are released over a single period of time, thus providing a concentrated, finite flow of the metal oxide particles through the particulate filter, which flow accomplishes commissioning.

[0036] In a preferred form of this embodiment, a particulate filter is first installed in a gas line downstream of a source of the gas stream remote from the apparatus, thereafter step (i) is carried out on a gas stream other than the engine exhaust gas from the apparatus, and the metal oxide particles used in step (ii) are discharged directly into this gas stream upstream of the particulate filter, and in step (iii) the particulate filter is removed from the remote gas line and operatively placed in the exhaust system of the apparatus. In this embodiment, in step (ii), the metal oxide particles are preferably either released directly into the gas stream via delivery from a remotely mounted particle reservoir, or directly into the gas stream from a particle reservoir mounted upstream of the particulate filter and opening into a hole in the gas line.

[0037] A third aspect of the invention therefore provides an uncommissioned particulate filter assembly for use in the above embodiments comprising a particulate filter and a metal oxide particle reservoir in the form of a container mounted proximate the upstream end of the filter, the container further having means for providing a single discharge of particles therefrom when placed in the commissioning gas stream into a bore in an inlet pipe leading to the particulate filter.

[0038] The means for providing a single discharge of the metal oxide particles from the container can be modified by a person skilled in the art to suit the exhaust system of the device in question. Thus, in one embodiment, the discharge means may be a mechanical or electronic flap or valve mechanism, where the particles are present in the container in a loose particulate form and are released upon opening. In an alternative embodiment, the discharge means may be a particle-retaining matrix such as wax or a particle-retaining surface such as an adhesive layer, where the metal oxide particles are retained by this matrix or surface until conditions in the exhaust system or other triggers cause the matrix or layer to lose its retaining capacity, for example melting and releasing the metal oxide in response to an increase in exhaust gas temperature. In an alternative embodiment where the metal oxide used exhibits magnetic properties (such as iron oxide particles), the discharge means may release a magnetic field that holds the metal oxide particles in the container, thus causing the metal oxide particles to protrude into the exhaust line. The container in the assembly is preferably equipped with a flap or valve mechanism that opens to release the metal oxide particles into the commissioning gas stream, where the release mechanism is preferably triggered by engine start-up or a steady flow of exhaust gas.

[0039] Said container, provided with any of the above mentioned discharge means, may be any suitable receptacle for the metal oxide particles to be released. Preferably, however, it takes the form of an annular container mounted proximate to the upstream end of the particulate filter. The annular nature of the container ensures that the metal oxide particles are released in a circumferentially distributed manner into the holes in the exhaust line leading to the filter, thus providing a more regular distribution within the exhaust gases and thus into the body of the particulate filter.

[0040] This particulate filter assembly of the third aspect offers the advantage of a self-contained, self-commissioning filter unit that can be replenished with metal oxide particles upon reconditioning and then left in place on the vehicle without compromising space utilization elsewhere in the vehicle. The particulate reservoir may optionally be adapted in configuration to serve ancillary functions such as opening to contribute to managing exhaust gas flow to a particular filter during operation or providing additional fixed bed catalyst surface upstream of the filter to provide improved gas emission control.

[0041] Thus, in a fourth aspect, the present invention provides a commissioning fuel composition for initial use in an apparatus having an uncommissioned particulate filter installed in the exhaust system of an internal combustion engine, the fuel composition having not been treated with lubricating oil and / or additives derived therefrom, (a) a hydrocarbon-based liquid selected from diesel or gasoline petroleum fuels or biofuels or mixtures thereof; and (b) A fuel additive comprising a metal oxide or precursor stabilized by one or more organic compounds in a hydrocarbon-based dispersion, the fuel additive being free of any lubricating oil or other heavier petroleum fractions or additives derived therefrom. The present invention provides a fuel composition comprising:

[0042] In addition to components (a) and (b) above, and in addition to the absence of lubricating oils and / or additives derived therefrom, the commissioning fuel composition of the present invention is suitable for facilitating or protecting the initial break-in of an engine of an apparatus, for example, to protect the fuel system from potential problems encountered during extended storage that may be experienced by newly manufactured apparatus awaiting distribution and sale. Thus, the commissioning fuel composition may additionally contain additives that provide protection against initial wear, corrosion, oxidative degradation, water contamination, and higher levels of sedimentation than regular fuels (such as those sold at gas stations) that are not subject to the same extended storage and other pre-sale considerations. Thus, in a preferred embodiment, the commissioning fuel composition additionally comprises one or more anti-wear agents, anti-corrosion agents, antioxidants, anti-agglomerates, and demulsifiers, typically in the form of chemical additives, to a level of protection suitable for equipment subjected to the rigors of long-term storage and onshore and offshore distribution.

[0043] In a fifth aspect, the present invention provides the use of the fuel composition of the fourth aspect, comprising a fuel additive (b) as defined above, in a device powered wholly or partly by an internal combustion engine, as an initial fuel for running the engine when a particulate filter is installed in its exhaust system, for commissioning the particulate filter by improving its filtering efficiency for hydrocarbon particulate emissions over a period of engine operation with said initial fuel, before the device is put into operation with a fuel not comprising fuel additive (b). This fifth aspect may additionally or instead be a method of using the fuel composition, the use as described above, and a method comprising the step of running an internal combustion engine having a particulate filter installed in its exhaust system using the initial fuel.

[0044] In a sixth aspect, the present invention provides the use of a fuel additive (b) comprising a metal oxide or a precursor thereof stabilized by one or more organic compounds in a hydrocarbon-based diluent, and not containing any lubricating oil or other heavier petroleum fractions or additives derived therefrom, to provide a commissioning fuel composition for use in the fourth or fifth aspect. This sixth aspect may additionally or instead be a method of use of the fuel additive, the use as described above, and a method comprising the step of adding the fuel additive to a hydrocarbon-based liquid, which may be selected from diesel or gasoline petroleum fuels or biofuels or mixtures thereof. The essential metal oxide or precursor contained in the fuel additive (b) is preferably one or more compounds of a rare earth metal such as cerium, or one or more transition metals such as iron or manganese, or one or more platinum group metals, or a mixture thereof. Preferably, the essential metal oxide or precursor thereof is one or more compounds of a rare earth metal or transition metal or a mixture thereof, preferably in the form of a colloidal dispersion thereof.

[0045] In the context of the present invention, the term "precursor" should be understood to mean a metal compound that is chemically converted or reacted under engine combustion chamber conditions to form a metal oxide, so that the exhaust gas discharged from the engine contains the metal required for commissioning the particulate filter. Thus, as precursors, organometallic compounds or complexes of the above metals that combust into metal oxides and other combustion products are suitable for the present invention. By way of example, organometallic complexes of iron, such as ferrocene, diferrocene, iron carboxylates, or other salts or mixtures thereof, can be used. The fuel additive may be an organometallic compound or complex containing any of the above-mentioned metals, preferably iron and / or cerium, more preferably iron.

[0046] Preferably, however, the metal compound in the fuel additive will be a metal oxide. In this regard, preferably, the present invention uses a metal compound comprising at least one rare earth oxide, or at least one iron oxide, or a mixture thereof, preferably in the form of a colloidal dispersion thereof. More preferably, the metal compound comprises one or more cerium oxides or iron oxides, or a mixture thereof. Even more preferably, the fuel additive comprises a colloidal dispersion of iron oxide or cerium oxide or a mixture thereof. Most preferably, the fuel additive comprises iron oxide colloidally dispersed with one or more organic compounds in a hydrocarbon solvent.

[0047] In the preferred embodiment in which a colloidal dispersion of iron oxide is used, and especially in the most preferred embodiment consisting of colloidal iron oxide, the iron oxide may be crystalline or amorphous, but is preferably crystalline. In this context, the terms "crystalline" and "amorphous" used in relation to the iron oxide (forming the core of the colloid) have the defined meaning. The core is crystalline if, under X-ray diffraction of the colloid, one or more sharp peaks are observed that can be attributed to the presence of a distinct crystal structure or lattice within the core. If no such attributable peaks are observed, the core is amorphous. A suitable protocol for performing X-ray diffraction of the required colloids is to first prepare the sample for scanning by applying the relevant liquid (colloid) directly to a silicon low background substrate and allowing the sample to dry. The sample forms a viscous, sticky film which can then be examined. Suitable X-ray data can be collected from 2 degrees to 70 degrees 2-theta on a Philips PW1800 automated powder X-ray diffractometer using copper K alpha radiation generated at 40 kV and 55 mA with a count time of 4 seconds per point.

[0048] The iron oxide itself can exist in a variety of forms, depending on the oxidation state (or mixture of oxidation states) of the iron therein and the conditions to which it is exposed. In this context, the term "iron oxide" is used generally to mean both true iron oxide, as well as iron hydroxide and iron hydroxide oxide, which are also commonly referred to in the art under the term "iron oxide". Most preferably, no other metals are present within the iron oxide, and the colloidal core consists of iron as the only metal, combined with oxygen and / or hydrogen, depending on the exact form of iron oxide present. Most preferably, the iron oxide particles within the colloid consist essentially of crystalline forms of iron oxide, specifically including the oxides magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3), as well as other forms of iron(III) oxide, such as the iron(II) oxide "wustite FeO." Of these true oxides, magnetite, hematite, and maghemite are preferred, with magnetite being the most preferred. Magnetite and hematite, in particular, can be mined in large quantities in the form of ores.

[0049] Crystalline forms of iron hydroxides and oxide hydroxides include goethite (α-FeOOH) and lepidocrocite (γ-FeOOH), as well as δ-FeOOH (synthetic) and δ'-FeOOH (mineral) forms, ferrihydrite Fe5O8·4H2O, bernalite Fe(OH)3, and Fe(OH)2. Goethite, in particular, is the thermodynamically stable form and is available from rocks and loess deposits. Lepidocrocite occurs in rocks and soils, and ferrihydrite is widespread in natural surface environments. Of the iron hydroxides and oxide hydroxides, the goethite and lepidocrocite forms are the most preferred. Preferably, from a performance standpoint, the colloidal crystalline iron oxide core consists essentially of the crystalline form of magnetite, optionally incorporating smaller amounts of one or more of hematite, maghemite, goethite, or lepidocrocite forms. A core consisting of magnetite, optionally in combination with goethite, is the most preferred form of crystalline iron oxide for use in the present invention.

[0050] The metal oxide, particularly cerium oxide, or most preferably iron oxide core (whether crystalline or amorphous), is dispersed in a hydrocarbon-based solvent by a dispersing means, preferably an organic dispersing means, which is preferably one or more carboxylic acids. At least one of such acids is preferably a hydrocarbyl-substituted dicarboxylic acid containing 8-200 carbon atoms, and any additional carboxylic acids are preferably either aliphatic monocarboxylic acids containing 8-20 carbon atoms, or hydrocarbyl-substituted dicarboxylic acids containing 8-200 carbon atoms, or mixtures thereof. Preferably, the mass ratio of carboxylic acid:metal in the colloid (measured as total mass of acid compounds:mass of elemental metal contained within the metal oxide particles) is in the range of 6:1 to 1:4. Most preferably, the metal is cerium or iron, most preferably iron. In a preferred embodiment, the dispersing means within the colloid comprises one or more hydrocarbyl-substituted dicarboxylic acids containing from 8 to 200 carbon atoms. Preferably, the or each hydrocarbyl-substituted dicarboxylic acid is a hydrocarbyl-substituted succinic acid, more preferably an alkenyl or polyalkenyl succinic acid, preferably a polyalkenyl succinic acid.

[0051] As used herein, the term "hydrocarbyl substituent" means a univalent chemical substituent having a hydrocarbon character and consisting of carbon and hydrogen atoms (and optionally heteroatoms such as oxygen, nitrogen, and sulfur, provided that the presence of such heteroatoms does not affect the hydrocarbon character of the substituent). In each of the preferred embodiments of the dicarboxylic acid, the hydrocarbyl substituent consists (only) of carbon and hydrogen atoms, in which case the hydrocarbyl substituent is preferably a monovalent saturated substituent (i.e., alkyl), or more preferably a mono- or polyunsaturated substituent such as alkenyl. Branched chain substituents are preferred. The preferred maximum size of such hydrocarbyl substituents is 160 carbon atoms, preferably 80 carbon atoms. Preferably, the substituents contain at least 12 carbon atoms, more preferably at least 18 carbon atoms. Branched chain substituents, especially alkenyl or polyalkenyl substituents, containing from 18 to 80 carbon atoms are most preferred. Preferably, a mixture of hydrocarbyl-substituted dicarboxylic acids is used to disperse the metal oxide. More preferably, the mixture is a mixture of dicarboxylic acids where each acid is an alkenyl- or polyalkenyl-substituted succinic acid, and the mixture preferably consists essentially of (more preferably consists of) succinic acid bearing only one branched polyalkenyl substituent and preferably containing from 18 to 80 carbon atoms.

[0052] In this latter preferred embodiment, the substituent on each succinic acid may be derived from a polymerized olefin such as polyethylene, polypropylene, or (preferably) a polybutylene such as polyisobutene. A preferred substituent is derived from polyisobutene of number average molecular weight (as measured by gel permeation chromatography ("GPC") against polystyrene standards) ranging from 450 to 2250, preferably 750 to 1300. Such polyisobutenes can be made by conventional polymerization techniques known in the art and then coupled to maleic anhydride by well-known chlorination or thermal reaction routes to provide the preferred polyisobutenyl-succinic acids.

[0053] A further preferred embodiment of the invention is one in which the dispersing means comprises one or more aliphatically substituted succinic acids derived from structure (II). [ka] where x and y are independent integers whose sum is from 1 to 30, preferably from 9 to 29, more preferably from 11 to 21, and most preferably 11 or 13. Such mixtures of materials may again result from the maleation of a mixture of internal olefins of different chain length or from the maleation of an isomeric mixture of internal olefins of the same chain length. The internal olefins may be generated in situ by acid catalyzed isomerization of terminal olefins prior to reaction with maleic anhydride.

[0054] In another preferred embodiment of the invention, the dispersing means within the colloid consists of one or more hydrocarbyl-substituted dicarboxylic acids containing from 8 to 200 carbon atoms in combination with one or more monocarboxylic acids containing from 8 to 20 carbon atoms. In this embodiment, the preferred embodiments previously described for the hydrocarbyl-substituted dicarboxylic acids may be suitably combined with one or more of the aforementioned monocarboxylic acids. Thus, one or more monocarboxylic acids containing from 8 to 20 carbon atoms may be combined with one or more hydrocarbyl-substituted dicarboxylic acids containing from 8 to 200 carbon atoms, the or each hydrocarbyl-substituted dicarboxylic acid being preferably a hydrocarbyl-substituted succinic acid, more preferably an alkenyl succinic acid, or most preferably a polyalkenyl succinic acid.

[0055] In such mixtures, the preferred maximum size of such hydrocarbyl substituents is 160 carbon atoms, preferably 80 carbon atoms. Preferably, the substituents contain at least 12 carbon atoms, more preferably at least 18 carbon atoms. Branched chain substituents, especially alkenyl or polyalkenyl substituents, containing from 18 to 80 carbon atoms are most preferred. Preferably, a mixture of hydrocarbyl-substituted dicarboxylic acids is used in such mixtures, more preferably each acid in the mixture is an alkenyl- or polyalkenyl-substituted succinic acid, and the mixture preferably consists essentially of (more preferably consists of) succinic acids each bearing only one branched polyalkenyl substituent, preferably containing from 18 to 80 carbon atoms.

[0056] In this latter preferred embodiment, the substituent on each succinic acid may be derived from a polymerized olefin such as polyethylene, polypropylene, or (preferably) a polybutylene such as polyisobutene. A preferred substituent is derived from polyisobutene of number average molecular weight (as measured by gel permeation chromatography ("GPC") against polystyrene standards) ranging from 450 to 2250, preferably 750 to 1300. Such polyisobutenes can be made by conventional polymerization techniques known in the art and then coupled to maleic anhydride by well-known chlorination or thermal reaction routes to provide the preferred polyisobutenyl-succinic acids.

[0057] Further preferred embodiments are those obtained by using one or more aliphatically substituted succinic acids from structure (II) in combination with one or more carboxylic acids. [ka] where x and y are independent integers whose sum is from 1 to 30, preferably from 9 to 29, more preferably from 11 to 21, and most preferably 11 or 13. Such mixtures of materials may again result from the maleation of a mixture of internal olefins of different chain length or from the maleation of an isomeric mixture of internal olefins of the same chain length. The internal olefins may be generated in situ by acid catalyzed isomerization of terminal olefins prior to reaction with maleic anhydride.

[0058] Thus, in this embodiment, the intracolloidal dispersion means preferably comprises one or more polyalkenyl-substituted succinic acids in combination with one or more aliphatic monocarboxylic acids containing from 8 to 20 carbon atoms, preferably the or each monocarboxylic acid containing from 10 to 18 carbon atoms. Such acids may be straight or branched chain acids, including saturated straight chain acids such as decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic (stearic) acid, and mixtures thereof; saturated branched chain acids such as neodecanoic acid and isostearic acid; and monounsaturated acids such as cis-9-hexadecenoic acid (palmitoleic acid), cis-6-octadecenoic acid (petroselinic acid), cis-9-octadecenoic acid (oleic acid), cis-11-octadecenoic acid (cis-vaccenic acid), and cis-15-tetradecenoic acid (nervonic acid), and polyunsaturated fatty acids such as 9,12-octadecadienoic acid (linoleic acid), 6,9,12-octadecatrienoic acid (γ-linoleic acid), and 9,12,15-octadecatrienoic acid (α-linoleic acid). Of these acids, the unsaturated acids are preferred, with oleic acid, or a mixture consisting essentially of oleic acid, being most preferred as the means for dispersing the colloids.

[0059] In a particularly preferred embodiment, the dispersion means within the colloid consists of oleic acid and one or more polyisobutenyl succinic acids, the polyisobutenyl groups of which have a number average molecular weight (measured by gel permeation chromatography against polystyrene standards) of 450 to 2300. In the present invention, most preferably, the dispersion means within the colloid consists of one or more polyisobutenyl-substituted succinic acids, preferably in combination with one or more aliphatic monocarboxylic acids containing 10 to 18 carbon atoms. Most preferred is a combination of a mixture of oleic acid and a polyisobutylene-substituted succinic acid, the number average molecular weight of the polyisobutylene substituent being in the range of 700 to 1300, especially in the range of 900 to 1000, as measured by GPC. It is particularly preferred in the present invention that said mixture of monocarboxylic acid and hydrocarbyl-substituted dicarboxylic acid forms a dispersion means for particles consisting essentially of cerium oxide and / or iron oxide in crystalline form, more preferably iron oxide, especially magnetite.

[0060] In the present invention, the mass ratio of carboxylic acid:metal in the colloid (measured as mass of acid compound: mass of elemental metal contained within the metal oxide particles) is in the range of 6:1 to 1:4. Preferably, this mass ratio is in the range of 4:1 to 1:2, more preferably 2:1 to 1:2. Most preferably, this mass ratio is in the range of 1.5:1 to 1:2. Most preferably, the metal is iron. The fuel additive may be provided at a concentration level suitable for use in bulk fuel production or blending operations at a refinery or fuel terminal. In such concentrates, the fuel additive is typically present in a concentration containing from 1 to 30 mass %, preferably from 4 to 25 mass %, more preferably from 10 to 25 mass %, and most preferably from 12 to 25 mass % metal per unit mass of fuel additive.

[0061] In addition, the fuel additives of the present invention can be made into high concentration levels suitable for use in small volume commissioning fuel compositions, particularly where commissioning is to be accomplished with a single tankful of fuel or less. In such concentrated additives, the dispersed metal oxide or precursor is typically present in a concentration providing up to 40% by weight, preferably 10-30% by weight, more preferably 15-25% by weight of metal per unit weight of additive. Suitable hydrocarbon solvents for colloids include aromatic solvents such as the commercially available mixed aromatic solvents Solvesso and Shellsol, and aliphatic solvents such as isoalkanes, including Isopar L. Other suitable solvents known in the additive art may also be used, such as Norpar (pentane), Exxsol (dearomatized hydrocarbon fluid), Nappar (naphthenic acid), Varsol (non-dearomatized hydrocarbon fluid), xylene, and HAN8080 (aromatic solvent).

[0062] Under all aspects of the present invention, the concentration of metal oxide deployed in the fuel additive, and therefore in the commissioning fuel, will be that desired by the skilled artisan to provide the desired degree of commissioning. This will be in accordance with the emission targets of the device in question. Typically, such factors will allow the skilled artisan to set the level of metal (preferably iron) in the commissioning fuel composition that corresponds to the desired accumulation of metal oxide in the filter, based on the desired filtration efficiency of hydrocarbon-based particulates. Typically, such levels are set during the development of the engine or exhaust system and as a result of routine optimization. As illustrated in the examples, the filtration efficiency of the particulate filter can be easily measured and routine tests can be performed varying the amount of metal oxide required to achieve the desired efficiency increase of the particulate filter of the specific design of the particular device. This amount of metal oxide is then determined to be the appropriate treatment level and converted into the amount of additive added to the fuel depending on the amount of fuel used in the commissioning method.

[0063] However, for general purposes, the desired amount of metal oxide accumulation in the particulate filter will be in the range of 0.5 to 4.0 grams of metal oxide per liter of particulate filter gas volume, preferably in the range of 1.0 to 3.3 grams of metal oxide per liter of particulate filter gas volume, and more preferably in the range of 1.5 to 3.0 grams of metal oxide per liter of particulate filter gas volume. Thus, by way of example, a particulate filter having a gas volume of 2 liters (i.e., a total internal filtration channel gas volume of 2 liters) would require a total accumulation of 6.0 grams of metal oxide therein to meet the target of 3.0 grams per liter of filter gas volume. Thus, one skilled in the art would add a corresponding amount of metal oxide to the commissioning fuel composition to achieve the commissioning to the desired accumulation level.

[0064] Similarly, if the metal oxide of step (ii) is not added via the fuel, the appropriate amount of metal oxide accumulation will be established by routine testing to determine the amount of metal oxide required to achieve the desired efficiency increase in the particulate filter of the specific design of the particular device. This amount of metal oxide is then determined to be the appropriate treatment level for adding directly to the gas stream during step (ii) of the commissioning method. However, for general purposes, the desired amount of metal oxide accumulation in the particulate filter will again be in the range of 0.5 to 4.0 grams of metal oxide per liter of particulate filter gas volume, preferably in the range of 1.0 to 3.3 grams of metal oxide per liter of particulate filter gas volume, and more preferably in the range of 1.5 to 3.0 grams of metal oxide per liter of particulate filter gas volume. Thus, by way of example, a particulate filter having a gas volume of 2 liters (i.e., 2 liters of total internal filtration channel volume) would require a total accumulation of 6.0 grams of metal oxide therein to meet the target of 3.0 grams per liter of filter gas volume. Thus, one skilled in the art would add the required amount of metal oxide directly to the gas stream during step (ii) of the commissioning method to achieve the desired accumulation level.

[0065] The commissioning fuel to be treated with the fuel additive may be a petroleum-based diesel fuel oil. Such diesel fuel oils generally boil within the range of 150°C to 400°C. The fuel oil may include atmospheric or vacuum distillates, cracked gas oils, or blends of straight run and hot and / or refined streams, such as catalytic cracking distillates and hydrocracked distillates, in any proportion. The diesel fuel may be a fuel for road vehicles. Such fuels are typically classified by various well-known industry standards in Europe and may contain low or very low sulfur content, such as up to 50 ppm sulfur per unit mass of fuel, or even up to 10 ppm or less sulfur.

[0066] Alternatively, the fuel may be a marine diesel fuel having in particular one or more of the following characteristics: (i) a 95% distillation point (ASTM D86) greater than 330° C., preferably greater than 360° C., more preferably greater than 400° C., and most preferably greater than 430° C.; (ii) a cetane number (measured by ASTM D613) of less than 55, such as less than 53, preferably less than 49, more preferably less than 45, and most preferably less than 40; (iii) an aromatic content of greater than 15% by weight, preferably greater than 25% by weight, more preferably greater than 40% by weight; (iv) a Ramsbottom carbon residue (according to ASTM D524) of greater than 0.01%, preferably greater than 0.15%, more preferably greater than 0.3%, for example, 1% or 5%, most preferably greater than 10%, by weight; and (v) A maximum sulfur content of 0.5% by mass in the absence of an on-board scrubber (as defined by IMO 2020), preferably a maximum of 0.1% by mass sulfur.

[0067] Such diesel fuels (and particularly such marine diesel fuels) are in particular streams produced from fluid catalytic cracking, such materials typically having a viscosity of 900-970 kg / m at 15°C. 3 streams having a density of 850-970, typically characterized by a low cetane value ranging from 10 or lower to around 30-35; streams produced from pyrolysis processes such as visbreaking and coking, typically having a density range of 830-930 kg / m at 15°C; 3 and a flowable cetane number of 20-50; and using severe conditions, e.g., temperatures above 400°C combined with pressures of 130 bar or higher, a cetane number of 45-60 and a density range of 800-860 kg / m at 15°C. 3 The present invention may also include streams such as those produced from hydrocracking in which a stream characterized by Typically, marine fuels comply with standard specification ASTM D-2069 and may be either distillate or residual fuels as described therein, and in particular may have a sulphur content as defined in international standard ISO 8217, preferably 0.5% by mass sulphur, more preferably a maximum of 0.1% by mass sulphur.

[0068] Other examples of diesel fuel oils include Fischer-Tropsch fuels. Fischer-Tropsch fuels, also known as FT fuels, include fuels described as gas-to-liquid (GTL) fuels, biomass-to-liquid (BTL) fuels, and coal-converted or coal-to-liquid (CTL) fuels. To make such fuels, synthesis gas (CO+H2) is first generated and then converted to normal paraffins by the Fischer-Tropsch process. The normal paraffins can then be modified by methods such as catalytic cracking / reforming or isomerization, hydrocracking, and hydroisomerization to obtain various hydrocarbons such as iso-paraffins, cyclo-paraffins, and aromatics. The resulting FT fuels can be used as such or in combination with other fuel components and fuel types to arrive at a fuel suitable for use as a diesel fuel.

[0069] The fuel may be a biofuel, i.e. a fuel derived from animal and / or plant material, preferably derived from fats and oils of plant or animal material, such as rapeseed oil, coriander oil, soybean oil, cottonseed oil, sunflower oil, castor oil, olive oil, peanut oil, corn oil, almond oil, palm kernel oil, coconut oil, mustard oil, jatropha oil, beef tallow, and fish oil. Further examples include oils derived from corn oil, jute oil, sesame oil, shea nut oil, groundnut oil, and linseed oil, which may be derived therefrom by methods known in the art. Rapeseed oil, soybean oil, and palm oil are mixtures of fatty acids partially esterified with glycerol, are available in large quantities, and can be obtained in a simple manner from rapeseed, soybean, or palm by pressing. Recycled oils, such as used household oil, are also suitable.

[0070] Alkyl ester derivatives of fatty acid components of animal and vegetable fats and oils are also suitable. Such esters can be obtained by conventional means, for example by transesterification or by saponification and subsequent re-esterification. For example, the following can be considered as commercially available mixtures: ethyl, propyl, butyl and especially methyl esters of fatty acids having 12 to 22 carbon atoms, such as lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, petroselic acid, ricinoleic acid, elaeostearic acid, linoleic acid, linolenic acid, eicosanoic acid, gadoleic acid, docosanoic acid or erucic acid, which have an iodine value of 50 to 150, especially 90 to 125. Mixtures having particularly advantageous properties are those which contain predominantly, i.e. at least 50% by weight, methyl esters of fatty acids having 16 to 22 carbon atoms and 1, 2 or 3 double bonds. Preferred lower alkyl esters of fatty acids are the methyl esters of oleic acid, linoleic acid, linolenic acid and erucic acid.

[0071] Commercially available mixtures of the aforementioned type are obtained, for example, by cleavage and esterification of animal and vegetable fats and oils by transesterification with lower aliphatic alcohols. The production of alkyl esters of fatty acids advantageously starts from fats and oils containing low levels of saturated acids, less than 20%, and having an iodine value of less than 130. The following ester or oil blends are suitable: for example, rapeseed, sunflower, coriander, castor, soybean, peanut, cottonseed, beef tallow, etc. Preferred are alkyl esters of fatty acids based on various rapeseed oils, the fatty acid component of which is derived in an amount of more than 80% by weight from unsaturated fatty acids having 18 carbon atoms.

[0072] While many of the oils listed above can be used as biofuels, vegetable oil derivatives are preferred, with particularly preferred biofuels being the alkyl ester derivatives of rapeseed oil, cottonseed oil, soybean oil, sunflower oil, olive oil, or palm oil, with rapeseed oil methyl ester being especially preferred. Biofuels derived from animals and / or plants are most commonly used in combination with petroleum-derived fuels. The present invention is applicable to mixtures of such fuels in any ratio. For example, at least 2% by weight, preferably at least 5% by weight, more preferably at least 25% by weight, for example more than 50% by weight, of such a fuel mixture may be derived from plant or animal sources.

[0073] The commissioning fuel to be treated with the fuel additive is preferably a gasoline fuel. Such fuels generally boil within the range of 25°C to 240°C, more preferably 30°C to 225°C, and are composed of a variety of compounds, including saturated aliphatic compounds, unsaturated aliphatic compounds, and aromatic compounds. The gasoline fuel may simply consist of straight run gasoline, or may contain the product of one or more refinery conversion or upgrading processes to blended stocks, including cracked hydrocarbon stocks or reformate stocks. Gasoline fuels include leaded and preferably unleaded gasoline fuels.

[0074] Gasoline fuels may also include synthetic blend components such as esters, alcohols, ethers, and ketones, including those derived from the aforementioned biological sources. Gasoline fuels typically include ethanol, for example, ethanol conforming to standard EN15376:2014. Ethanol may be present in an amount of up to 85% by volume of the gasoline fuel, preferably 1% to 30% by volume, more preferably 3% to 20% by volume, and even more preferably 5% to 15% by volume. For example, the fuel may include ethanol in an amount of about 5% by volume (i.e., E5 fuel), about 10% by volume (i.e., E10 fuel), or about 15% by volume (i.e., E15 fuel). Fuels that do not include ethanol are commonly referred to as E0 fuels. The gasoline fuel is preferably a gasoline fuel for road vehicles powered wholly or partly by spark ignition internal combustion engines. Such fuels are typically classified under various well-known industry standards in Europe and may contain low or very low sulphur contents, such as an average maximum of 10 ppm by weight, with maximum sulphur levels not exceeding 80 ppm by weight, preferably 50 ppm by weight, more preferably a maximum of 10 ppm by weight.

[0075] In some embodiments, the gasoline fuel meets the requirements of EN228, for example as set out in BS EN228:2012. In other embodiments, the gasoline fuel meets the requirements of ASTM D4814, for example as set out in ASTM D4814-15a. It will be appreciated that the gasoline fuel may meet both requirements and / or other fuel standards. For example, the gasoline fuel oxygen content is 2.7% by mass. The gasoline fuel may exhibit one or more (e.g., all) of the following, for example as specified by BS EN228:2012: a minimum research octane number of 95.0 or 98.0, a minimum motor octane number of 85.0, a maximum lead content of 5.0 mg / 1, a maximum oxygen content of 720.0 to 775.0 kg / m 3 density of 1.0%, oxidation stability for at least 360 minutes, maximum actual gum content of 5 mg / 100 ml (solvent washed), class 1 copper strip corrosion (3 hours at 50° C.), clear and bright appearance, maximum olefin content of 18.0% by weight, maximum aromatic content of 35.0% by weight, and maximum benzene content of 1.00% by volume; and maximum oxygenate content as specified in EN228, e.g., methanol: 3.0% by volume, ethanol: 5.0% by volume, iso-propanol: 10.0% by volume, iso-butyl alcohol: 10.0% by volume, tert-butanol: 7.0% by volume, ethers (e.g., with 5 or more carbon atoms): 10% by volume, and other oxygenates (depending on the preferred final boiling point): 10.0% by volume.

[0076] In some embodiments, the gasoline fuel contains one or more additives selected from surfactants, friction modifiers / antiwear additives, corrosion inhibitors, combustion modifiers, antioxidants, valve seat recession additives, dehazers / demulsifiers, dyes, markers, odorants, antistatic agents, antibacterial agents, and lubricity improvers in corresponding amounts known to those skilled in the art to be effective, optionally with the inclusion of a solvent with which any or all of such additives may be combined.

[0077] Step (iii) of the method of the first aspect of the invention comprises placing the particulate filter commissioned according to steps (i) and (ii) into service on exhaust gases emitted by an internal combustion engine of the in-service device. This step terminates the filter operation on the gas stream developed in steps (i) and (ii) and designates the filter for operation on exhaust gases emitted by the engine of the in-service device.

[0078] If the commissioning of the filter is performed prior to installation of the filter on the equipment, this transition requires the specification or provision of a commissioning filter for installation on the equipment for use in operation. If the commissioning is performed with a particulate filter already installed in its operational position in the exhaust system of the equipment, the filter is specified for operation on exhaust gases emitted from the engine during normal operation upon completion of a single period of exposure to metal oxide deposition. Thus, in embodiments where the metal oxides are released directly into the exhaust gas stream, this transition occurs automatically upon completion of the single release period. In embodiments where the metal oxides are provided via a single amount of commissioning engine fuel, this transition occurs when engine operation on the commissioning fuel is completed and replaced with operational fuel that does not contain metal oxides or precursors. In this latter regard, replacement with operational fuel involves refilling the fuel tank with a first amount of operational fuel within its most common range until all residual metal oxides are cleared from the fuel system, as any residual metal oxides left at the bottom of the commissioning fuel inside the fuel tank and / or fuel lines are subsequently passed through the engine as the operational fuel is consumed. In this manner, the filling of operational fuel serves to "flush" the residual metal oxides from the fuel tank and establishes the end of the single release period, after which extended operation with normal operational fuel takes place. However, preferably, only a small amount of metal oxides are left at the bottom of the tank prior to filling with normal fuel. After the step of running the particulate filter on exhaust gases emitted from the internal combustion engine of the operational device, a step of running the engine using operational fuel, such as operational fuel that can be obtained from a gas station, may be performed, or may alternatively be performed, with the particulate filter in its operational position in the exhaust system.

[0079] In a further aspect, the present invention provides a method for operating an internal combustion engine having an exhaust system with a particulate filter, comprising the steps of: (a) commissioning a particulate filter according to the method of the first aspect, and then (b) operating the engine with the particulate filter in its operational position in the exhaust system in the absence of any further deposition of metal oxide particles by the means used in the commissioning method of step (a). The present invention provides a method comprising:

[0080] In this further aspect of the invention, step (a) may advantageously be each of the preferred embodiments of the method of the first aspect described above. In this further aspect of the invention, step (b) does not use an additional filter commissioning step. In embodiments in which the commissioning step (a) is performed on a particulate filter installed in its operational position in the exhaust system of the device, it is required that during the operational life of the filter (or until it is reconditioned), no further release of metal oxides into the exhaust gas stream occurs by the means used in step (a), either by direct release or by periodic use in the engine of additional amounts of commissioning fuel containing metal oxides or precursors thereof.

[0081] Selected embodiments of the present invention include the following. 1. A method for commissioning a particulate filter for an exhaust system of a machine powered in whole or in part by an internal combustion engine fueled by either a liquid hydrocarbon-based fuel or a gaseous hydrocarbon-based fuel that is not treated with lubricating oil, comprising: (i) passing the gas stream through an uncarbonized new particulate filter or a decarbonized reconditioned particulate filter; (ii) discharging a flow of metal oxide particles into the gas stream upstream of the particulate filter for a single discharging period sufficient to deposit the metal oxide particles on uncarbonized or decarbonized surfaces of the channels of the filter exposed to the gas stream, thereby resulting in a measurable increase in filtration efficiency for hydrocarbon particulate emissions; and (iii) operating the particulate filter on exhaust gas emitted from an internal combustion engine of the device in operation; The method includes:

[0082] 2. The method of embodiment 1, wherein the apparatus is a vehicle or vessel or a stationary generator or plant. 3. The method of embodiment 1 or embodiment 2, wherein the internal combustion engine is fueled by a liquid hydrocarbon-based fuel that is not treated with a lubricating oil. 4. The method of embodiment 3, wherein the internal combustion engine is fueled by diesel or gasoline petroleum fuel, or biofuel, or a mixture thereof. 5. The method of embodiment 4, wherein the internal combustion engine is fueled by gasoline fuel or biofuel or a mixture thereof. 6. The method of embodiment 5, wherein the internal combustion engine is fueled by gasoline fuel.

[0083] 7. The method according to any one of embodiments 1 to 6, preferably embodiment 5, more preferably embodiment 6, wherein the apparatus is powered by a hybrid power source comprising an internal combustion engine and one or more electric drive motors. 8. The method according to any one of the preceding embodiments, preferably embodiment 7, wherein the particulate filter of step (i) comprises a ceramic monolith, and the metal oxide formed in step (ii) is deposited on at least a portion of the uncarbonized or decarbonized surfaces of the end plugs of the channels of the monolithic filter exposed to the gas flow. 9. The method of any one of the preceding claims, wherein the commissioning steps (i) and (ii) are carried out with the particulate filter installed in its operational position in the exhaust system of the apparatus of step (iii). 10. The gas stream in the commissioning step (i) is an exhaust gas stream discharged from the internal combustion engine of the device when the particulate filter is first put into operation after installation, and the metal oxide particles used in the commissioning step (ii) are (a) A single direct release of metal oxide particles into the exhaust gas stream; or (b) adding a metal oxide or a precursor thereof to a quantity of engine fuel in a form such that upon combustion of the fuel, the metal oxide particles are released into the exhaust gas stream discharged from the combustion chamber. 10. The method of embodiment 9, wherein the exhaust gas is released into the exhaust gas stream upstream of the particulate filter by either

[0084] 11. The method of embodiment 10, option (a), wherein the metal oxide particles are released directly into the exhaust gas stream via delivery from a remotely mounted particle reservoir. 12. The method of embodiment 10, option (a), wherein the metal oxide particles are released directly into the exhaust gas stream from a particulate reservoir that is mounted in the exhaust system upstream of the particulate filter and that opens into a hole in the exhaust system. 13. The method of embodiment 12, wherein the particle reservoir takes the form of an annular container mounted proximal to the upstream end of the particulate filter. 14. The method of embodiment 10, option (b), wherein the engine fuel is a liquid hydrocarbon-based fuel that has not been treated with a lubricating oil, and the metal oxide or a precursor thereof is added to the single quantity of fuel in the form of a fuel additive that disperses the metal oxide or precursor in the fuel. 15. The method of embodiment 14, wherein the fuel additive comprises a metal oxide or precursor stabilized by one or more organic compounds in the form of a dispersion in a hydrocarbon diluent, and the fuel additive does not contain lubricating oil or other heavier petroleum fractions or additives derived therefrom.

[0085] 16. The method according to embodiment 14 or embodiment 15, wherein after installation of the particulate filter, the internal combustion engine is first operated on a single amount of fuel containing the fuel additive, which constitutes the commissioning steps (i) and (ii) of the method, and then operated on a fuel not containing the fuel additive, thereby operating the filter with exhaust gases that do not contain metal oxide particles derived from the fuel. 17. The method of any one of embodiments 14-16, wherein the single quantity of fuel is equal to or less than the amount required to fill the device's on-board fuel tank. 18. The method according to any one of embodiments 14 to 17, wherein the total deposition of metal oxide or a precursor thereof in the channels of the particulate filter is in the range of 0.5 to 4.0 grams of metal oxide per liter of particulate filter gas volume, preferably in the range of 1.0 to 3.3 grams of metal oxide per liter of particulate filter gas volume, more preferably in the range of 1.5 to 3.0 grams of metal oxide per liter of particulate filter gas volume. 19. The method of any one of embodiments 14-18, wherein the fuel additive comprises a dispersion of iron oxide or cerium oxide or a mixture thereof. 20. The method of embodiment 19, wherein the fuel additive comprises iron oxide colloidally dispersed in a hydrocarbon solvent with one or more organic compounds.

[0086] 21. The method of any one of embodiments 14-18, wherein the fuel additive is an iron-containing organometallic compound or complex. 22. The method according to any one of the preceding embodiments, wherein the commissioning steps (i) and (ii) are carried out on the particulate filter before it is installed in its operational position in the exhaust system of the apparatus of step (iii). 23. The method of embodiment 22, in which a particulate filter is first installed in a gas line downstream of a source of the gas stream remote from the apparatus, and then step (i) is carried out on a gas stream other than the engine exhaust gas from the apparatus, and the metal oxide particles used in step (ii) are released directly into this gas stream upstream of the particulate filter, and in step (iii), the particulate filter is removed from the remote gas line and operably placed in the exhaust system of the apparatus. 24. The method of embodiment 23, wherein in step (ii), the metal oxide particles are either released directly into the gas stream via feeding from a remotely mounted particle reservoir, or released directly into the gas stream from a particle reservoir mounted upstream of the particulate filter and opening into a hole in the gas line.

[0087] 25. A method for operating an internal combustion engine having an exhaust system with a particulate filter, comprising: (a) commissioning a particulate filter according to any one of the methods of embodiments 1 to 24, and then (b) operating the engine with the particulate filter in its operational position in the exhaust system in the absence of any further deposition of metal oxide particles by the means used in the commissioning method of step (a). The method includes: 26. The method according to embodiment 25, wherein step (a) is a step of the method as defined in any one of embodiments 14 to 21, and after the commissioning steps (i) and (ii), the engine is operated on a liquid hydrocarbon-based fuel that has not been treated with a lubricating oil and does not contain a fuel additive as defined in embodiments 14 to 21. 27. A commissioned particulate filter obtainable and preferably obtained by a method according to any one of embodiments 1 to 24. 28. An uncommissioned particulate filter assembly for use in the method described in embodiment 13, comprising a particulate filter and a metal oxide particle reservoir in the form of a container mounted proximate to the upstream end of the filter, the container further having means for providing a single discharge of particles into a hole in an inlet pipe leading to the particulate filter when placed in the commissioning gas stream. 29. A particulate filter assembly as described in embodiment 28, wherein the container is an annular container.

[0088] 30. A fuel composition for initial use in an apparatus having an uncommissioned particulate filter installed in the exhaust system of an internal combustion engine, the fuel composition having not been treated with lubricating oil and / or additives derived therefrom; (a) a hydrocarbon-based liquid selected from diesel or gasoline petroleum fuels or biofuels or mixtures thereof; and (b) A fuel additive comprising a metal oxide or precursor stabilized by one or more organic compounds in a hydrocarbon-based dispersion, the fuel additive not containing lubricating oil or other heavier petroleum fractions or additives derived therefrom. 1. A fuel composition comprising:

[0089] 31. The composition of embodiment 30, wherein the fuel additive comprises a dispersion of iron oxide or cerium oxide or a mixture thereof, or comprises an iron-containing organometallic compound or complex. 32. The fuel composition of embodiment 31, wherein the fuel additive consists of iron oxide colloidally dispersed in a hydrocarbon solvent with one or more organic compounds. 33. Use of a fuel composition according to any one of embodiments 30 to 32, comprising a fuel additive (b) as defined above, in a device powered wholly or partly by an internal combustion engine, as an initial fuel for running the engine when a particulate filter is installed in its exhaust system, for commissioning the particulate filter by improving its filtering efficiency for hydrocarbon particulate emissions over a period of engine operation with said initial fuel, prior to putting the device into operation with a fuel not containing fuel additive (b). 34. Use of a fuel additive comprising a metal oxide or a precursor thereof stabilized by one or more organic compounds in a hydrocarbon diluent, and not containing any lubricating oil or other heavier petroleum fractions or additives derived therefrom, to provide a fuel composition as defined in any one of embodiments 30 to 32 or as used in embodiment 33. 35. The use according to embodiment 34, wherein the fuel additive comprises a dispersion of iron oxide or cerium oxide or both, or comprises an iron-containing organometallic compound or complex. 36. The method of embodiment 35, wherein the fuel additive comprises iron oxide colloidally dispersed in a hydrocarbon solvent with one or more organic compounds. The operation of the present invention can be further illustrated by the following examples. EXAMPLES

[0090] The operation of a preferred embodiment in which the commissioning step is performed with the particulate filter installed in its operating position in the exhaust system of the apparatus, and the commissioning gas stream is the exhaust gas stream exiting the engine of the apparatus on the first operation after installation of the particulate filter, was demonstrated in the following series of tests. Test Method Summary A series of three freshly manufactured, unused gasoline particulate filters of the same type were subjected to a three-stage test regime. In Phase 1, the filter filtration efficiency and exhaust backpressure of the three new gasoline particulate filters were measured individually in an engine dynamometer set-up, which represents the baseline filter function of the new filters at the start of the test. In stage 2, the filters were each installed in a gasoline road vehicle exhaust system and then run on a single tank of gasoline fuel. The test fuel composition was varied between the filters to allow the effect of the present invention (metal oxide particles delivered via the fuel) to be compared with untreated fuel or fuel treated with an ash-providing lubricant additive. In Phase 3, each of the three filters was removed from the vehicle and reinstalled in the dynamometer setup from Phase 1, and the filtration efficiency and exhaust backpressure were remeasured at the end of the test. By comparing the results of Phases 1 and 3, the benefits of the present invention were illustrated.

[0091] Phase 1 - Start of test measurements Each gasoline particulate filter ("GPF") was a ceramic monolith with an internal volume of 1.5 liters and was intended for use in the exhaust system of a commercial BMW 530i gasoline passenger car. In stage 1, baseline filtration efficiency and backpressure were measured for each new filter. Each GPF was first installed on an engine test bed using a 2 liter displacement, 4-cylinder gasoline engine equipped with an exhaust turbocharger and direct fuel injection. The measurement cycle shown in FIG. 1 was run on each GPF, with data points collected continuously throughout the test cycle by various sensors mounted in the exhaust line before and after the filter. Two successive measurement cycles were run, which included filter regeneration periods at the beginning and end of each cycle to remove any carbonaceous deposits, and the results of the two cycles were averaged to obtain an average "start of test" measurement for each new, uncarbonized GPF. The cycle illustrated in FIG. 1 had the following conditions and timing:

[0092] [Table 1]

[0093] The inclusion of both a transient cycle and three steady state operating points allowed filter data to be collected at the start of the test and mapped to various engine conditions to gain further insight into the effectiveness of the present invention. Normal engine operating parameters were measured during the measurement cycle to ensure that each GPF was subjected to equivalent conditions. In each case, the engines were run on the same 98 octane gasoline base fuel that had not been treated with any additives. In addition, pressure sensors placed before and after the GPF measured the pressure difference (mbar) across each GPF, capturing the backpressure generated by resistance within the filter to exhaust gas flow. Similarly, particle number sensors recorded particle numbers before and after each GPF (two separate measurements, both 1 / s) to allow calculation of the start-of-test efficiency of each GPF for particle filtration. TIFF0007660369000005.tif15116

[0094] Phase 2 - Commissioning execution During stage 2, each filter from stage 1 was installed in the exhaust system of a BMW 530i passenger vehicle powered by a 2 liter, 4 cylinder, gasoline direct injection (GDI) engine producing a maximum power output of 185 kW and torque of 350 Nm, except that each filter was then commissioned by exposing it to exhaust gases of various fuel compositions as follows: GPF1 (the control test) was exposed to exhaust gases from a single tank of the same gasoline-based fuel used in Stage 1, which had not been treated with any additives. GPF2 (invention) was exposed to exhaust gas from a single tank of the same base fuel that had been treated with a colloidal iron oxide fuel additive to provide a total ash loading of 3 g / liter of the filter internal volume over one tank of fuel. GPF3 (comparative) was exposed to the exhaust gas of a single tank of the same base fuel that had instead been treated with the lubricant additive component of the lubricant formulation, again providing a total ash loading of the filter inner volume of 3 g / liter over the one tank of fuel.

[0095] The vehicle's fuel tank had a capacity of 68 litres. In the case of GPF1, the vehicle's fuel tank was simply filled with the base fuel. In the cases of GPF2 and GPF3, 34 litres of gasoline base fuel was first filled into the fuel tank and then the appropriate additive, premixed with 5 litres of the same base fuel, was added to the fuel tank. In each case, the fuel tank was then filled to capacity with additional base fuel and the resulting agitation allowed the additive to be well dispersed within the fuel tank. A total metal oxide / salt deposit of 4.5 g (or 3 g / liter considering that the GPF has a 1.5 liter volume) was the target for GPF deposit when dosing the additive into the fuel. The fuel additive used with GPF2 in the examples of this invention consisted of iron oxide colloidally stabilized with PIBSDA (polyisobutylene succinic diacid) in a hydrocarbon solvent. The specifications for the iron oxide fuel additive were as follows:

[0096] [Table 2]

[0097] The theoretical amount of iron required to provide 4.5 g of iron oxide was 3.15 g, which equates to 26.25 g of additive when considering its solvent dilution. Therefore, 26.25 g of fuel additive was added to the fuel to provide 4.5 g of total ash in GPF2. GPF3 was treated with a complete lubricant additive package. This comparative example represented the prior art solution of dosing the fuel with a lubricant formulation, but was modified by excluding the lubricant base oil to avoid other adverse effects of heavy hydrocarbons (such as sticky deposits on critical engine surfaces) that would otherwise hinder interpretation of the results. Thus, testing on GPF3 focused on the impact of metallic ash deposits from the complete lubricant additive package added to the test base fuel.

[0098] TGA (Thermogravimetric Analysis) was used to establish the metallic ash content of the lubricant additive package for dosage purposes. The remaining % residue represents the oxidized ash content. The TGA was performed using the following test method: Additive samples were analyzed to determine thermal stability in a typical TGA instrument under air atmosphere. 10 mg samples were heated from 30 to 825°C at 10°C / min under an air flow of 50 ml / min. The pan used was made of platinum. At 825°C, it is assumed that only ash remaining comes from the additive. Using this TGA method, it was found that the lubricant additive package provided 6.8% residuals. A total of 66.18 g of this additive in concentrated form in a hydrocarbon solvent was added to the fuel of GPF3, contributing a total of 4.5 g of ash to GPF3. The lubricant additive package used in the GPF3 tests contained the same additive components as the fresh lubricant used in the engine in this test series, therefore this represents the addition to the fuel of the additional lubricant additives present in the engine and did not result in the exposure of the engine to any additional types of chemical species. A lubricant additive package was prepared using typical commercial lubricant components including metal-based surfactants. The elemental analysis was as follows:

[0099] [Table 3]

[0100] In each commissioning run, the car was driven on the same mixed driving route, approximately 800 km in distance, on that tank of fuel, which included approximately equal distances of city, suburban, and highway driving. At the end of each tank of fuel, the associated GPF was carefully removed from the car and submitted for remeasurement in Phase 3 to determine the effect of the commissioning run on the filtration efficiency and backpressure before and after the GPF.

[0101] Phase 3 - Completion of test measurements Subsequently, each gasoline particulate filter ("GPF") from Phase 2 was reinstalled on the engine test bed used in Phase 1. The same predefined measurement cycle shown in FIG. 1 was performed on each GPF, and data points were again collected continuously throughout the cycle by various sensors installed in the exhaust line before and after the filter. Two consecutive measurement cycles, which included filter regeneration periods at the beginning and end of each cycle to remove any carbonaceous material deposits, were performed, and the results of the two cycles were averaged to determine the "end of test" measurement for each GPF after commissioning according to Phase 2.

[0102] result A) GPF filtration efficiency The results of commissioning filters GPF1, GPF2, and GPF3 are illustrated in Figure 2. The average filtration efficiency measured for each filter at stage 1 (before commissioning) and stage 3 (after commissioning) is compared for each engine operating condition in the measurement cycle. First, Figure 2 illustrates that the filtration efficiency results after commissioning with GPF2 are significantly higher than the control test GPF1 (untreated base fuel). Thus, the commissioning method of the present invention (exemplified by GPF2) improves the filtration efficiency of the particulate filter compared to running it on a conventional base fuel that has not been treated with an iron oxide additive. Second, Figure 2 illustrates that GPF2 provides the same improvement in filtration efficiency as prior art solutions involving the addition of ash-producing lubricant additives to the fuel. Similar filtration efficiency levels are reached at the same total ash loading. Thus, the present invention allows for the attainment of higher filtration efficiency without the drawbacks of adding lubricant species to the fuel.

[0103] Figure 3 is a zoomed in view of the results shown in Figure 2 for an engine operating point of 5500 rpm and 300 Nm torque. The interquartile range shows the difference in filtration efficiency due to commissioning stage 2 seen for GPF2 and GPF3 at this operating point.

[0104] B) Pressure difference before and after the GPF Pressure sensors placed before and after the GPF were used to measure the pressure differential, and therefore the degree of backpressure, that built up in a particular GPF sample. A higher pressure differential indicates a greater degree of resistance to gas flow through the GPF, which may be due to a greater degree of blockage of the porous walls of the filter channels.

[0105] FIG. 4 illustrates the average GPF filtration efficiency and average pressure difference before and after each GPF at engine operating points of 5,500 rpm and 300 Nm torque. It can be seen that the control sample GPF1 does not show a significant increase in pressure difference before and after the commissioning run with base fuel. GPF2 shows a substantial increase in filtration efficiency as a result of the commissioning method of the present invention, but at the same time, the pressure difference shows only a slight increase. In contrast, GPF3 shows an increase in filtration efficiency similar to GPF2, but results in a very large increase in pressure difference before and after GPF. The results in Figure 4 demonstrate that the method of the present invention provides an improved solution to the commissioning of such particulate filters. By increasing the filtration efficiency, the filter can function as an effective trap for hydrocarbon particulate matter exiting the engine and better meet tailpipe particulate emissions. By providing this increased filtration with a correspondingly less negative effect on the pressure differential across the filter, the commissioning method of the present invention not only contributes less to the secondary problem of exhaust backpressure build-up, but also avoids other negative effects caused by the prior art of adding lubricating oil and its additives to the fuel.

[0106] C) X-ray analysis of commissioned filters GPF X-ray scans were performed using a Custom 225kV / 450kV Hatch instrument (for overall scans) and a Nikon 225 HMX (for regions of interest; entrance and exit channels). GPFs from the commissioning test were scanned at 234.4 μm in full view with 32.1 μm ROIs for the inlet and outlet. In addition, GPF2 containing iron oxide was scanned at 70.3 μm in full view. The GPFs were mounted in the analysis chamber for scanning. Intensity was normalized across all data sets. Reconstructed data was processed in Matlab and then analyzed using ImageJ for depth profile analysis and Avizo for image segmentation to provide measurements of channel and plug areas. 3D rendering was performed using Drishti and separate transfer functions were assigned to the filter, plug, and iron signals.

[0107] Figure 5 shows an X-ray image of GPF2 after the three-stage experiment described above. X-ray analysis revealed that iron oxide deposition was concentrated in the end plugs of the filter channels, visible in the image as dark shading at the top and bottom of the channels (which are driven vertically in the figure). Figure 6 shows the X-ray depth profile along the length of the filter channel. The intensity of the signal correlates to the density of the structures, which in turn allows mapping of the metal oxide deposition distribution along the length of the channel. For GPF1, the baseline shows peaks at both ends of the slice depth, which correspond to a higher density of the end plugs of the channel. The lower intensity between these ends indicates the density of the porous longitudinal channel walls through which the exhaust gas passes during filtration. In GPF3, the commissioning phase, which resulted in the deposition of lubricant additive residues on the filter, resulted in a significant increase in signal intensity, including along the filter channel walls. This indicates the accumulation of metal ash deposits throughout the filter, including a thickness of deposits along the channel walls through which filtration occurs. This observation is consistent with the finding that the pressure difference across GPF3 increases as seen in FIG. 4. In contrast, the increase in intensity seen in GPF2 (commissioned according to the invention) is concentrated in the region of the top and bottom plugs, with much less increase along the longitudinal channel walls. This, in turn, is consistent with the observation that the method of the invention increases filtration efficiency with a concomitant smaller increase in pressure difference across the filter. [Industrial Applicability]

[0108] Thus, the method according to the present invention provides an improved balance of filtration characteristics and allows commissioning of new or reconditioned particulate filters with a single metal oxide treatment resulting in higher filtration efficiency without the drawbacks of the prior art of adding lubricating oil to fuel.

Claims

1. 1. A method for commissioning a particulate filter for an exhaust system of a machine powered in whole or in part by an internal combustion engine fueled by either a liquid hydrocarbon-based fuel or a gaseous hydrocarbon-based fuel that is not treated with lubricating oil, comprising: (i) passing the gas stream through an uncarbonized new particulate filter or a decarbonized reconditioned particulate filter; (ii) discharging a flow of metal oxide particles into the gas stream upstream of the particulate filter for a single discharging period sufficient to deposit metal oxide particles on uncarbonized or decarbonized surfaces of the channels of the filter exposed to the gas stream; and (iii) operating the particulate filter on exhaust gas emitted from the internal combustion engine of the apparatus during operation; Including, wherein said metal oxide or precursor thereof is added to a single quantity of said fuel in the form of a fuel additive which disperses said metal oxide or precursor thereof in said fuel, and said metal oxide or precursor thereof is dispersed by a dispersing means which is a hydrocarbyl-substituted dicarboxylic acid containing from 8 to 200 carbon atoms.

2. The method of claim 1 , wherein the device is a vehicle or vessel or a stationary generator or plant.

3. 3. The method of claim 1 or claim 2, wherein the internal combustion engine is fuelled with a liquid hydrocarbon-based fuel that is not treated with a lubricating oil, preferably the internal combustion engine is fuelled with diesel or gasoline petroleum fuel or a biofuel or a mixture thereof, more preferably the internal combustion engine is fuelled with gasoline fuel or a biofuel or a mixture thereof, even more preferably the internal combustion engine is fuelled with gasoline fuel.

4. A method according to any one of claims 1 to 3, preferably the method according to claim 3, wherein the internal combustion engine is fuelled with gasoline fuel or biofuel or a mixture thereof, more preferably the method according to claim 3, wherein the internal combustion engine is fuelled with gasoline fuel, the apparatus is powered by a hybrid power source including the internal combustion engine and one or more electric drive motors; method.

5. 5. The method according to any one of claims 1 to 4, preferably claim 4, wherein the particulate filter of step (i) comprises a ceramic monolith and the metal oxide formed in step (ii) accumulates on at least a portion of the uncarbonized or decarbonized surfaces of the end plugs of the channels of the particulate filter exposed to the gas flow.

6. A method according to any one of the preceding claims, wherein the commissioning steps (i) and (ii) are carried out with the particulate filter installed in its operational position in the exhaust system of the apparatus of step (iii).

7. The gas stream in the commissioning step (i) is an exhaust gas stream discharged from the internal combustion engine of the device during the first operation after installation of the particulate filter, and the metal oxide particles used in the commissioning step (ii) are (a) adding the metal oxide or a precursor thereof to a quantity of engine fuel in a form such that upon combustion of the fuel, metal oxide particles are released into the exhaust gas stream exiting a combustion chamber; or (b) a single direct release of said metal oxide particles into said exhaust gas stream.

7. The method of claim 6, wherein the particulate matter is released into the exhaust gas stream upstream of the particulate filter by either

8. 8. The method of claim 7, wherein in option (a), the engine fuel is a liquid hydrocarbon-based fuel that has not been treated with lubricating oil.

9. 9. The method of claim 8, wherein the fuel additive comprises the metal oxide or a precursor thereof stabilized by one or more organic compounds in the form of a dispersion in a hydrocarbon diluent, and the fuel additive does not contain any lubricating oil or other heavier petroleum fractions or additives derived therefrom.

10. 10. The method of claim 8 or claim 9, wherein after installation of the particulate filter, the internal combustion engine is initially run on a single amount of the fuel containing the fuel additive, which constitutes the commissioning steps (i) and (ii) of the method, and then operationally run on a fuel not containing the fuel additive to operate the filter with exhaust gases that do not contain metal oxide particles derived from the fuel.

11. A method according to any one of claims 8 to 10, wherein the single quantity of fuel is no more than the amount required to fill an on-board fuel tank of the device.

12. 12. A method according to any one of claims 8 to 11, wherein the total deposition of metal oxide or a precursor thereof in the channels of the particulate filter is in the range of 0.5 to 4.0 grams of metal oxide per litre of particulate filter gas volume, preferably in the range of 1.0 to 3.3 grams of metal oxide per litre of particulate filter gas volume, more preferably in the range of 1.5 to 3.0 grams of metal oxide per litre of particulate filter gas volume.

13. 13. A method according to any one of claims 8 to 12, wherein the fuel additive comprises a dispersion of iron oxide or cerium oxide or a mixture thereof, preferably the fuel additive consists of iron oxide colloidally dispersed in a hydrocarbon solvent with one or more organic compounds.

14. A method according to any one of claims 8 to 12, wherein the fuel additive is an iron-containing organometallic compound or complex.

15. commissioning steps (i) and (ii) are carried out on the particulate filter prior to installation of the apparatus of step (iii) in its operational position in the exhaust system; Preferably, said particulate filter is initially installed in a gas line downstream of a source of the gas stream remote from said apparatus, and thereafter step (i) is carried out on a gas stream other than engine exhaust gas from said apparatus, and said metal oxide particles used in step (ii) are released directly into this gas stream upstream of said particulate filter, and in step (iii) said particulate filter is removed from said gas line and operably placed in said exhaust system of said apparatus; More preferably, In step (ii), the metal oxide particles are released directly into the gas stream via a feed from a remotely mounted particle reservoir or directly into the gas stream from a particle reservoir mounted upstream of the particulate filter and opening into a hole in the gas line. The method according to any one of claims 1 to 5.

16. 1. A method for operating an internal combustion engine having an exhaust system having a particulate filter, comprising the steps of: (a) commissioning the particulate filter according to the method of any one of claims 1 to 15, and thereafter (b) operating the engine with the particulate filter in its operational position in the exhaust system in the absence of a period of further deposition of metal oxide particles by means used in the commissioning method of step (a); Preferably, step (a) is a method as defined in any one of claims 8 to 14, and wherein following the commissioning steps (i) and (ii) the engine is operated on a liquid hydrocarbon-based fuel that has not been treated with a lubricating oil and does not contain a fuel additive as defined in claims 8 to 14.

17. 1. A fuel composition for initial use in an apparatus having an uncommissioned particulate filter installed in the exhaust system of an internal combustion engine, the fuel composition having not been treated with lubricating oil and / or additives derived therefrom; (a) a hydrocarbon-based liquid selected from diesel or gasoline petroleum fuels or biofuels or mixtures thereof; and (b) A fuel additive comprising a metal oxide or a precursor thereof stabilized by one or more organic compounds in a hydrocarbon-based dispersion, the fuel additive being free of any lubricating oil or other heavier petroleum fractions or additives derived therefrom. Includes The metal oxide or precursor thereof is dispersed by a dispersing means which is a hydrocarbyl-substituted dicarboxylic acid containing from 8 to 200 carbon atoms; Preferably, the fuel additive comprises a dispersion of iron oxide or cerium oxide or a mixture thereof, or comprises an iron-containing organometallic compound or complex, more preferably the fuel additive comprises a fuel composition comprising iron oxide colloidally dispersed in a hydrocarbon solvent by one or more organic compounds.

18. 20. Use of a fuel composition as claimed in claim 17, comprising a fuel additive (b) as defined above, in a device powered wholly or partly by an internal combustion engine, as an initial fuel for running the engine when a particulate filter is installed in its exhaust system, for commissioning the particulate filter by improving its filtering efficiency for hydrocarbon particulate emissions over a period of engine operation on said initial fuel, prior to putting the device into operation on a fuel not containing said fuel additive (b).

19. 19. Use of a fuel additive comprising a metal oxide or a precursor thereof stabilized by one or more organic compounds in a hydrocarbon diluent, and not containing any lubricating oil or other heavier petroleum fractions or additives derived therefrom, to provide a fuel composition as claimed in claim 17 or as used in claim 18, preferably the fuel additive comprises a dispersion of iron oxide or cerium oxide or both, or comprises an organometallic compound or complex containing iron, more preferably the fuel additive consists of iron oxide colloidally dispersed by one or more organic compounds in a hydrocarbon solvent.

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