JP7832112B2 - Use of paraffin-based gas oil - Google Patents

Description

This invention relates to the use of paraffinic gas oil to provide specific benefits in a selective catalytic reduction (SCR) system installed in a compression ignition engine. In particular, this invention relates to the use of paraffinic gas oil to reduce the amount of SCR reagent required in a selective catalytic reduction system installed in a compression ignition engine.

Selective catalytic reduction (SCR) is a NOx emission control technique applicable to a wide range of diesel engines, from small, medium, and large diesel engine systems to two-stroke low-speed marine engines. Essentially, in an SCR system, an SCR reagent (e.g., urea) is injected into the engine exhaust gas flow. When mixed with the exhaust gas, the SCR reagent decomposes to produce ammonia. The mixture of ammonia and exhaust gas enters the SCR catalyst, where the ammonia reduces NOx to nitrogen.

SCR systems are renowned for their efficient removal of NOx emissions, but they require an "onboard" supply of SCR reagent. The consumption of this SCR reagent varies depending on engine operating conditions, but typically ranges from 3% to 8% of parallel fuel consumption for average operating conditions. This can be a costly and/or health and safety burden for vehicle owners, especially vehicle fleet operators. AdBlue® can corrode some metals, and if spilled on skin, it should be washed off immediately; wearing protective gloves during the filling procedure is recommended.

Therefore, it would be desirable to reduce the amount of SCR reagent required and provide a fuel-based solution applicable to all SCR systems, regardless of the equipment used by the manufacturer.

It would also be desirable to provide a fuel-based solution that reduces the number of SCR reagent vehicle refuelings per year, thereby minimizing user exposure to corrosive liquids.

Remarkably, it was discovered that using paraffinic gas oil in the diesel fuel composition can achieve a remarkable and previously unrecognized reduction in the amount of SCR reagent required to achieve the necessary reduction of NOx emissions by the SCR system.

According to the present invention, the use of paraffinic gas oil in a diesel fuel composition is provided to reduce the amount of SCR reagent required by an SCR (Selective Catalytic Reduction) system installed in a compression-ignition internal combustion engine.

According to another aspect of the present invention, a method is provided for reducing the amount of SCR reagent required by an SCR (Selective Catalytic Reduction) system installed in a compression-ignition internal combustion engine, the method comprising the step of introducing a diesel fuel composition containing paraffinic gas oil into the engine.

According to another aspect of the present invention, the use of paraffinic gas oil in a diesel fuel composition is provided for reducing the number of SCR reagent vehicle refills per year.

It has been found that the use of paraffinic gas oil in diesel fuel compositions can lead to a reduction in the amount of SCR reagent required by the SCR (Selective Catalytic Reduction) system installed in compression-ignition internal combustion engines.

The following is a graph of the results shown in Table 3.

As used herein, the use of paraffinic gas oil in a diesel fuel composition is provided for the purpose of reducing the amount of SCR reagent required by an SCR (Selective Catalytic Reduction) system attached to a compression ignition engine. In the context of this aspect of the present invention, the term "reducing the amount of SCR reagent required" encompasses any degree of reduction in the amount of SCR reagent required by the SCR system. The reduction in the amount of SCR reagent required may be about 5% or more, preferably about 10% or more, more preferably about 20% or more, and particularly about 40% or more, compared to the amount of SCR reagent required by a similar SCR system when a similar fuel formulation is used to fuel a compression ignition engine but does not contain paraffinic gas oil (for example, when a similar fuel formulation contains or consists of EN590 refined diesel fuel instead of paraffinic gas oil).

As used herein, the term "SCR reagent" means a substance or solution of a substance that is stored on a vehicle and introduced (e.g., sprayed) into the exhaust gas stream for reaction with exhaust NOx on an SCR catalyst, according to the engine exhaust system requirements. For use herein, an SCR reagent is any reagent suitable for use in an SCR system that can react (i.e., reduce) NOx in the exhaust gas through itself or its decomposition products to produce nitrogen. Essentially, an SCR reagent may be ammonia itself, or any substance whose decomposition products include ammonia.

Preferably, the SCR reagent is selected from urea, ammonia, ammonium salts such as ammonium formate and ammonium carbamate, and mixtures thereof. The SCR reagent can exist in an anhydrous form or as an aqueous solution. In a preferred embodiment, the SCR reagent is urea, preferably an aqueous solution of urea.

The commercially available SCR reagent for use in this specification is AdBlue®, a registered trademark, commercially available from fuel and other suppliers as defined in Specification ISO 22241.

The first essential component of the diesel fuel composition described herein is paraffinic gas oil. The paraffinic gas oil fuel is present in the diesel fuel composition described herein at a level ranging from 20% v/v to 100% m/m, preferably 50% v/v to 100% v/v, more preferably 80% v/v to 100% v/v, and even more preferably 90% v/v to 100% v/v, based on the total diesel fuel composition.

In another embodiment described herein, paraffinic gaseous oil fuel is present in the diesel fuel composition as a blend with a diesel fuel such as EN590 refined diesel fuel. In this embodiment, the paraffinic gaseous oil fuel is present in the diesel fuel composition at a level ranging from 10% v/v to 99% v/v, more preferably 20% v/v to 70% v/v, even more preferably 20% v/v to 50% v/v, and particularly 20% v/v to 30% v/v, based on the total diesel fuel composition.

The paraffinic gas oil used in this invention can be obtained from any suitable source, as long as it is suitable for use in a diesel fuel composition.

Suitable paraffinic gas oils include, for example, gas oils derived from Fischer-Tropsch, gas oils derived from hydrogenated vegetable oil (HVO), and mixtures thereof.

From the viewpoint of reducing the amount of SCR reagent required by the SCR (Selective Catalytic Reduction) system, while ensuring that other properties such as viscosity, density, and distillation characteristics fall within the requirements of diesel specifications, the paraffinic gas oil used herein is preferably Fischer-Tropsch derived gas oil fuel. The paraffinic properties of Fischer-Tropsch derived gas oil mean that the diesel fuel composition containing it has a higher cetane number compared to conventional diesel.

Fischer-Tropsch-derived gas oils are preferred paraffinic gas oils for use herein; however, the term “paraffinic gas oil” as used herein also includes those paraffinic gas oils derived from the hydrogenation (HVO) of vegetable oils. The HVO process is based on petroleum refining technology. In this process, hydrogen is used to remove oxygen from triglyceride vegetable oil molecules, splitting the triglycerides into three separate chains to produce paraffinic hydrocarbons.

According to the present invention, the paraffinic gas oil for use herein (i.e., gas oil derived from Fischer-Tropsch, gas oil derived from hydrogenated vegetable oil, etc.) will preferably consist of at least 95% w/w, more preferably at least 98% w/w, even more preferably at least 99.5% w/w, and most preferably up to 100% w/w of paraffinic components, preferably isoparaffin and normal paraffin.

"Fischer-Tropsch derived" means that the fuel or base oil is a synthetic product of the Fischer-Tropsch condensation process, or is derived from a synthetic product of the Fischer-Tropsch condensation process. The term "non-Fischer-Tropsch derived" may be interpreted accordingly. Fischer-Tropsch derived fuels may also be referred to as GTL (gaseous-to-liquid) fuels.

The Fischer-Tropsch reaction, in the presence of a suitable catalyst and usually at high temperatures (e.g., 125–300°C, preferably 175–250°C) and/or pressures (e.g., 5–100 bar, preferably 12–50 bar), converts carbon monoxide and hydrogen into longer chains, usually paraffinic hydrocarbons:
n(CO + _2H₂ ) = ( _-CH₂- ) _n + _nH₂O + heat. Hydrogen:carbon monoxide ratios other than 2:1 may be used as desired.

Carbon monoxide and hydrogen may themselves be derived from organic or inorganic, natural or synthetic sources, typically from natural gas or organically derived methane.

Recently, techniques for deriving carbon monoxide and hydrogen from other sources, including more sustainable ones, have been explored and used. For example, starting with carbon dioxide and water, the water can be electrolyzed to yield free hydrogen, typically using electricity from a sustainable source. This hydrogen can then react with carbon dioxide in a “reverse water shift” reaction to produce a source of carbon monoxide. Alternatively, instead of the “reverse water shift” reaction, electrolysis can be used for the electrochemical conversion of carbon dioxide to the required carbon monoxide. This carbon monoxide (from the described source) can then be reacted with the remaining hydrogen in a typical Fischer-Tropsch synthesis process. Due to the use of electrolysis, some of these production processes are referred to as “Power-to-Liquid.”

Gas oils, kerosene fuels, and base oil products can be obtained directly from the Fischer-Tropsch reaction, indirectly, for example, by fractionation of Fischer-Tropsch synthetic products, or from hydrogenated Fischer-Tropsch synthetic products. Hydrogenation involves hydrocracking (see, e.g., GB2077289 and EP0147873) to adjust the boiling point range and/or hydroisomerization, which can improve cold flow characteristics by increasing the proportion of branched paraffins. EP0583836 describes a two-step hydrogenation process in which the Fischer-Tropsch synthetic product is first subjected to hydrogenation under conditions that are substantially free from isomerization or hydrocracking (this hydrogenates the olefin and oxygen-containing components), and then at least a portion of the resulting product is hydrogenated under conditions that undergo hydrocracking and isomerization, producing a substantially paraffinic hydrocarbon fuel or oil. The desired diesel fuel fraction can then be isolated, for example, by distillation.

Other post-synthesis treatments, such as polymerization, alkylation, distillation, decomposition-decarboxylation, isomerization, and hydrogenation, may be used to modify the properties of the Fischer-Tropsch condensation product, as described, for example, in US-A-4125566 and US-A-4478955.

Typical catalysts for the Fischer-Tropsch synthesis of paraffinic hydrocarbons contain, as catalytically active components, metals from Group VIII of the periodic table, particularly ruthenium, iron, cobalt, or nickel. Such suitable catalysts are described, for example, in EP0583836.

An example of a Fischer-Tropsch-based process is the Shell Middle Distillate Synthesis (SMDS) described by van der Burgt et al. (see above). This process (sometimes also referred to as Shell "Gas to Liquid" or "GTL" technology) produces diesel-range products by converting synthesis gas derived from natural gas (primarily methane) into heavy long-chain hydrocarbon (paraffinic) waxes, which can then be hydrogenated and fractionated to produce gaseous oils and kerosene and other liquid transport fuels. Versions of the SMDS process that utilize fixed-bed reactors for the catalytic conversion step are currently used at the Bintulu and Ras Laffan Pearl GTLs in Malaysia and Qatar. Kerosene and (gas) oils prepared by the SMDS process are commercially available, for example, from the Royal Dutch/Shell Group of Companies.

Thanks to the Fischer-Tropsch process, gaseous oils derived from Fischer-Tropsch are either essentially free of sulfur and nitrogen, or contain undetectable levels of sulfur and nitrogen. Compounds containing these heteroatoms tend to act as poisons to the Fischer-Tropsch catalyst and are therefore removed from the synthesis gas feedstock. Furthermore, the processes typically operated produce no aromatic components at all, or substantially none.

For example, the aromatic content of Fischer-Tropsch gas oil is typically less than 1% w/w, preferably less than 0.5% w/w, and more preferably less than 0.1% w/w, as determined, for example, by ASTM D4629.

Generally speaking, Fischer-Tropsch fuels have relatively low levels of polar components, particularly polar surfactants, compared to, for example, petroleum-derived fuels. This is thought to contribute to improved defoaming and de-fogging performance. Such polar components may include, for example, oxygenated compounds, sulfur, and nitrogen-containing compounds. The low levels of sulfur in Fischer-Tropsch fuels are generally indicators of low levels of both oxygenated and nitrogen-containing compounds, as they are all removed by the same processing method.

The Fischer-Tropsch-derived gaseous fuel used in this invention is a liquid hydrocarbon middle distillate fuel with a distillation range similar to petroleum-derived diesel, specifically, a T95 of 360°C or less, typically within the range of 160°C to 400°C. Again, Fischer-Tropsch-derived fuels tend to have lower levels of undesirable fuel components such as sulfur, nitrogen, and aromatics.

The Fischer-Tropsch derived gaseous fuel used in the present invention will typically have a density of 0.76 to 0.80 g/ ^cm³ , preferably 0.77 to 0.79 g/ ^cm³ , and more preferably 0.775 to 0.785 g/ ^cm³ (measured according to EN ISO 12185) at 15°C.

The Fischer-Tropsch derived gaseous fuel used in this invention preferably has a cetane number greater than 70 (ASTM D613), more preferably between 70 and 85, and most appropriately between 70 and 77.

The Fischer-Tropsch derived gaseous fuel used in the present invention preferably has a kinematic viscosity at 40°C (measured according to ASTM D445) in the range of 2.0 ^mm² /sec to 5.0 ^mm² /sec, preferably 2.5 ^mm² /sec to 4.0 ^mm² /sec.

The Fischer-Tropsch derived gas oil used in this invention has a sulfur content (ASTM D2622) of 5 ppmw (1 part per million by weight) or less, preferably 2 ppmw or less.

The Fischer-Tropsch-derived gaseous fuel used in this invention is manufactured as a separate end product suitable for sale and used in applications requiring specific properties of the gaseous fuel. In particular, it exhibits a distillation range that falls within the range typically associated with Fischer-Tropsch-derived gaseous fuel as described above.

The fuel composition according to the present invention may contain a mixture of two or more gaseous oil fuels derived from Fischer-Tropsch.

According to the present invention, the Fischer-Tropsch-derived component used herein (i.e., Fischer-Tropsch-derived gas oil) will contain, by weight, preferably 3% w/w or less, more preferably 2% w/w or less, and even more preferably 1% w/w or less of cycloparaffin (naphthene) of the Fischer-Tropsch-derived component.

The Fischer-Tropsch-derived components used herein (i.e., Fischer-Tropsch-derived gas oils) preferably contain olefins at a weight of 1% w/w or less, more preferably 0.5% w/w or less.

The diesel fuel compositions described herein are particularly suitable for use as diesel fuel and, due to their excellent cold-flow characteristics, can be used as winter-grade diesel fuel for extremely cold applications.

For example, a cloud point below -10°C (EN 23015) or a low-temperature filter clogging point (CFPP) below -20°C (measured by EN 116) may be possible with the fuel compositions described herein.

The diesel fuel compositions described herein may include diesel fuel in addition to paraffinic gas oil.

The diesel fuel may be any petroleum-derived diesel suitable for use in internal combustion engines, such as low-sulfur diesel containing less than 50 ppm of sulfur, for example, ultra-low-sulfur diesel (ULSD) or zero-sulfur diesel (ZSD). Preferably, the low-sulfur diesel contains less than 10 ppm of sulfur.

A petroleum-derived low-sulfur diesel preferred for use in the present invention would typically have a density of 0.81 to 0.865 g/ ^cm³ , preferably 0.82 to 0.85 g/ ^cm³ , more preferably 0.825 to 0.845 g/ ^cm³ at 15°C, a cetane number of at least 51 (ASTM D613), and a kinematic viscosity (ASTM D445) of 1.5 to 4.5 ^mm² /sec, preferably 2.0 to 4.0 ^mm² /sec, more preferably 2.2 to 3.7 ^mm² /sec at 40°C.

In one embodiment, the diesel fuel is conventional petroleum-derived diesel.

Generally speaking, in the context of the present invention, fuel compositions may contain fuel additives. Unless otherwise specified, the concentration of each such additive (active substance) in the fuel composition is preferably up to 10,000 ppmw, more preferably 5 to 1,000 ppmw, and advantageously 75 to 300 ppmw, for example, in the range of 95 to 150 ppmw. Such additives may be added at various stages during the production of the fuel composition. Those added to the base fuel at the refinery may be selected from, for example, antistatic agents, pipeline drag reducers, middle distillate flow improvers (MDFIs) (e.g., ethylene/vinyl acetate copolymers or acrylate/maleic anhydride copolymers), lubricity improvers, antioxidants, and wax settling inhibitors.

The fuel composition may contain a detergent, meaning an agent (preferably a surfactant) that can act to remove and/or prevent the accumulation of combustion-related deposits inside the engine, particularly in the fuel injection system, for example, in the injector nozzles. Such materials are sometimes referred to as dispersant additives. When the fuel composition contains a detergent, the preferred concentration of the active detergent is in the range of 20 to 500 ppmw, more preferably 40 to 500 ppmw, most preferably 40 to 300 ppmw, or 100 to 300 ppmw or 150 to 300 ppmw based on the entire fuel composition. Detergent-containing diesel fuel additives are known and commercially available. Examples of suitable detergent additives include polyolefin-substituted succinimides or polyamine succinamides, e.g., polyisobutylene succinimide or polyisobutyleneamine succinamide, aliphatic amines, Mannich bases or amines, and polyolefins (e.g., polyisobutylene) and maleic anhydride. In particular, polyolefin-substituted succinimides such as polyisobutylene succinimide are preferred.

Other components that may be incorporated as fuel additives, for example in combination with detergents, include lubricity enhancers, de-fogging agents, e.g., alkoxylated phenol-formaldehyde polymers, defoamers (e.g., commercially available polyether-modified polysiloxanes), ignition enhancers (cetane number enhancers) (e.g., 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate, di-tert-butyl peroxide, and those disclosed in columns 2, row 27 to 3, row 21 of US 4208190), rust inhibitors (e.g., propane-1,2-diol semiester of tetrapropenylsuccinate, or succin). Examples include polyhydric alcohol esters of acid derivatives, succinic acid derivatives having an unsubstituted or substituted aliphatic hydrocarbon group containing 20 to 500 carbon atoms on at least one of its alpha carbon atoms (e.g., pentaerythritol diester of polyisobutylene-substituted succinic acid), corrosion inhibitors, deodorants, wear-resistant additives, antioxidants (e.g., phenols such as 2,6-di-tert-butylphenol, or phenylenediamines such as N,N'-di-sec-butyl-p-phenylenediamine), metal deactivators, electrostatic dissipatives, and mixtures thereof.

The additive preferably contains an antifoaming agent, more preferably in combination with a rust inhibitor and/or corrosion inhibitor and/or lubricating additive.

In particular, lubricity enhancers are especially preferable to be included in the fuel composition if they have a low sulfur content (e.g., 500 ppmw or less). The lubricity enhancer is conveniently present in the entire fuel composition at a concentration of 50 to 1000 ppmw, preferably 100 to 1000 ppmw.

The concentration of the de-fogging agent (active substance) in the fuel composition is preferably in the range of 1 to 20 ppmw, more preferably 1 to 15 ppmw, even more preferably 1 to 10 ppmw, and advantageously 1 to 5 ppmw. The concentration of any ignition enhancer (active substance) present is preferably 600 ppmw or less, more preferably 500 ppmw or less, and conveniently 300 to 500 ppmw.

The present invention may be particularly applicable when a fuel composition is used, or intended to be used, in, for example, in a rotary pump, inline pump, unit pump, electronic unit injector, or common rail direct injection diesel engine, or in a pre-chamber diesel engine. The fuel compositions described herein may be suitable for use in large and/or small diesel engines, as well as in engines designed for on-road or off-road use.

To be suitable for at least the above-described use, the diesel fuel compositions described herein preferably have one or more of the following characteristics:
At -40°C, the kinematic viscosity is 1.9 ^mm² /second or more, more preferably in the range of 1.9 to 4.5 ^mm² /second.
- A density of 800 kg/ ^m³ or more, more preferably 800 to 860 kg/ ^m³ , and even more preferably in the range of 800 to 845 kg/ ^m³ ,
T95 below -360℃,
Cloud point in the range of -0°C to -13°C, more preferably -5°C to -8°C.
CFPP in the range of -8°C to -30°C, more preferably -15°C to -20°C.

The present invention will be explained by the following non-limiting embodiments.

Example 1
In Example 1, two different fuels were used. Fuel 1 was a GTL gas oil containing 10 ppm of a hindered phenol antioxidant (2,6-di-tert-butyl-4-methylphenol, also known as BHT). Table 1 shows the physical and compositional characteristics of the GTL gas oil (fuel 1) used in Example 1. The GTL gas oil (fuel 1) was obtained from Pearl GTL, Ras Laffan, and is commercially available from Shell/Royal Dutch Group of Companies.

Fuel 2 was conventional diesel fuel (Diesel B7). The physical characteristics of the conventional diesel fuel (Diesel B7) used in the example (Fuel 2) are shown in Table 2. As used herein, "Diesel B7" means a diesel fuel containing 7% biofuel components.

Test Method The vehicle used in Example 1 was a state-of-the-art (Euro VI) Mercedes Actros HGV truck fitted with an SCR system. AdBlue® (as defined by specification ISO 22241), readily available on the European market, was used as the SCR reagent for the SCR system.

Before each test run, the DPF (diesel particulate filter) was forcibly regenerated, and it was confirmed that the post-treatment was in the same state at the start of each test. For each test run, the truck was driven on an oval test course at 89 kph for 3 hours.

During each test run, the system had the capability to monitor and record various output parameters from the ECU (Engine Control Unit), which provided instantaneous status information for the engine, DPF, and SCR aftertreatment systems. Such ECU parameters included SCR status, SCR reagent measurement amount, SCR reagent tank level, NOx pre-catalyst, and NOx post-catalyst.

Table 3 below shows the average amount of SCR reagent used in Example 1 versus fuel type.

The results in Table 3 show that GTL fuel provides a 0.08 (8%) benefit compared to B7 diesel fuel. Figure 1 is a graph of the results shown in Table 3.

Example 2
The model calculations were prepared to illustrate the benefits of GTL fuel in reducing the number of SCR reagent packings per year.

Knowing various vehicle parameters allows for the calculation of the number of SCR reagent refills required per year, thus enabling a reduction in the number of refills when GTL fuel is used. For the purposes of these calculations, the SCR reagent is AdBlue®.

The following calculations use the following abbreviations:
AFC = Annual fuel consumption liters ATV = AdBlue tank volume α = 0.05 (i.e., 5%) AdBlue consumption β = expressed as a fraction of fuel consumption AAF = AdBlue refill per year RAF = Reduction in AdBlue refill per year AAF and RAF can be expressed by the following formulas.

These equations can now be applied to typical medium- and long-distance vehicles to calculate the expected benefit in reducing the number of AdBlue fills per year through the use of GTL fuel.

The following assumptions were made in the calculation:
For vehicles in these classes, AdBlue consumption is typically 4% to 6% of fuel consumption, and therefore a value of 5% is used, i.e., α is considered to be 0.05.
- 144,000 miles is typical for the annual mileage of one long-haul truck, resulting in an annual fuel consumption of 100,716 liters and an annual AdBlue consumption of 5,036 liters.
- 72,000 miles is typical for the annual mileage of a single medium-distance truck, resulting in an annual fuel consumption of 28,968 liters and an annual AdBlue consumption of 1,448 liters.
- The fleet size was estimated to be 30 units.
- The value of β (AdBlue consumption benefit from GTL fuel, experimentally determined to be 0.08 (i.e., 8%) from Example 1). The various benefits of GTL use will differ depending on the engine's sensitivity to the chemical properties of the GTL. For example, regulated emissions (PM, NOx, HC, CO) measurements (published literature) show a wide range of benefits depending on numerous factors, including test conditions and engine type. It can be reasonably assumed that there will also be a large level of variation in the AdBlue requirement percentage benefit observed in different engine-SCR combination systems. Therefore, the value of β takes into account a reasonable level of variation. Thus, β takes a value in the range of 2% to 30%, which is the midpoint between 8% and 20%.

The results of these model calculations are shown in Table 4 below.

Example 3
In Example 3, two different fuels were used. Fuel 3 was a GTL gas oil containing 10 ppm of a hindered phenol antioxidant (2,6-di-tert-butyl-4-methylphenol, also known as BHT). Table 5 shows the physical and compositional characteristics of the GTL gas oil (fuel 3) used in Example 3. The GTL gas oil (fuel 3) was obtained from Pearl GTL, Ras Laffan, and is commercially available from Shell/Royal Dutch Group of Companies.

Fuel 4 was conventional diesel fuel (Diesel B7). The physical characteristics of the conventional diesel fuel (Diesel B7) used in the example (Fuel 4) are also shown in Table 5. As used herein, "Diesel B7" means a diesel fuel containing 7% biofuel components.

The objective of Example 3 of the test method was to generate further experimental data supporting the results obtained in Example 1, particularly by expanding the test to a larger number of vehicles, specifically a fleet of four.

In Example 3, four vehicles were used. These were state-of-the-art Mercedes Actros HGV trucks (three Euro VI-C and one Euro V1-D) equipped with an SCR system. AdBlue® (as defined by specification ISO 22241), readily available in the European market, was used as the SCR reagent in the SCR system of each vehicle.

Prior to each test run, forced regeneration of the DPF (diesel particulate filter) was performed, and it was confirmed that the post-treatment was in the same state at the start of each test. The test runs of the four trucks were extended in duration compared to the 3-hour test run in Example 1. For the test runs, each of the four trucks was driven on an elliptical test course at 70 kph with two driver shifts per day until the DPF (diesel particulate filter) gutta-load reached the DPF regeneration point. For some truck/fuel combinations, this meant test runs exceeding 40 hours at 70 kph. (Braking occurred approximately every 2-2.5 hours to accommodate driver breaks or shift changes, during which time the engine remained idle. The vehicle was stationary for 8 hours overnight with the engine turned off.)

During each test run, the system had the capability to monitor and record various output parameters from the ECU (Engine Control Unit), which provided instantaneous status information for the engine, DPF, and SCR aftertreatment systems. Such ECU parameters included SCR status, SCR reagent measurement amount, SCR reagent tank level, NOx pre-catalyst, and NOx post-catalyst.

The average amount of SCR reagent used in Example 3 versus the fuel type for each of the four vehicles is shown in Table 6 below.

The results in Table 6 show that GTL fuel provides a benefit ranging from 1.1% to 15.2% compared to B7 diesel fuel.

Discussion: As can be seen from the results in Table 3, the graph in Figure 1, and Table 6, there is a significant reduction in the amount of SCR reagent required in the case of paraffin-based GTL fuel compared to conventional diesel B7 fuel.

As shown in the model calculations in Table 4, using paraffin-based GTL fuel compared to B7 diesel fuel results in a reduction in the number of AdBlue refills required per year across a wide fleet. The model values cover the benefits for various tank sizes and AdBlue consumption rates. The reduction in the number of SCR reagent vehicle refills per year offers the advantage of minimizing user exposure to corrosive liquids.
This specification includes the disclosure of the following inventions.
[Item 1]
The use of paraffinic gas oil in diesel fuel compositions to reduce the amount of SCR reagent required by an SCR system installed in a compression ignition internal combustion engine.
[Item 2]
The use described in item 1, wherein the SCR reagent is selected from urea, ammonia, ammonium salts, and mixtures thereof.
[Item 3]
The use described in item 1 or 2, wherein the SCR reagent is urea.
[Item 4]
The use according to any one of items 1 to 3, wherein the paraffinic gas oil contains more than 95% by weight of paraffin, preferably more than 98% by weight of paraffin, based on the total weight of the paraffinic gas oil.
[Item 5]
The use according to any one of items 1 to 4, wherein the paraffinic gas oil is selected from gas oil derived from Fischer-Tropsch, gas oil derived from hydrogenated vegetable oil (HVO), and mixtures thereof.
[Item 6]
The use described in any one of items 1 to 5, wherein the paraffinic gas oil is gas oil derived from Fischer-Tropsch.
[Item 7]
The use according to item 5 or 6, wherein the Fischer-Tropsch derived gas oil is present at a level of 50% v/v to 100% v/v based on the total diesel fuel composition.
[Item 8]
The use according to any one of items 5 to 7, wherein the gas oil derived from Fischer-Tropsch has a kinematic viscosity in the range of 2.0 to 5.0 ^mm² /second and a density in the range of 0.76 to 0.80 g/cm³ at ⁴⁰ °C.
[Item 9]
The use according to any one of items 1 to 8, wherein the diesel fuel composition further comprises a diesel fuel.
[Item 10]
A method for reducing the amount of SCR reagent required by an SCR system attached to a compression ignition internal combustion engine, the method comprising the step of introducing a diesel fuel composition containing paraffinic gas oil into the engine.
[Item 11]
Use of paraffinic gas oil in diesel fuel compositions to reduce the number of SCR reagent vehicle refills per year.

Claims (5)

The use of paraffinic gas oil in a diesel fuel composition to reduce the number of SCR reagent vehicle refills per year,
The number of SCR reagent vehicle refills per year is calculated using the following formula:
Here,
AAF = Number of SCR reagent vehicles filled per year,
SCR reagent consumption as a fraction of fuel consumption, which is considered to be α = 0.05 (i.e., 5%).
AFC = Annual Fuel Consumption in Liters
ATV = SCR reagent tank volume, and the SCR reagent is selected from urea, ammonia, ammonium salts, and mixtures thereof .
The paraffinic gas oil contains more than 95% by weight of paraffin based on the total weight of the paraffinic gas oil, the paraffinic gas oil is a Fischer-Tropsch derived gas oil, and the Fischer-Tropsch derived gas oil has a kinematic viscosity in the range of 2.0 to 5.0 ^mm² /sec and a density in the range of 0.76 to 0.80 g/cm³ at ⁴⁰ °C.
use. The use according to claim 1, wherein the SCR reagent is urea. The use according to claim 1 or 2 , wherein the paraffinic gas oil contains more than 98% by weight of paraffin based on the total weight of the paraffinic gas oil. The use according to any one of claims 1 to 3 , wherein the Fischer-Tropsch derived gas oil is present at a level of 50% v/v to 100% v/v based on the total diesel fuel composition. The use according to any one of claims 1 to 4 , wherein the diesel fuel composition further comprises a diesel fuel.