Fuel compositions with hydrogen

Abstract

A fuel composition for an internal combustion engine comprising hydrogen gas and a gaseous additive, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof. Use of the gaseous additives in the present invention provides protection against friction loss and wear of moving parts of a hydrogen-fuelled internal combustion engine.

Description

[0001]SP3112 - 1 - FUEL COMPOSITIONS Field of the Invention The present invention relates to fuel compositions suitable for an internal combustion engine, wherein the fuel compositions comprise hydrogen. In particular, the 5 fuel compositions of the present invention have improved friction and wear properties. Background of the Invention Hydrogen (H2) as fuel for an Internal Combustion Engine (ICE) has been considered as carbon free fuel for 10 transportation powertrains, due to its carbon free emissions and high energy efficiency (Berry, G.D.; Pasternak, A.D.; Smith, J.R.; Schock, R.N.; ‘Hydrogen as a future transportation fuel’, Energy 1996, 21, 289-303). The Hydrogen Council, a global initiative composed of 15 various energy and transportation companies, estimated that approximately 25% of passenger car vehicles and 20% of non-electrified rail transportation would be fuelled with hydrogen by 2050, reducing daily oil consumption for transportation use by up to 20% (Hydrogen Scaling Up: A 20 Sustainable Pathway for the Global Energy Transition; Hydrogen Council: Belgium, 2017 and Oil Market Report; International Energy Agency: Paris, France, 2019.). Although hydrogen as fuel can be used in both fuel cells and internal combustion engines (ICEs), the 25 hydrogen ICE can leverage the current production infrastructure for vehicle manufacture and existing powertrains, with some modifications enabling hydrogen as fuel, and therefore, presents a near term opportunity to reduce Greenhouse Gas (GHG) emissions. 30 Both Port Fuel Injection (PFI) and Direct Injection SP3112 - 2 - (DI) technologies have been used in Hydrogen ICEs. A hydrogen DI system with up to 300 bar injection pressure has been developed and integrated into a spark ignition (SI) engine, achieving a maximum efficiency of 42%, 5 paralleling diesel engine with turbo charging (‘BMW Hydrogen Engine Reaches Top Level Efficiency, BMW: Munich, Germany, 2009). The hydrogen gas must be pumped and injected into a combustion chamber, and both pump and injector require 10 effective lubrication to limit friction, wear and seizure of rubbing surfaces. Unfortunately, hydrogen gas is a poor lubricant for most engineering metals, so additional lubrication must be provided, for example an oil or grease, or by employing coatings on rubbing parts. 15 CN116478760A discloses an engine oil for a hydrogen- fuelled internal combustion engines comprising 89% to 92% of a synthetic base oil. CN115125053 discloses a lubricating oil composition for a hydrogen-fuelled internal combustion engine wherein 20 the lubricating oil composition comprises a base oil. It would be desirable to find alternative ways of improving the friction and wear properties of hydrogen- containing fuel compositions. Summary of the Invention 25 According to the present invention there is provided a fuel composition for an internal combustion engine comprising hydrogen gas and a gaseous additive, wherein the gaseous additive is selected from ammonia, an amine, and mixtures thereof. 30 According to the present invention there is further provided a process for preparing a fuel composition for an internal combustion engine comprising blending hydrogen gas with a gaseous additive, wherein the gaseous SP3112 - 3 - additive is selected from ammonia, an amine, and mixtures thereof. According to the present invention there is further provided a method for operating an internal combustion 5 engine comprising fuelling the internal combustion engine with a fuel composition, and combusting the fuel composition within a combustion chamber of the internal combustion engine, wherein the fuel composition comprises hydrogen gas and a gaseous additive, wherein the gaseous 10 additive is selected from ammonia, an amine, and mixtures thereof. According to the present invention there is further provided a method for reducing friction within an internal combustion engine fuelled with a fuel 15 composition comprising hydrogen gas, wherein the method comprises adding to the fuel composition a gaseous additive selected from ammonia, an amine and mixtures thereof, and combusting the fuel composition in a combustion chamber of the internal combustion engine. 20 According to the present invention there is further provided the use of a gaseous additive in a fuel composition comprising hydrogen gas for reducing the friction coefficient of the fuel composition, wherein the gaseous additive is selected from ammonia, an amine, and 25 mixtures thereof. According to the present invention there is further provided a method for reducing engine wear within an internal combustion engine fuelled with a fuel composition comprising hydrogen gas, wherein the method 30 comprises a step of adding to the fuel composition a gaseous additive and combusting the fuel composition in a combustion chamber of the internal combustion engine, wherein the gaseous additive is selected from ammonia, an SP3112 - 4 - amine and mixtures thereof. According to the present invention there is further provided the use of a gaseous additive in a fuel composition comprising hydrogen gas for reducing the wear 5 scar of the fuel composition, wherein the gaseous additive is selected from ammonia, an amine, and mixtures thereof. It has been surprisingly found that by adding a very small amounts, (i.e. additive amounts) of a chemically- 10 active, lubricious gas or vapour species to the hydrogen gas flow, the required pump and injector lubrication is provided and the friction and wear properties of the fuel system are improved. It has been found that the present invention is 15 analogous to using dissolved lubricity additives in liquid hydrocarbon fuels but based in the gas rather than a liquid phase. It has been found by the present inventors that this approach can provide excellent friction and wear control of hydrogen supply systems. 20 The reduction in friction and wear control provided by the present invention could be achieved by co- injecting a lubricant oil with a hydrogen fuel or a co- injecting diesel fuel along with gaseous hydrogen fuel. However, the single fuel solution for hydrogen ICEs 25 provided by the present invention is preferable because it reduces carbon-based emissions and handling and storage is easier. Further, the powertrain system design is simplified. With the single fuel solution of the present invention, there is no need for separate 30 injection systems for co-injecting lubricating oil or diesel fuel. Brief Description of the Drawings Figure 1 shows the friction coefficient plotted SP3112 - 5 - against the Rubbing Time in seconds for Examples 1 and 2 and Comparative Example 1. Figure 2 shows the average friction coefficient for Examples 1 and 2 and Comparative Example 1. 5 Figure 3 shows the friction coefficient plotted against the Rubbing Time in seconds for Examples 3-6 and Comparative Example 1. Figure 4 shows the average friction coefficient for Examples 3-6 and Comparative Example 1. 10 Figure 5 shows the friction coefficient plotted against the Rubbing Time in seconds for Examples 7-10 and Comparative Example 1. Figure 6 shows the average friction coefficient for Examples 7-10 and Comparative Example 1. 15 Figure 7 shows the wear scar diameter for Examples 1-2 and Comparative Example 1. Figure 8 shows the wear scar diameter for Examples 3-6 and Comparative Example 1. Figure 9 shows the wear scar diameter for Examples 20 7-10 and Comparative Example 1. Detailed Description of the Invention The fuel composition of the present invention comprises hydrogen gas and a gaseous additive. The hydrogen gas used in the fuel composition of the 25 present invention can be any hydrogen gas suitable for use in an internal combustion engine. The internal combustion engine herein is preferably a hydrogen-fuelled internal combustion engine. The gaseous additive is aminic compound, preferably 30 selected from ammonia, an amine, and mixtures thereof. The amine compound is preferably selected from methylamine, dimethylamine, and trimethylamine, and mixtures thereof. In a preferred embodiment, herein the SP3112 - 6 - gaseous additive is an amine. In an especially preferred embodiment herein, the gaseous additive is dimethylamine. The gaseous additive is preferably present in the fuel composition in an amount from 1 ppmw to 10,000 ppmw, 5 more preferably from 50 to 5000 ppmw, even more preferably from 50 ppmw to 2000 ppmw, and especially from 50 ppmw to 500 ppmw. In one embodiment, the gaseous additive is present in an amount from 100 ppmw to 500 ppmw. 10 The fuel compositions are prepared by mixing the additive with the hydrogen. The fuel compositions of the present invention provide reduced friction and wear. In the context of the present invention, the term 15 “reducing the friction’ and ‘reducing the friction coefficient’ embraces any degree of reduction in the friction and friction coefficient achieved by the fuel composition. The reduction in the coefficient of friction of the fuel composition may be of the order of 20 1% or more, preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more, and especially 35% or more compared to the coefficient of friction of an analogous fuel composition comprising hydrogen gas alone and which does not contain the 25 specified gaseous additive. In one embodiment, the reduction in coefficient of friction of the fuel composition is of the order of 70% or more, compared to the coefficient of fraction of an analogous fuel composition comprising hydrogen gas alone and which does 30 not contain the specified gaseous additive. Even a 1% reduction in friction coefficient is worthwhile, as such a reduction can bring a material within prevailing fuel specifications, which it would not otherwise meet. SP3112 - 7 - As well as reducing the average friction coefficient, the gaseous additives used herein have also shown benefits in instantaneous friction reduction. As used herein, the term ‘instantaneous friction reduction’ means that the 5 moving parts of the engine will be protected from friction and wear as soon as they are exposed to the additised fuel composition. Hence according to the present invention there is a provided a method for reducing the instantaneous friction within an internal combustion 10 engine fuelled with a fuel composition comprising hydrogen gas, wherein the method comprises adding to the fuel composition a gaseous additive and combusting the fuel composition within a combustion chamber of the internal combustion engine, wherein the gaseous additive 15 is selected from ammonia, an amine compound, and mixtures thereof. There is further provided the use of a gaseous additive in a fuel composition comprising hydrogen gas for reducing the instantaneous friction in an internal combustion engine, wherein the gaseous additive is 20 selected from ammonia, an amine compound, and mixtures thereof. In the context of this aspect of the invention, the term “reducing engine wear’ and ‘reducing the wear scar diameter’ embraces any degree of reduction in the engine 25 wear and wear scar diameter achieved by the fuel composition. The reduction in the wear scar diameter may be of the order of 1% or more, preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and especially 35% or more compared to the wear 30 scar diameter of an analogous fuel composition comprising hydrogen gas alone and which does not contain the specified gaseous additive. In one embodiment, the reduction in coefficient of friction of the fuel SP3112 - 8 - composition is of the order of 70% or more, compared to the coefficient of fraction of an analogous fuel composition comprising hydrogen gas alone and which does not contain the specified gaseous additive. Even a 1% 5 reduction in wear scar diameter is worthwhile, as such a reduction can bring a material within prevailing fuel specifications, which it would not otherwise meet. While the fuel compositions of the present invention are particularly advantageous for reducing friction and 10 wear in a hydrogen-fuelled internal combustion engine, the fuel compositions of the present invention can also be used as fuel in a Proton-exchange membrane (PEM) fuel cell application. The invention is illustrated by the following non- 15 limiting examples. Examples Examples 1-10 and Comparative Example 1 Hydrogen fuel was blended with a series of gaseous hydrocarbon additives and the resulting fuel compositions 20 were tested for friction and wear properties in a sealed HFR rig experiment. Example 1 consisted of hydrogen gas and an additive amount (1000 ppmw) of ammonia gas. Example 2 consisted of hydrogen gas and an additive 25 amount (5000 ppmw) of ammonia gas. Example 3 consisted of hydrogen gas and an additive amount (100 ppmw) of methylamine gas. Example 4 consisted of hydrogen gas and an additive amount (500 ppmw) of methylamine gas. 30 Example 5 consisted of hydrogen gas and an additive amount (1000 ppmw) of methylamine gas. Example 6 consisted of hydrogen gas and an additive amount (5000 ppmw) of methylamine gas. SP3112 - 9 - Example 7 consisted of hydrogen gas and an additive amount (100 ppmw) of dimethylamine gas. Example 8 consisted of hydrogen gas and an additive amount (500 ppmw) of dimethylamine gas. 5 Example 9 consisted of hydrogen gas and an additive amount (1000 ppmw) of dimethylamine gas. Example 10 consisted of hydrogen gas and an additive amount (5000 ppmw) of dimethylamine gas. Comparative Example 1 consisted of hydrogen gas 10 without any gaseous additives. The fuel compositions were subjected HFR tests as described in Zhang,J.,Bolle,B., Wong,J.S.S., Spikes,H.S. ‘Influence of Atmosphere on Carbonaceous Film Formation in Rubbing, Metallic Contacts’, Tribol Lett 72, 4(2024), 15 in order to determine friction coefficients and wear scar diameter. A sealed HFR (HPR) from PCS Instruments was used. This is a fully automated ball-on-plate reciprocating system for the measurement of friction and wear under fully sealed, pressurised, and controlled 20 conditions. It has a fully sealed pressure chamber which is able to run under high pressure or vacuum. It comprises a removable chamber design which maintains pressure or vacuum even when off the system, which allows test blends to be made in situ. The small volume of the 25 chamber allows test fluids to be changed in situ and / or during a test. This instrument has the same contact configuration as the conventional HFR and uses the same ball and disc specimen. The entire unit is enclosed in a stainless steel casing with a small internal volume of 30 60ml. Sealing of reciprocating shaft is via two flexible bellows, while an external transducer monitors friction by displacement of the disc holder. The latter differs from the conventional HFR only in that the shaft to SP3112 - 10 - transducer is attached to and passes through a flexible, metal membrane to enable complete sealing. The test rig can operate up to 10 bar pressure and 150°C. The HPR test conditions are shown below in Table 1. 5 Table 1 Applied load 1.96N (200g), Pmax = 0.82 GPa Stroke length Isooctane 1mm, hexadecane 2mm Stroke frequency Isooctane 50Hz, Hexadecane 20Hz Test fluid volume 6cm3(when fluid used) Test Temperature Isooctane 25°C, hexadecane 60°C Disc roughness, Rq 4.8 ± 1.2 nm Ball roughness, Rq 9.9 ± 1.2 nm Ball hardness 790 HV Ball hardness Hard disc = 775 HV Table 2 below shows the average friction coefficient (µ) and the average ball wear scar diameter (WSD) for Examples 1-10 and Comparative Example 1. 0 Table 2 Example Average ball wear Average friction scar diameter coefficient (µm) Comparative 496.2 0.901 Example 1 (hydrogen, no additive) Example 1 (H2, 406.8 0.720 1000 ppmw NH3) Example 2 (H2, 361.9 0.351 5000 ppmw NH3) Example 3 (H2, 100 405.6 0.686 ppmw methylamine) Example 4 (H2, 500 223.9 0.346 ppmw methylamine) Example 5 (H2, 204.0 0.315 1000 ppmw methylamine) Example 6 (H2, 143.5 0.213 5000 ppmw methylamine) Example 7 (H2, 100 200.6 0.336 ppmw dimethylamine) Example 8 (H2, 500 173.5 0.278 ppmw dimethylamine) Example 9 (H2, 158.7 0.264 1000 ppmw dimethylamine) Example 10 (H2, 103.2 0.203 5000 ppmw dimethylamine) Figure 1 shows the friction coefficient as a function of Rubbing time (seconds) for Examples 1 and 2 and Comparative Example 1 and shows that ammonia showed 5 instantaneous friction reduction at treat rates of 1000 ppmw and 5000 ppmw. Figure 2 shows the average friction coefficient for Examples 1 and 2 and Comparative Example 1, as well as the %reduction in friction coefficient for each of0 Examples 1 and 2 and Comparative Example 1. Figure 2 shows that all the gaseous additives provided a significant reduction in average friction coefficient at both treat rates. In particular, Figure 2 shows that addition of ammonia to hydrogen gas at a treat rate of5 1000 ppmw (Example 1) provided over 20% reduction in friction coefficient compared with hydrogen gas alone (Comparative Example 1). Also, Figure 2 shows that addition of ammonia to hydrogen gas at a treat rate of 5000 ppmw (Example 2) provided 61% reduction in friction0 coefficient compared with hydrogen gas alone. Figure 3 shows the friction coefficient as a function of Rubbing time (seconds) for Examples 3-6 and Comparative Example 1 and shows that methylamine showed instantaneous friction reduction at a treat rate of 50005 ppmw. Figure 4 shows the average friction coefficient for Examples 3-6 and Comparative Example 1, as well as the %reduction in friction coefficient for each of Examples 1 and 2 and Comparative Example 1. Figure 4 shows that 5 methylamine provided a significant reduction in average friction coefficient at all treat rates. Surprisingly, even a treat rate as low as 100ppmw methylamine provided a significant reduction in average friction coefficient. In particular, Figure 4 shows that addition methylamine 10 to hydrogen gas at a treat rate of 100 ppmw (Example 3) provided over 23% reduction in average friction coefficient compared with hydrogen gas alone (Comparative Example 1). Also, Figure 4 shows that addition of methylamine to hydrogen gas at a treat rate of 500 ppmw 15 (Example 4) provided over 61% reduction in average friction coefficient compared with hydrogen gas alone. Figure 4 also shows that addition of methylamine to hydrogen gas at a treat rate of 1000 ppmw (Example 5) provided 65% reduction in average friction coefficient 20 compared with hydrogen gas alone. Figure 4 also shows that addition of methylamine to hydrogen gas at a treat rate of 5000 ppmw (Example 6) provided over 76% reduction in average friction coefficient compared with hydrogen gas alone. 25 Figure 5 shows the friction coefficient as a function of Rubbing time (seconds) for Examples 7-10 and Comparative Example 1 and shows that dimethylamine showed instantaneous friction reduction was observed for hydrogen fuel blends at as low as 500 ppmw additive treat 30 rate. Figure 6 shows the average friction coefficient for Examples 7-10 and Comparative Example 1, as well as the %reduction in friction coefficient for each of Examples - 13 - 7-10 compared with hydrogen gas alone. Figure 6 shows that dimethylamine provided a significant reduction in average friction coefficient at all treat rates. Surprisingly, even a treat rate as low as 100ppmw 5 dimethylamine provided a significant reduction in average friction coefficient. In particular, Figure 6 shows that addition dimethylamine to hydrogen gas at a treat rate of 100 ppmw (Example 7) provided over 62% reduction in average friction coefficient compared with hydrogen gas 10 alone (Comparative Example 1). Also, Figure 6 shows that addition of dimethylamine to hydrogen gas at a treat rate of 500 ppmw (Example 8) provided over 69% reduction in average friction coefficient compared with hydrogen gas alone. Figure 6 also shows that addition of 15 dimethylamine to hydrogen gas at a treat rate of 1000 ppmw (Example 9) provided over 70% reduction in average friction coefficient compared with hydrogen gas alone. Figure 6 also shows that addition of dimethylamine to hydrogen gas at a treat rate of 5000 ppmw (Example 10) 20 provided over 77% reduction in average friction coefficient compared with hydrogen gas alone. Figure 7 shows the wear scar diameter for Examples 1 and 2 and Comparative Example 1, as well as the % reduction in wear scar diameter for each of Examples 1 25 and 2 compared with hydrogen gas alone. Examples 1 and 2 achieved a significant reduction in wear scar compared with hydrogen gas alone. In particular, Figure 7 shows that addition of ammonia to hydrogen gas at a treat rate of 1000 ppmw (Example 1) provided an 18% reduction in 30 wear scar diameter compared with hydrogen gas alone (Comparative Example 1). Also, Figure 7 shows that addition of ammonia to hydrogen gas at a treat rate of 5000 ppmw ammonia (Example 2) provided over 27% reduction SP3112 - 14 - in wear scar diameter compared with hydrogen gas alone. Figure 8 shows the wear scar diameter for Examples 3-6 and Comparative Example 1, as well as the % reduction in wear scar diameter for each of Examples 3-6 compared 5 with hydrogen alone. All Examples 3-6 achieved a significant reduction in wear scar compared with hydrogen gas alone. In particular, Figure 8 shows that addition of methylamine to hydrogen gas at a treat rate of 100 ppmw (Example 3) provided over 18% reduction in wear scar 10 diameter compared with hydrogen gas alone (Comparative Example 1). Also, Figure 8 shows that addition of methylamine to hydrogen gas at a treat rate of 500 ppmw (Example 4) provided over 54% reduction in wear scar diameter compared with hydrogen gas alone. Further, 15 Figure 8 shows that addition of methylamine to hydrogen gas at a treat rate of 1000 ppmw (Example 5) provided over 58% reduction in wear scar diameter compared with hydrogen gas alone. Figure 8 also shows that addition of methylamine to hydrogen gas at a treat rate of 5000 ppmw 20 provided over 71% reduction in wear scar diameter compared with hydrogen gas alone. Figure 9 shows the wear scar diameter for Examples 7-10 and Comparative Example 1, as well as the % reduction in wear scar diameter for each of Examples 7-10 25 compared with hydrogen gas alone. All Examples 7-10 achieved a significant reduction in wear scar compared with hydrogen gas alone. In particular, Figure 9 shows that addition of dimethylamine to hydrogen gas at a treat rate of 100 ppmw (Example 7) provided over 59% reduction 30 in wear scar diameter compared with hydrogen gas alone (Comparative Example 1). Also, Figure 9 shows that addition of dimethylamine to hydrogen gas at a treat rate of 500 ppmw (Example 8) provided a 65% reduction in wear SP3112 - 15 - scar diameter compared with hydrogen gas alone. Further, Figure 9 shows that addition of dimethylamine to hydrogen gas at a treat rate of 1000 ppmw (Example 9) provided a 68% reduction in wear scar diameter compared with 5 hydrogen gas alone. Further, Figure 9 shows that addition of dimethylamine to hydrogen gas at a treat rate of 5000 ppmw (Example 10) provided over 79% reduction in wear scar compared with hydrogen gas alone. 10

Claims

SP3112 - 16 - C L A I M S 1. A fuel composition for an internal combustion engine comprising hydrogen gas and a gaseous additive, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof. 5 2. A fuel composition according to Claim 1 wherein the gaseous additive is an amine compound.

3. A fuel composition according to Claim 1 or 2 wherein the amine compound is selected from methylamine, dimethylamine, and trimethylamine, and mixtures thereof. 10 4. A fuel composition according to any of Claims 1 to 3 wherein the amine compound is dimethylamine.

5. A fuel composition according to any of Claims 1 to 4 wherein the gaseous additive is present in an amount of 1 ppmw to 10,000 ppmw, based on the fuel composition. 15 6. A process for preparing the fuel compositions of any Claims to 5 comprising blending hydrogen gas with a gaseous additive, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof. 20 7. Method for operating an internal combustion engine comprising fuelling the internal combustion engine with a fuel composition, and combusting the fuel composition within a combustion chamber of the internal combustion engine, wherein the fuel composition comprises hydrogen 25 gas and a gaseous additive, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof.

8. Method for reducing the friction within an internal combustion engine fuelled with a fuel composition 30 comprising hydrogen gas, wherein the method comprisesSP3112 - 17 - adding to the fuel composition a gaseous additive and combusting the fuel composition within a combustion chamber of the internal combustion engine, wherein the gaseous additive is selected from ammonia, an amine 5 compound, and mixtures thereof.

9. Use of a gaseous additive in a fuel composition comprising hydrogen gas for reducing the friction coefficient of the fuel composition, wherein the gaseous additive is selected from ammonia, an amine compound, and 10 mixtures thereof.

10. Method for reducing engine wear within an internal combustion engine fuelled with a fuel composition comprising hydrogen gas, wherein the method comprises a step of adding to the fuel composition a gaseous additive 15 and combusting the fuel composition in a combustion chamber of the internal combustion engine, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof.

11. Use of a gaseous additive in a fuel composition 20 comprising hydrogen gas for reducing the wear scar of the fuel composition, wherein the gaseous additive is selected from ammonia, an amine compound, and mixtures thereof.

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