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 an unsaturated C2-C4 hydrocarbon. 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] FUEL COMPOSITIONS WITH HYDROGEN

[0002] Field of the Invention

[0003] The present invention relates to fuel compositions suitable for an internal combustion engine, wherein the fuel compositions comprise hydrogen. In particular, the fuel compositions of the present invention have improved friction and wear properties. Background of the Invention

[0004] Hydrogen (H2) as fuel for an Internal Combustion Engine (ICE) has been considered as carbon free fuel for 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 various energy and transportation companies, estimated that approximately 25% of passenger car vehicles and 20% of non-electrif ied rail transportation would be fuelled with hydrogen by 2050, reducing daily oil consumption for transportation use by up to 20% (Hydrogen Scaling Up: A Sustainable Pathway for the Global Energy Transition; Hydrogen Council: Belgium, 2017 and Oil Market Report; International Energy Agency: Paris, France, 2019. ) .

[0005] Although hydrogen as fuel can be used in both fuel cells and internal combustion engines (ICEs) , the 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.

[0006] Both Port Fuel Injection (PFI) and Direct Injection (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%, paralleling diesel engine with turbo charging ( 'BMW Hydrogen Engine Reaches Top Level Efficiency, BMW: Munich, Germany, 2009) .

[0007] The hydrogen gas must be pumped and injected into a combustion chamber, and both pump and injector require 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.

[0008] CN116478760A discloses an engine oil for a hydrogen- fuelled internal combustion engines comprising 89% to 92% of a synthetic base oil.

[0009] CN115125053 discloses a lubricating oil composition for a hydrogen-fuelled internal combustion engine wherein the lubricating oil composition comprises a base oil.

[0010] It would be desirable to find alternative ways of improving the friction and wear properties of hydrogencontaining fuel compositions. Summary of the Invention

[0011] 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 an unsaturated C2- C4 hydrocarbon.

[0012] 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 additive is selected from an unsaturated C2-C4 hydrocarbon .

[0013] According to the present invention there is further provided a method for operating an internal combustion engine compri sing fuelling the internal combustion engine with a fuel compos ition , and combusting the fuel composition within a combustion chamber of the internal combustion engine , wherein the fuel composition comprise s hydrogen ga s and a ga seous additive , wherein the ga seous additive is an unsaturated C2_C4 hydrocarbon .

[0014] According to the present invention there is further provided a method for reducing f riction within an internal combustion engine fuelled with a fuel composition compri sing hydrogen gas , wherein the method comprise s adding to the fuel composition a ga seous additive selected from an unsaturated C2-C4 hydrocarbon , and combusting the fuel composition in a combustion chamber of the internal combustion engine .

[0015] According to the present invention there is further provided the use of a gaseous additive in a fuel composition compri sing hydrogen gas for reducing the f riction coef ficient of the fuel composition, wherein the gaseous additive i s an unsaturated C2_C4 hydrocarbon .

[0016] 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 compri sing hydrogen gas , wherein the method comprise s a step of adding to the fuel compos ition a gaseous additive and combusting the fuel composition in a combustion chamber of the internal combustion engine , wherein the gaseous additive is an unsaturated C2_C4 hydrocarbon .

[0017] 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 scar of the fuel composition, wherein the gaseous additive is an unsaturated C2-C4 hydrocarbon.

[0018] It has been surprisingly found that by adding very small amounts, (i.e. additive amounts) of a chemically- 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.

[0019] It has been found that the present invention is 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.

[0020] The reduction in friction and wear control provided by the present invention could be achieved by coinjecting a lubricant oil with a hydrogen fuel or a coinjecting diesel fuel along with gaseous hydrogen fuel. However, the single fuel solution for hydrogen ICEs 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 injection systems for co-injecting lubricating oil or diesel fuel.

[0021] Brief Description of the Drawings

[0022] Figure 1 shows the friction coefficient plotted against the Rubbing Time in seconds for Example 1 (containing 5000ppmw ethane) and Comparative Example 1.

[0023] Figure 2 shows the friction coefficient plotted against the Rubbing Time in seconds for Examples 2 and 3 (containing lOOOppmw ethylene and 5000ppmw ethylene, respectively) and Comparative Example 1.

[0024] Figure 3 shows the average friction coefficient for Examples 2 and 3 (containing 1000 ppmw ethylene and 5000ppmw ethylene, respectively) and Comparative Example 1.

[0025] Figure 4 shows the friction coefficient plotted against the Rubbing Time in seconds for Examples 4 and 5 (containing 1000 ppmw acetylene and 5000ppmw acetylene, respectively) and Comparative Example 1.

[0026] Figure 5 shows the average friction coefficient for Examples 4 and 5 (containing 1000 ppmw acetylene and 5000 ppmw acetylene, respectively) , and Comparative Example 1.

[0027] Figure 6 shows the wear scar diameter for Examples 2 and 3 (containing 1000 ppmw ethylene and 5000ppmw ethylene, respectively) and Comparative Example 1.

[0028] Figure 7 shows the wear scar diameter for Examples 4 and 5 (containing 1000 ppmw acetylene and 5000ppmw acetylene, respectively) and Comparative Example 1. Detailed Description of the Invention

[0029] The fuel composition of the present invention comprises hydrogen gas and a gaseous additive.

[0030] The hydrogen gas used in the fuel composition of the present invention can be any hydrogen gas suitable for use in an internal combustion engine. The internal combustion herein is preferably a hydrogen-fuelled internal combustion engine.

[0031] The gaseous additive is a gaseous unsaturated hydrocarbon additive comprising from 2 to 4 carbon atoms. The unsaturated C2-C4 hydrocarbon is preferably selected from ethylene, propene, butylene, isobutylene, acetylene, methylacetylene, and mixtures thereof. In one embodiment, the unsaturated C2-C4 hydrocarbon is selected from ethylene and acetylene, and mixtures thereof. In an especially preferred embodiment, the unsaturated C2_C4 hydrocarbon is acetylene.

[0032] The gaseous unsaturated C2-C4 hydrocarbon is preferably present in the fuel composition in an amount from 1 ppmw to 10, 000 ppmw, more preferably from 500 ppmw to 5000 ppmw, even more preferably from 1000 ppmw to 5000 ppmw, and especially from 2000 ppmw to 5000 ppmw. In one embodiment, the gaseous unsaturated C2_C4 hydrocarbon is present in an amount from 2000 ppmw to 5000 ppmw.

[0033] The fuel compositions are prepared by blending hydrogen gas with a gaseous additive.

[0034] The fuel compositions of the present invention provide reduced friction and wear.

[0035] As used herein, the term "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 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 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 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 .

[0036] As well as reducing the average friction coefficient , the gaseous additive s used herein have also shown benefits in instantaneous friction reduction . As used herein, the term 'instantaneous friction reduction' means that the moving parts of the engine will be protected from friction and wear as soon as they are exposed to the additised fuel composition of the present invention . Hence according to the present invention there is a provided a method for reducing the instantaneous friction within an internal combustion engine fuelled with a fuel composition comprising hydrogen gas , wherein the method comprises adding to the fuel compos ition a gaseous additive and combusting the fuel composition within a combustion chamber of the internal combustion engine , wherein the gaseous additive i s selected from ammonia , an amine compound , and mixture s thereof . There is further provided the use of a gaseous additive in a fuel composition compri sing hydrogen gas for reducing the instantaneous friction in an internal combustion engine , wherein the gaseous additive is selected from ammonia , an amine compound, and mixtures thereof .

[0037] As used herein , the term " reducing engine wear' and ' reducing the wear scar diameter ' embrace s any degree of reduction in the engine 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 scar diameter of an analogous fuel composition compri sing hydrogen gas alone and which does not contain the specified gaseous additive . In one embodiment , the reduction in coefficient of f riction 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 not contain the specified gaseous additive. Even a 1% 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.

[0038] While the fuel compositions of the present invention are particularly advantageous for reducing friction and 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.

[0039] The invention is illustrated by the following nonlimiting examples. Examples Examples 1-3 and Comparative Example 1

[0040] Hydrogen fuel was blended with a series of gaseous hydrocarbon additives and the resulting fuel compositions were tested for friction and wear properties in a sealed HER rig experiment.

[0041] Example 1 consisted of hydrogen gas and an additive amount (5000 ppmw) of ethane gas.

[0042] Example 2 consisted of hydrogen gas and an additive amount (1000 ppmw) of ethylene gas.

[0043] Example 3 consisted of hydrogen gas and an additive amount (5000 ppmw) of ethylene gas.

[0044] Example 4 consisted of hydrogen gas and an additive amount (1000 ppmw) of acetylene gas.

[0045] Example 5 consisted of hydrogen gas and an additive amount (5000 ppmw) of acetylene gas.

[0046] Comparative Example 1 consisted of hydrogen gas without any gaseous additives. The fuel compositions were subjected HER 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' , Tribal Lett 72, 4 (2024) , in order to determine friction coefficients and wear scar diameter. A sealed HER (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 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 chamber allows test fluids to be changed in situ and / or during a test. This instrument has the same contact configuration as the conventional HER and uses the same ball and disc specimen. The entire unit is enclosed in a stainless steel casing with a small internal volume of 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 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.

[0047] Table 1

[0048] Table 2 below shows the average friction coefficient ( p) and the average ball wear scar diameter (WSD) for Examples 1-5 and Comparative Example 1 . Table 2

[0049] *Not according to the present invention

[0050] Figure 1 shows the friction coefficient a s a function of Rubbing time ( Seconds ) for Example 1 ( 5000ppmw ethane ) and shows that ethane was ineffective in reducing the friction coefficient .

[0051] Figure 2 shows the friction coefficient a s a function of Rubbing time ( seconds ) for Examples 2 and 3 ( containing 1000 ppmw and 5000 ppmw of ethylene respectively) and shows that ethylene exhibited instantaneous friction reduction at a 5000 ppmw treat rate . Figure 3 shows the average friction coefficient for Examples 2 and 3 and Comparative Example 1, as well as the ireduction in friction coefficient for each of Examples 2 and 3 compared with Comparative Example 1. In particular, Figure 2 shows that addition of 5000 ppmw ethylene to hydrogen gas (Example 3) provided over 35% reduction in friction coefficient compared with hydrogen gas alone (Comparative Example 1) . Also, Figure 2 shows that addition of a lower treat rate of ethylene (1000 ppmw) (Example 2) did not result in a reduction in the average friction coefficient compared with hydrogen gas alone .

[0052] Figure 4 shows the friction coefficient as a function of Rubbing time (seconds) for Examples 4 and 5 (containing 1000 ppmw and 5000 ppmw of acetylene respectively) and shows that acetylene was effective in reducing friction at both low and high treat rates (1000 ppmw and 5000 ppmw, respectively) . At 5000ppmw treat rate of acetylene, the friction reduction was instantaneous .

[0053] Figure 5 shows the average friction coefficient for Examples 4 and 5 and Comparative Example 1, as well as the %reduction in friction coefficient for each of Examples 4 and 5 compared with Comparative Example 1. In particular, Figure 5 shows that addition of 1000 ppmw acetylene to hydrogen gas provided over 35% reduction in friction coefficient compared with hydrogen gas alone. Figure 5 also shows that addition of 5000 ppmw acetylene to hydrogen gas provided over 70% reduction in friction coefficient compared with hydrogen gas alone.

[0054] Figure 6 shows the wear scar diameter for Examples 2 and 3 and Comparative Example 1, as well as the % reduction in wear scar diameter for each of Examples 2 and 3 and Comparative Example 1. Examples 2 and 3 achieved a significant reduction in wear scar compared with hydrogen gas alone. Both treat rates, low and high (1000 ppmw and 5000 ppmw) of ethylene blended fuels were effective in reducing the wear scar. In particular, Figure 6 shows that addition of 1000 ppmw ethylene to hydrogen gas (Example 2) provided over 13% reduction in wear scar diameter compared with hydrogen gas alone (Comparative Example 1) . Also, Figure 6 shows that addition of 5000 ppmw ethylene to hydrogen gas (Example 3) provided over 28% reduction in wear scar diameter compared with hydrogen gas alone.

[0055] Figure 7 shows the wear scar diameter for Examples 4 and 5 and Comparative Example 1, as well as the % reduction in wear scar diameter for each of Examples 4 and 5 and Comparative Example 1. Examples 4 and 5 achieved a significant reduction in wear scar compared with hydrogen gas alone. Both treat rates, low and high (1000 ppmw and 5000 ppmw) of ethylene blended fuels were effective in reducing the wear scar. In particular, Figure 7 shows that addition of 1000 ppmw acetylene to hydrogen gas (Example 4) provided over 26% reduction in wear scar diameter compared with hydrogen gas alone (Comparative Example 1) . Also, Figure 7 shows that addition of 5000 ppmw acetylene to hydrogen gas (Example 5) provided over 57% reduction in wear scar diameter compared with hydrogen gas alone.

[0056] In summary, the Examples show that a series of gaseous additives based on carbon and hydrogen provided excellent friction and wear protection.

Claims

C L A I M S1. A fuel composition for an internal combustion engine comprising hydrogen gas and a gaseous additive, wherein the gaseous additive is selected from an unsaturated C2-C4 hydrocarbon.

2. A fuel composition according to Claim 1 wherein the unsaturated C2_C4 hydrocarbon is selected from ethylene and acetylene, and mixtures thereof.

3. A fuel composition according to Claim 1 or 2 wherein the unsaturated C2-C4 hydrocarbon is acetylene.

4. A fuel composition according to any of Claims 1 to 3 wherein the gaseous additive is present in an amount of 1 ppmw to 10, 000 ppmw, based on the fuel composition.

5. A process for preparing the fuel composition of any of Claims 1 to 4 comprising blending hydrogen gas with a gaseous additive, wherein the gaseous additive is an unsaturated C2-C4 hydrocarbon.

6. 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 gas and a gaseous additive, wherein the gaseous additive is an unsaturated C2-C4 hydrocarbon.

7. Method for reducing friction within an internal combustion engine fuelled with a fuel composition comprising hydrogen gas, wherein the method comprises adding to the fuel composition a gaseous additive selected from an unsaturated C2_C4 hydrocarbon, and combusting the fuel composition in a combustion chamber of the internal combustion engine.8 . Use of a gaseous additive selected from an unsaturated C2_C4 hydrocarbon in a fuel composition comprising hydrogen gas for reducing the friction coefficient of the fuel composition . 9 . 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 ga seous additive selected from an unsaturated C2_C4 hydrocarbon and combusting the fuel composition in a combustion chamber of the internal combustion engine .10 . Use of a gaseous additive selected from an unsaturated C2_C4 hydrocarbon in a fuel composition comprising hydrogen gas for reducing the wear scar of the fuel compos ition .

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