Replaceable on-board carbon dioxide capture system for internal combustion engines

Abstract

Replaceable on-board carbon dioxide capture system for internal combustion engine Replaceable on-board CO2 capture system (1) for internal combustion engine to reduce the amount of CO2 released into the atmosphere by the internal combustion engine, the system comprising: a main exhaust gas path (17) configured to discharge the exhaust gas stream (2) into the atmosphere without further treatment for CO2 capture; a secondary exhaust gas path (18) configured to direct the exhaust gas stream (2) through a CO2 capture zone (19); the CO2 capture zone (19) comprising a container (5) containing a CO2 capture material; a first CO2 level detector (4) at the inlet of the secondary exhaust gas path (18) to determine the CO2 content of the exhaust gas stream (2) exiting the internal combustion engine;a second CO2 level detector (21) at the outlet of the secondary exhaust gas path (18) to determine the CO2 content of the exhaust gas stream (2) exiting the CO2 capture zone (19); a distribution means (10) disposed at the inlet of the secondary exhaust gas path (18) to direct the exhaust gas stream (2) towards the CO2 capture zone (19); wherein the main exhaust gas path (17) is configured to guide said exhaust gas stream (2) when the CO2 content as determined by said first CO2 level detector (4) is less than a predetermined value; the secondary exhaust gas path (18) is configured to guide said exhaust gas stream (2) when the CO2 content as determined by said first CO2 level detector (4) is greater than a predetermined value;said container (5) comprises at least two reactors, a reactor in use (8) and a reserve reactor (20); the CO2 capture material is an alkali metal oxide; the CO2 capture zone (19) is configured so as to manually replace the saturated reactor in use (8), as detected by said second CO2 level detector (21), with the reserve reactor (20); the saturated reactor in use (8) is configured such that after being replaced by said reserve reactor (20), it is emptied and then refilled with a new charge of CO2 capture material. Figure for the abstract: [Fig. 1];

Description

Title of the invention: Replaceable on-board carbon dioxide capture system for internal combustion engines. Technical field of the invention

[0001] The present invention relates to the field of automotive technology and, more specifically, to the field of carbon dioxide (CO2) removal from the exhaust gas stream of an internal combustion engine used to power a motor vehicle. In particular, the invention relates to a replaceable on-board CO2 capture system. Furthermore, the invention relates to a method for removing CO2 from the exhaust gas stream of an internal combustion engine using the replaceable on-board CO2 capture system, and to a vehicle using such a system. State of the art

[0002] When internal combustion engines are operated, exhaust gases are generated that are contaminated by pollutants such as carbon dioxide. Because these pollutants are harmful to the environment, stricter limit values ​​are continually being set for their concentration in the exhaust gases of internal combustion engines. Previous methods of treating exhaust gases to reduce the concentration of pollutants emitted by an internal combustion engine were based on the oxidation or reduction of pollutants using catalysts. These conventional methods are no longer sufficient to meet the new regulations.

[0003] European Regulation 2019 / 631 sets CO2 emission performance requirements for cars, which are very difficult to meet. From 1 January 2020, the regulation sets an EU-wide fleet target of 95 g / km of CO2 for the average emissions of new passenger cars registered in the Union. If this limit is exceeded, manufacturers will pay penalties. The cost of technologies to reduce CO2 emissions varies between €10 / g of CO2 and €200 / g of CO2 (PHEV). CO2 emissions are directly linked to fuel consumption and, without additional systems such as hybridization, the target is significantly exceeded.

[0004] EP 3 523 516 discloses a method for purifying exhaust gases generated by an internal combustion engine. The exhaust gases generated by the internal combustion engine are conducted through an exhaust gas circuit which is equipped with at least one adsorption element to which the pollutants contained in the exhaust gases bind at least partially. The at least one adsorption element is regenerated by at least partial desorption of bound pollutants, and the pollutants desorbed from at least one adsorption element during the desorption process are stored in at least one storage unit.

[0005] The technical solution disclosed in document EP 3 523 516 is a dual exhaust system at the engine outlet, each line incorporating a CO2 capture system. In this document, all exhaust gases pass through one or the other line, depending on which capture system is active; the other system can be regenerated by heating (for example, regeneration can occur while the vehicle is not running). The gases necessarily pass through a capture system. This system should result in significantly more radical CO2 purification, but at the cost of a higher regeneration frequency and therefore increased fuel consumption due to the electrical heating.

[0006] The present invention aims to eliminate the defects of existing state-of-the-art solutions, i.e. to efficiently purify CO2 without the fuel consumption problem of the latter.

[0007] In this context, the present invention proposes a simple on-board technical solution for capturing and storing CO2 in a reactor, similar to a replaceable filter. The system is designed to also provide a direct display of emission rates and on-demand optimization of the engine operating speed in order to reduce CO2 emissions. Presentation of the invention

[0008] The invention aims to remedy the shortcomings of known CO2 capture systems and methods, by proposing a system and method for capturing CO2 contained in the exhaust gases of an internal combustion engine intended to power a motor vehicle, without regeneration of the CO2 capture material and therefore having low system consumption and reduced costs. Summary of the invention

[0009] The invention achieves this goal by providing a replaceable, on-board CO2 capture system for internal combustion engine emissions in order to reduce the amount of CO2 from exhaust gases released into the atmosphere. Unlike the technical solution described in prior art documents, the solution of the present invention will not have high fuel consumption because it does not involve regeneration of the CO2 capture material; the CO2 capture area is configured so that the reactor in use, detected as saturated by a CO2 level detector, is manually replaced by a spare reactor; furthermore, the saturated reactor is configured so that after being replaced by a spare reactor, it is emptied and then refilled with a new charge of CO2 capture material. Thus, the technical solution of the present invention should therefore allow a purification to the "just necessary" of the standard, which allows for significant fuel savings.

[0010] According to a first aspect, the invention provides a replaceable on-board CO2 capture system for internal combustion engines to reduce the amount of CO2 discharged from the internal combustion engine into the atmosphere, the system comprising a main exhaust gas path configured to discharge the exhaust gas stream into the atmosphere without any further treatment for CO2 capture; a secondary exhaust gas path configured to direct the exhaust gas stream through a CO2 capture zone comprising: a container containing a CO2 capture material; a first CO2 level detector at the inlet of the secondary exhaust gas path to determine the CO2 content of the exhaust gas stream exiting the internal combustion engine;a second CO2 level detector at the outlet of the secondary exhaust gas path to determine the CO2 content of the exhaust gas stream exiting the CO2 capture zone; a distribution means disposed at the inlet of the secondary exhaust gas path to direct the exhaust gas stream towards the CO2 capture zone; characterized in that: the main exhaust gas path is configured to guide said exhaust gas stream when the CO2 content as detected by said first CO2 level detector is less than a predetermined value; the secondary exhaust gas path is configured to guide said exhaust gas stream when the CO2 content as detected by said first CO2 level detector is greater than a predetermined value; said container comprises at least two reactors, one reactor in use and one spare reactor;The CO2 capture material is an alkali metal oxide; the CO2 capture zone is configured so that the reactor in use, detected in a saturated state, is manually replaced by the reserve reactor; the saturated reactor is configured so that after being replaced by the reserve reactor, it is emptied and then refilled with a new charge of CO2 capture material.

[0011] The advantages of using the replaceable on-board CO2 capture system for internal combustion engine emissions of the present invention are as follows: the cost of this technology is very low, and the system is simple compared to technologies already applied, such as electrification, hybridization, etc.; the by-product of the replaceable on-board CO2 capture system according to the invention, calcium oxide, CaO, is a very inexpensive product, so the reactors can be manufactured and sold at very low prices. Furthermore, the CO2-laden product, calcium carbonate, CaCO3, will be used in agriculture, animal husbandry, and industry. It is not recommended to decarbonize CaCO3 to obtain CaO, because CO2 will be generated, and the absorption efficiency decreases with the number of decarbonizations (according to published articles).

[0012] In a second aspect, the invention proposes a replaceable on-board CO2 capture system for internal combustion engines in which the alkali metal oxide is CaO.

[0013] In a third aspect, the invention provides a replaceable on-board CO2 capture system for an internal combustion engine in which the reaction inside the reactor in use contained in the CO2 capture zone is carbonation.

[0014] In a fourth aspect, the invention provides a replaceable on-board CO2 capture system for internal combustion engines, in which the CO2 capture material is in powder form.

[0015] In a fifth aspect, the invention provides a replaceable on-board CO2 capture system for internal combustion engines, in which the reactor in use and the reserve reactor can be made in the form of replaceable cartridges.

[0016] In a sixth aspect, the invention provides a replaceable on-board CO2 capture system for an internal combustion engine, wherein the system is mounted on a mobile vehicle.

[0017] In a seventh aspect, the invention provides a replaceable on-board CO2 capture system for an internal combustion engine, in which the mobile vehicle is a motor vehicle, a van, a truck.

[0018] In an eighth aspect, the invention provides a replaceable on-board CO2 capture system for an internal combustion engine in which the predetermined value of the amount of CO2 in the exhaust gas stream is stored in the memory of a CO2 supervisor.

[0019] In a ninth aspect, the invention provides a method for reducing the amount of CO2 from the exhaust gas stream of an internal combustion engine, the method being characterized in that it comprises:

[0020] -a step in which the exhaust gas flow is directed through the secondary exhaust gas path when the CO2 content as determined by the first CO2 level detector at the inlet of the secondary exhaust gas path is greater than a predetermined value;

[0021] -a step in which the exhaust gas flow is passed through a CO2 capture zone included in the secondary exhaust gas path;

[0022] -a step in which the exhaust gas stream is brought into contact with a CO2 capture material contained in a reactor in use in the CO2 capture zone to extract CO2 from the exhaust gas stream;

[0023] -a step in which the reactor in use is replaced by the reserve reactor when the CO2 capture equipment is saturated with CO2;

[0024] -a step during which the saturated CO2 capture material is removed from the saturated reactor;

[0025] -a step during which the empty reactor is filled with a new charge of CO2 capture material;

[0026] -a step in which the exhaust gas flow is directed through the main exhaust gas path when the CO2 content as determined by the first CO2 level detector at the inlet of the secondary exhaust gas path is less than a predetermined value and it is released into the atmosphere without any further treatment for CO2 capture.

[0027] In a tenth aspect, the invention provides a replaceable on-board CO2 capture system for internal combustion engines that can be mounted in large mobile installations, such as large 20-30 ton trucks that can travel or park in cities and absorb CO2 in which air circulation in the reactors is ensured by large fans.

[0028] The novelty of the present invention compared to other known solutions lies in the architecture of the CO2 storage system: a reactor with an absorbent that can be replaced when saturated. The system is designed as a replaceable filter. Another difference from other known solutions is the ability to automatically optimize the engine's operating speed to comply with the CO2 limit. Furthermore, the system is very simple: CO2 is captured by a product such as calcium oxide (CaO), which, upon absorbing CO2, is transformed into calcium carbonate (CaCO3), which can then be used for industrial, agricultural, and other applications. Numerous CO2 capture solutions used in industry are known. Some patents present complex solutions, integrated into the vehicle, for capturing CO2, but with a pressurized CO2 storage system that is expensive and energy-intensive. Presentation of the figures

[0029] Now, a preferred embodiment of the invention will be described in relation to the accompanying drawings in which:

[0030] [Fig-1] Fig. 1 is a schematic representation of a CO2 capture system replaceable embedded part for internal combustion engine according to the invention;

[0031] [Fig.2] The [Fig.2] is a table showing the components of the exhaust gases of internal combustion engines. Detailed description

[0032] The invention will be better understood upon reading the following description of a non-limiting embodiment of the invention.

[0033] To capture CO2, a chemical reaction between CO2 and an absorbent is used. An example of such a chemical reaction is carbonation.

[0034] [Math. 1] CO2 + CaO = CaCO3,

[0035] in a replaceable reactor. The engine emission stream is distributed, after the catalyst, by a distribution means 10, controlled by a CO2 supervisor 13, which can direct the emission stream to the reactor in use 8 if the CO2 emission rate exceeds a programmed limit (e.g., 95 g / km CO2), or to the silencer 11 if the rate is below the limit. The CO2 supervisor is an electronic control unit connected to a number of sensors (CO2 detectors) and actuators (distribution means). The CO2 level is measured using CO2 level detectors. A first CO2 level detector 4 is placed before the distribution means 10 to direct the stream to the reactor when the limit is exceeded, and a second CO2 level detector 21 is placed at the outlet of the reactor in use 8 to detect reactor saturation.

[0036] An alert will be displayed on the vehicle's dashboard 16 when the CO2 level at the outlet of the reactor in use 8 is close to the limit for changing reactors. The saturated reactor will be manually replaced by a spare reactor 20, and the saturated reactor will be manually retrieved. The emission stream at the reactor outlet will reconnect with the exhaust before the silencer. The reactor in use 8 operates in the container 5; the container is equipped with a heating system, in particular an electric heating element 6, for additional heating of the reactor to ensure the optimal reaction temperature.

[0037] For manual replacement of the saturated reactor 8 during use, a hatch may be provided on the side of the upper part of the vehicle body. The driver retrieves the saturated reactor, exchanges the saturated reactor for the spare reactor 20, discards the saturated CO2 capture material, and refills the empty reactor with a new charge of CO2 capture material.

[0038] A temperature measurement and control system 7 for the reactor is provided. CO2 system control is ensured by the CO2 supervisor 13, which is connected to all elements of the CO2 system and also to the engine computer 14. Operating modes can be selected by the controls 15. The composition The average emissions from combustion engines are consistent with the table in [Fig. 2]. The kinetics of the carbonation reaction are as follows:

[0039] [Math. 2] CaO +CO2 -> CaCO3

[0040] [Math. 3] CaO +CO2 +H2O -> Ca(OH)2 +CO2 -> CaCO3 +H2O

[0041] The optimal temperature for CO2 capture is in the range of 400-450°C. Since the temperature of the emissions at the catalyst outlet is of this order of magnitude, the reactor is heated by the thermal energy of the emissions; during the engine start-up phase, an electric reactor heating system will be used. The feasibility calculation for this technology is as follows:

[0042] -One mole of CaO (40+16)=56g

[0043] -One mole of CO2 (12+2*16)=44g

[0044] -One mole of CaCO3 (40+12+3* 16)=100g;

[0045] A 10 kg reactor is considered easy to replace manually, so that theoretically 4.4 kg of CO2 can be captured with 5.6 kg of CaO. Published studies show good efficiency of the reaction, particularly for the first absorption cycle. If, for example, we propose to reduce CO2 emissions by an average of 10 g / km / vehicle, we must capture 10 * 100 / 1000 = 1 kg of CO2 for every 100 km of driving; the reactor must be changed after 440 km.

[0046] The operating modes of the replaceable on-board CO2 capture system according to the invention are as follows:

[0047] -Automatic: The system uses the reactor in operation to reduce CO2 emissions. Control is ensured by the CO2 supervisor 13. The CO2 emission level is displayed at the engine outlet and at the reactor outlet. Regardless of engine speed, if the CO2 emission level is higher than the predetermined value, the exhaust gas flow 2 is diverted to the secondary exhaust gas path 18 and through the reactor in operation 8. At very high engine speeds, it is possible that the CO2 emission level cannot be reduced below the predetermined value, even by passing through the reactor in operation 8.

[0048] - Manual environmental mode: The CO2 level is measured using the first CO2 level detector 4, and the instantaneous and average CO2 emissions are displayed in the instrument panel 16 relative to the maximum limit. An alert can be triggered when the limit is exceeded. Environmentally conscious drivers can adjust their driving style to ensure that the limit is not exceeded.

[0049] -Automatic eco mode: The first CO2 level detector 4 is connected to an engine control unit 14 via the CO2 supervisor 13 allowing The engine's operating mode is optimized to ensure compliance with emission limits. At the same time, the emissions are also displayed.

[0050] - CO2 emissions recording mode; the amount of CO2 released into the atmosphere in correlation with distance will be recorded in a vehicle control unit in ROM format (non-modifiable) and will be accessible and transferable to the manufacturer and by the manufacturer to the authorities via the vehicle's connectivity or via a diagnostic cable. This mode will make it possible to prove that the engine complied with applicable regulations.

[0051] Each "ecological" mode is automatically accompanied by the capture of CO2 in the reactor in use 8 if the limit is exceeded.

[0052] As shown in [Fig. 1], the exhaust gas stream 2 from the internal combustion engine enters a conventional catalyst 3, for example a three-way catalyst in the case of a gasoline engine, which removes some of the pollutants but not CO2. After exiting the catalyst 3, the exhaust gas stream 2 encounters the first CO2 level sensor 4 located upstream of the distribution means 10. The first CO2 level sensor 4 determines the amount of CO2 in the exhaust gas stream and when the amount of CO2 exceeds a predetermined value stored in a memory of the CO2 supervisor 13 (for example 95 g / km of CO2), the CO2 supervisor 13 commands the distribution means 10 to direct the exhaust gas stream 2 to the secondary exhaust gas path 18.

[0053] Passing through the secondary exhaust gas passage 18, the exhaust gas stream 2 passes through an interchangeable reactor unit 9. This interchangeable reactor unit 9 comprises a container 5 including a reactor in use 8 and at least one spare reactor 20. The reactor in use 8 and the spare reactor 20 contain a quantity of CO2 capture material which is an alkali metal oxide. The reactor in use 8 and the spare reactor 20 are designed to be interchangeable. When the reactor in use 8 is saturated with CO2, it can be replaced by the spare reactor 20 of the interchangeable reactor unit 9 in order to continue absorbing CO2 from the exhaust gas stream 2 without interruption. The reactor in use 8 and the spare reactor 20 can be designed as replaceable cartridges.

[0054] The alkali metal oxide used as a CO2 capture material is, in particular, CaO. The present inventor has found that CaO in powder form is the best CO2 capture material. As mentioned above, the optimal temperature for CO2 capture is around 400-450°C. Since the temperature of the emissions at the catalyst outlet is around this value, the reactor is heated by the thermal energy of the emissions. During the engine start-up phase... Internal combustion, when the temperature of the exhaust gas stream 2 is still low, the necessary heat will be supplied by a heating element 6, which is in particular an electrical element that will heat the reactor in use 8.

[0055] To conserve the vehicle's battery power, the heating element will only be switched on when the temperature of the exhaust gas stream 2 is below approximately 400-450°C. Therefore, the interchangeable reactor unit 9 is equipped with a temperature sensor to measure the temperature of the exhaust gas stream 2, which is connected to the CO2 supervisor 13. When the temperature detected by the temperature sensor 6 is below approximately 400-450°C, the CO2 supervisor 13 switches on the heating element 6. When the temperature of the exhaust gas stream 2 is above approximately 400-450°C, the CO2 supervisor 13 switches off the heating element 6.

[0056] After passing through the interchangeable reactor unit 9 and thus through the reactor in use 8, the exhaust gas stream 2, which now contains less CO2 than before entering the secondary exhaust gas path 18, is directed through the exhaust 10 and into the main exhaust gas path 17 and towards the silencer IL

[0057] Immediately after the point of intersection of the main exhaust gas path 17 and the secondary exhaust gas path 18, a second CO2 level detector 21 is provided. The second CO2 level detector 21 measures the amount of CO2 in the exhaust gas stream 2 after it has passed through the interchangeable reactor unit 9 to determine whether the reactor in use 8 is saturated or not. If the first CO2 level detector 24 detects that the CO2 value in the exhaust gas stream 2 is below the predetermined limit stored in the memory of the CO2 supervisor 13, the distribution means 10 will not divert the exhaust gas stream 2 through the secondary exhaust gas path 18, and the exhaust gas stream 2 will pass through the main exhaust gas path 17 to the silencer 11 and the exhaust outlet 12.In this case, the reactor in use 8 will not be used and therefore the CO2 supervisor 13 will determine that the reactor in use 8 is not saturated.

[0058] If the first CO2 level detector 4 detects that the CO2 value in the exhaust gas stream 2 is greater than the predetermined limit stored in the memory of the CO2 supervisor 13, the distribution means 10 will divert the exhaust gas stream 2 through the secondary exhaust gas path 18, and the CO2 capture material will capture the CO2. After a certain operating time, the CO2 capture material will be saturated. If the second CO2 level detector 21 detects that the amount of CO2 in the exhaust gas stream 2 does not decrease after a predetermined period of time, the CO2 supervisor 13 determines that the reactor in use 8 is saturated and an alert message will be displayed on the dashboard regarding the situation and that it is time to change the reactors.

[0059] The replacement of the reactor in use 8 with the reserve reactor 20 is carried out manually. Once the reactor in use 8 is saturated and replaced by the reserve reactor 20, which then becomes the reactor in use 8, the saturated reactor can be emptied of the CO2 capture material, which is no longer CaO but CaCO3 due to the carbonation reaction. The saturated reactor can be emptied into specially designed areas at gas stations where it can be recovered and used for various industrial purposes.

[0060] Calcium carbonate is primarily used in the construction industry, either as a building material, as a limestone aggregate for road construction, as an ingredient in cement manufacturing, or as a raw material for the preparation of building lime by combustion in a kiln. Calcium carbonate is also suitable for a wide variety of agricultural applications, including pH control, fertilizers, and animal feed formulations. Landscaping and recreation uses include decorative stone for landscaping, applications on golf courses, and marking athletic field lines.Instead of emptying the saturated reactor into specially designed locations, the CaCO3 could be dumped at the roadside, as it is not harmful to the environment and, as mentioned above, could be used in agriculture as fertilizer.

[0061] The saturated reactor that has been emptied must now be filled with a new charge of CO2 capture material in order to be ready to replace the reactor in use 8 when the CO2 supervisor 13 determines, based on information from the second CO2 level detector 21, that the reactor in use 8 is saturated and must be replaced.

[0062] Whether the exhaust gas flow 2 is directed through the main exhaust gas path 17 or through the secondary exhaust gas path 18, it will ultimately be directed to the silencer 11 and then to the outside atmosphere through the exhaust gas outlet.

[0063] The invention also relates to a method for reducing the amount of CO2 from the exhaust gas stream of an internal combustion engine using the replaceable on-board CO2 capture system 1 of the present invention. The method consists of directing the exhaust gas stream 2 from an internal combustion engine used to power a motor vehicle to a secondary path of the Exhaust gas 18 is captured when the CO2 content, as determined by the first CO2 level detector 4 located before the inlet of the secondary exhaust gas passage 18, exceeds a predetermined amount. To direct the exhaust gas flow 2 to the secondary exhaust gas passage 18, a distribution means 10 is provided. In a preferred embodiment, the distribution means 10 is a valve. The exhaust gas flow 2 passing through the secondary exhaust gas passage 18 will encounter a CO2 capture zone 19 comprising an interchangeable reactor unit 9. This interchangeable reactor unit 9 includes a reactor in use 8 and at least one spare reactor 20. The reactor in use 8 and the spare reactor 20 contain a CO2 capture material, which is notably CaO.Through the carbonation reaction, the CO2 capture material will capture CO2 from the exhaust gas stream 2 and the exhaust gas stream 2, now with a lower CO2 content, will be returned to the main exhaust gas path 17 and into the outside atmosphere.

[0064] When the reactor in use 8 becomes saturated, as determined by the CO2 supervisor 13 based on information from the second CO2 level detector 21 located at the outlet of the secondary exhaust gas path 18, an alert will be displayed on the vehicle's dashboard and the reactor in use 8 will be manually replaced by the backup reactor 20. The carbonation reaction product, CaCO3, could be discharged at designated locations, such as service stations, or even at the roadside, as CaCO3 also has certain agricultural uses as a fertilizer. The empty reactor must be filled with CO2 capture material so that it is ready to replace the reactor in use 8 again if necessary.

[0065] If the CO2 supervisor 13 determines, based on information from the first CO2 level detector 4 disposed before the inlet of the secondary exhaust gas path 18, that the amount of CO2 in the exhaust gas stream 2 is less than a predetermined value stored in the memory of the CO2 supervisor 13, the distribution means 10 will direct the exhaust gas stream 2 to the main exhaust gas path 17 and through the silencer 11 into the atmosphere, without further CO2 capture treatment.

[0066] In another embodiment of the replaceable on-board CO2 capture system 1 of the invention, the interchangeable reactor unit 9 could accommodate more than two reserve reactors 20.

[0067] The technology of the present invention can be easily developed for stationary applications, installed in areas with high CO2 pollution, such as intersections in large cities, for example. Similarly, it is possible to develop Large mobile units weighing 20 to 30 tons, installed in large trucks, can travel or park in cities and absorb CO2. In addition to the system described, ambient air CO2 absorption units must be equipped with fans to ensure forced air circulation through the reactors.

[0068] The invention is useful in the automotive industry for a replaceable on-board system to reduce the CO2 content of the exhaust gas stream of an internal combustion engine used to propel a mobile vehicle.

Claims

Demands

1. A replaceable on-board CO2 capture system (1) for an internal combustion engine to reduce the amount of CO2 emitted into the atmosphere by the internal combustion engine, the system comprising: - a main exhaust gas path (17) configured to discharge the exhaust gas stream (2) into the atmosphere without further treatment for CO2 capture; - a secondary exhaust gas path (18) configured to direct the exhaust gas stream (2) through a CO2 capture zone (19); - the CO2 capture zone (19) comprising a container (5) containing a CO2 capture material; - a first CO2 level detector (4) at the inlet of the secondary exhaust gas path (18) to determine the CO2 content of the exhaust gas stream (2) exiting the internal combustion engine;- a second CO2 level detector (21) at the outlet of the secondary exhaust gas path (18) to determine the CO2 content of the exhaust gas stream (2) exiting the CO2 capture zone (19); - a distribution means (10) disposed at the inlet of the secondary exhaust gas path (18) to direct the exhaust gas stream (2) towards the CO2 capture zone (19); characterized in that - the main exhaust gas path (17) is configured to guide said exhaust gas stream (2) when the CO2 content as determined by said first CO2 level detector (4) is less than a predetermined value; - the secondary exhaust gas path (18) is configured to guide said exhaust gas stream (2) when the CO2 content as determined by said first CO2 level detector (4) is greater than a predetermined value;-said container (5) comprises at least two reactors, a reactor in use (8) and a reserve reactor (20); -the CO2 capture material is CaO; -the CO2 capture zone (19) is configured so as to manually replace the saturated reactor in use (8), as detected by said second CO2 level detector (21), with the reserve reactor (20); -the saturated reactor in use (8) is configured so that after being replaced by said reserve reactor (20), it is emptied and then filled with a new charge of CO2 capture material.

2. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claim 1, characterized in that the reaction in the reactor in use (8) contained in said CO2 capture zone (19) is carbonation.

3. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claims 1 to 2, characterized in that the CO2 capture material is in powder form.

4. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claims 1 to 3 characterized in that the reactor in use (8) and the reserve reactor (20) can be made in the form of replaceable cartridges.

5. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claims 1 to 4 characterized in that the system is mounted on a mobile vehicle.

6. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claims 1 to 5 characterized in that the mobile vehicle is a motor vehicle, a van, a truck.

7. The replaceable on-board CO2 capture system (1) for internal combustion engine according to claims 1 to 6, characterized in that the predetermined value of the quantity of CO2 in said exhaust gas stream (2) is stored in the memory of a CO2 supervisor (13).

8. A method for reducing the amount of CO2 from the exhaust gas stream (2) of an internal combustion engine, the method being characterized in that it comprises: - a step in which the exhaust gas stream (2) is directed through the secondary gas passage exhaust (18) when the CO2 content as determined by the first CO2 level detector (4) at the inlet of the secondary exhaust gas path (18) is greater than a predetermined value; - a step in which the exhaust gas stream (2) is passed through a CO2 capture zone (19) included in the secondary exhaust gas path (18); - a step in which the exhaust gas stream (2) is contacted with a CO2 capture material formed of CaO and contained in a reactor in use (8) in the CO2 capture zone (19) to extract CO2 from the exhaust gas stream (2); - a step in which the reactor in use (8) is replaced by the reserve reactor (20) when the CO2 capture material is saturated with CO2; - a step in which the saturated CO2 capture material is removed from the saturated reactor;-a step in which the empty reactor is filled with a new charge of CO2 capture material; and -a step in which the exhaust gas stream (2) is directed through the main exhaust gas path (17) when the CO2 content as determined by the first CO2 level detector (4) at the inlet of the secondary exhaust gas path (18) is below a predetermined value and is discharged into the atmosphere without any further treatment for CO2 capture.;

9. The replaceable on-board CO2(1) capture system for internal combustion engines according to claims 1 to 7, characterized in that the system can be mounted in large mobile installations, such as large 20-30 ton trucks that can travel or park in cities and absorb CO2 in which air circulation in the reactors is ensured by large fans.

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