NL2017963B1 - A microchannel reactor and method for decomposition of ammonia - Google Patents

Abstract

The invention provides a microchannel reactor for the decomposition of ammonia, comprising a first chamber with a first catalyst for operatively receiving a mixture of a first stream of ammonia and a stream of substantially pure oxygen to provide exothermic combustion of the first stream of ammonia. A second chamber of the reactor with a second catalyst, receives a second stream of ammonia to provide endothermic decomposition of the second stream of ammonia. The exothermic combustion of the ammonia in the first chamber generates the required heat for facilitating the endothermic decomposition of the ammonia in the second chamber the heat being transferred from the first chamber to the second chamber through a wall.

Description

A MICROCHANNEL REACTOR AND METHOD FOR DECOMPOSITION OF AMMONIA

FIELD OF INVENTION

The current invention relates to the decomposition of ammonia. More particularly, it relates to a microchannel reactor and a method of using said microchannel reactor for the decomposition of ammonia, and a system for generating electricity, incorporating said microchannel reactor and method for decomposition of ammonia.

BACKGROUND OF INVENTION

The gradual depletion of fossil fuels seen in the wake of an ever-increasing world population with growing energy demands and expanding economies in developing countries, coupled with the increased focus on clean energy has led to progressive development or sustainable alternatives to fossil fuels.

The aforementioned scenario has already begun to exert substantial pressure on the current electricity generating infrastructure. In response, utilities in developing countries have more often implemented power rationing strategies, often termed "load shedding". In a bid to reduce the socio-economic issues related to load shedding, hospitals and other service providers located in poor-grid or even off-grid areas often resort to battery banks and diesel generators to produce electricity.

It is furthermore often uneconomical to connect remote areas to the existing electricity grid over long distances due to the installation and maintenance cost of hardware and inevitable transmission losses. A typical example of the abovementioned problem arises when telecoms operators have base stations located in remote areas that require electrical power. In such instances, these operators often have resort to alternative power sources such as solar power or diesel generators. Since the base stations need to be operational 24 hours a day, the use of solar power goes hand in hand with expensive and maintenance-intensive battery banks. In addition, diesel generators need refueling at regular intervals, and furthermore produce harmful greenhouse gases. Maintenance related to diesel generators operating for extended time periods also contributing to the high operating costs of these power sources.

The fuel used in diesel generators, and the components of solar power systems, especially the solar panels and batteries, are moreover targets for theft and security measures have to be put in place in order to prevent theft and vandalism or the base stations.

There are approximately one million cell phone towers world-wide that are located in poor-grid and off-grid areas worldwide, with new installations growing at a rate of 12% per annum. Over 90% of these towers are powered by diesel generators.

Fuel-cell systems are rapidly gaining consideration as an alternative energy source and are a potential solution for distributed power generation in remote or poor-grid areas. In contrast to other power sources such as diesel generators and batteries, fuel cells have high power densities as well as the inherent ability to operate quietly at near-zero pollution levels.

The commercial viability of fuel cell systems in distributed power applications is however currently hindered by the logistical challenges surrounding the storage and supply of hydrogen for use as a fuel source. The storage and transportation difficulties associated with hydrogen are further increased by its low volumetric energy density (5.6 MJ / L) even under 700 bar compression.

Forever, it is foreseen that the on-site and on-demand generation of hydrogen for use in hydrogen powered fuel cells will substantially alleviate the current barriers associated with the use of fuel cells as an alternative energy source.

Various hydrogen carriers are available for the production of hydrogen gas through fuel processing for the purpose of on-site hydrogen decomposition. Among these, ammonia has been widely suggested as a “clean” alternative, and its decomposition produces carbon-free hydrogen in a single-step process

Furthermore, ammonia is available at fairly low costs and has high hydrogen content per unit mass. Most importantly, ammonia has limited household applications and therefore the threat of theft and associated vandalism in rural areas is reduced.

Chiuta et al. Reviewed the state-of-the-art related to ammonia decomposition reactor technologies and revealed that microchannel reactors pose an attractive method of producing hydrogen gas, especially in portable and distributed applications. The use of microchannel (sub-millimeter) reactors leads to increased heat and mass transfer characteristics, due to the increased surface area-to-volume ratios of the channels. In these microchannel reactors, the heat required for the decomposition or ammonia is supplied by electric heating elements. These heating elements do however, severely reduce the reactor efficiency and have the technology rendered unsuitable for practical use.

As an alternative, Arana et al. Suggested using catalytic butane combustion as a source or heat for the decomposition or ammonia.

Chellappa et al. Patented an ammonia-based hydrogen generation apparatus where the preferred embodiment constituted or inserted porous substrates into meso-scale fluid flow channels. Carbon build-up, however, represents a major disadvantage and operational challenge to their construction. For this reason, smaller flow channels (such as microchannels) are not considered, nor suitable, despite its potential improved transport phenomena and performance.

The combustion of butane or any other hydrocarbon further defeats the objective of "clean" energy production. In practical terms, the supply and storage or an additional fuel source (in this example, butane) poses further difficulties such as capital costs and maintenance requirements, and represents a further decrease in overall system efficiency. Furthermore, butane has wide non-commercial applications such as a fuel source and theft and vandalism may pose potential problems again.

OBJECT OF THE INVENTION

Consider it is an object of the present invention to provide an apparatus and method of decomposing ammonia in order to produce carbon-free hydrogen which, in turn, can be used in a system for generating electricity with which the applicant believes the aforementioned disadvantages may be overcome or at least be alleviated, or which would provide useful alternatives for the known apparatuses and methods.

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided a microchannel reactor for the decomposition of ammonia, the microchannel reactor comprising: a first chamber having an inlet for operatively receiving a mixture of a first stream of ammonia and a stream of substantially pure oxygen, the first chamber further containing a first catalyst for facilitating exothermic combustion or the first stream of ammonia, and an outlet through which the mixture exits the first chamber; a second chamber having an inlet for operatively receiving a second stream of ammonia, the second chamber further containing a second catalyst for facilitating the endothermic decomposition of the second stream of ammonia, and an outlet through which the decomposed second stream of ammonia exits the second chamber ; and a heat conducting wall, separating the first and second chambers to prevent fluid exchange between the first and second chambers; in use, the exothermic combustion of the ammonia in the first chamber generates the required heat for facilitating the endothermic decomposition of the ammonia in the second chamber, the heat being transferred from the first chamber to the second chamber through the wall.

The first catalyst may comprise a compound or alloy including a platinum group metal, and the second catalyst may comprise a compound or alloy including ruthenium.

The first catalyst may further comprise a compound or alloy including 5 wt.% Pt / Al2C> 3 with a Brunauer-Emmett-Counter (BET) surface area of 134.7 m2 g'1, whereas the second catalyst may include a compound or alloy including 8.5 wt.% RU / Al 2 O 3 with a Brunauer-Emmett-Teller (BET) surface area of 113 m2 g'1.

The inner surfaces of the first and second chambers may be wash coated with the first and second catalyst respectively and may have a thickness between 30 and 50 microns, preferably 40 microns.

The first and second chambers and their respective inlets and outlets may be in the form of a stack or at least three plates. The stack may include a first and second end plate and a micro-structured plate located there between. The micro-structured plate may have a first recess on a first side to form the first chamber and a second, opposite side provided with a second recess to form the second chamber. The heat conducting wall may be formed by the micro-structured plate.

The microchannel reactor may include an even number of micro-structured plates that may be alternately stacked to form a first chamber between each pair or micro-structured plates with their first ends in contact, and a second chamber between each pair of micro-structured plates in contact with their second ends. A central plate, not having a first or second recess may be provided in the middle of the stack so that the microchannel reactor comprises an equal number of first and second chambers.

The first and second recesses of the micro-structured plates may further include a variety of parallel protrusions such that closed channels within the first or second chambers may be formed when the plates are stacked to form the microchannel reactor.

The length of each channel may be less than 7 cm, preferably 5 cm.

The plates may be manufactured from stainless steel and may have a length of 70 mm, a width of 21 mm and a thickness of 1 mm.

The microchannel reactor may comprise a stack of sixteen micro-structured plates, a central plate and a first and second plate, to form nine first chambers, nine second chambers, ninety first channels, and ninety second channels. The microchannel reactor may comprise a total volume exceeding 25 cm3.

The first channels may cumulatively contain a total of 133 mg or the first catalyst while the second chambers may cumulatively contain a total of 125 mg or the second catalyst.

The microchannel reactor may be provided with a housing consisting of heating cartridges and heating blocks for start-up. The housing may be furthermore provided with insulation to prevent heat loss to the surroundings.

According to a second aspect of the invention there is provided a method for decomposing ammonia in a microchannel reactor, the method including: introducing a mixture to an inlet or a first chamber in the microchannel reactor, the mixture having a mixture equivalence ratio and flowing at a mixture flow rate, the mixture including a first stream of the ammonia at a first ammonia flow rate and a stream of substantially pure oxygen at an oxygen flow rate, to facilitate exothermic combustion of the first stream of ammonia; introducing a second stream of ammonia to an inlet or a second chamber in the microchannel reactor at a second ammonia flow rate to facilitate endothermic decomposition of the second stream of ammonia; and allowing heat generated by the exothermic combustion of the first stream of ammonia in the first chamber to be transferred to the second chamber to provide the heat required for the decomposition of the second stream of ammonia.

The mixture flow rate may be between 0.4 and 1.2 normal liters per minute (NLPM) while the second ammonia flow rate may be between 0.1 and 1 NLPM. The mixture equivalence ratio may be between 0.8 and 1.2.

The mixture flow rate and mixture equivalence ratio may be adjusted to achieve self-sustained combustion or the first stream of ammonia and autothermal decomposition or the second stream of ammonia.

The inlets of the first and second chambers may be disposed proximate the same end of the microchannel reactor. In this way the flow of the mixture through the first chamber, and the flow of the second stream of ammonia through the second chamber may be in a substantially identical direction.

The flow direction of the mixture and second stream of ammonia relative to the first and second channels may be reversed at predetermined intervals to facilitate improved heat distribution along a length of the reactor. A maximum temperature of the reactor may be maintained below 700 ° C.

The mixture equivalence ratio may be maintained above 1 to reduce the prevalence of NOx species forming as a by-product or the exothermic combustion of ammonia. This may be achieved by homogeneous reaction of the NOx species with residual ammonia within the first chamber.

The method may include the preceding step of heating the microchannel reactor with electric heating cartridges and heating blocks to a temperature which is not lower than a catalyst-specific light-off temperature to initiate the combustion of the mixture in the first chamber.

Less than 1% residual ammonia may remain after decomposition or the second stream or ammonia in the second chamber. This may be achieved when the microchannel reactor operates at stable autothermal conditions. The stable autothermal conditions may be achieved at a temperature below 700 ° C.

The reactor may have a potential power density of 1.5kWe per m3 or reactor volume.

The hydrogen formed by the decomposition of the ammonia in the second chamber may be used as a fuel source in a fuel cell to generate electricity.

The fuel cell may be an alkaline fuel cell that does not require strainers or separators to remove residual ammonia or nitrogen before entering the fuel cell.

According to a third aspect of the invention there is provided a system for generating electricity from a source of hydrogen, the system including: a microchannel reactor having a first chamber for facilitating combustion or a mixture including a first stream of ammonia and a substantially pure stream or oxygen, a second chamber for facilitating decomposition or a second stream of ammonia, and a heat conducting wall separating the first and second chambers for transferring heat from the first chamber to the second chamber; and a fuel cell provided in fluid flow communication with the second chamber of the microchannel reactor to utilize hydrogen obtained from the decomposed second stream or ammonia to generate electricity.

The system may further comprise an in-line mixer for mixing the first stream of ammonia and the stream of oxygen before entering the first chamber of the microchannel reactor.

The system may further comprise a water cooler to cool the decomposed second stream or ammonia before entering the fuel cell.

The system may include an ammonia container and an oxygen container for failure the ammonia and oxygen used in the microchannel reactor.

The fuel cell used in the system may be an alkaline fuel cell.

LETTER DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example only, with reference to the accompanying diagrams: figure 1 is a perspective view or a first side of a micro-structured plate for operatively facilitating catalytic combustion or ammonia; figure 2 is a perspective view or a second side of the micro-structured plate or figure 1 for operatively facilitating catalytic decomposition or ammonia; figure 3 is a perspective view showing a variety of micro-structured plates or figures 1 and 2 to be stacked and form a microchannel reactor in accordance with the invention; figure 4 is a perspective view of the stacked micro-structured plates or figure 3; Figure 5 is a perspective view of the microchannel reactor or Figure 3; figure 6 shows a sectioned view along the lines X-X1 or figure 5, further including a housing, heating cartridges and heating blocks; and figure 7 is a diagrammatic representation of a system for generating electricity, incorporating the microchannel reactor or figure 5.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

As shown in the accompanying drawings, a microchannel reactor for the decomposition of ammonia according to an example of the invention is generally designated by reference numeral 10.

The microchannel reactor 10 comprises a first chamber 12 for facilitating exothermic, catalytic combustion or a first stream of the ammonia. The first chamber 12 has an inlet 14 for operatively receiving a mixture of the first stream of ammonia and a first stream of substantially pure oxygen from a source (not shown). The first chamber 12 also contains a first catalyst for facilitating the exothermic combustion or the first stream of ammonia. The first chamber furthermore comprises an outlet through which the mixture exits the first chamber 12.

The microchannel reactor 10 also comprises a second chamber 18 for facilitating the endothermic, catalytic decomposition or a second stream of ammonia. The second chamber 18 comprises an inlet 20 for operatively receiving the second stream of ammonia from a source (not shown). The second chamber also contains a second catalyst for facilitating the decomposition of the second steam or ammonia. The second chamber furthermore comprises an outlet through which the decomposed second stream or ammonia exits the second chamber.

The first and second chambers (12, 18) are separated by a heat conducting wall 24. The heat conducting wall 24 allows and facilitates heat transfer by means of conduction from the first chamber 12 to the second chamber 18, while preventing fluid exchange between the respective chambers.

In use, the heat generated in the first chamber 12 by the catalytic combustion of the ammonia is transferred through the wall 24 by means of conduction, to the second chamber 18, where it facilitates the catalytic decomposition of the ammonia.

The first and second catalysts are wash coated to the inner surfaces or the first and second chambers respectively.

As can be seen in figures 3 and 4, the first and second chambers (12, 18) and their respective inlets and outlets are in the form of a stack or at least three plates. The stack comprises a first and second end plate (42, 44) and at least one micro-structured plate 26 located there between. The micro-structured plate 26 has a first recess 34 on a first side, to form the first chamber 12. The micro-structured plate 26 has a second recess 32 on a second side 30, to form the second chamber 18.

The microchannel reactor may include an even number of micro-structured plates 26, alternately stacked to form a first chamber 12 between each pair or micro-structured plates 26 with their first ends 28 in contact, and a second chamber 18 between each pair of micro -structured plates 26 with their second ends 30 in contact. A central plate 27 is furthermore provided in the middle of the stack. The central plate 27 is not micro-structured and therefore does not include a first nor second recess. Due to the central plate 27 not being micro-structured, the microchannel reactor comprises an even number of first and second chambers (12, 18). "Alternately stacked" in this context means that the first side 28 or a micro-structured plate will never be in contact with the second side 30 or another micro-structured plate.

As can be seen in figure 6, the wall 24 which separates the first side 28 and second side 30, and thus the first recess 32 and the second recess 34 is actually formed by the micro-structured plate 26 itself.

Also seen in figures 5 and 6, the first and second end plates (42, 44) are provided on first and second ends of the stacked micro-structured plates 26 (micro-structured plate 26.1 representing the first end of the stack, and micro -structured plate 26.2 representing the second end of the stack in figures 4 and 5). Micro-structured plates 26.1 and 26.2 Therefore form Micro-structured plates of the microchannel reactor and the number of micro-structured plates can be varied according to operational requirements.

Furthermore, a first chamber 12 is formed between the first end pate 42 and micro-structured plate 26.1 while a second chamber 18 is formed between the second end plate 44 and microchannel plate 26.2.

In this particular embodiment, each of the first and second recesses (32, 34) of the micro-structured plates 26 comprises a variety or parallel, open-ended half-channels disposed between a variety or parallel protrusions 36. The channels are 50 mm long, 150 μηη wide, and 450 μηη deep. The half-channels 36 of the respective first and second recesses (32, 34) line up when the first or second chamber (12, 18) are formed by the stacking of the plates as described above. This forms a variety or parallel first channels 38 and second channels 40 within the respective first and second chambers (12.18). In this embodiment, the totality of first channels 38 formed between two particular plates therefore forms the first chamber 12 between those particular two plates, whereas the totality of second channels 40 formed between two particular plates forms the second chamber 18 between those particular two plates.

To illustrate this, figure 6 shows a partial section view of a microchannel reactor 10 or figure 5.

Each first and second recess (30, 32) comprises open-ended half-channels 36, so that first channels 38 are formed within each first chamber 12, and at least channels 40 are formed within each second chamber 18.

Each open-ended half-channel 36 has a length of 50 mm. Each micro-structured plate 26 has a total length of 70 mm, a width of 21 mm and a thickness of 1 mm, and is manufactured from stainless steel.

The microchannel reactor 10 shown in figure 5 comprises a total of sixteen micro-structured plates 26, a central plate 27 and a first and second end plate (42, 44) so that a total of nine first chambers 12, nine second chambers 18, ninety first channels 38 and ninety second channels 40 are formed in the way described above. The microchannel reactor 10 has a total volume exceeding 25 cm3.

As shown in figure 6, the microchannel reactor 10 is furthermore provided with an insulating housing 42 to prevent heat loss to the surroundings. Heating cartridges 46 and heating blocks are also located within the housing 48. The heating cartridges and heating blocks 46 and housing 48 are omitted in figure 5.

The first catalyst (not shown) comprises a platinum group metal (PGM), while the second catalyst comprises ruthenium. In particular, the first catalyst is a commercially available platinum-based catalyst (Sigma Aldrich) comprising 5 wt.% Pt / AI203 with a Brunauer-Emmett-Teller (BET) surface area or 134.7 m2g'1. The second catalyst is a commercially available Ruthenium-based catalyst (Hypermec 10010 ™) including 8.5 wt.% RU / AI2O3 with a Brunauer-Emmett-Counter (BET) surface area of 113 m2g'1.

The first and second catalysts are deposited in the first and second channels (38, 40) respectively, by means of a known sequential wash coating, drying and calcination procedure, which results in a uniform thickness of the first and second catalysts in the respective first and second channels (38, 40). The uniform thickness of the first and second catalysts is in a range of between 30 and 50 microns, with a thickness of 40 microns having experimentally proven to provide adequate results.

The first channels 38 of a microchannel reactor 10 including seventeen micro-structured plates 26 and a first and second end plate (42, 44), as shown in figure 5, contain a total of 133 mg of the first catalyst, whereas the second channels 40 contains a total or 125 mg of the second catalyst.

In use, a mixture or a first stream or ammonia and a stream or substantially pure oxygen is introduced through a first inlet manifold 50 to the inlets 14 or the first chambers 12 at a mixture flow rate. Initially, the heating cartridges and heating blocks 46 are used to heat the microchannel reactor 10 to a temperature above the combustion temperature of ammonia. The mixture introduced into the first chambers 12 undergoes exothermic catalytic combustion within the first chamber 12, generating heat within the first chamber 12. As soon as the combustion of the first stream ensues, the heating cartridges and heating blocks 46 are switched off. The first stream of ammonia is introduced at a first ammonia flow rate, while the substantially pure oxygen is introduced at an oxygen flow rate. A second, separate stream of ammonia is introduced at a second ammonia flow rate via a second inlet manifold 52 to the inlets 20 of the second chambers 18. The heat generated by the exothermic catalytic combustion of the first stream or ammonia in the first chambers 12 is transferred through the walls 24 via conduction, to the second chambers 18. This heat facilitates the endothermic, catalytic decomposition or the second stream of ammonia in the second chamber 18. The microchannel reactor 10 therefore facilitates autothermal decomposition or ammonia.

The catalytic combustion or ammonia is known to occur according to the following chemical reactions:

The catalytic decomposition of ammonia is known to occur according to the following chemical reaction:

The exothermic combustion of ammonia according to the abovementioned reactions generates an average of 273 kJ heat per mole or ammonia, whereas the endothermic decomposition of ammonia requires 46 kJ heat per mole. This means that one mole or ammonia is burned within the first chamber 12 can potentially facilitate the decomposition of around six moles or ammonia in the second chamber 18 (under adiabatic conditions). Heat losses may have a detrimental effect on the required flow rate or the first stream of ammonia. One way in which the heat losses in microchannel reactor 10 can be reduced is by reducing the overall surface area to volume ratio. This is achieved by stacking the micro-structured plates as aforementioned, instead of using a single multi-channel micro-structured platelet. A microchannel reactor 10 as shown in figure 5, having a total reactor volume of around 30 cm2 is capable of receiving a mixture flow rate between 0.4 and 1.2 normal liters per minute (NLPM). The second ammonia flow rate is between 0.1 and 1 NLPM.

The mixture introduced to the first chamber 12 has an equivalence ratio of between 0.8 and 1.2. A lean mixture results when the equivalence ratio is below 1, while a fuel-rich mixture results when the equivalence ratio is above 1. In the current setup, a stoichiometric equivalence ratio or is attained when the first stream of ammonia flow rate is 0.25 NLPM and the oxygen flow rate is 0.3 NLPM.

From a practical point of view, it is important to maintain the microchannel reactor 10 below a temperature at which the micro-structured plates, end plates and catalysts becomes unstable. For the current set of parameters, a material stability limit has been set at 700 ° C.

The heat generated in the first chamber 12, and thus the reactor temperature, is a function of, among others, the equivalence ratio, the first ammonia flow rate, the oxygen flow rate and the mixture flow rate.

The mixture flow rate, on the other hand, has been adjusted in accordance with the second ammonia flow rate. The efficiency of the decomposition is again dependent on the flow rates as aforementioned. Thus, a set of parameters is required to ensure that a desired efficiency is achieved, while maintaining the microchannel reactor below the material stability limit of 700 ° C. This set is selected to furthermore ensure that the combustion in the first chamber 12 is self-sustaining, while facilitating the autothermal decomposition or the second ammonia stream in the second chamber 18.

It has been experimentally determined that the microchannel reactor 10 as shown in figure 5, achieves an overall efficiency of 58%, while the microchannel reactor 10 is maintained below the material stability limit, when the mixture flow rate is 0.8 NLMP, the equivalence ratio is 1.2 and the second ammonia flow rate is 0.4 NLPM. When this set of parameters was used, the microchannel reactor generated enough hydrogen for use in a 45 We fuel cell system at a reactor power density or 1.5 kWe per m3.

With the aforementioned set of parameters, and while operating at steady, autothermal conditions, less than 1% residual ammonia (that has not been decomposed) exits the outlet 22 and a second outlet manifold 56.

It has been found that the combustion of the first stream of ammonia occurs predominantly in a region towards the inlet 14 or the first chamber 12, and similarly, that the decomposition of the second stream of ammonia occurs predominantly in a region towards the inlet 20 or the second chamber 18. From a practical point of view, it is essential that the reaction zones or the combustion and the decomposition overlap. For this reason, the flow direction of the mixture through the first chamber 12 and the flow direction of the second stream of ammonia through the second chamber 18 have to be unidirectional. For this reason the inlets (14, 20) or the first and second chambers (12, 18) are located at a same end region of the micro-structured plate 26. The flow directions of the mixture and the second stream of ammonia will therefore be substantially identical.

The flow direction of the mixture stream and the second ammonia stream is reversed at predetermined intervals to ensure that the heat distribution along the length of the microchannel reactor 10 is improved.

The combustion of ammonia generally leads to the formation of NOx species as a byproduct exiting a first exit manifold 54. The prevalence of NOx species formed during the combustion of the ammonia is reduced by maintaining a fuel-rich mixture (equivalence ratio above 1). This leads to excess or residual ammonia which is available in the first chamber 12 to react with any NOx species that might have formed. In this way, the microchannel reactor has a self-cleaning capability.

Typically, the hydrogen which forms as a result of the decomposition of the ammonia in the second channel is used as a fuel source for generating electricity. This may be achieved by utilizing an alkaline fuel cell. Typically, the stream leaving the second outlet manifold (the decomposed second stream of ammonia) contains approximately 75% hydrogen and 25% oxygen (with less than 1% residual ammonia). The system is thus particularly efficient in providing a source of hydrogen.

Typically, the microchannel reactor 10 is utilized in a system 100 for generating electricity. The system comprises the microchannel reactor 10 as described above, an alkaline fuel cell 110, an in-line mixer 112, a water cooler 114, an ammonia container 118, and an oxygen container 120.

The alkaline fuel cell 110 is provided in fluid flow communication with the outlet 20 of the second chamber 18 of the microchannel reactor 10, and uses the hydrogen produced by the decomposition of the ammonia, together with a further source of substantially pure oxygen to generate electricity . The residual ammonia, and nitrogen species in the stream exiting the second chamber 18 through the second outlet manifold 56, and thus entering the alkaline fuel cell 110, does not pose a threat to the operation of the alkaline fuel cell 110.

The in-line mixer 112 has two inlets, one being connected to the ammonia container 118 and one connected to the oxygen container 120, and one outlet connected to the inlet 14 or the first chamber 12 via the first inlet manifold 50. The first stream or ammonia and the stream of oxygen are mixed in the in-line mixer 112, so that an even mixture of ammonia and oxygen enters the first chamber 12 through inlet 14.

The decomposed second stream of ammonia exits the microchannel reactor 10 through outlet 22 and second outlet manifold 56, and is cooled by the water cooler 114. The stream of combusted ammonia exiting through the first outlet manifold 54 may be cooled down using water (dispensed from a chiller at 5 ° C) in a condenser (not shown). The cooled gas may be passed through a separator to remove any residual water (not shown).

When the system 100 operates according to the set of parameters as aforementioned, the system has a potential power generating capability or 1.5 kWe per cubic meter or microchannel reactor 10 volume. The system is capable of operating on a daily start-up and shut-down cycle.

The current microchannel reactor itself is scaled up to the kW range.

The ammonia used in the system has a minimum purity of 99.99%. Importantly, the less than 1% residual ammonia exiting the second chambers 18 via the second outlet manifold 56 can be achieved with an isoflow rate ration or 0.5 and for a mixture stream flow ratio or above 0.8 NLPM.

The equivalent electrical output of the system may be around 48% of the thermal wattage of the hydrogen produced by the decomposition of the ammonia in the second chamber of the microchannel reactor.

The manifolds (50, 52, 54 and 56) are designed to ensure good equipment of the fluid flow.

Mass flow controllers are provided to regulate the mass flow rates of the first and second ammonia streams and oxygen stream. A battery may furthermore be provided to power the heating cartridges and heating blocks 46 during the start-up procedure of the microchannel reactor 10.

The applicant believes that the disadvantages of the prior art are overcome by the current invention. Firstly, since hydrogen has been generated on-site, the need for hydrogen storage has been removed. The generation of electricity is furthermore not dependent on outside factors such as the intensity of sunlight, wind speed or a fuel source such as diesel. Since electricity can be generated as the need therefore arises, no electricity storage facilities, such as battery banks are required. The ergonomics surrounding the system is improved by the fact that a common carbon-free fuel source is used both as a hydrogen carrier and for supplying the heat required to decompose the hydrogen carrier. Furthermore, the source used for these purposes have very few industrial applications, which means that theft with regards to the source will be minimized. Since carbon is not present in the source, and since the presence of NOx species can be naturally reduced by the system, the system according to the invention can be seen as a "clean" means of generating electricity. Lastly, the overall efficiency, and therefore the running cost of the system represent a further, significant improvement over prior art systems.

The applicant furthermore foresees that the current invention, being portable and offering means for distributed electricity generation, may potentially be used to supply the need for fossil fuel generators in remote areas where the supply of electricity by means of an electrical grid is not feasible.

It is foreseen that variations of the detail as provided is possible without departing from the claimed invention. Various constructions may be provided to ensure an equal number or first and second chambers in a microchannel reactor. For example, the microchannel reactor may contain an uneven number of micro-structured plates 26 without a central plate 27. It may be furthermore possible that the end plates may be provided with first and second recesses respectively in order to correspond to the recesses of adjacent micro -structured plates.

CLAUSES 1. A microchannel reactor for the decomposition of ammonia, the microchannel reactor comprising: - a first chamber having an inlet for operatively receiving a mixture of a first stream of ammonia and a stream of substantially pure oxygen, the first chamber further containing a first catalyst for facilitating exothermic combustion of the first stream of ammonia, and an outlet through which the mixture exits the first chamber; - a second chamber having an inlet for operatively receiving a second stream of ammonia, the second chamber further containing a second catalyst for facilitating the endothermic decomposition of the second stream of ammonia, and an outlet through which the decomposed second stream of ammonia exits the second chamber; and - a heat conducting wall, separating the first and second chambers to prevent fluid exchange between the first and second chambers; in use, the exothermic combustion of the ammonia in the first chamber generates the required heat for facilitating the endothermic decomposition of the ammonia in the second chamber, the heat being transferred from the first chamber to the second chamber through the wall. 2. The microchannel reactor according to clause 1, the first catalyst comprising a compound or alloy including a platinum group metal, and the second catalyst comprising a compound or alloy containing ruthenium. 3. The microchannel reactor according to clause 2, the first catalyst comprising a compound or alloy containing 5 wt.% Pt / Al2C> 3 with a Brunauer-Emmett-Teller (BET) surface area of 134.7 m2g'1. 4. The microchannel reactor according to any one of clauses 2 and 3, comprising the second catalyst comprising a compound or alloy containing 8.5 wt.% RU / AI2O3 with a Brunauer-Emmett-Teller (BET) surface area of 113 m2g'1. 5. The microchannel reactor according to any one of the preceding clauses, the inner surfaces of the first and second chambers are wash coated with the first and second catalyst respectively. 6. The microchannel reactor according to clause 5, the thickness of the wash-coated catalysts and the thickness of the wash-coated catalysts is between 30 and 50 microns, preferably 40 microns. 7. The microchannel reactor according to any one of the preceding clauses, the first and second chambers and its respective inlets and outlets are in the form of a stack of at least three plates, the stack including a first and second end plate, and at least one micro-structured plate located there between; the micro-structured plate having a first recess on a first side to form the first chamber, and a second recess on a second opposite side to form the second chamber; The heat conducting wall is formed by the micro-structured plate. 8. The microchannel reactor according to clause 7, which includes an even number of micro-structured plates alternately stacked to form a first chamber between each pair or micro-structured plates with their first ends in contact and a second chamber between each pair of micro -structured plates with their second ends in contact; not having a first or second recess is provided in the middle of the stack, so that the microchannel reactor comprises an equal number of first and second chambers. 9. The microchannel reactor according to any one of clauses 7 and 8, the first and second recesses of the micro-structured plates each further includes a variety of parallel protrusions such that closed channels within the first or second chambers are formed when the plates are stacked. 10. The microchannel reactor according to clause 9, the length or each channel is less than 7 cm. 11. The microchannel reactor according to any clause 10, the length or each channel is 5 cm. 12. The microchannel reactor according to any one of clauses 7 to 11, including the plates are manufactured from stainless steel, each plate having a length of 70 mm, a width of 21 mm and a thickness of 1 mm. 13. The microchannel reactor according to any one of clauses 7 to 12, including sixteen stacked micro-structured plates, a central plate and a first and second end plate, to form nine first chambers, nine second chambers, ninety first channels, and ninety second channels. 14. The microchannel reactor according to clause 13, including a total volume exceeding 25 cm3. 15. The microchannel reactor according to clause 14, containing the first channels contain a total of 133 mg or the first catalyst, and the second channels contain a total or 125 mg of the second catalyst. 16. The microchannel reactor according to any one of the preceding clauses, further including a housing for the micro-reactor consisting of heating cartridges and heating blocks, the housing further provided with insulation to prevent heat loss to the surroundings. 17. A method for decomposing ammonia in a microchannel reactor, the method including: - introducing a mixture to an inlet or a first chamber in the microchannel reactor, the mixture having a mixture equivalence ratio and flowing at a mixture flow rate, the mixture included a first stream of ammonia at a first ammonia flow rate and a stream of substantially pure oxygen at an oxygen flow rate, to facilitate exothermic combustion of the first stream of ammonia; - introducing a second stream of ammonia to an inlet or a second chamber in the microchannel reactor at a second ammonia flow rate to facilitate endothermic decomposition of the second stream of ammonia; and - allowing heat generated by the exothermic combustion of the first stream of ammonia in the first chamber to be transferred to the second chamber to provide the heat required for the decomposition of the second stream of ammonia. 18. The method for decomposing ammonia according to clause 17, according to the mixture flow rate is between 0.4 and 1.2 normal liters per minute (NLPM) and the second ammonia flow rate is between 0.1 and 1 NLPM. 19. The method for decomposing ammonia according to any one of clauses 17 and 18, where the mixture equivalence ratio is between 0.8 and 1.2. 20. The method for decomposing ammonia according to any one of clauses 17 to 19, where the mixture flow rate and mixture equivalence ratio are adjusted to achieve self-sustained combustion of the first stream of ammonia and autothermal decomposition of the second stream of ammonia. 21. The method for decomposing ammonia according to any one of clauses 17 to 20, requiring the inlets of the first and second chambers are disposed proximate the same end of the microchannel reactor such that the flow of the mixture through the first chamber, and the flow of the second stream of ammonia through the second chamber are in a substantially identical direction. 22. The method for decomposing ammonia according to clause 21, whether the flow direction of the mixture and second stream or ammonia relative to the first and second channels is reversed at predetermined intervals to facilitate improved heat distribution along a length of the reactor. 23. The method for decomposing ammonia according to any one of clauses 17 to 22, with a maximum temperature of the reactor maintained below 700 ° C. 24. The method for decomposing ammonia according to any one of clauses 17 to 23, the mixture equivalence ratio is maintained above 1 to reduce the prevalence of NOx species forming as a by-product of the exothermic combustion of ammonia, by homogeneous reaction or the NOx species with residual ammonia within the first chamber. 25. The method for decomposing ammonia according to any one of clauses 17 to 24, which includes the preceding step of heating the microchannel reactor with electric heaters to a temperature which is not lower than a combustion temperature or ammonia to initiate the combustion of the mixture in the first chamber. 26. The method for decomposing ammonia according to any one of clauses 17 to 25, less than 1% residual ammonia remains after decomposition or the second stream of ammonia in the second chamber, when the microchannel reactor operates at stable autothermal conditions. 27. The method for decomposing ammonia according to clause 26, where the autothermal condition is achieved at a temperature below 700 ° C. 28. The method for decomposing ammonia according to any one of clauses 17 to 27, where the reactor has a potential power density or 1.5kWe per m3 or reactor volume. 29. The method for decomposing ammonia according to any one of clauses 17 to 28, hydrogen formed by the decomposition of the ammonia is used as a fuel source in a fuel cell to generate electricity. 30. A system for generating electricity from a source of hydrogen, the system including: a microchannel reactor having a first chamber for facilitating combustion or a mixture containing a first stream of ammonia and a substantial pure stream of oxygen, a second chamber for facilitating decomposition or a second stream of ammonia, and a heat conducting wall separating the first and second chambers for transferring heat from the first chamber to the second chamber; and a fuel cell provided in fluid flow communication with the second chamber of the microchannel reactor to utilize hydrogen obtained from the decomposed second stream or ammonia to generate electricity. 31. The system for generating electricity according to clause 30, further including an in-line mixer for mixing the first stream of ammonia and the stream of oxygen before entering the first chamber. 32. The system for generating electricity according to any one of clauses 30 and 31, further including a water cooler to cool the decomposed second stream or ammonia before entering the fuel cell. 33. The system for generating electricity according to clause 32, further including a water cooler to cool down hot decomposed ammonia exiting the microchannel reactor and a separator to remove residual water from the cooled and combusted first stream or ammonia before entering the fuel cell. 34. The system for generating electricity according to any one of clauses 30 to 33, further including an ammonia container and an oxygen container for failure the ammonia and oxygen used in the microchannel reactor. 35. A system for generating electricity from a source of hydrogen according to any one of clauses 30 to 34, where the fuel cell is an alkaline fuel cell. 36. The microchannel reactor according to clause 1, substantially as described with reference to the drawings. 37. The method according to clause 17, substantially as described with reference to the drawings. 38. The system according to clause 30, substantially as described with reference to the drawings.

Claims (38)

CLAUSES 1. A microchannel reactor for the decomposition of ammonia, the microchannel reactor comprising: - a first chamber having an inlet for operatively receiving a mixture of a first stream of ammonia and a stream of substantially pure oxygen, the first chamber further containing a first catalyst for facilitating exothermic combustion or the first stream of ammonia, and an outlet through which the mixture exits the first chamber; - a second chamber having an inlet for operatively receiving a second stream of ammonia, the second chamber further containing a second catalyst for facilitating the endothermic decomposition of the second stream of ammonia, and an outlet through which the decomposed second stream of ammonia exits the second chamber; and - a heat conducting wall, separating the first and second chambers to prevent fluid exchange between the first and second chambers; in use, the exothermic combustion of the ammonia in the first chamber generates the required heat for facilitating the endothermic decomposition of the ammonia in the second chamber, the heat being transferred from the first chamber to the second chamber through the wall. 2. The microchannel reactor according to clause 1, the first catalyst comprising a compound or alloy including a platinum group metal, and the second catalyst comprising a compound or alloy containing ruthenium. 3. The microchannel reactor according to clause 2, containing the first catalyst comprising a compound or alloy containing 5 wt.% Pt / AI ₂ O3 with a Brunauer Emettett-Counter (BET) surface area of 134.7 m ² g ' ¹ . 5 4. The microchannel reactor according to any one of clauses 2 and 3, comprising the second catalyst comprising a compound or alloy including 8.5 wt.% RU / AI2O3 with a Brunauer-Emmett-Counter (BET) surface area of 113 m ² g " ¹ . 5. The microchannel reactor according to any of the preceding clauses, 10 within the inner surfaces of the first and second chambers are wash coated with the first and second catalyst respectively. 6. The microchannel reactor according to clause 5, the thickness of the wash-coated catalysts and the thickness of the wash-coated catalysts is between 30 15 and 50 microns, preferably 40 microns. 7. The microchannel reactor according to any one of the preceding clauses, the first and second chambers and its respective inlets and outlets are in the form of a stack or at least three plates, the stack including a first and 20 second end plate, and at least one micro-structured plate located there between; the micro-structured plate having a first recess on a first side to form the first chamber, and a second recess on a second opposite side to form the second chamber; the heat conducting wall is formed by the microstructured plate. 8. The microchannel reactor according to clause 7, which includes an even number of micro-structured plates alternately stacked to form a first chamber between each pair or micro-structured plates with their first ends in contact and a second chamber between each pair of micro -structured plates with their second ends in 5 contact; not having a first or second recess is provided in the middle of the stack, so that the microchannel reactor comprises an equal number of first and second chambers. 9. The microchannel reactor according to any one of clauses 7 and 8, being the 10 first and second recesses of the micro-structured plates each further includes a variety of parallel protrusions such that closed channels within the first or second chambers are formed when the plates are stacked. 10. The microchannel reactor according to clause 9, the length of each 15 channel is less than 7 cm. 11. The microchannel reactor according to any clause 10, the length or each channel is 5 cm. 12. The microchannel reactor according to any one of clauses 7 to 11, the plates are manufactured from stainless steel, each plate having a length of 70 mm, a width of 21 mm and a thickness of 1 mm. 13. The microchannel reactor according to any one of clauses 7 to 12, including 25 sixteen stacked micro-structured plates, a central plate and a first and second end plate, to form nine first chambers, nine second chambers, ninety first channels, and ninety second channels. 14. The microchannel reactor according to clause 13, including a total volume exceeding 25 cm ³ . 15. The microchannel reactor according to clause 14, containing the first channels contain a total of 133 mg or the first catalyst, and the second channels contain a total or 125 mg of the second catalyst. 16. The microchannel reactor according to any one of the preceding clauses, further including a housing for the micro-reactor consisting of heating cartridges and heating blocks, the housing further provided with insulation to prevent heat loss to the surroundings. 17. A method for decomposing ammonia in a microchannel reactor, the method including: - introducing a mixture to an inlet or a first chamber in the microchannel reactor, the mixture having a mixture equivalence ratio and flowing at a mixture flow rate, the mixture including a first stream of the ammonia at a first ammonia flow rate and a stream or substantially pure oxygen at an oxygen flow rate, to facilitate exothermic combustion or the first stream of ammonia; - introducing a second stream of ammonia to an inlet or a second chamber in the microchannel reactor at a second ammonia flow rate to facilitate endothermic decomposition of the second stream of ammonia; and 28 - allowing heat generated by the exothermic combustion of the first stream of ammonia in the first chamber to be transferred to the second chamber to provide the heat required for the decomposition of the second stream of ammonia. 18. The method for decomposing ammonia according to clause 17, according to the mixture flow rate is between 0.4 and 1.2 normal liters per minute (NLPM) and the second ammonia flow rate is between 0.1 and 1 NLPM. 10 19. The method for decomposing ammonia according to any one of clauses 17 and 18, the mixture equivalence ratio is between 0.8 and 1.2. 20. The method for decomposing ammonia according to any one of clauses 17 to 19, the mixture flow rate and mixture equivalence ratio are adjusted to 15 achieve self-sustained combustion of the first stream of ammonia and autothermal decomposition of the second stream of ammonia. 21. The method for decomposing ammonia according to any one of clauses 17 to 20, the inlets or the first and second chambers are disposed proximate 20 the same end of the microchannel reactor such that the flow of the mixture through the first chamber, and the flow of the second stream of ammonia through the second chamber are in a substantially identical direction. 22. The method for decomposing ammonia according to clause 21, regarding the flow 25 direction of the mixture and second stream of ammonia relative to the first and second channels is reversed at predetermined intervals to facilitate improved heat distribution along a length of the reactor. 23. The method for decomposing ammonia according to any one of clauses 17 to 5 22, with a maximum temperature of the reactor maintained below 700 ° C. 24. The method for decomposing ammonia according to any one of clauses 17 to 23, the mixture equivalence ratio is maintained above 1 to reduce the prevalence of NOx species forming as a by-product of the exothermic 10 combustion of ammonia, by homogeneous reaction of the NOx species with residual ammonia within the first chamber. 25. The method for decomposing ammonia according to any one of clauses 17 to 24, which includes the preceding step of heating the microchannel reactor with 15 electric heaters to a temperature which is not lower than a combustion temperature or ammonia to initiate the combustion or the mixture in the first chamber. 26. The method for decomposing ammonia according to any one of clauses 17 to 20 25, less than 1% residual ammonia remains after decomposition or the second stream or ammonia in the second chamber, when the microchannel reactor operates at stable autothermal conditions. 27. The method for decomposing ammonia according to clause 26, regarding the 25 autothermal condition is achieved at a temperature below 700 ° C. 28. The method for decomposing ammonia according to any one of clauses 17 to 27, the reactor has a potential power density or 1.5kWe per m ³ or reactor volume. 29. The method for decomposing ammonia according to any one of clauses 17 to 28, hydrogen formed by the decomposition of the ammonia is used as a fuel source in a fuel cell to generate electricity. 30. A system for generating electricity from a source of hydrogen, the system 10 including: a microchannel reactor having a first chamber for facilitating combustion or a mixture comprising a first stream of ammonia and a substantial pure stream of oxygen, a second chamber for facilitating decomposition or a second stream of ammonia, and a heat conducting wall separating the first 15 and second chambers for transferring heat from the first chamber to the second chamber; and a fuel cell provided in fluid flow communication with the second chamber of the microchannel reactor to utilize hydrogen obtained from the decomposed second stream or ammonia to generate electricity. 31. The system for generating electricity according to clause 30, further including an in-line mixer for mixing the first stream of ammonia and the stream of oxygen before entering the first chamber. 32. The system for generating electricity according to any one of clauses 30 and 31, further including a water cooler to cool the decomposed second stream or ammonia before entering the fuel cell. 5 33. The system for generating electricity according to clause 32, further including a water cooler to cool down hot decomposed ammonia exiting the microchannel reactor and a separator to remove residual water from the cooled and combusted first stream or ammonia before entering the fuel cell. 10 34. The system for generating electricity according to any one of clauses 30 to 33, further including an ammonia container and an oxygen container for failure the ammonia and oxygen used in the microchannel reactor. 35. A system for generating electricity from a source or hydrogen according to any 15 one of clauses 30 to 34, the fuel cell is an alkaline fuel cell. 36. The microchannel reactor according to clause 1, substantially as described with reference to the drawings. 20 37. The method according to clause 17, substantially as described with reference to the drawings. 38. The system according to clause 30, substantially as described with reference to the drawings. CONCLUSIONS A microchannel reactor for the decomposition of ammonia, wherein the microchannel reactor comprises: - a first chamber with an inlet for effectively receiving a mixture of a first ammonia stream and a stream of substantially pure oxygen, the first chamber containing a first catalyst for facilitating the exothermic combustion of the first stream of ammonia which further, and an outlet through which the mixture leaves the first chamber; - a second chamber with an inlet for effectively receiving a second ammonia stream, the second chamber further comprising a second catalyst for facilitating the endothermic decomposition of the second ammonia stream, and an outlet through which the decomposed second stream of ammonia the second leave room; and a thermally conductive wall separating the first and second chambers to prevent fluid exchange between the first and second chambers; wherein, in use, the exothermic combustion of ammonia in the first chamber generates the heat required to facilitate the endothermic decomposition of the ammonia in the second chamber, the heat being transferred from the first chamber to the second chamber through the wall. The microchannel reactor according to claim 1, wherein the first catalyst comprises a compound or alloy comprising a platinum group metal, and wherein the second catalyst comprises a compound or alloy comprising ruthenium. The microchannel reactor according to claim 2, wherein the first catalyst comprises a compound or alloy comprising 5 wt% Pt / Al 2 O 3 with Brunauer-EmmettTeller (BET) area of 134.7 m ² g ' ¹ . The microchannel reactor according to any of claims 2 and 3, wherein the second catalyst comprises a compound or alloy comprising 8.5 wt% Ru / Al 2 O 3 with Brunauer-Emmett-Teller (BET) surface area of 113 m ² g ' ¹ 1. The microchannel reactor according to any one of the preceding claims, wherein the inner surfaces of the first and second chambers are wash-coated with the first and second catalyst, respectively. The microchannel reactor according to claim 5, wherein the thickness of the wash-coated catalysts is between 30 and 50 microns, preferably 40 microns. The micro channel reactor according to any one of the preceding claims, wherein the first and second chambers and its respective inlets and outlets are in the form of a stack of at least three plates, the stack comprising a first and second end plate, and at least one micro -structured plate between them; wherein the micro-structured plate has a first recess on a first side to form the first chamber and a second recess on a second opposite side thereof to form the second chamber; and wherein the thermally conductive wall is formed by the micro-structured plate. The microchannel reactor according to claim 7, which includes an even number of microstructured plates stacked alternately to form a first chamber between each pair of microstructured plates with their first ends in contact and a second chamber between each pair of microstructured plates with their second ends in contact; and wherein a central plate which has no first or second recess is arranged in the center of the stack, such that the microchannel reactor comprises the same number of first and second chambers. The microchannel reactor according to any of claims 7 and 8, wherein the first and second recesses of the microstructured plates each further comprise a number of parallel protrusions such that closed channels are formed within the first and second chambers when the plates are stacked. The micro channel reactor according to claim 9, wherein the length of each channel is less than 7 cm. The micro channel reactor according to claim 10, wherein the length of each channel is 5 cm. The microchannel reactor according to any of claims 7-11, wherein the plates are made of stainless steel, each plate having a length of 70 mm, a width of 21 mm and a thickness of 1 mm. The microchannel reactor according to any of claims 7-12, comprising sixteen stacked microstructured plates, a central plate and a first and second end plate, to form nine first chambers, nine second chambers, ninety first channels and ninety second channels. The micro channel reactor according to claim 13, comprising a total volume of more than 25 cm ³ . The micro channel reactor according to claim 14, wherein the first channels contain a total of 133 mg of the first catalyst, and the second channels contain a total of 125 mg of the second catalyst. The microchannel reactor according to any one of the preceding claims, further comprising a housing for the microreactor consisting of heating coils and heating blocks further providing the housing with insulation to prevent heat loss to the environment. A process for decomposing ammonia in a microchannel reactor, the process comprising: - introducing a mixture at an inlet of a first chamber into the microchannel reactor wherein the mixture has a mixture equivalence ratio and flows at a mixture flow rate, wherein the mixture comprises a first ammonia stream with a first ammonia stream velocity and a stream of substantially pure oxygen with an oxygen flow rate, to promote exothermic combustion of the first stream of ammonia; introducing a second stream of ammonia to an inlet of a second chamber in the microchannel reactor with a second ammonia flow rate to facilitate the endothermic decomposition of the second ammonia stream; and - transferring the heat generated by the exothermic combustion of the first ammonia stream in the first chamber to the second chamber to provide the heat required for decomposing the second stream of ammonia. The ammonia decomposition method according to claim 17, wherein the mixture flow rate is between 0.4 and 1.2 normal liters per minute (NLPM) and wherein the second ammonia flow rate is between 0.1 and 1 NLPM. The method for decomposing ammonia according to any of claims 17 and 18, wherein the mixture has an equivalence ratio between 0.8 and 1.2. The method of decomposing ammonia according to any of claims 17 to 19, wherein the mixture flow rate and mixture equivalence ratio are adjusted to achieve self-sustained combustion of the first stream of ammonia and autothermal decomposition of the second stream of ammonia. The method for decomposing ammonia according to any of claims 17 to 20, wherein the inlets of the first and second chambers are arranged near the same end of the microchannel reactor such that the flow of the mixture through the first chamber, and the flow of the second ammonia flow through the second chamber in a substantially identical direction. The ammonia decomposition method of claim 21, wherein the flow direction of the mixture and second ammonia stream relative to the first and second channels is reversed at predetermined intervals to facilitate better heat distribution over the length of the reactor. The method for decomposing ammonia according to any of claims 17 to 22, wherein a maximum temperature of the reactor is maintained below 700 ° C. The ammonia decomposition method according to any of claims 17 to 23, wherein the mixture equivalence ratio is maintained above 1 to reduce the prevalence of NOx species formed as a by-product of the exothermic combustion of ammonia, by homogeneous conversion of the NOx species with residual ammonia within the first room. The method of decomposing ammonia according to any of claims 17 to 24, wherein in a preceding step of heating the microchannel reactor with electrical heating to a temperature not lower than an ammonia combustion temperature for the combustion of the ammonia start the mixture in the first chamber. The method for decomposing ammonia according to any of claims 17 to 25, wherein less than 1% residual ammonia remains after decomposition of the second ammonia stream in the second chamber, while the microchannel reactor operates under stable autothermal conditions. The ammonia decomposition method according to claim 26, wherein the autothermal state is achieved at a temperature below 700 ° C. The ammonia decomposition method according to any of claims 17 to 27, wherein the reactor has a potential power density of 1.5 kWe per m3 reactor volume. The ammonia decomposition method according to any of claims 17 to 28, wherein hydrogen formed by the decomposition of the ammonia is used as a fuel in a fuel cell to generate electricity. 30. A system for generating electricity from a hydrogen source, the system comprising: - a microchannel reactor with a first chamber for facilitating the combustion of a mixture comprising a first ammonia stream and substantially pure stream of oxygen, a second chamber for facilitating the decomposition of a second ammonia stream and a heat-conducting partition between the first and second chamber for transferring heat from the first chamber to the second chamber; and - a fuel cell provided in fluid flow communication with the second chamber of the microchannel reactor to use hydrogen obtained from the decomposed second stream of ammonia to generate electricity. The electricity generating system according to claim 30, further comprising an in-line mixer for mixing the first stream of ammonia and the oxygen stream before entering the first chamber. The electricity generating system according to any of claims 30 and 31, further comprising a water cooler to cool the decomposed second stream of ammonia before it enters the fuel cell The electricity generating system of claim 32, further comprising a water cooler to cool hot decomposed ammonia exiting the microchannel reactor and a separator to remove residual water from the cooled and burned first stream of ammonia before it enters the fuel cell goes in. The electricity generating system according to any of claims 30 to 33, further comprising an ammonia container and an oxygen container for storing the ammonia and oxygen used in the microchannel reactor. A system for generating electricity from a hydrogen source according to any of claims 30-34, wherein the fuel cell is an alkaline fuel cell. The microchannel reactor of claim 1, substantially as described herein with reference to the drawings. The method of claim 17, substantially as described herein with reference to the drawings. The system of claim 30, substantially as described herein with reference to the drawings. ί / 5 FIGURE 2 FIGURE 3 3/5 FIGURE 4 4/5 FIGURE 5 5/5 100 ^ C ²⁶ · ² 38 38 46 FIGURE 6 FIGURE 7