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The fuel cartridge stores the methanol fuel. Depending on the system design either 100% methanol (IMPCA industrial standard) or a mixture of methanol with up to 40 vol% water is usually used as fuel for the RMFC system. 100% methanol results in lower fuel consumption than water-methanol mixture (Premix) but goes along with higher fuel cell system complexity for condensing of cathode moisture.
A mixture of water and methanol with a molar concentration ratio (water:methanol) of 1.0 - 1.5 is pressurized to approximately 20 bar, vaporized and heated to a temperature of 250 - 360 °C. The hydrogen that is created is separated through the use of Pressure swing adsorption or a hydrogen-permeable membrane made of polymer or a palladium alloy.
[1] [2] Synthesis gas is conventionally produced via the steam reforming reaction or coal gasification. In recent years, increased concerns on the contribution of greenhouse gases to global warming have increased interest in the replacement of steam as reactant with carbon dioxide. [3] The dry reforming reaction may be represented by:
Methanation is an important step in the creation of synthetic or substitute natural gas (SNG). [7] Coal or wood undergo gasification which creates a producer gas that must undergo methanation in order to produce a usable gas that just needs to undergo a final purification step.
Autothermal reforming (ATR) uses oxygen and carbon dioxide or steam in a reaction with methane to form syngas. The reaction takes place in a single chamber where the methane is partially oxidized. The reaction is exothermic due to the oxidation. When the ATR uses carbon dioxide the H 2:CO ratio produced is 1:1; when the ATR uses steam the H 2 ...
After removing hydrogen sulfide and carbon dioxide , which form as side products during the gasification step, methanol can be made using conventional methods. [15] This route can offer renewable methanol production from biomass at efficiencies up to 75%. [17] Production methods using carbon dioxide as a feedstock have also been proposed.
The process uses carbon dioxide in manufacturing and releases around the same amount of carbon dioxide into the air when the fuel is burned, for an overall low carbon footprint. Electrofuels are thus an option for reducing greenhouse gas emissions from transport, particularly for long-distance freight, marine, and air transport.
One way of dealing with the excess hydrogen is to inject carbon dioxide into the methanol synthesis reactor, where it, too, reacts to form methanol according to the equation CO 2 + 3 H 2 → CH 3 OH + H 2 O. In terms of mechanism, the process occurs via initial conversion of CO into CO 2, which is then hydrogenated: [54] CO 2 + 3 H 2 → CH 3 ...