The Bosch reaction is a chemical reaction between carbon dioxide and hydrogen that produces elemental carbon (graphite), water, and a 10% return of invested heat. It is named after the German chemist Carl Bosch. This reaction requires the introduction of iron as a catalyst and requires a temperature level of 530-730 degrees Celsius.
The overall reaction is as follows:
The above reaction is actually the result of two reactions. The first reaction, the reverse water gas shift reaction, is a fast one:
CO2 + H2 → CO + H2O
The second reaction controls the reaction rate:
CO + H2 → C + H2O
The overall reaction produces 2.3×103 joules for every gram of carbon dioxide reacted at 650 °C. Reaction temperatures are in the range of 450 to 600 °C.
The Bosch reaction is being investigated for use in maintaining space station life support. Though the Bosch reaction would present a completely closed hydrogen and oxygen cycle which only produces atomic carbon as waste, difficulties in maintaining its higher required temperature and properly handling carbon deposits mean that significantly more research will be required before a Bosch reactor can become a reality. One problem is that the production of elemental carbon tends to foul the catalyst's surface, which is detrimental to the reaction's efficiency.