Carbon Dioxide - Isolation and Production

Isolation and Production

Carbon dioxide is mainly produced as an unrecovered side product of four technologies: combustion of fossil fuels, production of hydrogen by steam reforming, ammonia synthesis, and fermentation. It can be obtained by or from air distillation, however, this method is inefficient.

The combustion of all carbon-containing fuels, such as methane (natural gas), petroleum distillates (gasoline, diesel, kerosene, propane), but also of coal and wood, will yield carbon dioxide and, in most cases, water. As an example the chemical reaction between methane and oxygen is given below.

CH₄+ 2 O₂→ CO₂+ 2 H₂O

The production of quicklime (CaO), a compound that enjoys widespread use, involves the heating (calcining) of limestone at about 850 °C:

CaCO₃→ CaO + CO₂

Iron is reduced from its oxides with coke in a blast furnace, producing pig iron and carbon dioxide:

Fe₂O₃+ 3 CO → 2 Fe + 3 CO₂

Yeast metabolizes sugar to produce carbon dioxide and ethanol, also known as alcohol, in the production of wines, beers and other spirits, but also in the production of bioethanol:

C₆H₁₂O₆ → 2 CO₂+ 2 C₂H₅OH

All aerobic organisms produce CO₂ when they oxidize carbohydrates, fatty acids, and proteins in the mitochondria of cells. The large number of reactions involved are exceedingly complex and not described easily. Refer to (cellular respiration, anaerobic respiration and photosynthesis). The equation for the respiration of glucose and other monosachharides is:

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O

Photoautotrophs (i.e. plants, cyanobacteria) use another modus operandi: Plants absorb CO₂ from the air, and, together with water, react it to form carbohydrates:

nCO₂ + nH₂O → (CH₂O)_n + nO₂