Editing Carbon monoxide (section)

== Production ==
Thermal [[combustion]] is the most common source for carbon monoxide. Carbon monoxide is produced from the partial oxidation of [[carbon]]-containing compounds; it forms when there is not enough oxygen to produce [[carbon dioxide]] ({{CO2}}), such as when operating a [[stove]] or an [[internal combustion engine]] in an enclosed space.

A large quantity of CO byproduct is formed during the oxidative processes for the production of chemicals. For this reason, the process off-gases have to be purified.

Many methods have been developed for carbon monoxide production.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 200. {{ISBN|0-12-352651-5}}.</ref>

===Industrial production===
A major industrial source of CO is [[producer gas]], a mixture containing mostly carbon monoxide and nitrogen, formed by combustion of carbon in air at high temperature when there is an excess of carbon. In an oven, air is passed through a bed of [[coke (fuel)|coke]]. The initially produced {{CO2}} equilibrates with the remaining hot carbon to give CO.<ref>{{Cite web|title=Carbon Monoxide|url=http://www.chm.bris.ac.uk/motm/co/coh.htm|access-date=21 May 2021}}</ref> The reaction of {{CO2}} with carbon to give CO is described as the [[Boudouard reaction]].<ref>{{cite book|author1=Higman, C|url=https://archive.org/details/gasification00higm|title=Gasification|author2=van der Burgt, M|publisher=Gulf Professional Publishing|year=2003|isbn=978-0-7506-7707-3|page=[https://archive.org/details/gasification00higm/page/n22 12]|url-access=limited}}</ref> Above 800&nbsp;°C, CO is the predominant product:
:{{chem2|CO2 (g) + C (s) -> 2 CO (g)}} (Δ''H''<sub>r</sub> = 170 kJ/mol)

Another source is "[[water gas]]", a mixture of [[hydrogen]] and carbon monoxide produced via the endothermic reaction of [[steam]] and carbon:
:{{chem2|H2O (g) + C (s) -> H2 (g) + CO (g)}} (Δ''H''<sub>r</sub> = 131 kJ/mol)

Other similar "[[syngas|synthesis gas]]es" can be obtained from [[natural gas]] and other fuels.

Carbon monoxide can also be produced by [[high-temperature electrolysis]] of carbon dioxide with [[solid oxide electrolyzer cell]]s.<ref>{{cite journal|last1=Zheng|first1=Yun|last2=Wang|first2=Jianchen|last3=Yu|first3=Bo|last4=Zhang|first4=Wenqiang|last5=Chen|first5=Jing|last6=Qiao|first6=Jinli|last7=Zhang|first7=Jiujun|date=2017|title=A review of high temperature co-electrolysis of H O and CO to produce sustainable fuels using solid oxide electrolysis cells (SOECs): advanced materials and technology|journal=Chem. Soc. Rev.|volume=46|issue=5|pages=1427–1463|doi=10.1039/C6CS00403B|pmid=28165079}}</ref> One method developed at DTU Energy uses a cerium oxide catalyst and does not have any issues of fouling of the catalyst.<ref>{{Cite web|title=New route to carbon-neutral fuels from carbon dioxide discovered by Stanford-DTU team - DTU|url=https://www.dtu.dk/english/news/2019/09/new-route-to-carbon-neutral-fuels-from-carbon-dioxide-discovered-by-stanford-dtu-team?id=4feafcd3-bf1d-4e02-80ea-ea018bfc6caf|website=dtu.dk}}</ref><ref>{{Cite journal|last1=Skafte|first1=Theis L.|last2=Guan|first2=Zixuan|last3=Machala|first3=Michael L.|last4=Gopal|first4=Chirranjeevi B.|last5=Monti|first5=Matteo|last6=Martinez|first6=Lev|last7=Stamate|first7=Eugen|last8=Sanna|first8=Simone|last9=Garrido Torres|first9=Jose A.|last10=Crumlin|first10=Ethan J.|last11=García-Melchor|first11=Max|date=October 8, 2019|title=Selective high-temperature CO 2 electrolysis enabled by oxidized carbon intermediates|url=https://www.nature.com/articles/s41560-019-0457-4|journal=Nature Energy|volume=4|issue=10|pages=846–855|doi=10.1038/s41560-019-0457-4|via=www.nature.com|last12=Bajdich|first13=William C.|last13=Chueh|first14=Christopher|last14=Graves|first12=Michal|bibcode=2019NatEn...4..846S|hdl=2262/93685|s2cid=202640892|hdl-access=free}}</ref>
:{{chem2|2 CO2 -> 2 CO + O2}}

Carbon monoxide is also a byproduct of the reduction of metal [[oxide]] [[ore]]s with carbon, shown in a simplified form as follows:
:MO + C → M + CO

Carbon monoxide is also produced by the direct oxidation of carbon in a limited supply of oxygen or air.
:{{chem2|2 C + O2 -> 2 CO}}

Since CO is a gas, the reduction process can be driven by heating, exploiting the positive (favorable) [[entropy]] of reaction. The [[Ellingham diagram]] shows that CO formation is favored over {{CO2}} in high temperatures.