Editing Hydrogen peroxide (section)

==Production==
[[File:Riedl-Pfleiderer process.svg|class=skin-invert-image|420px|right|thumb|[[Catalytic cycle]] for the [[anthraquinone process]] to produce hydrogen peroxide: an anthraquinone (right) is reduced using hydrogen to produce the corresponding anthrahydroquinone (left). This is oxidized using oxygen to produce hydrogen peroxide and recover anthraquinone.]]
In 1994, world production of {{chem2|H2O2}} was around 1.9 million tonnes and grew to 2.2 million in 2006,<ref name="HageLienke"/> most of which was at a concentration of 70% or less. In that year, bulk 30% {{chem2|H2O2}} sold for around 0.54 [[USD]]/[[Kilogram|kg]], equivalent to US$1.50/kg (US$0.68/[[pound (mass)|lb]]) on a "100% basis".<ref name="Antra"/>{{clarify|date=September 2020}}

Today, hydrogen peroxide is manufactured almost exclusively by the [[anthraquinone process]], which was originally developed by [[BASF]] in 1939. It begins with the reduction of an [[anthraquinone]] (such as [[2-Ethylanthraquinone|2-ethylanthraquinone]] or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by [[hydrogenation]] on a [[palladium]] [[catalysis|catalyst]]. In the presence of [[oxygen]], the anthrahydroquinone then undergoes [[autoxidation]]: the labile hydrogen atoms of the [[hydroxy group]]s transfer to the oxygen molecule, to give hydrogen peroxide and regenerating the anthraquinone. Most commercial processes achieve oxidation by bubbling [[compressed air]] through a solution of the anthrahydroquinone, with the hydrogen peroxide then [[Liquid–liquid extraction|extracted]] from the solution and the anthraquinone recycled back for successive cycles of hydrogenation and oxidation.<ref name="Antra">{{cite journal |vauthors = Campos-Martin JM, Blanco-Brieva G, Fierro JL |title = Hydrogen peroxide synthesis: an outlook beyond the anthraquinone process |journal = Angewandte Chemie |volume = 45 |issue = 42 |pages = 6962–84 |date = October 2006 |pmid = 17039551 |doi = 10.1002/anie.200503779 |s2cid = 23286196}}</ref><ref name="Riedl&Pleiderer">H. Riedl and G. Pfleiderer, U.S. Patent 2,158,525 (2 October 1936 in the US, and 10 October 1935 in Germany) to I. G. Farbenindustrie, Germany</ref>

The net reaction for the anthraquinone-catalyzed process is:<ref name="Antra"/>

:{{chem2|H2 + O2 → H2O2}}

The economics of the process depend heavily on effective recycling of the extraction solvents, the [[hydrogenation]] catalyst and the expensive [[quinone]].

[[File:Container JOTU501003 9.jpg|thumb|ISO tank container for hydrogen peroxide transportation]]
[[File:HydrogenPeroxideTankCarBoltonON.jpg|thumb|A tank car designed for transporting hydrogen peroxide by rail]]

===Historical methods===
Hydrogen peroxide was once prepared industrially by [[hydrolysis]] of [[ammonium persulfate]]:
:{{chem2|[NH4]2S2O8 + 2 H2O -> 2 [NH4]HSO4 + H2O2}}
{{chem2|[NH4]2S2O8}} was itself obtained by the [[electrolysis]] of a solution of [[ammonium bisulfate]] ({{chem2|[NH4]HSO4}}) in [[sulfuric acid]].<ref>{{Cite web|title=Preparing to manufacture hydrogen peroxide|url=https://www.idc-online.com/technical_references/pdfs/chemical_engineering/Preparing_to_Manufacture_Hydrogen_Peroxide.pdf|website=IDC Technologies|access-date=14 February 2022|archive-date=3 August 2021|archive-url=https://web.archive.org/web/20210803040838/http://www.idc-online.com/technical_references/pdfs/chemical_engineering/Preparing_to_Manufacture_Hydrogen_Peroxide.pdf|url-status=live}}</ref>

===Other routes===
Small amounts are formed by electrolysis, [[photochemistry]], [[electric arc]], and related methods.<ref Name="Mell1922">{{cite book |title=Modern Inorganic Chemistry| vauthors = Mellor JW |publisher=Longmans, Green and Co. |pages=192–5 |year=1922 |url=https://archive.org/details/b29807712}}</ref>

A commercially viable route for hydrogen peroxide via the reaction of hydrogen with oxygen favours production of water but can be stopped at the peroxide stage.<ref>{{citation | doi = 10.1002/9783527627547.ch8| chapter = Direct Synthesis of Hydrogen Peroxide: Recent Advances| title = Modern Heterogeneous Oxidation Catalysis| date = 2009| last1 = Centi| first1 = Gabriele| last2 = Perathoner| first2 = Siglinda| last3 = Abate| first3 = Salvatore| pages = 253–287| isbn = 978-3-527-31859-9}}</ref><ref name="Hutchings">{{cite journal |vauthors = Edwards JK, Solsona B, N EN, Carley AF, Herzing AA, Kiely CJ, Hutchings GJ |title = Switching off hydrogen peroxide hydrogenation in the direct synthesis process |journal = Science |volume = 323 |issue = 5917 |pages = 1037–41 |date = February 2009 |pmid = 19229032 |doi = 10.1126/science.1168980 |s2cid = 1828874 |bibcode = 2009Sci...323.1037E }}</ref> One economic obstacle has been that direct processes give a dilute solution uneconomic for transportation. None of these has yet reached a point where it can be used for industrial-scale synthesis.