Editing Steam reforming (section)

== Autothermal reforming ==
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. When the ATR uses carbon dioxide, the H<sub>2</sub>:CO ratio produced is 1:1; when the ATR uses steam, the H<sub>2</sub>:CO ratio produced is 2.5:1. The outlet temperature of the syngas is between 950–1100&nbsp;°C and outlet pressure can be as high as 100 bar.<ref>[http://www.topsoe.com/business_areas/methanol/Processes/AutothermalReforming.aspx Topsoe ATR]</ref>

In addition to reactions [1] – [3], ATR introduces the following reaction:<ref>{{Cite journal|last1=Blumberg|first1=Timo|last2=Morosuk|first2=Tatiana|last3=Tsatsaronis|first3=George|date=December 2017|title=A Comparative Exergoeconomic Evaluation of the Synthesis Routes for Methanol Production from Natural Gas|journal=Applied Sciences|language=en|volume=7|issue=12|pages=1213|doi=10.3390/app7121213|doi-access=free}}</ref>

<math>[4]\qquad \mathrm{CH}_4 + 0.5\,\mathrm{O}_2 \rightleftharpoons \mathrm{CO} + 2\,\mathrm{H}_2
\qquad \Delta H_{R} = -24.5\ \mathrm{kJ/mol}</math>

The main difference between SMR and ATR is that SMR only uses air for combustion as a heat source to create steam, while ATR uses purified oxygen. The advantage of ATR is that the H<sub>2</sub>:CO ratio can be varied, which can be useful for producing specialty products. Due to the exothermic nature of some of the additional reactions occurring within ATR, the process can essentially be performed at a net enthalpy of zero (Δ''H'' = 0).<ref>{{Citation|last=Semelsberger|first=T. A.|title=FUELS – HYDROGEN STORAGE {{!}} Chemical Carriers|date=2009-01-01|url=https://www.sciencedirect.com/science/article/pii/B9780444527455003312|encyclopedia=Encyclopedia of Electrochemical Power Sources|pages=504–518|editor-last=Garche|editor-first=Jürgen|place=Amsterdam|publisher=Elsevier|language=en|doi=10.1016/b978-044452745-5.00331-2|isbn=978-0-444-52745-5|access-date=2021-11-16|url-access=subscription}}</ref>