Editing Alkane (section)

===Petroleum refining===
[[Image:ShellMartinez-refi.jpg|thumb|right|An [[oil refinery]] at [[Martinez, California]].]]
The most important source of alkanes is natural gas and [[crude oil]].<ref name=m&b/> Alkanes are separated in an [[oil refinery]] by [[fractional distillation]]. Unsaturated hydrocarbons are converted to alkanes by [[hydrogenation]]:<ref name=Ull/>
: {{chem2|RCH\dCH2 + H2 --> RCH2\sCH3}} (R = [[alkyl]])

Another route to alkanes is [[hydrogenolysis]], which entails cleavage of C-heteroatom bonds using hydrogen.  In industry, the main substrates are organonitrogen and organosulfur impurities, i.e. the heteroatoms are N and S.  The specific processes are called [[hydrodenitrification]] and [[hydrodesulfurization]]: 
:{{chem2|R3N  +  3 H2  ->  3 RH  +  H3N}}
:{{chem2|R2S  +  2 H2  ->  2 RH  +  H2S}}
Hydrogenolysis can be applied to the conversion of virtually any functional group into hydrocarbons.  Substrates include haloalkanes, alcohols, aldehydes, ketones, carboxylic acids, etc.  Both hydrogenolysis and hydrogenation are practiced in refineries.  The can be effected by using [[lithium aluminium hydride]], [[Clemmenson reduction]] and other specialized routes.