Hydrogen from hydrocarbons

Many of the reactions of halogens can be considered as either oxidation or displacement reactions the redox potentials (Table 11.2) give a clear indication of their relative oxidising power in aqueous solution. Fluorine, chlorine and bromine have the ability to displace hydrogen from hydrocarbons, but in addition each halogen is able to displace other elements which are less electronegative than itself. Thus fluorine can displace all the other halogens from both ionic and covalent compounds, for example... 

These processes all produce hydrogen from hydrocarbons and water. 

Radical substitution reactions by iodine are not practical because the abstraction of hydrogen from hydrocarbons by iodine is endothermic, even for stable radicals. The enthalpy of the overall reaction is also slightly endothermic. Thus, because of both the kinetic problem excluding a chain reaction and an unfavorable equilibrium constant for substitution, iodination cannot proceed by a radical-chain mechanism. 

The f-butoxy radicals thus formed then abstract hydrogen from hydrocarbons to generate hydrocarbon radicals and f-butyl alcohol. The hydrocarbon radicals in turn generate more r-butoxy radicals by attacking the t-butyl-hypochlorite ... 

Lin, S.-Y. et al., Developing an innovative method, HyPr-RING, to produce hydrogen from hydrocarbons, Energ. Corners. Manag., 43, 1283, 2002. 

RKN A process for making hydrogen from hydrocarbon gases (from natural gas to naphtha) by steam reforming. Developed by Haldor Topsoe in the 1960s as of 1975, 24 plants were operating. 

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