Fischer—Tropsch synthesis surface carbide mechanism

A new mechanism to interpret alkene formation in Fischer-Tropsch synthesis has been presented 499-501 There is a general agreement that hydrocarbon formation proceeds according to the modified carbene mechanism. Specifically, CO decomposes to form surface carbide and then undergoes hydrogenation to form surface methine (=CH), methylene (=CH2), methyl and, finally, methane. Linear hydrocarbons are formed in a stepwise polymerization of methylene species. When chain growth is terminated by p-hydride elimination [Eq. (3.61)], 1-alkenes may be formed,502 which is also called the alkyl mechanism ... 

Here Z is a Ni surface site. The equation they derive is complex but can be simplified (see Table 4) for full-scale application. These workers point out that the same equation can be derived from a mechanism involving surface carbon as an intermediate similar to carbide theories for Fischer-Tropsch synthesis. In that case steps (b) and (c) in the above equation would be replaced by (b ) and (c ). 

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