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This post was last edited by jordan569 on 2013-1-6 22:41. There are many reaction mechanisms for F-T synthesis, but none of them can fully explain all the phenomena that occur during this process. Some of the more typical reaction mechanisms are as follows: (1) Surface carbide mechanism. This mechanism was first proposed by Fischer and Tropsch; they believed that CO first adsorbs on the catalyst surface to form metal carbides, which are then hydrogenated to form methylene groups, and these methylene groups polymerize to yield the reaction products. This mechanism can well explain the formation of hydrocarbons, but it cannot explain the formation of oxygenated compounds during the F-T synthesis process. (2) Polycondensation mechanism of oxygen-containing intermediates: This mechanism can explain the formation of oxygen-containing compounds during the F-T synthesis process. It suggests that an oxygen-containing intermediate, M=CHOH, is formed during this synthesis, and this intermediate further reacts to produce oxygen-containing organic products. Through this mechanism description, the formation process of oxygen-containing organic products can be understood more intuitively. (3) Carbon monoxide insertion mechanism: This mechanism suggests that the formation of C-C bonds is the result of chain growth achieved through the insertion of CO into metal-alkyl bonds. (4) CH2 insertion mechanism: The essence of this mechanism is chain growth through successive addition of C1 species, and its expressions are as follows: H2 + 2* = 2H*; CO + 2* = C* + O*; C* + H* = CH* + *; CH* + H* = CH2* + *; CH2* + H* = CH3* + *; CH3* + H* = CH4* + *; O* + H* = OH* + *; OH* + H* = H2O + 2*. Chain initiation: CH3* + CH2* = CH3–CH2* + *; Chain growth: CH3–CH2* + CH2* = CH3–CH2–CH2* + *; Chain termination: CH3–CH2–CH2* + * = CH3–CH=CH2 + H*; CH3–CH2–CH2* + H* = CH3–CH2–CH3 + 2*. This mechanism indicates that the initiators for chain initiation in the F-T synthesis process are species formed by the dissociation of H2 and CO on the catalyst followed by their combination. Chain growth proceeds through the gradual addition of CH2 monomers. Chain termination occurs when the chain growing on the catalyst undergoes desorption; 1-olefins are formed through β-H elimination desorption, while alkanes are formed through α-hydration. . Note $ # , $ $