Lumped mechanism kinetics of Fischer-Tropsch synthesis over ultrafine particle Fe-Mn commercial catalyst(I) Reaction mechanism and kinetic model description
The objective of this paper is to establish a kinetic model description of CO conversion over the ultrafine particle Fe-Mn commercial catalyst in the Fischer-Tropsch process to provide the design basis for scaling up commercial reactor.Fischer-Tropsch process, including hundreds of reactions, was lumped into two kinds of reactions.One was Fischer-Tropsch reaction, in which the main product hydrocarbons were formed.The other was Water Gas Shift (WGS)reaction, in which the main by-product CO_2 was formed. Thus, the reaction rate of CO was approximately expressed as the sum of hydrocarbon formation rate and CO_2 formation rate.The description of the elementary step in the hydrocarbon formation was established based on the carbide mechanism.The rate-controlling step in the hydrocarbon formation model was the one controlling the formation of the structure unit CH*__2. Meanwhile, the description of the elementary step in Water Gas Shift reaction was found based on the formate mechanism,and the rate-controlling step in Water Gas Shift reaction model was the formation of formate species.The kinetic model description of the Fischer-Tropsch process, including both Fischer-Tropsch reaction and Water Gas Shift reaction, was acquired by the combination of the above two kinds of kinetic models.