Kinetic particularities of strained alicyclic compounds formation in catalytic methanol to hydrocarbon transformation process
Authors: Doluda, V., Brovko, R., Giniatullina, N.,& Sulman, M.
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The catalytic transformation of methanol into hydrocarbons is a complex chemical process, accompanied by chain parallel chemical transformation reactions. The most valuable products of the methanol to hydrocarbons catalytic transformation reaction are the strained hydrocarbons — cyclopropane derivatives. These compounds can be used as a high-energy fuel, and also as a valuable chemical raw material. However, the yield of strained compounds in methanol to hydrocarbons catalytic transformation reaction is extremely low. One of the possible methods for increasing the yield of target products is the development of the kinetic model of the reaction and its analysis. The kinetic models most often used to describe the process of catalytic transformation of methanol into hydrocarbons are analyzed in the paper. The analysis of the reaction mixture made it possible to determine the main strained hydrocarbons formed during the reaction, among which are 1,1-dimethylcyclopropane, 1,2-dimethylcyclopropane, 1,1,2-trimethylcyclopropane, 1,2,3-trimethylcyclopropane, 1,1, 2,2-tetramethylcyclopropane, 1,1,2,3-tetramethylcyclopropane. Based on the list of products, a reaction scheme was proposed for chemical transformations occurring during the synthesis of strained hydrocarbons. At the first stage, cyclopropane derivatives are formed during the reaction of propene with carbene, followed by the formation of di, tri and tetramethyl derivatives of cyclopropane. On the basis of the reaction scheme, a kinetic model of the process is proposed in the form of a system of differential equations. The solution of the differential equations from the experimentally obtained data was carried out in the Matlab system by the Levenberg–Marquard method. The obtained values of reaction rate constants allow determining the limiting stages of the methanol transformation process with the formation of strained hydrocarbons. The calculated values of the Fisher’s adequacy criterion indicate the applicability of the obtained model results. The obtained values of the chemical reactions constants can be used to optimize the process of synthesis of strained hydrocarbons.