This paper deals with a phenomenological model for methanol conversion to olefins. A system of linear independent reactions is built from the global reaction of methanol transformation. The mechanism of reaction, a development based on carbenoid intermediates of the above set of chemical reactions, has 27 reactions and 18 molecular species. The kinetic parameters identified using nonlinear optimization techniques, and the model predictions, agree satisfactorily with experimental data and data available in the literature.

The process of methanol conversion to dimethyl ether over an H-SAPO-34 molecular sieve was studied, using the catalyst as synthesized or formulated in an alumina matrix. The experiments were performed on the temperature interval 100−250 °C, liquid space velocities of 1−5 h−1, and pressures between 1 and 10 bar. The results evidenced a high catalytic activity of the H-SAPO-34 molecular sieve, providing in these conditions a practically total methanol transformation to dimethyl ether. Also, a special run, performed at 180 °C, with an output composition close to chemical equilibrium, showed no significant change of catalyst activity during an on-stream time of 50 h, this proving a good stability and resistance to deactivation. A published rate expression for the methanol dehydration reaction was selected and adapted to describe the experimentally observed process kinetics.

The purpose of this paper is to illustrate the possibility of using stochastic and fuzzy methods to obtain reduced kinetic models of methanol conversion to olefins. Simulations of the reaction system by Markov chains coupled with the calculus of the informational entropy of the lumped chain are presented. A rough description of the kinetics may be supplied by fuzzy relationships. The fuzzy approach could also engage practical experience in solving the problem. A fuzzy entropy, considered as the measure of loss of information by lumping, was introduced.

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