Kinetic Modeling of Catalyst Deactivation in Conversion of Methanol to Olefins

The deactivation of the catalyst in conversion of methanol to olefins over zeotype catalysts was studied. A two-step autocatalytic reaction network was considered for methanol conversion reactions. A rate expression, first order in methanol feed concentration and activity, which is an approximation of concentration-dependent deactivation kinetic, was used for modeling reversible catalyst decay, that is, deactivation by coke formation. A correlation was obtained between methanol conversion and time on stream. Methanol conversions showed the reverse s-shaped form with time which is observed in practice. A correlation was developed for catalyst lifetime as a function of Damkohler number and dimensionless rate constants ratios. It was found that for a given catalyst the lifetime is strongly affected by methanol concentration in the feed with a weak dependence on space velocity of the feed. The catalyst lifetime is roughly inversely proportional to methanol concentration in the feed which is consistent with the literature experimental data.

کلیدواژه ها:

Methanol to Olefins ، Kinetic Modeling ، Zeolite ، Deactivation ، Catalyst lifetime