Dynamics of selectivity of methanol conversion on zeolites,depending on time, temperature and spatial constraints

PETR 60

Hans Schulz, hans.schulz@ciw.uni-karlsruhe.de, Engler-Bunte Institute, University of Karlsruhe, Karlsruhe, Germany
Selectivity of methanol conversion on acidic zeolites refers to a multicompound product of volatile hydrocarbons and a hydrocarbon retainate on the catalyst. This composition is controlled by the pore architecture of the catalyst and it varies with temperature and particularly with time-on-stream and depends on the nature, location and amount of accumulating retainate - the retainate playing an important role as intermediate of the conversion and as deactivating material as well.

In this context the methanol conversion has been studied with HZSM5 and HY as catalysts in a low temperature (270 - 300 °C) and a high temperature (400 – 475 °C) range.

As of particular importance, the formation of methane as coproduct of ionic retainate dehydrogenation has been observed.

In dependence of the mentioned parameters, different regimes of the conversion have been noticed, as initiation, acceleration, retardation, reanimation and coking/deactivation and mechanistic implications are elucidated.

The attained insight is thought to be useful in commercial process development, for example in the methanol-to-olefin process.

Keywords: Methanol conversion, zeolites, methane formation, kinetic regimes.