PARTIAL OXIDATION OF ISOBUTENE TO METHACROLEIN ON BIW FECOMOK MIXED-OXIDE CATALYSTS/

The partial oxidation of isobutene to methacrolein and methacrylic aci d was studied on oxidic catalysts containing mainly a mixture of bismu th tungstate and iron cobalt potassium molybdate. The catalysts were p repared via different synthesis methods. The content of bismuth tungst ate and iron cobalt potassium molybdate was varied. Catalyst shaping w as done by extrusion. The kinetic measurements were performed by monit oring the gas-phase composition along the length of a fixed bed of cat alyst. The reactor was treated as an isothermal plug-flow system. The network of parallel and consecutive reactions taking place in this sys tem can be described by a simplified scheme. It is possible to predict the gas-phase composition prevailing in the reactor using five differ ent kinetic parameters. In the temperature range 380 degrees C < theta < 420 degrees C grain selectivities as high as 85% combined with yiel ds of methacrolein and methacrylic acid about 70% at 92% conversion we re obtained on catalysts prepared via a slurry synthesis method and co ntaining bismuth tungstate in the range between 20 and 70 wt%. Calcula tions based on the experimentally determined kinetic constants promise an increase in yield if the reactor containing catalysts of different composition is treated at non-uniform temperature. In the case of tem perature structuring alone an increase of the methacrolein and methacr ylic acid yield of about three points has been verified experimentally .