Olefine Production from Methanol over ZrO₂/Al₂O₃(SO₄)^2- Catalyst

Abstract

A catalyst of ZrO₂/Al₂O₃ supported ammonium sulfate was found to be effective for the reaction of methanol to olefines (MTO). The catalyst formed 25% of ethylene, 18% of propylene, 9% of isobutane as well as 11% of oily products which were analyzed by NMR and GC-MS techniques to be mainly a mixture of polyalkylbenzenes.
Formation of ethylene and propylene started at 280°C, isobutane was formed at 300°C and the oily producte were formed at 320°C. This fact indicates that propylene is formed by homologation of ethylene, isobutane by decomposition of the surface species on the catalyst and alkylbenzenes by cyclization of the olefines.
Concerning the intermediate, it has been proposed that an acid site makes carbenium ion a key intermediate for the MTO, and our results seem to follow the intermediate. However, even Al₂O₃ supported aluminium sulfate (H⁰=1.5) produced a small amount of olefins, We therefore, postulated that a pair of active sites such as the protonic sites for the methyl cation formation and the other sites for the dehydrogenation of methyl groups bifunctionally proceeds the MTO.