PROCESS FOR THE PRODUCTION OF PROPYLENE AND ETHYLENE MIXTURES AND THE CATALYTIC SYSTEMS USED THEREIN

摘要

Process for the production of mixtures containing propylene and ethylene having an ethylene/propylene molar ratio <1, STARTING FROM C4­-C8 hydrocarbon mixtures, prevalently olefinic, which comprises putting said hydrocarbon mixtures in contact with a catalytic system, under cracking conditions, at a temperature ranging from 400°C and 600°C, at a weight hourly space velocity (WHSV) ranging from 0.1 h<-1> to 20 h<-1> and at a pressure ranging from 0.1 to 30 atm, characterized in that the catalytic system contains a first zeolite with a Constraint Index (C.I.) of between 1.5 and 2.5, in a quantity ranging from 20 to 80% w/w, and a second zeolite with a Constraint Index (C.I.) of between 6.9 and 11.0, in a quantity ranging from 20 to 80% w/w, the molar ratio Si02/Al203 of both said zeolites being higher than 50. Catalytic systems of ZSM-12/ZSM-5 and ZSM-12/ZSM-23 mixtures are described in particular.