Patent ID: 8754277

Claim:
A process for preparing ethylene and/or propylene, comprising the steps of: a) providing a hydrocarbon stream, comprising C4+ normal olefins and C4+ iso-olefins; b) subjecting the hydrocarbon stream to an etherification process with methanol and/or ethanol wherein at least part of the iso-olefins are converted with methanol and/or ethanol to an tert-alkyl ether, and retrieving a first etherification product stream; c) separating at least part of the first etherification product stream into at least a first ether-enriched stream and an iso-olefin-depleted hydrocarbon stream; d) subjecting at least part of the iso-olefin-depleted hydrocarbon stream to an isomerisation process wherein at least part of the normal olefins are isomerised to iso-olefins in the presence of an isomerisation catalyst, and retrieving an iso-olefin-enriched hydrocarbon stream; e) subjecting at least part of the iso-olefin-enriched hydrocarbon stream to a further etherification process with methanol and/or ethanol wherein at least part of the iso-olefins are converted with methanol and/or ethanol to an tert-alkyl ether, and retrieving a further etherification product stream; f) separating at least part of the further etherification product stream into at least a further ether-enriched stream and an olefin-depleted hydrocarbon stream; g) converting at least part of the tert-alkyl ether in the first and/or further ether-enriched stream to ethylene and/or propylene by contacting at least part of the ether-enriched stream with a molecular sieve-comprising catalyst at a temperature in the range of from 350 to 1000° C. and retrieving an olefinic product comprising ethylene and/or propylene.