Process for preparing lower olefins

A process for preparing lower olefins, the process comprising the following steps:

• a) steam cracking a paraffinic feedstock under cracking conditions in a cracking zone to obtain a cracker effluent comprising olefins and C4 hydrocarbons including saturated and unsaturated C4 hydrocarbons;
• b) contacting an oxygenate feedstock with a molecular sieve-comprising catalyst, at a temperature in the range of from 350 to 1000° C. to obtain an oxygenate conversion effluent comprising olefins and C4 hydrocarbons including saturated and unsaturated C4 hydrocarbons;
• c) subjecting the cracker effluent and the oxygenate conversion effluent to one or more separation steps such that at least an olefin product stream comprising ethylene and/or propylene, and a stream comprising C4 hydrocarbons including saturated and unsaturated C4 hydrocarbons from both the cracker effluent and the oxygenate conversion effluent, are obtained;
• and
• d) subjecting at least part of the stream comprising C4 hydrocarbons from both the cracker effluent and the oxygenate conversion effluent to extractive distillation to obtain a stream enriched in unsaturated C4 hydrocarbons and a stream enriched in saturated C4 hydrocarbons.