| abstract |
The present invention relates to a process to make light olefins, in a XTO process, from an oxygen-containing, halogenide-containing or sulphur-containing organic feedstock comprising : a) providing a catalyst comprising zeolitic molecular sieves containing at least 10 membered ring pore openings or larger in their microporous structure, b) providing an XTO reaction zone, c) contacting said oxygen-containing, halogenide-containing or sulphur-containing organic feedstock in the XTO reactor with the catalyst at conditions effective to convert at least a portion of the feedstock to form a XTO reactor effluent comprising light olefins and a heavy hydrocarbon fraction; d) separating said light olefins from said heavy hydrocarbon fraction; e) fractionating said heavy hydrocarbon fraction to remove the essential part of the aromatics and recovering a heavy hydrocarbon fraction having a reduced aromatics content; f) recycling at least a part of said heavy hydrocarbon fraction having a reduced aromatics content at the inlet of the XTO reaction zone; wherein, to adjust the proportion of C4+ paraffins recycled at the inlet of the XTO reaction zone, a fraction of the stream recycled at step f) is purged. |