Methanol-to-olefin conversion over H-MCM-22 catalyst

• The H-MCM-22 catalysts with different Si/Al ratios for MTO reaction were studied.
• The Si/Al ratio influences the acidic properties and the catalytic performance.
• Most of the extraframework Al species in the H-MCM-22 can be selectively removed by ammonium hexafluorosilicate (AHFS).
• The dealuminated H-MCM-22 has higher selectivity of propylene and butylene and slow coke deposition.

H-MCM-22 zeolites with different Si/Al ratios were hydrothermally synthesized, also the parent sample was dealuminated by ammonium hexafluorosilicate (AHFS). Then all of the samples were characterized and evaluated for the methanol-to-olefin (MTO) conversion. The correlation of structural and acidic properties of H-MCM-22 with catalytic performance was investigated. The H-MCM-22 (Si/Al = 35.1) exhibits best catalytic stability in all the samples because of its suitable acid site amount and distribution. As for the H-MCM-22 (Si/Al = 35.1) after dealumination by AHFS, most of the extra-framework Al species were selectively removed, the selectivity of light olefin was enhanced further and the coke deposition seems to be inhibited.

The H-MCM-22 was dealuminated by ammonium hexafluorosilicate (AHFS), most of the extraframework Al species were selectively removed, the selectivity of propylene and butylene increased significantly and the coke deposition can be inhibited to some extent.Figure optionsDownload high-quality image (146 K)Download as PowerPoint slide