Confining Pore‐mouth: an Efficient Way to Increase the Selectivity to Ethylene in the MTO Reaction.

The chemical liquid deposition modification can decorate the pore aperture size by external surface deposition, which is a very efficient way to further improve the shape‐selective performance of zeolites. Here, SAPO‐34 zeolite was modified with silica by chemical liquid deposition, and then was applied in MTO reaction. It was found the Brønsted acid of SiO2‐modified SAPO‐34 zeolite increased, mainly due to the transformation from Al‐OH to Si‐OH‐Al, which can promote the selectivity to light olefins in MTO reaction. After the chemical liquid deposition, the silica located on the external surface of SAPO‐34 zeolite, reduces the apparent diffusion coefficient of propylene, which will restrain the formation and diffusion of propylene. So the selectivity to ethylene and the ratio of ethylene to propylene were significantly increased over the SiO2‐modified SAPO‐34 in the MTO reaction. Furthermore, the increase of the reactive sites can prolong the lifetime of catalyst effectively. [ABSTRACT FROM AUTHOR]