The study of the adsorption of 1,3-diethers on the MgCl2 surface

The interaction of 1,3-diethers and MgCl2 support was studied. It was found 1,3-diethers interact with the surface of MgCl2 support more selectively than esters. 1,3-Diethers form several surface complexes of different strength. At that, a strength of all surface complexes of 1,3-diethers considerably exceeds a strength of surface complexes of ethyl benzoate. The strength of some surface complexes of 1,3-diethers is close to that of surface complexes of dibutyl phthalate, and dibutyl phthalate is able to substitute 1,3-diethers from these complexes. The least strong surface complexes of 1,3-diethers are labile and can also be removed from the MgCl2 surface without action of any electron donors. In contrast to the MgCl2 support, the catalyst contains only more strong and unremovable surface complexes of 1,3-diether. This testifies on the formation of certain faces of MgCl2 during catalyst preparation in the presence of 1,3-diether contrary to the formation of different MgCl2 faces at the preparation of the MgCl2 support.

1,3-Diethers are used as electron donor compounds in supported Ziegler–Natta catalysts. Upon the adsorption of 1,3-diethers on the surface of the MgCl2 support, 1,3-diethers occupy not all adsorption sites of the MgCl2 surface. Ester electron donor ethyl benzoate is able to adsorb on these unoccupied surface sites and allows one to see what surface sites are occupied by 1,3-diethers. The adsorption of 1,3-diethers on the MgCl2 support was studied by chemical analysis and IR spectroscopy of diffuse reflection (DRIFTS).Figure optionsDownload high-quality image (65 K)Download as PowerPoint slideDRIFT spectra of ethyl benzoate adsorbed on the MgCl2 support (in the absence (A) and in the presence (B) of 1,3-diether) demonstrating the effect of 1,3-diethers on the coverage of surface sites of MgCl2 surface.Highlights
► 1,3-Diethers interact with the MgCl2 more selectively than esters.
► 1,3-Diethers form several surface complexes of different strength.
► The least strong complexes of 1,3-diethers can be removed from the MgCl2 surface.
► The catalyst contains only more strong and unremovable complexes of 1,3-diether.
► Certain MgCl2 faces form at catalyst preparation in the presence of 1,3-diether.