FTIR spectroscopic study of supported titanium-magnesium catalysts for propylene polymerization containing diether and succinate as internal donors

The data on the interaction of internal stereoregulating donors (IDs) diethyl 2,4-diisobutyl succinate (DIBS), 2isopropyl-2-isopentyl-1,3-dimethoxypropane (IPIPDMP) and a mixture of these IDs with the delta-MgCl2 support, and the data on the transformations occurring upon interaction between surface structures of these donors and TiCl4 in model MgCl2/ID/TiCl4 samples were obtained by the chemical analysis and IR spectroscopy. It was found that DIBS interacts with penta- and tetracoordinated Mg ions yielding three types of surface species, while IPIPDMP forms surface species with tetracoordinated Mg ions. In the mixed-donor sample MgCl2/ (DIBS+IPIPDMP) donors IPIPDMP and DIBS are anchored to different sites of the MgCl2 surface and do not compete with each other. The interaction of the MgCl2/DIBS sample with TiCl4 leads to the replacing of one third of DIBS anchored to tetracoordinated magnesium ions by TiCl4, while two thirds of TiCl4 are anchored to the vacant sites on MgCl2. In the case of MgCl2/IPIPDMP, TiCl4 is mostly anchored to the vacant sites of MgCl2. Treatment of the mixed-donor MgCl2/(DIBS+IPIPDMP) sample with TiCl4 results in partial removal of DIBS and IPIPDMP and TiCl4 fixation at both vacant and freed surface sites. The data obtained for real highly-active titanium-magnesium catalysts for propylene polymerization containing IPIPDMP, DIBS, and the DIBS+IPIPDMP mixture donors are close to those for the respective MgCl2/ID/TiCl4 model samples. The key difference is that the contents of ID and TiCl4 increase abruptly and the ID/TiCl4 molar ratio changes in real TMCs.