Surface Investigation and Morphological Analysis of Structurally Disordered MgCl2 and MgCl2/TiCl4 Ziegler Natta Catalysts
Activated MgCl2 nanocrystals were prepared by controlled dealcoholation of the MgCl2*6CH3OH adduct, mimicking the routinely adopted methods to synthesize industrial heterogeneous Ziegler Natta catalysts. The effect of the alcohol in driving the morphology of MgCl2 crystals, i.e. the type and extension of the exposed surfaces, was investigated by integrating a detailed structural, morphological, and surface characterization with a state of the art computational modeling. FT IR spectroscopy of CO adsorbed at 100 K emerged as a feasible, simple, and powerful method to characterize the surface of structurally disordered MgCl2 and MgCl2 based Ziegler Natta catalysts. Our computational morphological analysis revealed that the (012) (015) and (110) surfaces are highly stabilized by methanol as an electron donor, especially at the temperature typically adopted in the preparation of the precatalysts. FT IR spectroscopy of adsorbed CO allows distinguishing these surfaces from the other penta coordinated ones and.