The adsorption of TiCl4 on the surfaces of MgCl2 crystals has been investigated by means of state-of-the-art periodic hybrid DFT methods, as the first step of a comprehensive study aiming to elucidate the structure of the active species in industrial MgCl2-supported Ziegler-Natta catalysts for ethene and propene polymerization. A first distinctive feature of the approach was the thorough evaluation of dispersion forces, crucial because the binding of TiCl4 on MgCl2 surfaces turned out to be essentially dispersion-driven. Also important was a careful investigation of the effects of different choices on basis set and density functional (DF) on the quantitative aspects of the results; this allowed us to trace the unusually large disagreement in the previous literature and identify unambiguous trends. In particular, three full sets of calculations were run adopting the B3LYP(-D), PBE0(-D) and M06 approximations: to the best of our knowledge, the last represents the first case of M06 functional implementation in a periodic code (CRYSTAL) of widespread use. The results consistently indicated that the adsorption of TiCl4 on well-formed MgCl2 crystals under conditions relevant for catalysis can only occur on MgCl2(1 1 0) or equivalent lateral faces, whereas the interaction with MgCl2(1 0 4) - for decades claimed as the most important surface in stereoselective catalysts - is too weak for the formation of stable adducts. The implications of these findings for catalysis are discussed. (C) 2011 Elsevier Inc. All rights reserved.

A periodic hybrid DFT approach (including dispersion) to MgCl2-supported Ziegler-Natta catalysts-1: TiCl4 adsorption on MgCl2 crystal surfaces / D'Amore, Maddalena; R., Credendino; Budzelaar, Petrus Henricus Maria; Causa', Mauro; Busico, Vincenzo. - In: JOURNAL OF CATALYSIS. - ISSN 0021-9517. - 286:(2012), pp. 103-110. [10.1016/j.jcat.2011.10.018]

A periodic hybrid DFT approach (including dispersion) to MgCl2-supported Ziegler-Natta catalysts-1: TiCl4 adsorption on MgCl2 crystal surfaces

D'AMORE, MADDALENA;BUDZELAAR, Petrus Henricus Maria;CAUSA', Mauro;BUSICO, VINCENZO
2012

Abstract

The adsorption of TiCl4 on the surfaces of MgCl2 crystals has been investigated by means of state-of-the-art periodic hybrid DFT methods, as the first step of a comprehensive study aiming to elucidate the structure of the active species in industrial MgCl2-supported Ziegler-Natta catalysts for ethene and propene polymerization. A first distinctive feature of the approach was the thorough evaluation of dispersion forces, crucial because the binding of TiCl4 on MgCl2 surfaces turned out to be essentially dispersion-driven. Also important was a careful investigation of the effects of different choices on basis set and density functional (DF) on the quantitative aspects of the results; this allowed us to trace the unusually large disagreement in the previous literature and identify unambiguous trends. In particular, three full sets of calculations were run adopting the B3LYP(-D), PBE0(-D) and M06 approximations: to the best of our knowledge, the last represents the first case of M06 functional implementation in a periodic code (CRYSTAL) of widespread use. The results consistently indicated that the adsorption of TiCl4 on well-formed MgCl2 crystals under conditions relevant for catalysis can only occur on MgCl2(1 1 0) or equivalent lateral faces, whereas the interaction with MgCl2(1 0 4) - for decades claimed as the most important surface in stereoselective catalysts - is too weak for the formation of stable adducts. The implications of these findings for catalysis are discussed. (C) 2011 Elsevier Inc. All rights reserved.
2012
A periodic hybrid DFT approach (including dispersion) to MgCl2-supported Ziegler-Natta catalysts-1: TiCl4 adsorption on MgCl2 crystal surfaces / D'Amore, Maddalena; R., Credendino; Budzelaar, Petrus Henricus Maria; Causa', Mauro; Busico, Vincenzo. - In: JOURNAL OF CATALYSIS. - ISSN 0021-9517. - 286:(2012), pp. 103-110. [10.1016/j.jcat.2011.10.018]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/483854
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 113
  • ???jsp.display-item.citation.isi??? 106
social impact