Theoretical investigation of active sites at the corners of Mgcl 2 crystallites in supported ziegler-natta catalysts

Handle URI:
http://hdl.handle.net/10754/562181
Title:
Theoretical investigation of active sites at the corners of Mgcl 2 crystallites in supported ziegler-natta catalysts
Authors:
Correa, Andrea; Credendino, Raffaele; Pater, Jochem T M; Morini, Giampiero; Cavallo, Luigi ( 0000-0002-1398-338X )
Abstract:
We present a theoretical study on possible models of catalytic active species corresponding to Ti-chloride species adsorbed at the corners of MgCl 2 crystallites. First we focused our efforts on the interaction between prototypes of three industrially relevant Lewis bases used as internal donors (1,3-diethers, alkoxysilanes and succinates) and MgCl 2 units at the corner of a MgCl 2 crystallite. Our calculations show that the energetic cost to extract MgCl 2 units at the corner of (104) edged MgCl 2 crystallites is not prohibitive, and that Lewis bases added during catalyst preparation make this process easier. After removal of one MgCl 2 unit, a short (110) stretch joining the (104) edges is formed. Adsorption of TiCl 4 on the generated vacancy originates a Ti-active species. In the second part of this manuscript, we report on the stereo- and regioselective behavior of this model of active species in the absence as well as in the presence of the three Lewis bases indicated above. Surface reconstruction due to the additional adsorption of an extra MgCl 2 layer is also considered. We show that, according to experimental data, Lewis bases coordinated in the proximity of the active Ti center confer a remarkable stereoselectivity. Moreover, surface reconstruction as well as donor coordination would improve regioselectivity by disfavoring secondary propene insertion. While still models of possible active species, our results indicate that defects, corners and surface reconstruction should be considered as possible anchoring sites for the catalytically active Ti-species. © 2012 American Chemical Society.
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division; KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division; Chemical Science Program
Publisher:
American Chemical Society
Journal:
Macromolecules
Issue Date:
8-May-2012
DOI:
10.1021/ma3001862
Type:
Article
ISSN:
00249297
Sponsors:
L.C. thanks LyondellBasell for continuous financial support. This work is part of the Research Programme of the Dutch Polymer Institute, Eindhoven, The Netherlands, Project No. 707 SD-ZN. L.C. thanks the HPC team of Enea for using the ENEA-GRID and the HPC facilities CRESCO in Portici (Italy) and for access to remarkable computational resources.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC); Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorCorrea, Andreaen
dc.contributor.authorCredendino, Raffaeleen
dc.contributor.authorPater, Jochem T Men
dc.contributor.authorMorini, Giampieroen
dc.contributor.authorCavallo, Luigien
dc.date.accessioned2015-08-03T09:46:40Zen
dc.date.available2015-08-03T09:46:40Zen
dc.date.issued2012-05-08en
dc.identifier.issn00249297en
dc.identifier.doi10.1021/ma3001862en
dc.identifier.urihttp://hdl.handle.net/10754/562181en
dc.description.abstractWe present a theoretical study on possible models of catalytic active species corresponding to Ti-chloride species adsorbed at the corners of MgCl 2 crystallites. First we focused our efforts on the interaction between prototypes of three industrially relevant Lewis bases used as internal donors (1,3-diethers, alkoxysilanes and succinates) and MgCl 2 units at the corner of a MgCl 2 crystallite. Our calculations show that the energetic cost to extract MgCl 2 units at the corner of (104) edged MgCl 2 crystallites is not prohibitive, and that Lewis bases added during catalyst preparation make this process easier. After removal of one MgCl 2 unit, a short (110) stretch joining the (104) edges is formed. Adsorption of TiCl 4 on the generated vacancy originates a Ti-active species. In the second part of this manuscript, we report on the stereo- and regioselective behavior of this model of active species in the absence as well as in the presence of the three Lewis bases indicated above. Surface reconstruction due to the additional adsorption of an extra MgCl 2 layer is also considered. We show that, according to experimental data, Lewis bases coordinated in the proximity of the active Ti center confer a remarkable stereoselectivity. Moreover, surface reconstruction as well as donor coordination would improve regioselectivity by disfavoring secondary propene insertion. While still models of possible active species, our results indicate that defects, corners and surface reconstruction should be considered as possible anchoring sites for the catalytically active Ti-species. © 2012 American Chemical Society.en
dc.description.sponsorshipL.C. thanks LyondellBasell for continuous financial support. This work is part of the Research Programme of the Dutch Polymer Institute, Eindhoven, The Netherlands, Project No. 707 SD-ZN. L.C. thanks the HPC team of Enea for using the ENEA-GRID and the HPC facilities CRESCO in Portici (Italy) and for access to remarkable computational resources.en
dc.publisherAmerican Chemical Societyen
dc.titleTheoretical investigation of active sites at the corners of Mgcl 2 crystallites in supported ziegler-natta catalystsen
dc.typeArticleen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.identifier.journalMacromoleculesen
dc.contributor.institutionDipartimento di Chimica e Biologia, Università di Salerno, Via Ponte don Melillo, I-84084 Fisciano (SA), Italyen
dc.contributor.institutionDutch Polymer Institute, Eindhoven, Netherlandsen
dc.contributor.institutionCentro Ricerche Giulio Natta, Basell Poliolefine It. SrL (A LyondellBasell Company), Piazzale Guido Donegani 12, Ferrara, I-44100, Italyen
kaust.authorCredendino, Raffaeleen
kaust.authorCavallo, Luigien
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