Revisiting the identity of δ-MgCl2: Part I. Structural disorder studied by synchrotron X-ray total scattering

Wada, Toru; Takasao, Gentoku; Piovano, Alessandro; D’Amore, Maddalena; Thakur, Ashutosh; Chammingkwan, Patchanee; Bruzzese, Paolo Cleto; Terano, Minoru; Civalleri, Bartolomeo; Bordiga, Silvia; Groppo, Elena; Taniike, Toshiaki

doi:10.1016/j.jcat.2020.03.002

Cited by 65 publications

(71 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…19MgCl 2 , which has a size of about 1.5 nm, was not far from the experimentally determined size of primary particles (ca. 2.4–4.0 nm) [3] , [4] , [5] , [6] . The number of TiCl 4 molecules ([Ti] < 10 wt%) referred to a typical Ti content of commercial Ziegler–Natta catalysts, which is 1–3 wt% for propylene polymerization and up to 10 wt% for ethylene polymerization [7] .…”

Section: Experimental Design Materials and Methodsmentioning

confidence: 99%

Dataset of energetically accessible structures of MgCl2/TiCl4 clusters for Ziegler-Natta catalysts

et al. 2021

Self Cite

View full text Add to dashboard Cite

This data article provides a dataset of the energetically accessible structures including the most stable structures of x MgCl 2 / y TiCl 4 nanoplates ( x = 6–19, y = 0–4). TiCl 4 -capped MgCl 2 nanoplates are regarded as the building block of the Ziegler–Natta catalyst. The most stable structures were determined for MgCl 2 /TiCl 4 nanoplates of different sizes and chemical compositions using a combination of the genetic algorithm and the DFT geometry optimization. The evolution in the genetic algorithm produced a number of meta-stable structures. A set of isomeric structures having similar energy to the most stable structure (termed energetically accessible structures) are provided as realistic models of MgCl 2 /TiCl 4 nanoplates. These structures are useful for further investigation on the structural distribution of Ti species on MgCl 2 regarding the Ziegler-Natta catalyst.

show abstract

Section: Experimental Design Materials and Methodsmentioning

confidence: 99%

Dataset of energetically accessible structures of MgCl2/TiCl4 clusters for Ziegler-Natta catalysts

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…The size of nanoclusters is about 3 nm 134 in diameter, comparable with the experimental size of the catalyst primary particles (ca. 135 2.4-4.0 nm) [42]; at the meantime the ratio between TiCl 4 molecules and MgCl 2 units 136 equal to 50/3 corresponds to 2.69 wt%, similar to Ti content in a typical Ziegler-Natta 137 catalyst. [59,60,66,67] The DFT [68,69] calculations reported in this paper were mainly 138 based on the B3LYP global hybrid functional, [70,71] as implemented in the CRYSTAL 139 program.…”

Section: Computational Models and Dft Calculations Detailsmentioning

confidence: 84%

Effect of Internal Donors on Raman and IR Spectroscopic Fingerprints of MgCl2/TiCl4 Nanoclusters Determined by Machine Learning and DFT

D’Amore¹,

Taniike²,

Terano³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Understanding the structure and properties of MgCl2/TiCl4/ID nanoclusters is a key to uncover the origin of Ziegler-Natta catalysis. In this work MgCl2/TiCl4 nanoplatelets derived by machine learning and DFT calculations have been used to model the interaction with ethyl-benzoate EB (as internal donor) with available exposed sites of binary TixCly/MgCl2 systems. The influence of vicinal Ti2Cl8 and coadsorbed TiCl4 on energetic, structural and spectroscopic behaviour of EB has been considered. The adsorption of homogeneous-like TiCl4EB and TiCl4(EB)2 at the various surface sites have been also simulated. Calculations have been carried out by employing B3LYP-D2 and M06 functionals. The adducts have been characterized by computing IR and Raman spectra that have been found to provide specific fingerprints useful to identify surface species; IR spectra have been successfully compared to available experimental data.

show abstract

“…The size of nanoclusters is about 3 nm in diameter, comparable with the experimental size of the catalyst primary particles (ca. 2.4-4.0 nm) [40]; at the meantime the ratio between TiCl 4 molecules and MgCl 2 units equal to 50/3 corresponds to 2.69 wt%, similar to Ti content in a typical Ziegler-Natta catalyst [57,58,64,65]. The DFT [66,67] calculations reported in this paper were mainly based on the B3LYP global hybrid functional [68,69], as implemented in the CRYSTAL program [70,71].…”

Section: Computational Models and Dft Calculations Detailsmentioning

confidence: 97%

“…The hypothesis supported by experimental investigation, mostly by TEM microscopy, encountered a lot of limits in characterization due to these nanosize and disordered features, heterogeneity of sites, dilution of the active centres, air sensitivity. Theoretical and computational chemistry provided crucial insights in δ-MgCl 2 , made feasible the modelling of each component and the analysis of different catalytic sites [39][40][41].…”

Section: Introductionmentioning

confidence: 99%

“…Thanks to Bravais' law it was possible to identify the most stable surfaces in terms of (surface) Gibbs Free Energy: (107), (012), (101), (015) and (110) ones [53]. The combination of a careful structural analysis of the supporting δ-MgCl 2 nanocrystals by synchrotron X-ray total scattering [40] with the definition of Wulff's polyhedron of MgCl 2 crystallites suggested that ball-milling of naked MgCl 2 produces a larger total surface area and modifies the relative extension of the surfaces, too. That would increase the stability of the lateral surfaces exposing strongly acidic tetracoordinated Mg 2+ sites (i.e., the (110), (012) and (015) ones) at the expenses of the basal (001) one.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Internal Donors on Raman and IR Spectroscopic Fingerprints of MgCl2/TiCl4 Nanoclusters Determined by Machine Learning and DFT

et al. 2022

Self Cite

View full text Add to dashboard Cite

To go deep into the origin of MgCl2 supported Ziegler-Natta catalysis we need to fully understand the structure and properties of precatalytic nanoclusters MgCl2/TiCl4 in presence of Lewis bases as internal donors (ID). In this work MgCl2/TiCl4 nanoplatelets derived by machine learning and DFT calculations have been used to model the interaction with ethyl-benzoate EB as ID, with available exposed sites of binary TixCly/MgCl2 systems. The influence of vicinal Ti2Cl8 and coadsorbed TiCl4 on energetic, structural and spectroscopic behaviour of EB has been considered. The adsorption of homogeneous-like TiCl4EB and TiCl4(EB)2 at the various surface sites have been also simulated. B3LYP-D2 and M06 functionals combined with TZVP quality basis set have been adopted for calculations. The adducts have been characterized by computing IR and Raman spectra that have been found to provide specific fingerprints useful to identify surface species; IR spectra have been successfully compared to available experimental data.

show abstract

Revisiting the identity of δ-MgCl2: Part I. Structural disorder studied by synchrotron X-ray total scattering

Cited by 65 publications

References 43 publications

Dataset of energetically accessible structures of MgCl2/TiCl4 clusters for Ziegler-Natta catalysts

Dataset of energetically accessible structures of MgCl2/TiCl4 clusters for Ziegler-Natta catalysts

Effect of Internal Donors on Raman and IR Spectroscopic Fingerprints of MgCl2/TiCl4 Nanoclusters Determined by Machine Learning and DFT

Effect of Internal Donors on Raman and IR Spectroscopic Fingerprints of MgCl2/TiCl4 Nanoclusters Determined by Machine Learning and DFT

Contact Info

Product

Resources

About