STRUCTURE, COMPOSITION, AND MECHANISM OF ACTION OF HETEROGENEOUS ZIEGLER-NATTA CATALYSTS IN PROPYLENE POLYMERIZATION (REVIEW)
Rubrics: 1. CHEMISTRY
Authors:
1.
Kazan National Research Technological University
2.
Samara State Technical University
3.
Kazanskiy nacional'nyy issledovatel'skiy tehnologicheskiy universitet
4.
KNITU
Type:
Article
Pages:
from 5
to 15
Status:
Published
Received:
17.02.2026
Accepted:
13.03.2026
Published:
05.04.2026
Language:
Russian
Keywords:
POLYPROPYLENE, HETEROGENEOUS ZIEGLER-NATTA CATALYSTS, ACTIVE SITES, POLYMERIZATION MECHANISM, STEREOSPECIFICITY
Abstract:
This review article is devoted to the systematization of current concepts related to the structure, composition, and mechanism of action of heterogeneous Ziegler-Natta catalysts applied in propylene polymerization processes. The objective of the review is to summarize and analyze literature data concerning the relationship between the structure of multicomponent catalytic systems and the formation of active sites that determine the activity and stereospecificity of the process. The structural features of polypropylene and their relationship with the conditions of coordination- anionic propylene polymerization are consistently considered. Particular attention is paid to catalytic systems of the titanium tetrachloride, triethylaluminum, internal (ID) and external (ED) electron donors electron donors supported on magnesium chloride (TiCl₄/ID/MgCl₂ + AlR₃/ED) type. The functions of the support, the chemical nature of titanium precursors, and the role of organoaluminum cocatalysts at the stages of catalyst activation and chain growth are discussed. Data on the crystallographic modifications of MgCl₂, the types of surface facets and defects, as well as their influence on the adsorption and stabilization of titanium species, are systematized. Contemporary models describing the interaction of TiCl₄ with the MgCl₂ surface are analyzed, and controversial issues related to the formation and distribution of stereospecific active sites are discussed. A separate section is devoted to the role of Lewis bases as a structural element of the catalytic system, their coordination modes on the MgCl₂ surface, and their influence on active site formation. A distinguishing feature of this review is its focus on the fundamental aspects of the structure and functioning of heterogeneous Ziegler-Natta catalysts without considering specific factors governing polypropylene property control, such as the influence of external electron donors. In contrast to most existing reviews, which are primarily oriented toward polymerization kinetics and catalyst modification, the present work provides a systematization based on the structural organization of the catalyst and the mechanisms of active site formation.
This review article is devoted to the systematization of current concepts related to the structure, composition, and mechanism of action of heterogeneous Ziegler-Natta catalysts applied in propylene polymerization processes. The objective of the review is to summarize and analyze literature data concerning the relationship between the structure of multicomponent catalytic systems and the formation of active sites that determine the activity and stereospecificity of the process. The structural features of polypropylene and their relationship with the conditions of coordination- anionic propylene polymerization are consistently considered. Particular attention is paid to catalytic systems of the titanium tetrachloride, triethylaluminum, internal (ID) and external (ED) electron donors electron donors supported on magnesium chloride (TiCl₄/ID/MgCl₂ + AlR₃/ED) type. The functions of the support, the chemical nature of titanium precursors, and the role of organoaluminum cocatalysts at the stages of catalyst activation and chain growth are discussed. Data on the crystallographic modifications of MgCl₂, the types of surface facets and defects, as well as their influence on the adsorption and stabilization of titanium species, are systematized. Contemporary models describing the interaction of TiCl₄ with the MgCl₂ surface are analyzed, and controversial issues related to the formation and distribution of stereospecific active sites are discussed. A separate section is devoted to the role of Lewis bases as a structural element of the catalytic system, their coordination modes on the MgCl₂ surface, and their influence on active site formation. A distinguishing feature of this review is its focus on the fundamental aspects of the structure and functioning of heterogeneous Ziegler-Natta catalysts without considering specific factors governing polypropylene property control, such as the influence of external electron donors. In contrast to most existing reviews, which are primarily oriented toward polymerization kinetics and catalyst modification, the present work provides a systematization based on the structural organization of the catalyst and the mechanisms of active site formation.
Keywords:
POLYPROPYLENE, HETEROGENEOUS ZIEGLER-NATTA CATALYSTS, ACTIVE SITES, POLYMERIZATION MECHANISM, STEREOSPECIFICITY
POLYPROPYLENE, HETEROGENEOUS ZIEGLER-NATTA CATALYSTS, ACTIVE SITES, POLYMERIZATION MECHANISM, STEREOSPECIFICITY
