Article
Chemistry, Multidisciplinary
Lujain Alrais, Walid Al Maksoud, Baraa Werghi, Anissa Bendjeriou-Sedjerari, Edy Abou-Hamad, Mohamed N. Hedhili, Jean-Marie Basset
Summary: The synthesis of heterogeneous Ti(iv)-based catalysts for ethylene polymerization according to the concepts of surface organometallic chemistry is described. These catalysts utilize a unique silica support with a 3D fibrous morphology and an aluminum-bound hydroxyl group. The combination of morphological and electronic properties of the support leads to enhanced catalytic performance in ethylene polymerization, resulting in the formation of high-density polyethylene.
CHEMICAL COMMUNICATIONS
(2023)
Article
Polymer Science
Farshid Nouri-Ahangarani, Naeimeh Bahri-Laleh, Hossein Abedini, Mehdi Nekoomanesh
Summary: In this study, the relationship between the structure and performance of MgCl2 based Ziegler Natta catalysts in ethylene polymerizations was investigated. Different adduct precursors were prepared using the melt quenching method with various reaction conditions. The heating rate and N-2 flow during thermal dealcoholation had the most significant effect on the porosity and particle size of the adducts. The results showed that the alcohol content in the final adduct had a significant impact on the H-2 response and molar mass distribution of the catalysts, providing valuable insights for polyethylene producers in optimizing reaction conditions for different polymer grades.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Engineering, Chemical
Guodong Su, Shuwei Wang, Jiangang Yu
Summary: A modified tetra-needle like ZnO whiskers filler is synthesized through a coagglomeration method, and it exhibits good activity towards ethylene polymerization, leading to enhanced thermal stability and mechanical properties of polyethylene.
POLYMER ENGINEERING AND SCIENCE
(2022)
Article
Polymer Science
Mohammed S. Alsuhybani, Eid M. Alosime
Summary: The study aimed to evaluate the polymerization of ethylene using titanium Ti(IV) alkyloxy compounds supported by PVC with TEA as a cocatalyst. The optimal [Al]/[Ti] molar ratio was found to be 773:1, and the copolymer produced had a molecular weight ranging from 97 kg/mol to 326 kg/mol. The addition of comonomers like 1-hexene led to significant decrease in molecular weight and broadening of PDI.
Article
Chemistry, Multidisciplinary
Arash Shams, Mohammadreza Mehdizadeh, HamidReza Teimoury, Mehrsa Emami, Seyed Amin Mirmohammadi, Samahe Sadjadi, Eduard Bardaji, Albert Poater, Naeimeh Bahri-Laleh
Summary: The study on the pore architecture of Ziegler-Natta (ZN) catalysts in propylene polymerizations reveals its significant impact on catalyst activity, H2- and comonomer-response, and final polymer properties. The catalyst with larger pore diameter, Cat-A, shows slightly higher activities in homopolymerization and copolymerization experiments, resulting in copolymers with lower isotactic sequence length and lamellar thickness.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2022)
Article
Chemistry, Applied
Reza Bazvand, Naeimeh Bahri-Laleh, Hossein Abedini, Mehdi Nekoomanesh, Albert Poater
Summary: The chemical dealcoholation of MgCl2nEtOH adducts has a significant impact on the industrial production of polyethylenes. This study investigates the use of aluminum-based compounds in the dealcoholation process and their effects on the microstructure of catalysts and properties of polymers. The results show that the choice of Lewis acid compound during dealcoholation can lead to different Ziegler-Natta catalysts for different polyethylene grades, affecting the polymerization kinetics and flow characteristic of the final polymers.
APPLIED ORGANOMETALLIC CHEMISTRY
(2023)
Article
Polymer Science
Mohammadreza Mehdizadeh, Fereshteh Karkhaneh, Mehdi Nekoomanesh, Samahe Sadjadi, Mehrsa Emami, HamidReza Teimoury, Mehrdad Salimi, Miquel Sola, Albert Poater, Naeimeh Bahri-Laleh, Sergio Posada-Perez
Summary: The influence of ethanol content in adducts on the catalytic behavior of Ziegler-Natta catalysts in propylene homo- and copolymerizations was investigated. The results showed that higher ethanol content in the adducts led to increased catalyst activity, particularly in homopolymerization reactions in the absence of H2. Additionally, the catalyst with the highest ethanol content produced a copolymer with lower isotacticity index and more uniform distribution of comonomer. These findings highlight the importance of controlling ethanol content in catalyst/support during the preparation process. Molecular simulation was also utilized to explain the iso-specificity of the polypropylene produced by the synthesized catalysts.
Article
Chemistry, Physical
Adriano G. Fisch
Summary: The development of catalysts for the production of polyethylene and polypropylene involves a trial-and-error experimentation approach. Support porosity plays a crucial role in determining the mechanical support resistance and fragmentation process during early moments of polymerization. This article presents a methodology to optimize support porosity using a fundamental model of the fragmentation process, enabling the design of fragmentation-oriented supports for polymerization reactors.
Article
Polymer Science
Tatiana B. Mikenas, Vladimir A. Zakharov, Mikhail A. Matsko
Summary: This paper presents experimental data on the formation of polyethylene particles with different molecular weights and morphologies using two samples of highly active supported titanium-magnesium catalysts. The effect of catalyst structural characteristics and titanium content on the molecular weight of the resulting polymers is discussed based on kinetic data and morphological analysis.
IRANIAN POLYMER JOURNAL
(2022)
Article
Materials Science, Multidisciplinary
Xiuming Liu, Yawei Qin, Songmei Zhao, Jin-Yong Dong
Summary: This paper introduced a in situ method for incorporating LCB structure into PE synthesized by Ziegler-Natta catalysts. By controlling the concentration of the bifunctional reagent during copolymerization, gel-free LCB-PEs with controlled amounts of LCB structure were successfully synthesized, showing improved extensional flow properties. Moreover, LCB-PEs demonstrated increased crystallization rates and crystallinities when compared to linear plain PE.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Chemistry, Physical
Reza Bazvand, Naeimeh Bahri-Laleh, Hossein Abedini, Mehdi Nekoomanesh, Albert Poater
Summary: The activation of MgCl2 through the formation of MgCl2 & nEtOH adducts is crucial in the preparation of high performance Ziegler-Natta catalysts for olefins polymerizations in industry. However, the precise structural characterization of these compounds has been neglected due to their complex microstructure. In this study, four MgCl2.nEtOH adducts with different ethanol content were prepared and thoroughly evaluated. Despite the similarities in FTIR spectra, the SEM images showed that the adducts with n = 3.2 had a sticky nature, leading to increased particle size and broader SPAN. XRD spectra confirmed the presence of distinct peaks related to the distorted MgCl2 structure, and the ratio of α-MgCl2 to β-MgCl2 increased with higher ethanol content, which was further supported by DFT calculations. However, it should be noted that this study only provides a simplified characterization of the adducts.
JOURNAL OF MOLECULAR STRUCTURE
(2023)
Article
Multidisciplinary Sciences
Thomas Dietel, Fabian Lukas, Winfried P. Kretschmer, Rhett Kempe
Summary: Alpha-olefins are crucial for the production of plastics, pharmaceuticals, and chemicals. However, the selective synthesis of alpha-olefins from ethylene is limited. This study presents a catalytic reaction that combines an alpha-olefin with two ethylene molecules using a highly active and stable molecular titanium catalyst.
Article
Chemistry, Physical
Mohammad Hossein Jandaghian, Yasaman Maddah, Abdolhannan Sepahi, Reza Rashedi, Ehsan Nikzinat, Maryam Masoori
Summary: This study investigated the effects of milling and heat-treatment of Mg(OEt)2 as precursors in the synthesis of supported Ziegler-Natta catalysts. The support treatment did not affect elemental analysis results, but significantly influenced the morphology of catalyst pores. Catalysts made using different treated supports showed differences in activity, particle size, and distribution.
Article
Engineering, Chemical
Daniel Christian Pernusch, Gunnar Spiegel, Christian Paulik, Wolfgang Hofer
Summary: Chemically recycled monomer feed streams from postconsumer plastic packaging waste may contain impurities that act as catalyst poisons, impacting the activity levels of a commercial Ziegler-Natta catalyst system and influencing the molecular weight distribution and composition of the resulting polymer products. Purifying the chemically recycled monomer feed streams is crucial for ensuring the quality of polymer products.
MACROMOLECULAR REACTION ENGINEERING
(2022)
Article
Polymer Science
Majid Zeynali, Heidar Ranjbarbaranlo, Ali Olad
Summary: A titanium/vanadium (Ti/V) Ziegler-Natta hybrid catalyst was synthesized by loading TiCl4 and VOCl3 on MgCl2 support. The effects of vanadium content and different types of alkyl aluminums as cocatalyst on the efficiency of the hybrid catalyst were investigated. The results showed that the hybrid catalyst with both TEA and TnOA cocatalysts exhibited good activity and productivity, and the produced polyethylene had desirable characteristics.
JOURNAL OF POLYMER RESEARCH
(2023)
