Simulation & Modeling
Yogeshwar N Thakare; Ajay V Kothari; Saurabh Shinde; Pooja Kadam; Natarajan Venkateswaran; Virendrakumar Gupta
Abstract
MgCl2 supported Ti catalyst is used in commercial propylene polymerization process. Morphology is a key performance determination parameter for polymer resins produced by commercial olefin polymerization process. Higher resin flowability and bulk density (greater than 0.38g/cc) are demonstrated by ‘good’ ...
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MgCl2 supported Ti catalyst is used in commercial propylene polymerization process. Morphology is a key performance determination parameter for polymer resins produced by commercial olefin polymerization process. Higher resin flowability and bulk density (greater than 0.38g/cc) are demonstrated by ‘good’ morphological resins (sphericity close to ‘1’). Polymer resin morphology is controlled by morphology of the catalyst used as well as polymerization conditions. The industrially accepted approaches to control polymer resin morphology are by controlling catalyst morphology through various approaches like pre-polymerization of the catalysts. Morphology of the catalyst is dependent on precursor (support) morphology and process parameters for making the catalyst. In this work, we have developed magnesium alkoxide precursor, a Ziegler-Natta catalyst using the precursor and studied its performance in gas phase propylene polymerization process. Further, morphology of different precursor and catalyst samples is evaluated and correlated it using a “computer vision” based approach. The approach involves modeling the circularity (as an analog of sphericity) of a catalyst and precursor particle. It is observed that the circularity of catalyst particles is lower than that of precursor, due to attrition in the process. It is also reflected in increase in particle size distribution span from 0.83 to 1.32 while synthesis of catalyst from precursor. This approach provides a tool to evaluate and screen the catalysts for using in polymerization.
Olefin polymerization and copolymerization
Tingting Yang; Ao Li; Yawei Qin; Jin-Yong Dong
Abstract
Polypropylene is one of the most widely used synthetic resins, which is mainly synthesized with Ziegler-Natta catalysts. In this paper, the functionalized Ziegler-Natta catalyst is applied to prepare high-performance polypropylene. A new way to synthesize functionalized Ziegler-Natta catalysts is to ...
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Polypropylene is one of the most widely used synthetic resins, which is mainly synthesized with Ziegler-Natta catalysts. In this paper, the functionalized Ziegler-Natta catalyst is applied to prepare high-performance polypropylene. A new way to synthesize functionalized Ziegler-Natta catalysts is to dope with inorganic nanoparticles. The MgCl2/TiCl4/BMMF catalysts doped with halloysite nanotubes were prepared and applied to synthesize polypropylene containing less than 200ppm halloysite nanotubes. It is found that doping nanotubes in Ziegler-Natta catalyst has little impact on the structure, composition and activity of the catalyst, and polypropylene with high isotactic degree and molecular weight was synthesized with the functionalized Ziegler-Natta catalyst. Halloysite nanotubes are found to be dispersed in polypropylene in the form of individual nanotube, forming percolated network in the polymer melt effectively. Moreover, the polypropylene containing halloysite nanotubes exhibited better mechanical and thermal resistance properties as compared with conventional polypropylene, and the thermo-oxidative properties of which do not deteriorate as the introduction of nanotubes. This research provides a facile way to relieve the contradiction between the high activity of catalyst and high content of nanoparticles during the preparation of polyolefin nanocomposites by in-situ polymerization, and a new idea to prepare polyolefin nanocomposites by in-situ polymerization.
Olefin polymerization and copolymerization
Mohammad Reza Jozaghkar; Farshid Ziaee
Abstract
Innovative strides in polymer synthesis have led to the successful living anionic polymerization of styrene-olefin triblock copolymers, yielding varying molecular weights and a remarkably narrow dispersity (Đ) in cyclohexane solvent at 45°C, initiated by n-butyllithium. The novel approach employs ...
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Innovative strides in polymer synthesis have led to the successful living anionic polymerization of styrene-olefin triblock copolymers, yielding varying molecular weights and a remarkably narrow dispersity (Đ) in cyclohexane solvent at 45°C, initiated by n-butyllithium. The novel approach employs anionic polymerization, augmented by the aid of a coupling agent known as 1,12-dibromododecane. Unlike traditional alcohol-based methods employed in polystyrene synthesis, this coupling agent, introduced at the end of the reaction, grafts two living macro-styrene chains with the dodecane chain, effectively acting as the pivotal second component in the formation of the triblock copolymer. Extensive experimentation pinpointed 45°C as the optimal temperature for anionic copolymerization in cyclohexane solvent. The comprehensive analysis, encompassing 13C NMR, 1H NMR, FTIR spectroscopy, and GPC, confirms the successful synthesis of styrene-dodecane-styrene triblock copolymer. The NMR results illustrate successful molecular structures, while GPC attests to the precision, showing a narrow Đ of below 1.2. This pioneering approach not only underscores the efficiency of anionic polymerization in the synthesis of styrene-olefin-styrene triblock copolymer using termination strategy but also promises extensive implications in material science and industrial applications.
Olefin synthesis
Sajjad Bahrami Reyhan; Seyed Mahdi Alavi; Davood Soudbar
Abstract
Ethylene dimerization is a significant process among the other petrochemical processes due to the production of alpha olefins as the most widely used industrial intermediate. Titanium tetra butoxide/tetrahydrofuran/triethyl aluminum is the main homogeneous catalyst complex in this process. On the other ...
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Ethylene dimerization is a significant process among the other petrochemical processes due to the production of alpha olefins as the most widely used industrial intermediate. Titanium tetra butoxide/tetrahydrofuran/triethyl aluminum is the main homogeneous catalyst complex in this process. On the other hand, the formation of polymer or oligomerization side reactions are the salient obstacles in the ethylene dimerization process. The effect of various promoters from the group of halo hydrocarbons, along with different modifiers from the group of esters and silane compounds had been investigated to conquer the barriers mentioned above. The reaction conversion, selectivity, and polymer production were the remarkable parameters that were evaluated to study the components’ impacts. The results indicated that the addition of promoters through reaction with Triethyl aluminum (TEA) (co-catalyst) increased the reaction speed and thus increased the conversion of the reaction to 88.26% and reduced the reaction time to 60 min. Among the promoters, the reaction conversion and selectivity of dichloromethane were 88.26% and 78.45%, higher than that of dibromopropane (48.52% and 39.52%), but a higher amount of polymer was produced by dichloromethane. Moreover, Esters strongly decreased the catalyst activity, resulting in a decrease in the conversion to under 25%. On the other hand, silanes showed a significant effect on the control of the polymer chains in Ziegler-Natta homogeneous catalysts. Dicyclopentyldimethoxysilane (DCPDS) modifier brought about an increase of 1.5% in ethylene conversion and a 6% increase in the 1-butene selectivity. At the same time, the polymer formation also prevented a significant amount so the amount of polymer decreased to about 2.1 mg. DCPDS modifier performed better than the Cyclohexylmethyldimethoxysilane (CHMDS) donor.
Characterization
Masayoshi Saito; Hiroshi Kashimura; Takuo Kataoka; Masahide Murata; Yusuke Sakuda; Hiroyuki Yamada; Hideyuki Takahashi
Abstract
This report is on the characterization of active Ti center in heterogeneous Ziegler-Natta catalysts with Soft X-ray Emission Spectrometer (SXES). Since titanium in the catalyst has various chemical bonds, it is important to grasp the chemical bond state. The outermost shell electrons are very important ...
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This report is on the characterization of active Ti center in heterogeneous Ziegler-Natta catalysts with Soft X-ray Emission Spectrometer (SXES). Since titanium in the catalyst has various chemical bonds, it is important to grasp the chemical bond state. The outermost shell electrons are very important for understanding the chemical bond state. SXES is the only method that can easily observe outermost shell electrons with current analytical instruments. Here, a co-milled solid of MgCl2, TiCl4, and Phthalate was used as a catalyst precursor, and three types of catalysts with significantly different catalytic activity levels were synthesized by changing the subsequent preparation process. The correlation between catalytic activity and the signal shape of Lα,β emission, which is the outermost shell electron of Ti in SXES analysis, was investigated. Lα,β emission was detected as broad signal. It could be observed that the high active catalyst had relatively strong signal intensity at the high energy side. The shape changes were also checked when the catalyst solids were treated by triethylaluminium. By this treatment, the relative intensity of the high energy side signal was further enhanced, suggesting that triethylaluminium treatment induced the elimination of inactive Ti from the catalyst solid. By comparing with the solid 13C-NMR analyses data of the Ziegler-Natta catalyst described in our previous report, the high energy side signal of Ti Lα,β in SXES results implies the relationship with the NMR results for carbonyl function.
Olefin polymerization and copolymerization
Majedeh Mroofi; Gholamhossein Zohuri; Saeid Ahmadjo; Navid Ramezanian
Abstract
Bicenter (BCn) cobalt-bis(imine) catalysts were synthesized, used to polymerize methyl methacrylate (MMA), and 1-hexene. The effect of catalyst structure, bridging ligand, and polymerization reaction conditions were investigated. Synthesis of primary ligand of (2,6-dibenzhydryl-4-ethoxyphenyl)-N=(CH3)-C(CH3)=O ...
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Bicenter (BCn) cobalt-bis(imine) catalysts were synthesized, used to polymerize methyl methacrylate (MMA), and 1-hexene. The effect of catalyst structure, bridging ligand, and polymerization reaction conditions were investigated. Synthesis of primary ligand of (2,6-dibenzhydryl-4-ethoxyphenyl)-N=(CH3)-C(CH3)=O is prepared. Following to that, the final ligands of BC1 and BC2 bicenter catalysts were prepared via reacting the primary ligand with 2,3,5,6-tetramethylbenzene-1,4-diamine and 4,4-methylenedianiline bridges, respectively. The BC1 catalyst demonstrated higher activity than the BC2 catalyst. The highest activity for the BC1 catalyst was obtained when the co-catalyst to catalyst molar ratio was [Al]/[Co]=1500:1, and the polymerization temperature was 40 °C. In comparison the BC2 catalyst demonstrated the highest activity in [Al]/[Co]=500:1 ratio, polymerization temperature of 70 °Cand showed higher thermal stability. 1HNMR analysis revealed that the highest branching density for poly(methyl methacrylates) (PMMA) produced by BC1 and BC2 catalysts was 222 and 249 branches per 1000 carbon atoms, respectively. PMMA synthesized with BC2 catalysts had the highest syndiotacticity (59%). The polymer produced with bicenter catalyst (BC1) had a relatively broad molecular weight distribution (2.9), according to GPC analysis. The synthesized catalysts demonstrated appropriate activity for the polymerization of MMA, but only moderate activity for 1-hexene monomer
