Next Article in Journal
Down-Regulation of Treg Cells and Up-Regulation of Th1/Th2 Cytokine Ratio Were Induced by Polysaccharide from Radix Glycyrrhizae in H22 Hepatocarcinoma Bearing Mice
Previous Article in Journal
Role of Kupffer Cells in Thioacetamide-Induced Cell Cycle Dysfunction
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Molecules
Volume 16
Issue 10
10.3390/molecules16108332
molecules-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Effect of EtOH/MgCl2 Molar Ratios on the Catalytic Properties of MgCl2-SiO2/TiCl4 Ziegler-Natta Catalyst for Ethylene Polymerization

by
Supanan Patthamasang
,
Bunjerd Jongsomjit
and
Piyasan Praserthdam
*
Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
*
Author to whom correspondence should be addressed.
Molecules 2011, 16(10), 8332-8342; https://doi.org/10.3390/molecules16108332
Submission received: 22 August 2011 / Revised: 21 September 2011 / Accepted: 27 September 2011 / Published: 29 September 2011
Browse Figures
Versions Notes

Abstract

:
MgCl2-SiO2/TiCl4 Ziegler-Natta catalysts for ethylene polymerization were prepared by impregnation of MgCl2 on SiO2 in heptane and further treatment with TiCl4. MgCl2·nEtOH adduct solutions were prepared with various EtOH/MgCl2 molar ratios for preparation of the MgCl2-supported and MgCl2-SiO2-supported catalysts in order to investigate the effect on polymerization performance of both catalyst systems. The catalytic activities for ethylene polymerization decreased markedly with increased molar ratios of [EtOH]/[MgCl2] for the MgCl2-supported catalysts, while for the bi-supported catalysts, the activities only decreased slightly. The MgCl2-SiO2-supported catalyst had relatively constant activity, independent of the [EtOH]/[MgCl2] ratio. The lower [EtOH]/[MgCl2] in MgCl2-supported catalyst exhibited better catalytic activity. However, for the MgCl2-SiO2-supported catalyst, MgCl2 can agglomerate on the SiO2 surface at low [EtOH]/[MgCl2] thus not being not suitable for TiCl4 loading. It was found that the optimized [EtOH]/[MgCl2] value for preparation of bi-supported catalysts having high activity and good spherical morphology with little agglomerated MgCl2 was 7. Morphological studies indicated that MgCl2-SiO2-supported catalysts have good morphology with spherical shapes that retain the morphology of SiO2. The BET measurement revealed that pore size is the key parameter dictating polymerization activity. The TGA profiles of the bi-supported catalyst also confirmed that it was more stable than the mono-supported catalyst, especially in the ethanol removal region.

1. Introduction

Ziegler-Natta (ZN) catalysts have been widely used in polyolefin industrial since the 1950s. The ZN catalyst systems consisted of a Group IV or V metal halide catalyst and Group II or III metal alkyl or alkylhalide cocatalysts. The advantages of supported ZN catalysts are that the morphology of the polymer particles produced can be controlled by varying the morphology of the support and high catalyst activity can be achieved. In the order to meet the requirement of the polyolefin industry, it is important to produce high performance ZN catalysts with good morphology. Among catalyst supports MgCl2 is the most widely used one for olefin polymerization Ziegler-Natta catalysts with high performance and high catalytic activity.
Typically, three methods have been used to prepare activated MgCl2 supports for ZN catalysts, including physical (ball-milling), and chemical routes (recrystallization and chemical conversion method). Currently, the activation of MgCl2 is usually done via the chemical route. The recrystallization of MgCl2 in alcoholic hydrocarbon solution is the well-known method to make spherical catalysts [1,2,3]. However, in the synthesis of MgCl2 supports via this method it is not easy to obtain compact and good catalyst morphology because it is difficult to control the alcohol content in MgCl2-ethanol complexes, which influences the porosity and strength of the catalyst particles and the subsequent polymer-particle morphology due to the replication phenomena [4,5,6,7]. The fragmentation of MgCl2-adduct-based catalyst particles is still the important problem during the polymerization, because it can result in undesirable polymer morphology, formation of fines and reactor fouling [8,9].
Silicas are commonly used as supports for many catalysts. They have relatively high surface areas and pore volumes per unit mass. They also have chemically reactive groups on the surface, most of which are within the pore structure. Their particles size and shapes are often controlled to optimize catalyst performance [10,11,12]. However, the disadvantage of SiO2-supported ZN catalyst is their low activity [12]. The catalytic activity of SiO2-supported Ziegler-Natta catalysts can be improved by addition of MgCl2. The bi-supported (MgCl2-SiO2) ZN catalysts combine the advantages of the controllable morphology of SiO2 and the high activity of MgCl2 [13,14,15]. Typically, the synthesis of bi-supported ZN catalysts can be done by combination of the MgCl2 with SiO2, then treating with TiCl4 [13,16]. In addition, an electron donor can be used to increase the isotacticity of the bi-supported catalyst for propylene polymerization [17,18]. The impregnation of MgCl2 on the SiO2 surface is usually used to control the morphology of the bi-supported catalyst. MgCl2·nEtOH adduct solution is usually prepared before impregnation on SiO2 [19,20]. Forte and Coutinho [5] found that the catalyst preparation conditions apparently affected the chemical composition and morphology of catalyst. The amount of ethanol has a remarkable effect on the preparation of MgCl2·nEtOH adduct. Besides, the precipitation of MgCl2 and the removal of ethanol are the important parameters to obtain catalyst supports and catalysts with good morphology having spherical catalyst and polymer product shapes.
Presently, it is known that the [EtOH]/[MgCl2] ratio is a very important parameter to control the morphology and catalyst performance for MgCl2-supported catalysts [4,7]. However, the effect of [EtOH]/[MgCl2] ratio on the preparation of MgCl2-SiO2-supported catalysts is still unknown, even though the deposition of MgCl2 on SiO2 via MgCl2·nEtOH adduct solutions has been used in the preparation of these catalysts. Therefore, in this present study, we have investigated the effect of [EtOH]/[MgCl2] ratio on the properties of MgCl2-SiO2-supported catalysts. The MgCl2/TiCl4 and MgCl2-SiO2/TiCl4 catalysts were synthesized with various [EtOH]/[MgCl2] ratios in the MgCl2·nEtOH adduct used for MgCl2 impregnation on SiO2. The catalytic activity, morphology of catalyst, BET surface area, pore size, pore volume, and thermal properties were investigated and are further discussed in more detail.

2. Results and Discussion

2.1. Polymerization Activity

MgCl2-supported catalysts (M) and MgCl2-SiO2-supported catalysts (SM) were synthesized with various MgCl2·nEtOH adducts having n values ranging from 6 to 10. The supports were then treated with TiCl4 to obtain the corresponding mono-supported and bi-supported catalysts. The preparation conditions of both catalyst systems are shown in Table 1. The results show that Ti content of MgCl2-supported catalysts was relatively higher than for MgCl2-SiO2-supported catalysts in the range of 7.00–7.60 and 6.70–7.32 wt%.
Table
Table 1. MgCl2-supported and MgCl2-SiO2-supported catalysts preparation conditions.
Table 1. MgCl2-supported and MgCl2-SiO2-supported catalysts preparation conditions.
MgCl2-supported catalyst
SampleEtOH (mL)[EtOH]/[MgCl2]TiCl4 (mL) aSiO2 (g)Ti (wt%)
M611.0618.307.00
M712.9721.407.34
M814.7824.407.54
M916.6927.507.43
M1018.01030.007.60
MgCl2-SiO2-supported catalyst
SampleEtOH (mL)[EtOH]/[MgCl2]TiCl4 (mL) aSiO2 (g)Ti (wt%)
SM611.0618.366.93
SM712.9721.466.80
SM814.7824.466.77
SM916.6927.566.70
SM1018.01030.067.32
Note: a The desired amount of TiCl4 using for removing of EtOH from MgCl2 adduct calculated by [EtOH]/[TiCl4] = 1.13.
Ethylene polymerization was performed using both catalyst systems. Figure 1 shows that the catalytic activities of the mono-supported (M) catalysts were markedly decreased with increased [EtOH]/[MgCl2] ratios of 6 to 10, whereas the activities were only slightly decreased for the bi-supported (SM) catalysts for the identical [EtOH]/[MgCl2] ratios. It should be mentioned that the MgCl2-SiO2-supported catalysts usually have lower activity than MgCl2-supported catalysts because of the high number of silanol groups on the SiO2 surface [21,22]. However, based on this study at [EtOH]/[MgCl2] ratios of 9 and 10, the bi-supported catalysts showed higher activity than the mono-supported catalyst, as seen in Figure 1 for SM9 and SM10 compared to M9 and M10.
In the case of MgCl2-supported catalysts, [EtOH]/[MgCl2] ratio is an important parameter and this catalyst system prefers lower [EtOH]/[MgCl2] during support preparation to give better catalytic activity and performance [6,23]. An excess amount of EtOH in the support could react with TiCl4, and produce inactive species like Ti alkoxide [24]. In contrast, the bi-supported catalysts showed the interesting result that the activity was relatively independent of the [EtOH]/MgCl2] ratio. This indicates that the SiO2 probably prevents the Ti active species from reacting further with ethanol.
Molecules 16 08332 g001 550
Figure 1. Effect of [Ethanol]/[MgCl2] on catalytic activity and relative activity of MgCl2-SiO2-supported catalyst (SM) and MgCl2-supported catalyst (M). Ethylene polymerization condition: temperature = 80 °C; catalyst loading = 10 mg; [A1]/[Ti] = 100; ethylene consumption = 18 mmol.
Figure 1. Effect of [Ethanol]/[MgCl2] on catalytic activity and relative activity of MgCl2-SiO2-supported catalyst (SM) and MgCl2-supported catalyst (M). Ethylene polymerization condition: temperature = 80 °C; catalyst loading = 10 mg; [A1]/[Ti] = 100; ethylene consumption = 18 mmol.
Molecules 16 08332 g001

2.2. Effect of [EtOH]/[MgCl2] on Morphology of bi-Supported Catalysts

Scanning electron microscopy (SEM) measurements revealed that the spherical morphology of SiO2 is retained by the catalyst. In this study, MgCl2-ethanol solutions with [EtOH]/[MgCl2] ratios of 6, 7, 8, 9 and 10 were used to prepare catalysts. The minimum amount of ethanol to completely dissolve the MgCl2 and for impregnation of the SiO2 was 6 under the experimental conditions used. The viscosity of the adduct solution increases with decreasing amounts of ethanol, hence being more difficult with impregnation at [EtOH]/[MgCl2] ratios <6.
The external morphology of the SiO2 and the MgCl2-SiO2-supported catalysts was seen by SEM (Figure 2). The SEM micrographs of the bi-supported catalysts shown in Figure 2 indicating that the catalyst particles retain the shape of the SiO2 precursor particles. However, the SEM images also revealed that some breakage of particles occurred. The surfaces of bi-supported catalysts were rough, with some agglomeration of MgCl2, as shown in the SEM images. Figure 2(c-d) show images of SM6 catalyst prepared with [EtOH]/[MgCl2] = 6. It was found that the MgCl2 was crystallized on the surface of bi-supported catalyst. The concentration of MgCl2 in ethanol is one of important factors in the impregnation process. As known, if the adduct solution prepared has a high concentration of MgCl2, it will exhibit high viscosity that will make it unable to disperse into the pores of SiO2 and resulting in agglomeration on the external surface.
Molecules 16 08332 g002 550
Figure 2. SEM images of (a) and (b) SiO2 and MgCl2-SiO2-supported catalysts prepared with various of [EtOH]/[MgCl2] ratios; (c) and (d) SM6, (e) and (f) SM7, (g) and (h) SM8, (i) and (j) SM9, (k) and (l) SM10.
Figure 2. SEM images of (a) and (b) SiO2 and MgCl2-SiO2-supported catalysts prepared with various of [EtOH]/[MgCl2] ratios; (c) and (d) SM6, (e) and (f) SM7, (g) and (h) SM8, (i) and (j) SM9, (k) and (l) SM10.
Molecules 16 08332 g002
However, upon drying precipitation of MgCl2 on the external surface of the SiO2 was observed as an external rough surface for SM6. On the other hand, at higher [EtOH]/[MgCl2] values of 7 and 8, the catalyst surface became smooth and very little agglomeration of MgCl2 on the catalyst surface was observed, as shown in Figure 2(e-f) and (g-h). However, at [EtOH]/[MgCl2] values of 9 and 10, cracking on the bi-supported catalyst surfaces was observed, as shown in Figure 2(i-j) and (k-l). This may be due to brittle films of impregnated MgCl2 caused by the high ethanol content. Therefore, the effect of [EtOH]/[MgCl2] on morphology structure of MgCl2 deposited on the SiO2 surface is similar to that on the MgCl2-supported catalyst in terms of producing loose and breakable MgCl2 structures with high ethanol content [1].
Therefore, MgCl2-SiO2-supported catalyst requires an optimal [EtOH]/[MgCl2] ratio due to the viscosity limitation that can affect the impregnation and dispersion of MgCl2 on the SiO2 surface. MgCl2 can agglomerate on the SiO2 surface with low [EtOH]/[MgCl2] and it is not suitable for loading TiCl4 on the MgCl2-SiO2-support. The optimized [EtOH]/[MgCl2] value for preparing bi-supported catalysts having high activity and good spherical morphology with little agglomeration of MgCl2 is 7 under these experimental conditions.

2.3. Determination of Surface Area

Surface areas of mono- and bi-supported catalysts were determined by the BET method. The results are listed in Table 2. The bi-supported catalysts exhibited much higher surface areas than the mono-supported catalysts prepared under similar [EtOH]/[MgCl2] ratios due to the high surface area of SiO2 in the bi-supported catalyst. The bi-supported catalysts containing different [EtOH]/[MgCl2] values of MgCl2 adduct exhibit similar surface area of 414–471 m2/g, pore size of 44.6–52.5 Å and pore volume of 0.46–0.60 cm3/g. Therefore, the relatively constant bi-supported catalyst structure is the reason for the relatively constant catalytic activity. The BET measurements of mono-supported catalyst showed that the surface area, pore size and pore volume of the catalysts depended on the [EtOH]/[MgCl2] ratios (as seen for M6 and M10 in Table 2). The results show that M6 prepared with a low [EtOH]/[MgCl2] value exhibited much larger pores than those of M10 prepared with a higher [EtOH]/[MgCl2] value. The larger pores size may be responsible for the higher catalytic activity of M6 compared to M10.
Table
Table 2. BET surface area measurement of MgCl2-supported catalysts and MgCl2-SiO2-supported catalysts.
Table 2. BET surface area measurement of MgCl2-supported catalysts and MgCl2-SiO2-supported catalysts.
Catalyst nameBET surface area(m2/g)Pore size (diameter) (Å)Pore volume (cm3/g)
SiO2 (SYLOPOL 2229)48997.221.60
M618788.000.53
M1036639.300.36
SM641949.600.51
SM745552.500.60
SM845050.400.57
SM947146.400.55
SM1041444.600.46

2.4. Thermal Analysis

Figure 3 shows TGA profiles of MgCl2-supported catalysts and MgCl2-SiO2-supported catalyst. It indicates that bi-supported catalysts exhibited the similar TGA profiles as SiO2, with a relative decrease the weight loss with temperature after 200 °C. The bi-supported catalysts retained over 80% of their mass when heated to 500 °C (mass loss ≤ 20%) while the mono-supported catalyst lost about 50% of their mass for the same thermal treatment. TGA profiles show that the mono-supported catalysts have significant mass losses in the range of 70 to 190 °C (30 to 40%). The ethanol content in MgCl2-supported catalyst was more than the MgCl2-SiO2-supported catalyst. This was due to the preparation procedures between MgCl2 and MgCl2-SiO2 supports were different in the weight ratio of support/EtOH.
Molecules 16 08332 g003 550
Figure 3. TGA profiles of MgCl2-supported catalysts (M) and MgCl2-SiO2-supported catalysts (SM).
Figure 3. TGA profiles of MgCl2-supported catalysts (M) and MgCl2-SiO2-supported catalysts (SM).
Molecules 16 08332 g003
EtOH and moisture escaped from surface and catalyst particles in this temperature range. The mono-supported catalysts have a maximum weight loss from 150–190 °C in M6 catalyst and 70–130 °C in M10 catalyst, indicating that at a higher [EtOH]/[MgCl2] value as 10, ethanol groups were removed easily from the catalysts because of the loose structure of M10 produced with a high content of ethanol [1]. This may be the reason why the decrease of weight loss of M10 was sharper and started earlier than those of M6. On the other hand, the bi-supported catalysts show only a slight decrease of weight loss profile. The results also show that at 200 °C, the bi-supported catalysts have an average weight of 90% corresponding to a weight loss of 10%, whereas the mono-supported catalysts exhibited average weights of 68%, corresponding to a weight loss of 33%.

3. Experimental

3.1. Chemicals

Anhydrous MgCl2 (Toho) was used as received. SiO2 (SYLOPOL 2229, received from Grace Davison having particle size of 40–50 mm and surface area of 270 m2/g) was calcined at 600 °C for 6 h. Ethanol (Merck Ltd.) was dried with 4 Å molecular sieves. TiCl4 (Merck Ltd.) was used as received. Heptane and toluene (Merck Ltd.) were purified by distillation with Na metal/benzophenonone in an atmosphere of high purity Ar to remove residual traces of moisture and oxygen. Ultra high purity (UHP) argon (99.999%) was purchased from Thai Industrial Gas Co., Ltd. and was further purified by passing through 3 Å molecular sieves, BASF catalyst R3-11G, NaOH and phosphorus pentoxide (P2O5) to remove traces of oxygen and moisture. Polymerization grade ethylene and triethylaluminum (TEA) were donated by PTT Public Co., Ltd. Standard Schlenk techniques and high purity argon were used for the handling of all compounds.

3.2. Catalyst Preparations

3.2.1. MgCl2-Supported Catalyst Preparation

A 300 mL 3-necked round bottom flask equipped with mechanical stirrer, Ar inlet and outlet lines and cooling system were used in the preparation. Anhydrous MgCl2 (3.0 g) was suspended in heptane (20 mL), and then the desired amount of ethanol was added to the slurry with a syringe under Ar. The mixture was heated to 80 °C and stirred until MgCl2 was completely dissolved. Then, the MgCl2 adduct solution was cooled to −20 °C and the desired amount of TiCl4 was added dropwise at a rate of 25 mL/h. The temperature was slowly increased to 80 °C and kept there for 1 h. The solid was washed with heptane (50 mL) for 3 times. TiCl4 (18 mL) and heptane (18 mL) was added into the mixture to activate an intermediate at 95 °C for 1 h. The supernatant was removed, and the solid catalyst was washed several times with heptane. The final catalysts were dried in a vacuum at room temperature and kept under Ar atmosphere.

3.2.2. MgCl2-SiO2-Supported Catalyst Preparation

The 300 mL 3-necked round bottom flask equipped with mechanical stirrer, Ar inlet and outlet line and cooling system were used in the preparation. Anhydrous MgCl2 (3.0 g) was suspended in heptane (20 mL), and then the desired amount of ethanol was added to the slurry under a stream of Ar. The mixture was heated to 80 °C and stirred until MgCl2 was completely dissolved. Then, SiO2 (6.0 g) in heptane (40 mL) was transferred to reactor using a Teflon tube while stirred. The slurry mixture was stirred for 1 h at 80 °C. The impregnated MgCl2 adduct/SiO2 was cooled to room temperature with continuous stirring. The solid was washed with toluene (50 mL) two times and heptane (50 mL) two times to remove the alcohol. Heptane (60 mL) was added into 3-necked flask, and then, the slurry was cooled to −20 °C. Consequently, TiCl4 was added dropwise at a rate of 25 mL/h. The temperature was slowly increased to 80 °C and kept there for 1 h. The solid was washed with heptane (50 mL) 3 times. TiCl4 (18 mL) and heptane (18 mL) were added into the mixture to activate an intermediate at 95 °C for 1 h. The supernatant was removed, and the solid catalyst was washed with heptane several times. The resultant bi-supported catalysts were dried in vacuum at room temperature and kept under Ar atmosphere.
The nomenclature used is as follows:
  • MI refers to the MgCl2-supported ZN catalyst with [EtOH]/[MgCl2] ratio of I.
  • SMI refer to the MgCl2-SiO2-supported ZN catalyst with [EtOH]/[MgCl2] ratio of I.

3.3. Ethylene Polymerization

A 100 mL stainless steel autoclave equipped with a magnetic agitator was used under semi-batch operation. Ethylene polymerization was conducted using catalyst powder (0.01 g), hexane (30 mL), triethylaluminum, Al/Ti = 100, and polymerization at 80 °C and 50 psia total pressure with continuous feeding of ethylene. The reaction was stopped when 18 mmol of ethylene monomer was consumed by venting the monomer and quenching with HCl/methanol. The obtained polymer was washed several times with methanol, filtered and dried under vacuum at 60 °C for 6 h. Due to the fixed ethylene consumption (18 mmol), the polymerization time was defined as the time that all ethylene monomer was completely consumed equivalent pressure drop of 42 kPa (6 psi). The polymerization time was recorded to calculate the catalytic activity.

3.4. Characterization

Morphological study of MgCl2-SiO2-supported catalyst was investigated using scanning electron microscopy (SEM, JEOL mode JSM-6400). Measurement of BET surface area, pore volume and pore size diameter of catalysts were determined by N2 physisorption and Kelvin condensation using a Micromeritics ASAP 2000 automated system. Thermogravimetric analysis (TGA) was performed using a TA Instruments SDT Q 600 analyzer with temperature ramping from 40 to 500 °C at 10 °C/min. The carrier gas was N2 (UHP). The Ti content in catalysts was determined by inductively coupled plasma spectroscopy (ICP) using the Perkin-Elmer Plasma 1000 system.

4. Conclusions

Mono-supported catalysts (MgCl2/TiCl4) and bi-supported catalysts (MgCl2-SiO2/TiCl4) were synthesized using various [EtOH]/[MgCl2] ratios. The bi-supported catalysts had relatively constant activities with increasing the ethanol/MgCl2 ratios due to prevention of the Ti active species from further reaction with ethanol. Activities of the bi-supported catalysts were slightly reduced from the maximum activity, but those of the mono-supported catalyst showed a remarkable reduction with increasing [EtOH]/[MgCl2] ratio. The bi-supported catalysts retain the morphology of the SiO2 precursor to the catalyst, with spherical shapes. The [EtOH]/[MgCl2] ratios affect the bi-supported catalyst morphology in terms of the impregnated film of MgCl2 on SiO2 surface. Even though lower [EtOH]/[MgCl2] ratios in MgCl2-supported ZN catalyst give better catalytic activity and particle morphology, the MgCl2-SiO2-supported ZN catalysts requires moderate [EtOH]/[MgCl2] ratios due to their viscosity limitation that can affect impregnation and dispersion of MgCl2 on the SiO2 surface. In addition, MgCl2 can agglomerate on the SiO2 surface at low [EtOH]/[MgCl2] ratios and this is not suitable for TiCl4 loading on the MgCl2-SiO2-support. The optimized [EtOH]/[MgCl2] value for preparing bi-supported catalysts with high activity and good spherical morphology with little agglomeration of MgCl2 is 7. The bi-supported catalyst has high specific surface area and porosity without any relationship between activity of catalyst and surface area. Additional, thermal properties show that TGA profiles of the bi-supported catalysts are more stable than the mono-supported catalysts, especially in the region of ethanol and moisture removal.

Acknowledgments

This work was also supported by the project for Higher Education Promotion and National Research University Development (AM1088A), Office of the Higher Commission (CHE). The supports from PTT Public Co., Ltd. and S.E. Wanke are also appreciated.

References

  1. Ye, Z.Y.; Wang, L.; Feng, L.F.; Gu, X.P.; Chen, H.H.; Zhang, P.Y.; Pan, J.; Jiang, S.; Feng, L.X. Novel spherical Ziegler-Natta catalyst for polymerization and copolymerization. I. Spherical MgCl2 support. J. Polym. Sci. Part A 2002, 40, 3112–3119. [Google Scholar] [CrossRef]
  2. Wu, L.; Lynch, D.T.; Wanke, S.E. Kinetics of gas-phase ethylene polymerization with morphology-controlled MgCl2-supported TiCl4 catalyst. Macromolecules 1999, 32, 7990–7998. [Google Scholar] [CrossRef]
  3. Ma, Z.; Wang, L.; Wang, W.; Feng, L.; Gu, X. Study of propylene polymerization catalyzed by a spherical MgCl2-supported Ziegler-Natta catalyst system: The effects of external donors. J. Appl. Polym. Sci. 2005, 95, 738–742. [Google Scholar]
  4. Jamjah, R.; Zohuri, G.H.; Vaezi, J.; Ahmadjo, S.; Nekomanesh, M.; Pouryari, M. Morphological study of spherical MgCl2.nEtOH supported TiCl4 Ziegler-Natta catalyst for polymerization of ethylene. J. Appl. Polym. Sci. 2006, 101, 3829–3834. [Google Scholar] [CrossRef]
  5. Forte, M.C.; Coutinho, F.M.B. Highly active magnesium chloride supported Ziegler-Natta catalysts with controlled morphology. Eur. Polym. J. 1996, 32, 223–231. [Google Scholar] [CrossRef]
  6. Sozzani, P.; Bracco, S.; Comotti, A.; Simonutti, R.; Camurati, I. Stoichiometric compounds of magnesium dichloride with ethanol for the supported Ziegler-Natta catalysis: First recognition and multidimensional MAS NMR study. J. Am. Chem. Soc. 2003, 125, 12881–12893. [Google Scholar] [CrossRef]
  7. JalaliDil, E.; Pourmahdian, S.; Vatankhah, M.; Taromi, F.A. Effect of dealcoholation of support in MgCl2-supported Ziegler-Natta catalysts on catalyst activity and polypropylene powder morphology. Polym. Bull. 2010, 64, 445–457. [Google Scholar] [CrossRef]
  8. Noristi, L.; Marchetti, E.; Baruzzi, G.; Sgarzi, P. Investigation on the particle growth mechanism in propylene polymerization with MgCl2-supported Ziegler-Natta catalysts. J. Polym. Sci. Part A 1994, 32, 3047–3059. [Google Scholar] [CrossRef]
  9. Abboud, M.; Denifl, P.; Reichert, K.H. Fragmentation of Ziegler-Natta catalyst particles during propylene polymerization. Macromol. Mater. Eng. 2005, 290, 558–564. [Google Scholar] [CrossRef]
  10. Kaminaka, M.; Soga, K. Polymerization of propene with the catalyst systems composed of Al2O3- or MgCl2-supported Et[IndH4]2ZrCl2 and AlR3 (R = CH3, C2H5). Die Makromol. Chem. Rapid Commun. 1991, 12, 367–372. [Google Scholar] [CrossRef]
  11. Soga, K.; Kaminaka, M. Polymerization of propene with the heterogeneous catalyst system Et[IndH4]2ZrCl2/MAO/SiO2 combined with trialkylaluminium. Die Makromol. Chem. Rapid Commun. 1992, 13, 221–224. [Google Scholar]
  12. Ochedzan-SiodLak, W.; Nowakowska, M. Titanium catalyst (TiCl4) supported on MgCl2(THF) (AlEt2Cl)0.34 for ethylene polymerization. Polim. Polym. 2007, 52, 184–189. [Google Scholar]
  13. Kim, I.; Woo, S.I. Morphological study of HDPE prepared with the highly active silica supported TiCl4/MgCl2 catalyst. Polym. J. 1989, 21, 697–707. [Google Scholar] [CrossRef]
  14. Kim, I.; Kim, J.H.; Woo, S.I. Kinetic study of ethylene polymerization by highly active silica supported TiCl4/MgCl2 catalysts. J. Appl. Polym. Sci. 1990, 39, 837–854. [Google Scholar]
  15. Zohuri, G.H.; Azimfar, F.; Jamjah, R.; Ahmadjo, S. Polymerization of propylene using the high-activity Ziegler-Natta catalyst system SiO2/MgCl2 (ethoxide type)/TiCl4/di-m-butyl phthalate/triethylaluminum/dimethoxy methyl cyclohexyl silane. J. Appl. Polym. Sci. 2003, 89, 1177–1181. [Google Scholar]
  16. Jiang, T.; Chen, W.; Zhao, F.; Liu, Y.; Wang, R.; Du, H.; Zhang, T. Preparation of porous spherical MgCl2/SiO2 complex support as precursor for catalytic propylene polymerization. J. Appl. Polym. Sci. 2005, 98, 1296–1299. [Google Scholar] [CrossRef]
  17. Dong, Q.; Fu, Z.; Xu, J.; Fan, Z. Strong influences of cocatalyst on ethylene/propylene copolymerization with a MgCl2/SiO2/TiCl4/diester type Ziegler-Natta catalyst. Eur. Polym. J. 2007, 43, 3442–3451. [Google Scholar] [CrossRef]
  18. Zohuri, G.; Ahmadjo, S.; Jamjah, R.; Nekoomanesh, M. Structural study of mono- and Bi-supported Ziegler-Natta catalysts of MgCl2/SiO2/TiCl4/donor systems. Iran. Polym. J. (Engl. Ed.) 2001, 10, 149–155. [Google Scholar]
  19. Lu, H.; Xiao, S. Highly isospecific SiO2/MgCl2 bisupported catalyst for propene polymerization. Die Makromol. Chem. 1993, 194, 2095–2102. [Google Scholar]
  20. Chung, J.S.; Cho, H.S.; Ko, Y.G.; Lee, W.Y. Preparation of the Ziegler-Natta/metallocene hybrid catalysts on SiO2/MgCl2 bisupport and ethylene polymerization. J. Mol. Catal. A 1999, 144, 61–69. [Google Scholar] [CrossRef]
  21. Armistead, C.G.; Tyler, A.J.; Hambleton, F.H.; Mitchell, S.A.; Hockey, J.A. The surface hydroxylation of silica. J. Phys. Chem. 1969, 73, 3947–3953. [Google Scholar] [CrossRef]
  22. Lu, H.; Xiao, S. Structure and behaviour of SiO2/MgCl2 bisupported Ziegler-Natta catalysts for olefin polymerization. Die Makromol. Chem. 1993, 194, 421–429. [Google Scholar] [CrossRef]
  23. Ma, Z.; Wang, L.; Wang, W.; Wang, J.; Yu, H. Study of propylene polymerization catalyzed by spherical MgCl2-supported Ziegler-Natta catalyst system: Preparation of spherical support. Polym. Plast. Technol. Eng. 2005, 44, 1475–1483. [Google Scholar]
  24. Chung, J.S.; Choi, J.H.; Song, I.K.; Lee, W.Y. Effect of ethanol treatment in the preparation of MgCl2 support for the propylene polymerization catalyst. Macromolecules 1995, 28, 1717–1718. [Google Scholar] [CrossRef]
  • Sample Availability: Samples of the PE are available from the authors.

Share and Cite

MDPI and ACS Style

Patthamasang, S.; Jongsomjit, B.; Praserthdam, P. Effect of EtOH/MgCl2 Molar Ratios on the Catalytic Properties of MgCl2-SiO2/TiCl4 Ziegler-Natta Catalyst for Ethylene Polymerization. Molecules 2011, 16, 8332-8342. https://doi.org/10.3390/molecules16108332

AMA Style

Patthamasang S, Jongsomjit B, Praserthdam P. Effect of EtOH/MgCl2 Molar Ratios on the Catalytic Properties of MgCl2-SiO2/TiCl4 Ziegler-Natta Catalyst for Ethylene Polymerization. Molecules. 2011; 16(10):8332-8342. https://doi.org/10.3390/molecules16108332

Chicago/Turabian Style

Patthamasang, Supanan, Bunjerd Jongsomjit, and Piyasan Praserthdam. 2011. "Effect of EtOH/MgCl2 Molar Ratios on the Catalytic Properties of MgCl2-SiO2/TiCl4 Ziegler-Natta Catalyst for Ethylene Polymerization" Molecules 16, no. 10: 8332-8342. https://doi.org/10.3390/molecules16108332

APA Style

Patthamasang, S., Jongsomjit, B., & Praserthdam, P. (2011). Effect of EtOH/MgCl2 Molar Ratios on the Catalytic Properties of MgCl2-SiO2/TiCl4 Ziegler-Natta Catalyst for Ethylene Polymerization. Molecules, 16(10), 8332-8342. https://doi.org/10.3390/molecules16108332

Article Metrics

Back to TopTop