다중금속 촉매에 의한 에틸렌 중합 : (Ⅱ) 중합속도론

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Polymer(Korea), Vol.20, No.1, 44-56, January, 1996

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다중금속 촉매에 의한 에틸렌 중합 : (Ⅱ) 중합속도론

Ethylene Polymerization over Multimetallic Catalysts : (Ⅱ) Kinetic Study

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초록

넓은 분자량분포의 폴리에틸렌을 제조할 수 있는 고활성 다중금속 촉매를 이용하여 에틸렌의 중합속도를 조사하였다. 촉매의 합성에 사용된 성분은 염화마그네슘과 전자공여체 화합물을 포함하여 사염화티탄, 사염화지르코늄, 삼염화바나듐 중에서 최소한 두가지로 구성되어 있다. 앞선 연구 결과로부터 그 성능이 우수하다고 판단된 Ti와 V(TV11), Ti와 Zr(TZ11), V와 Zr의 1 : 1 착물(VZ11)을 대상 촉매로 선정하였고, 공촉매의 종류와 양, 중합온도, 수소의 첨가여부, 공단량체의 첨가여부에 따라 달라지는 중합거동을 상세히 조사하였다. 또한 TV11을 SiO₂에 담지시킨 촉매(TV11/SiO₂)를 합성하여 여러가지 중합인자를 비교하였다. 공촉매로서 가장적합한것은 AlEt₃이었고 Al(i-Bu)₃나 AlEt₂Cl을 사용할 경우 중합속도가 크게 낮아졌으며, 중합시의 결정의 성장 형태도 달라졌다. AlEt₃ 공촉매의 최적량은 [Al]/[Ti+V]=70일 때 나타났으며, 과잉량의 공촉매를 가할 경우 중합속도가 낮아졌으며, 속도곡선의 형태도 달라졌다. 공촉매의 양에 따른 중합속도의 변화는 Langmuir-Hinshelwood 반응기구로 설명할 수 있었다. 본 연구에서 대상으로 한 모든 촉매는 30-80℃의 중합온도에서 안정하였으며, 평균중합속도를 이용한 Arrhenius 플롯 결과 전 중합온도구간에서 선형관계를 얻을 수 없었으며 대개 3구간의 불연속적인 선형관계를 얻을 수 있었다. 이와 같은 현상은 중합온도의 상승으로 촉매활성점의 비가역적인 비활성화가 촉진되기 때문으로 해석할 수 있었다. 40-70℃의 온도구간에서 VZ11촉매의 활성화에너지가 6.8kca1/mol로 가장 낮았고, TV11/SiO₂촉매가 11.4kca1/mol로 가장 높았다. 촉매를 SiO₂에 담지시킴으로서 활성점의 열안정도는 좋아졌다. 중합과정에서 수소나 공단량체로서 1-hexone을 첨가할 경우 중합속도는 떨어졌고, 속도곡선의 형태도 감소형곡선으로 변하였다. 수소 첨가에 대한 감응도가 가장 우수한 촉매는 TV11촉매이었으며 SiO₂에 담지시킨 TV11/SiO₂ 촉매의 감응도는 가장 낮았다. 4가지 촉매로 합성된 PE의 분자량분포는 6.5-14.8로 대단히 넓었으며, 특히 TV11촉매가 가장 큰값을 나타냈다. 공단량체를 첨가하여 고분자에 도입되는 공단량체의 양을 FTIR을 이용하여 조사한 결과 TV11촉매가 공단량체와의 반응성이 가장 우수하였다. 대개 활성점의 종류가 다양하여 분자량분포가 넓은 PE를 제조할 수 있는 촉매가 공단량체와의 반응성도 우수한 것으로 나타났다.

A kinetic study of ethylene polymerization over the multimetallic catalysts developed for the production of high density polyethylene (HDPE) with broad molecular weight distribution (MWD) has been carried out. Magnesium chloride and electron donor were utilized for the preparation of multimetallic catalysts with at least 2 components from Tic14, VCl₃, and ZrCl₄. Selecting the catalysts composed of 1 : 1 complex of Ti and V (TV11), Ti and Zr (TZ11), V and Zr (VZ11) which showed good performance in the previous study, the effects of type and concentration of cocatalyst, polymerization temperature, and the addition of hydrogen or comonorner on the polymerization ratewere investigated. In addition the effect of supporting TV11 onto SiO₂ (TV11/SiO₂) was studied. The highest rate of polymerization was obtained when using AlEt₃ as a cocatalyst. The nascent morphology of PE showed much differences by the type of cocatalyst, indicating that crystals were grown by different mechanism. When using AlEt₃ as a catalyst the maximum activity as well as to change the rate profile. The variation of activity according to the concentration of AlEt₃ could be explained by a Langmuir-Hinshelwood mechanism. All catalysts were thermally stable at the temperature range between 30 and 80℃. Arrhenius plot of average rate showed 3 definite sections representing linear lines of discontinuity. This result could be explained by the accelerated irreversible deactivation of active sites at higher temperatures. The apparent activation energy recorded highest with TV11/SiO₂, 11.4kcal/mol, and lowest with VZ11, 6.8kcal/mol, at the range between 40 and 70℃. Adding hydrogen or 1-hexene (comonomer) the rate was decreased and the rate profile was changed from acceleration type to decay type. The response to hydrogen was best for TV11 catalyst. The reactivity to the comonomer PE was very broad, 6.5 for TZ11, 14.8 for TV11 catalyst. The reactivity to the comonomer was studied by measuring the content of comonomer in copolymer by FTIR analysis. The reactivity to 1-hexene was best for TV11. In general catalyst characterized by broader MWD showed better reactivity to 1-hexene due to the severe heterogeneity of active sites.

Keywords:multimetallic catalyst;ethylene polymerization;kinetics;effect fo comonomer;effect of hydrogen

[References]

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McLaughlin KW, Hoeve CAJ, "Transition Metal Catalyzed Polymerization," Ed. by R.P. Quirk, P. 337, Cambridge Univ. Press (1988)
Bohm LL, "Catalytic Polymerization of Olefins," Eds. by T. Koii and K. Soga, p. 29, Kodansha (1986)
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Bohm LL, Polymer, 19, 553 (1978)
Bohm LL, Polymer, 19, 561 (1978)
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[1] Kim I, Catalysis, 9(1), 27 (1993)

[2] Zucchini U, Cecchin G, Adv. Polym. Sci., 51, 101 (1983)

[3] McLaughlin KW, Hoeve CAJ, "Transition Metal Catalyzed Polymerization," Ed. by R.P. Quirk, P. 337, Cambridge Univ. Press (1988)

[4] Bohm LL, "Catalytic Polymerization of Olefins," Eds. by T. Koii and K. Soga, p. 29, Kodansha (1986)

[5] Bohm LL, Polymer, 19, 545 (1978)

[6] Bohm LL, Polymer, 19, 553 (1978)

[7] Bohm LL, Polymer, 19, 561 (1978)

[8] Schramm KD, Karol FJ, U.S. Patent, 5,070,055 to Union Carbide (1991)

[9] Kenji N, Norio T, European Patent, 294,168 to Idemitsu Petrochem. Co. (1988)

[10] Carrick WL, J. Am. Chem. Soc., 82, 1502 (1960)

[11] Karol FJ, J. Am. Chem. Soc., 83, 2654 (1961)

[12] Jacob HW, Z. Anorg. Allg. Chem., 427, 75 (1976)

[13] Tochiichi C, Mitsuhiro M, Yozo K, Jpn. Kokai Tokkyo Koho 02,163,103 to Tosoh Co. (1990)

[14] Toshiyuki T, Kenji S, Takashi U, European Patent, Appl. 436,399 to Mitsui Petrochem. Co. (1991)

[15] Lo FY, Nowlin TE, Shirodka PP, U.S. Patent, 5,032,562 to Mobil Oil Co. (1991)

[16] Schell JG, Meiske LA, Marchand GR, U.S. Patent, 5,045,612 to Dow Chemical Co. (1991)

[17] Schramm KD, Karol FJ, U.S, U.S. Patent, 5,070,055 to Union Carbide Chemicals and Plastics Tech. Co. (1991) (1991)

[18] Kim I, Polym.(Korea), submitted with this paper (1995)

[19] Kim I, Kim JH, Woo SI, J. Appl. Polym. Sci., 39, 837 (1990)

[20] Keii T, "Catalytic Polymerization of Olefins," Eds. by T. Keii and K. Soga, p. 1, Kodansha, Tokyo (1986)

[21] Kissin YV, "Isospecific Polymerization of Olefins," p. 133, Springer-Verlag, New York (1985)

[22] Sindorf DW, Maciel GE, J. Phys. Chem., 87, 5516 (1983)

[23] Berger MN, Grieveson BM, Makromol. Chem., 83, 80 (1965)

[24] Keii T, Suzuki E, Tamura M, Murata M, Doi Y, Makromol. Chem., 183, 2285 (1982)

[25] Kim I, Woo SI, Polym.(Korea), 16(5), 570 (1992)

[26] Sinn H, Kaminsky W, Adv. Org. Chem., 18, 99 (1980)

[27] Pino P, Mulhaupt R, Angew. Chem.-Int. Edit., 19, 857 (1980)

[28] Bohm LL, Angew. Chem.-Int. Edit., 89, 1 (1980)

[29] Yermakov YI, Kuznentsov BN, Zakharov VA, "Catalysis by Supported Complexes," Amsterdam, Elsevier (1981)

[30] Carrick WL, Turbett FJ, Karol Gl, Karapinka GL, Fox AS, Johnson RN, J. Polym. Sci. A: Polym. Chem., 10, 2609 (1972)

[31] Petrova T, Eur. Polym. J., 12, 571 (1976)

[32] Gordon M, Roe RJ, Polymer, 2, 41 (1961)

[33] Berger MN, Boocock G, Haward RN, Adv. Catal., 19, 24 (1969)

[34] Taylor WC, Tung LH, Polym. Lett., 1, 157 (1963)

[35] Keii T, "Transition Catalyzed Polymerization," Ed. by R.P. Quirk, MMI Press (1983)

[36] Nowlin TE, Kissin YV, Wagner KP, J. Polym. Sci. A: Polym. Chem., 26, 755 (1988)