Preparation of Hafnium and Chromium Complexes for Olefin Poly/Oligomerizations
- 주제(키워드) catalyst , polyolefin , poly(alpha-olefin)
- 주제(DDC) 547
- 발행기관 아주대학교
- 지도교수 이분열
- 발행년도 2022
- 학위수여년월 2022. 8
- 학위명 박사
- 학과 및 전공 일반대학원 분자과학기술학과
- 실제URI http://www.dcollection.net/handler/ajou/000000031974
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
ABSTRACT This dissertation covers hafnium (Hf) and chromium (Cr) catalysts for polyolefin and poly(α-olefin). The catalysts we designed were aimed at improving catalytic performance in terms of activity and properties of products. Chapter 1 reviews background information to produce polyolefin and poly(α-olefin) and the history of organometallic catalysts for them. Chapter 2 shows Hf catalysts capable of coordinative chain transfer polymerization. Hf complexes have drawn attention for their application as post-metallocene catalysts with unique performance in olefin polymerization. In this work, a series of half-metallocene HfMe2 complexes, bearing a tetrahydroquinoline framework, as well as a series of [Namido,N,Caryl]HfMe2-type post-metallocene complexes, bearing a tetrahydrophenanthroline framework, were prepared; the structures of the prepared Hf complexes were unambiguously confirmed by X-ray crystallography. When the prepared complexes were reacted with anhydrous [(C18H37)2N(H)Me]+[B(C6F5)4]−, desired ion-pair complexes, in which (C18H37)2NMe coordinated to the Hf center, were cleanly afforded. The activated complexes generated from the half-metallocene complexes were inactive for the copolymerization of ethylene/propylene, while those generated from post-metallocene complexes were active. 8-(Tetramethylcyclopentadienyl)-1,2,3,4-tetrahydroquinoline dimethylhafnium complex (12), which bears bulky isopropyl substituents, exhibited the highest activity; however, the activity was approximately half that of the prototype pyridylamido-Hf Dow catalyst. The comonomer incorporation capability was also inferior to that of the pyridylamido-Hf Dow catalyst. However, 12 performed well in the coordinative chain transfer polymerization performed in the presence of (octyl)2Zn, converting all the fed (octyl)2Zn to (polyolefinyl)2Zn with controlled lengths of the polyolefinyl chain. Chapter 3 indicates that a poly(α-olefin)(PAO) prepared by trimerization of 1-octene and 1-dodecene using supported chromium catalyst, has better properties than commercial PAO-4.0. The demand for PAOs, which are high-performance group IV lubricant base oils, is increasingly high. PAOs are generally produced via the cationic oligomerization of 1-decene, wherein skeleton rearrangement inevitably occurs in the products. Hence, a transition-metal-based catalytic process that avoids rearrangement would be a valuable alternative for cationic oligomerization. In particular, transition-metal-catalyzed selective trimerization of α-olefins has the potential for success. In this study, (N,N’,N’’-tridodecyltriazacyclohexane)CrCl3 complex was reacted with MAO-silica (MAO, methylaluminoxane) for the preparation of a supported catalyst, which exhibited superior performance in selective α-olefin trimerization compared to that of the corresponding homogeneous catalyst, enabling the preparation of α-olefin trimers at ~200 g scale. Following hydrogenation, the prepared 1-decene trimer (C30H62) exhibited better lubricant properties than those of commercial-grade PAO-4 (kinematic viscosity at 40 °C, 15.1 vs. 17.4 cSt; kinematic viscosity at 100 °C, 3.9 vs. 3.9 cSt; viscosity index, 161 vs. 123). Moreover, it was shown that 1-octene/1-dodecene mixed co-trimers (i.e., a mixture of C24H50, C28H58, C32H66, and C36H74), generated by the selective supported Cr catalyst, exhibited outstanding lubricant properties analogous to those observed for the 1-decene trimer (C30H62). Chapter 4 describes catalysts system for the selective trimerization of α-olefins with high activity by a modified Phillips ethylene trimerization catalyst system despite the original Phillips system being inactive for α-olefin. α-Olefin trimers are used at a bulk scale as top-tier lubricant base oils, with putative future applications as diesel fuels obtainable from renewable ethylene. In this context, catalysts that can selectively convert α-olefin to its trimers are valuable. However, few examples have been reported. Herein, we report selective α-olefin trimerization catalysts and avoiding the use of expensive activators, such as methylaluminoxane (MAO), B(C6F5)3, and [B(C6F5)4]− salt. A catalytic system Cr(acac)3/[2,5-Me2C4H2N-Al(iBu)3]−Na+/(iBu)3Al demonstrating high turnover numbers (TONs) exceeding 10000 (31 kg/g-Cr for 1-decene), generating trimers selectively without other higher or lower fractions, was developed, confirmed by simulated distillation gas chromatography (SimDis GC) analysis. The hypothesized 2,5-pyrrolide chromium active species was partially confirmed by the structure elucidation of [2,5-Me2C4H2N-AlMe3]Cr(Me)[CH2C6H4(ortho-NMe2)-κ2C,N]. The prepared 1-decene trimers (after hydrogenation) exhibited an advantageously higher viscosity index (VI) than the commercial product PAO-4.0 (128 vs. 123). Fluids demonstrating similar lubricant characteristics as either the 1-decene trimers or 1-decene derived PAO-4.0 were obtained by using 1-octene/1-dodecene blend.
more목차
CHAPTER 1 1
General Introduction 1
1.1 Introduction 2
1.2 Olefin polymerization 2
1.2.1 Heterogeneous Ziegler-Natta catalysts 2
1.2.2 Homogeneous metallocene catalysts 4
1.2.3 Mechanism of polymerization by representative metallocene with cocatalysts 8
1.2.4 Coordinative Chain Transfer Polymerization 10
1.3 Olefin oligomerization 11
1.3.1 Ethylene oligomerization process 11
1.3.2 α-Olefin oligomerization: PAO prepared by organometallic compounds 12
1.3.3 Selective α-Olefin trimerization catalysts 14
1.4 References 15
CHAPTER 2 23
Preparation of Half- and Post-Metallocene Hafnium Complexes for Olefin Polymerization 23
2.1 Introduction 24
2.2 Results and Discussion 25
2.2.1 Preparation of Half-Metallocene Hf Complexes 25
2.2.2 Preparation of Post-Metallocene Hf Complexes 27
2.2.3 X-Ray Crystallographic Studies 29
2.2.4 Activation Reactions 32
2.3 Materials and Method 38
2.4 Conclusions 49
2.5 References 50
2.6 Supplementary Information: Figures (NMR and DSC) 59
CHAPTER 3 89
Immobilized Chromium Catalyst for α-Olefin Trimerization 89
3.1 Introduction 90
3.2 Results and Discussion 92
3.2.1. Catalyst screening 92
3.2.2. α-Olefin oligomerization studies with supported catalysts 93
3.2.3. Preparation of α-olefin trimers and lubricant properties 100
3.3. Materials and Method 105
3.4. Conclusions 107
3.5. References 108
3.6 Supplementary Information: Figures (GC, Graph, and NMR) 114
CHAPTER 4 117
Selective α-Olefin Trimerization by Modified Phillips Ethylene Trimerization Catalysts for Lubricant Base Oils 117
4.1 Introduction 118
4.2 Results and Discussion 120
4.2.1 Catalytic system of CrCl3(THF)2/2,5-Me2C4H2N-Li/(iBu)3Al 120
4.2.2 Catalytic system of Cr(acac)3/2,5-Me2C4H2N-Na/(iBu)3Al 122
4.2.3 Catalytic system of Cr(acac)3/[2,5-Me2C4H2N-Al(iBu)3]−Na+/(iBu)3Al 124
4.2.4 Catalytic system of 2,5-Me2C4H2N-Cr[CH2C6H4(ortho-NMe2)-κ2C,N]2/(iBu)3Al 128
4.2.5 Large scale preparation of α-olefin trimers 132
4.2.6 SimDis GC analysis of α-olefin trimers 133
4.2.7 Lubricant properties 137
4.3 Materials and Method 139
4.4 Conclusions 147
4.5 References 148
4.6 Supplementary Information: Figures (Crystallography Structure and NMR) 154
LIST OF PUBLICATIONS 169
LIST OF PATENTS 172
