한국 내 조선족 여성노동자에 관한 질적 연구 : 생활사재구성방법론을 중심으로 = (A) qualitative study on the female Chosunjok workers in South Korea : focused on the methodology of reconstruction of life history

다국어 초록 (Multilingual Abstract)

Environmental regulations imposed on chemical industry are getting more and more stringent in recent years. Furthermore, the chemical industry has been forced out to reduce production cost to survive from keen competition with each other. Accordingly, development of environmentally clean and more efficient catalytic process has been a major issue in chemical industry. In this respect, we have been
presented two practical examples of catalytic renovation of conventional homogeneous catalysis; epoxidation of 2,5-dihydrofliran (2,5DHF) using titaniumsilicalite and continuous synthesis of diarylethanes using zeolites. Conventional processes using organic synthesis methods produce equivalent amounts of harmful wastes and have low production efficiency. In this work, the possibility to substitute the homogeneous catalysis with heterogeneous catalysis has been systematically studied and finally the optimum catalyst and process conditions have been proposed.
As an example, it has been proved that 3,4-epoxytetrahydrofuran (ETHF) was selectively prepared by epoxidation of 2,5DHF using titanium silicalite-1 (TS-1) as a heterogeneous catalyst and 11202 as an oxidant in either batch or continuous reaction system. The reaction pathways were strongly influenced by the properties of solvents and reaction conditions. The activity order of the solvent was methanol > ethanol > n-propanol > n-butanol > acetonitrile > acetone. Methanol was the most effective solvent but allylic oxidation of 2,5DHF was the major side reactions. Examination of experimental conditions pointed out that 65 C, methanol/2,5DHF =10 (w/w), and H_(2)O_(2)/2,5DHF ratios in the range of 1.6 ~1.8 is the optimal set of conditions to achieve high ETHF selectivity (over 75%). In the continuous epoxidation reactions, selectivity to epoxidation product was greatly influenced by binding materials for catalytically active species. Catalyst pellets binded with alumina species showed superior stability but its selectivity to ETHF was lower than silica-binded TS-1.
Continuous synthesis of diarylethanes using zeolites has also been studied as a second example. In the Friedel-Crafts alkylation of xylene to prepare 1-phenyl-1-xylyl ethane (PXE), a-methyl benzyl alcohol (MBA) was used as an alkylating agent instead of styrene over a commercial H-mordenite catalyst. The catalyst was characterized by various techniques and was found to possess strong Bronsted acid sites. When temperature was low, the main product was bis-(α-methylbenzyl) ether. However, as the temperature went up, PXE and heavies, styrene trimers and heavier oligomers, became main products. The formation of PXE, occurring on strong acid sites, is favored by raising temperature, space velocity, pressure, and xylene/MBA ratio within the experimental ranges investigated. As the catalyst deactivates, the selectivities to PXE and heavy oligomers decrease and those to linear dimmer and styrene increase. The preparation of 1 -phenyl- 1 -tolyl ethane (PTE) by Friedel- Crafts alkylation of toluene with MBA was studied using large- and medium-pore zealites as solid acid catalysts to elucidate the effect of pore structure of the zeolites. The catalysts were characterized by 27A1 and ^(29)Si MAS- NMR, NH_(3)-TPD, SEM, N_(2) adsorption/desorption, and other techniques. Among the four zeolites investigated, the acid strength was approximately in the order of HMOR2O (H-mordenite, SiO_(2)/Al_(2)O_(3)=20) > HY5 (H-Y, SiO_(2)/Al_(2)O_(3)=5) ≥ HMFI30 (H-ZSM-5, SiO_(2)/Al_(2)O_(3)=30) > HBEA25 (H-beta, SiO_(2)/Al_(2)O_(3)=25) while the initial selectivity to PTE was in the order of HMOR2O > HBEA25 > HMFI3O > HY5. From the reaction and characterization studies, it is concluded that the formation of PTE requires both strong acid sites and suitable pore openings. HMOR2O showed the best overall performance as it satisfied these requirements. A reaction mechanism is proposed based on the results of reaction studies.

목차 (Table of Contents)

• ABSTRACT = I
• TABLE Of CONTENTS = IV
• LIST OF TABLES = VI
• LIST OF FIGURES = VII
• 1. Introduction = 1
• 2. Synthesis of ETHF using TS-1 as a heterogeneous epoxidation catalyst = 6
• 2.1. Introduction = 6
• 2.2. Experimental = 22
• 2.2.1. Preparation of TS-1 = 22
• 2.2.2. Epoxidation of 2,5DHF = 23
• 2.3. Results and discussion = 27
• 2.3.1. Characterization of TS-1 = 27
• 2.3.2. Preparation of ETHF using TS-1 in a batch system = 30
• 2.4.4. Preparation of ETHF using TS-1 in the continuous reaction mode = 45
• 2.4. Conclusions = 49
• 3. Continuous preparation of diarylethane over solid acid catalysts using α-methylbenzyl alcohol = 51
• 3.1 Introduction = 51
• 3.2 Experimental = 74
• 3.2.1. Catalysts preparation and characterization = 74
• 3.2.2. Alkylation reacion in a continuous mode = 77
• 3.3. Results and discussion = 89
• 3.3.1. Synthesis of PXE using Nafion and ASA catalysts = 89
• 3.3.2. Synthesis of PXE using mordenite catalysts = 98
• 3.3.3. Synthesis of PTE using large pore zeolite catalysts = 117
• 3.4. Conclusions = 138
• 4. Conclusions = 140
• References = 145
• List of Publications = 155
• APPENDIX A. H-NMR results of target components = 157
• APPENDIX B. ETHF products identification(GC-MSD) = 160