제올라이트형 촉매합성과 포리올레핀의 접촉분해 특성 = Syntheses of zeolite like catalysts and characteristics for catalytic cracking of polyolefins

다국어 초록 (Multilingual Abstract)

Coal fly ash was utilized to make a catalyst(zeolite) for pyrolysis of polyolefins(Polypropylene : PP, Polyethylene : LDPE). The syntheses of zeolite like catalysts from coal fly ash(FAZ : fly ash derived zeolite) were carried out by hydrothermal reaction with pre-treatment through fusion reaction.
Additionally, Na^(+) in FAZs was exchanged to H-type for improving the catalytic activity for pyrolysis.
The cation exchange was carried out by NH4Cl treatment. In this study, the experimental parameters were fusion ratio(NaOH/Coal fly ash : 0.7(HFAZ(0.7)), 1.2(HFAZ(1.2)), 1.7(HFAZ(1.7)),crystallization time (5hr(HFAZ(5)), 10hr(HFAZ(10)), 15hr(HFAZ(15)), 20hr(HFAZ(20)) and crystallization temperature(40℃(HFAZ(40), 100℃HFAZ(100), 130℃HFAZ(130)).
X-ray diffractometer(Model X'Pert-MPD, Phillips Analytical) was mainly used for the characterization of FAZs. The pyrolysis performances of HFAZs were assessed in terms of the boiling point distribution of liquid products obtained from the catalytic pyrolysis by SIMDIS(Simulated Distillation GC: ASTM D2887, HP 6890 GC) and the changes of degradation temperature by MSB(Magnetic Suspension Balance, Rubotherm). The pyrolysis performances of HFAZs were compared with that of commercial HY zeolites and no catalyst.
Generally, the pyrolysis performances of HFAZs were better than those of no catalyst. It indicates that HFAZs have catalytic effects for the pyrolysis of polyolefins.
According to fusion ratios, the crystalline types of FAZs synthesized were different. Therefore, the pyrolysis performances were also changed to HFAZs. The main type of zeolite in FAZ(0.7) was NaP1, which showed higher degradation temperature and boiling point distribution than HFAZ(1.2) and HFAZ(1.7). It says that NaP1 can hardly take effects for the pyrolysis of polyolefins. The X-type zeolite synthesized in fusion ratios of 1.2 and 1.7 showed a relatively good pyrolysis effects. It is due to the various pore size owing to the types of zeolites. X-type zeolite having a larger pore size(7.3A) than NaP1(4.6A) is comparatively easy to crack the carbon bond in polyolefins. Especially in the pyrolysis of PP, X-type zeolite of HFAZ(1.2) showed the effects as good as commercial HY zeolites. For the pyrolysis of LDPE, the catalytic effects of HFAZs were not resulted as good as PP because LDPE had a linear carbon bond. It means that the tertiary structure of methyl group in PP is broken more easily than the linear carbon bond in LDPE. Therefor, the pyrolysis performances of HFAZs are better in PP than in LDPE.
The changeability of degradation temperature can be different according to bonding properties. The degradation temperature was significantly changed to the types of HFAZs in PP. But these changes were not shown in LDPE with a strong carbon bond. It was caused by the reason that HFAZs' catalytic activity causing the changes of degradation temperature was generally not enough for degradation of LDPE.
The effects of the crystallization time on pyrolysis performance were not remarkable. It is resulted from the reason that the types of zeolites synthesized were X-type zeolites in all conditions of crystallization time. Therefore, it was hard to find the significant changes among HFAZs synthesized according to crystallization time.
The effects on pyrolysis of polyolefins were changed to the crystallization temperature. It is due to the different crystalline types of HFAZs synthesized according to the crystallization temperature. The main crystalline types of HFAZ(40) and HFAZ(100) were NaP1 with small amount of hydroxysodalite and X-type zeolite, respectively. In HFAZ(130), the crystalline structures of zeolite were almost disappeared. For the pyrolysis of PP, crystalline HFAZ(40)(NaP1) and amorphous HFAZ(130) resulted in a higher degradation temperature and boiling point distribution than HFAZ(100) of X-type zeolite. These results were inferred to the relatively large pore size of X-type zeolite like the results appeared in the fusion ratio parameter.
The degradation temperature of LDPE according to crystallization temperatures were not changed significantly like the results shown in the fusion ratio parameter. However, in terms of the boiling point distribution, HFAZ(130) and HFAZ(100) showed the worst and best effects, respectively. The catalytic performance of HFAZ(40) including NaP1 was as bad as amorphous HFAZ(130) in PP, but it was shown as good as HFAZ(100) of X-type zeolite in LDPE. These results were caused by the strong bond of LDPE which was difficult to be broken by the first cracking reactions at active sites out of pore in zeolites. It prevented the second cracking reactions from being occurred at active sites in pore. Therefore, the changes of effects connected to pore size are not remarkable between HFAZ(40) of NaP1 and HFAZ(100) of X-type zeolite.
NaP1 was synthesized in conditions at 40℃ of crystallization temperature and 0.7 of fusion ratio. Although the crystalline structure had a similarity, the catalytic effects of HFAZ(40) and HFAZ(0.7) on pyrolysis of LDPE were different. The effects of NaP1 of HFAZ(40) on boiling point distribution were as good as X-type zeolite but that of HFAZ(0.7) was worse than that of X-type zeolite significantly. It was occurred by the reason that HFAZ(0.7) included the residue untransformed to zeolites. It caused the low catalytic activity for the pyrolysis of LDPE.

목차 (Table of Contents)

• 목차
• 1. 서론 = 1
• 2. 이론적 고찰 = 7
• 2.1. 비산회(coal fly ash) = 7
• 2.2. 제올라이트 촉매특성 = 8
• 2.3. 크래킹 반응 메커니즘 = 22
• 2.3.1 열분해 = 22
• 2.3.2 접촉분해 = 24
• 3. 실험재료 및 방법 = 28
• 3.1. 실험재료 = 28
• 3.1.1 비산회 = 28
• 3.1.2 폴리올레핀 = 28
• 3.2. 촉매 제조 = 33
• 3.2.1 용융(fusion) 전처리 = 33
• 3.2.2 수열합성 = 34
• 3.3. 촉매 특성분석 = 39
• 3.3.1 XRD = 39
• 3.3.2 SEM = 39
• 3.3.3 BET = 39
• 3.3.4 NH₃-TPD = 39
• 4.3. 열분해 특성 = 42
• 4.3.1 MSB 분석 = 42
• 4.3.2 회분식 분해 = 42
• 4.3.3 SIMDIS 분석 = 47
• 4. 결과 및 고찰 = 49
• 4.1. 촉매특성 = 49
• 4.1.1 용융 전처리 영향 = 49
• 4.1.2 용융 혼합비의 영향 = 52
• 4.1.3 수열합성 시간에 따른 영향 = 60
• 4.1.4 수열합성 온도에 따른 영향 = 67
• 4.2. PP 분해 = 74
• 4.2.1 열적특성 = 74
• 4.2.2 오일생성물 특성 = 79
• 4.3. LDPE 분해 = 89
• 4.3.1 열적특성 = 89
• 4.3.2 오일생성물 특성 = 94
• 5. 결론 = 105
• REFERENCE = 107
• ABSTRACT = 117