Catalytic Co-pyrolysis of Cellulose and Thermoplastics over HZSM-5 and HY Zeolites

국문 초록 (Abstract)

HZSM-5 제올라이트를 이용한 바이오매스의 촉매 열분해는 방향족 탄화수소의 생산을 위한 환경친화적 방법으로 여겨지지만, 낮은 방향족 수율이 문제점으로 남아있다. 최근 바이오매스의 촉매 열분해에 수소가 풍부한 플라스틱을 혼합 투입함으로써 방향족 수율을 증대시키는 연구가 진행되고 있다. 따라서, 본 연구에서는 제올라이트 촉매의 기공 크기와 투입하는 플라스틱의 분자 직경이 촉매 혼합 열분해의 열적 거동 및 방향족 탄화수소 생성에 미치는 영향을 파악하기 위해 HZSM-5와 HY를 이용한 셀룰로오스와 플라스틱 고분자(폴리프로필렌(PP), 선형 저밀도 폴리에틸렌(LLDPE))의 촉매 혼합 열분해를 수행하였다. 비등온 열중량 분석 결과, HZSM-5를 사용한 셀룰로오스-PP 혼합물의 열분해에서 PP의 분해온도가 고온으로 상승하였으며, 이는 PP 분자의 HZSM-5의 작은 기공으로 유입될 때 셀룰로오스가 먼저 반응하여 생성된 촤(char)와 코크(coke)에 의해 방해받기 때문으로 판단된다. 분자 직경이 작은 LLDPE 또는 기공이 큰 HY를 적용할 경우, 이러한 방해작용이 줄어들었다. 상세한 생성물의 분포를 확인하기 위해 heart cut-evolved gas analysis (EGA)-GC/MS와 flash pyrolysis-GC/FID 분석을 수행하였다. HY 촉매를 사용할 경우, PP와 LLDPE 모두 방향족 생성에 있어 상승 효과가 관찰되었으며, 이는 촉매 혼합 열분해에서 큰 기공 크기가 효과적임을 보여준다. 반면, HZSM-5 촉매는 촉매비가 크거나(10:1) 반응온도가 높은(600˚C) 경우에 방향족 생성이 크게 증가하였다.

다국어 초록 (Multilingual Abstract)

Catalytic pyrolysis with HZSM-5 is a promising method for the production of renewable aromatic hydrocarbons directly from solid biomass, even though the aromatic yields are still very low. Recent studies have shown that co-feeding of biomass with plastic significantly improves the aromatic yield due to high hydrogen content in plastic. In an effort to determine the influence of the zeolite pore size and the molecular diameter of co-feeding plastic on the aromatic production, catalytic co-pyrolysis of cellulose and thermoplastics, including random polypropylene (PP) and linear low density polyethylene (LLDPE) was conducted over HZSM-5 and HY catalysts. Thermogravimetric (TG) results showed that maximum decomposition temperature of PP was shifted to the higher temperature when PP was co-pyrolyzed with cellulose over HZSM-5 because the diffusion of PP molecules was hindered by the cellulose-derived coke and char. This hindering effect was attenuated by employing LLDPE as the co-feeding plastic due to its smaller molecular diameter than PP, and/or applying HY due to its larger pore size than HZSM-5. Heart cut-evolved gas analysis (EGA)-GC/MS and flash pyrolysis-GC/FID were used to monitor the detailed product distribution and yields. The synergistic aromatic formation was easily achieved over HY catalyst for both PP and LLDPE, demonstrating the effectiveness of the larger pore zeolite for the catalytic co-pyrolysis. In contrast, HZSM-5 was very effective for the enhancement of aromatic production under severe reaction conditions, such as high catalyst to feed ratio (i.e. 10:1) or high pyrolysis temperature (i.e. 600˚C).

목차 (Table of Contents)

• CHAPTER I. INTRODUCTION 1
• 1-1. Research backgrounds 1
• 1-2. Research purpose 4
• CHAPTER II. LITERATURE REVIEW 5
• 2-1. Biomass 5
• 2-1-1. Biomass for sustainable energy production 5
• 2-1-2. Characteristics of biomass 7
• 2-2. Thermal and catalytic pyrolysis of biomass 9
• 2-2-1. Chemistry in thermal (non-catalytic) pyrolysis 9
• 2-2-2. Chemistry in catalytic pyrolysis 11
• 2-3. Co-pyrolysis 16
• 2-3-1. Thermal (non-catalytic) co-pyrolysis 16
• 2-3-2. Catalytic co-pyrolysis 21
• 2-4. Analytical pyrolysis 27
• CHAPTER III. EXPERIMENTAL METHODS 29
• 3-1. Sample preparation 29
• 3-1-1. Feedstock materials 29
• 3-1-2. Zeolite catalysts 31
• 3-2. Thermogravimetric analysis 34
• 3-3. Analytical pyrolysis reaction 34
• 3-3-1. Non-isothermal heart cut EGA-GC/MS 35
• 3-3-2. Isothermal Py-GC/FID 36
• CHAPTER IV. RESULTS AND DISCUSSION 38
• 4-1. Thermogravimetric analysis 38
• 4-2. Non-isothermal heart cut EGA-GC/MS analysis 47
• 4-2-1. Thermal and catalytic pyrolysis of cellulose 47
• 4-2-2. Thermal and catalytic pyrolysis of PP and LLDPE 54
• 4-2-3. Thermal and catalytic pyrolysis of cellulose-plastic mixtures 62
• 4-3. Isothermal Py-GC/FID analysis 72
• CHAPTER V. CONCLUSION AND FUTURE WORK 81
• 5-1. Conclusion 81
• 5-2. Future work 82
• REFERENCES 83
• SUMMARY (IN KOREAN) 97