Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst

Lee, Kyong-Hwan,Jeon, Sang-Gu,Kim, Kwang-Ho,Noh, Nam-Sun,Shin, Dae-Hyun,Park, Jaehyeon,Seo, Younghwa,Yee, Jurng-Jae,Kim, Geug-Tae 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430℃ into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.

Energy And Environmental Engineering : Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst

( Kyong Hwan Lee ),( Sang Gu Jeon ),( Kwang Ho Kim ),( Nam Sun Noh ),( Dae Hyun Shin ),( Jae Hyeon Park ),( Young Hwa Seo ),( Jurng Jae Yee ),( Geug Tae Kim ) 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4

Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430℃ into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.

Thermal Degradation and Cyclodepolymerization of Poly(ethylene terephthalate-co-isophthalate)s

Yoo, Dong Il,Shin, Younsook,Youk, Ji Ho The Korean Fiber Society 2001 Fibers and polymers Vol.2 No.2

The thermal degradation of poly(ethylene terephthalate-co-isophthalate)s (PETIs) is investigated by using isothermal thermogravimetric analysis at the temperature range of 280-31$0^{\circ}C$. The degradation rate of PETIs is increased as the mole ratio of ethylene isophthaloyl (EI) units in PETIs increases. The activation energies for the thermal degradation of poly(ethylene terephthalate), PETI(5/5), and poly(ethylene isophthalate) are 33.4, 16.6, and 8.9 kcal/mole, respectively. The degradation rate of PETIs is influenced by their volatile cyclic oligomer components formed during the polymerization and the thermal degradation. It is simulated by the rotational isomeric state model that the content of cyclic dimer in PETIs, which is the most volatile cyclic oligomer component, increases with the EI units in PETIs.

Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate

Pravin Sukharaj Bhandari,Parag Ratnakar Gogate 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.12

Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate (SDBS) was investigated, focusing on establishing the best conditions for maximum degradation. The study involving different persulfate based oxidants, such as potassium persulfate (KPS), ammonium persulfate (NH3PS) and sodium persulfate (NaPS), revealed that the extent of degradation as 98.3, 82.2 and 68.2% was obtained for the use of KPS, NH3PS and NaPS, respectively. The study of the effect of SDBS concentration (25-100mg/L), oxidant loading (0-3g/L) and power (140-350W) established that degradation decreased with an increase in the operating parameter beyond the optimum condition. Under optimized conditions using potassium persulfate (KPS) as an oxidant, 51.6% and 98.3% degradation of 50mg/L SDBS solution was obtained by conventional and microwave assisted chemical oxidation approach, respectively, under optimized conditions of power, oxidant loading, volume and time maintained as 280W, 2g/L, 250mL and 28min, respectively. Extending the conventional approach for 120min resulted in degradation of 92.5%, which establishes that microwave helps in reducing the treatment time significantly. Kinetic study revealed pseudo-first-order behavior for degradation of SDBS. Energy per order (EEO) for conventional and microwave assisted degradation was observed to be 840 and 317.33kWh/m3, respectively. Overall, microwave assisted persulfate induced degradation of SDBS has been established to be promising method giving rapid degradation and better economics.

핫프레스 공정 기반 CF-PEKK 복합재의 근적외선 고속가열에 의한 열적 열화 반응의 메커니즘 분석

이교문,박수정,박예림,박성재,김윤해 한국복합재료학회 2022 Composites research Vol.35 No.2

The application of infrared heating in the hot press forming of the thermoplastic composites is conducive to productivity with high-speed heating. However, high energy, high forming temperature, and high-speed heating derived from infrared heating can cause material degradation and deteriorate properties such as re-melting performance. Therefore, this study was conducted to optimize the process conditions of the hot press forming suitable for carbon fiber reinforced polyetherketoneketone(CF/PEKK) composites that are actively researched and developed as high-performance aviation materials. Specifically, the degradation mechanisms and properties that may occur in I9infrared high-speed heating were evaluated through morphological and thermal characteristics analysis and mechanical performance tests. The degradation mechanism was analyzed through morphological investigation of the crystal structure of PEKK. As a result, the size of the spherulite decreased as the degradation progressed, and finally, the spherulite disappeared. In thermal characteristics, the melting temperature, crystallization temperature and heat of crystallization tend to decrease as degradation progresses, and the crystal structure disappeared under long-term exposure at 460°C. In addition, the low bonding strength was observed on the degraded surface, and the bonding surfaces of PEKK did not melt intermittently. In conclusion, it was confirmed that the CF/PEKK composite material degraded at 420°C in the infrared high-speed heating. Furthermore, the spherulite experienced morphological changes and the re-melting properties of thermoplastic materials were degraded. 열가소성 복합재의 핫프레스 성형공정에서 근적외선 가열의 적용은 소재를 성형온도까지 고속가열함으로써 공정 전체의 생산성을 확보할 수 있으나, 고에너지, 높은 성형온도, 고속가열에 의해 소재의 열화가 발생하여 재용융 성능 등의 소재 특성이 저하될 수 있다. 이에 본 연구는 고성능 항공소재로 활발히 연구개발되고 있는Carbon fiber reinforced Polyetherketoneketone(CF/PEKK) 복합재에 적합한 핫프레스 성형공정의 최적화된 공정조건을 확립하기 위하여 근적외선 고속가열을 적용하였을 때, CF/PEKK 복합재에서 발생할 수 있는 열화 메커니즘과 그 특성을 형태학적, 열적 특성 및 기계적 성능 시험을 통해 평가하였다. 열화 반응에 따른 메커니즘 규명은 광학 현미경을 활용하여 PEKK의 결정구조의 형태학적 조사를 기반으로 분석하였다. 그 결과, 열화가 진행됨에 따라 구결정의 크기가 감소하며 최종적으로 완전 열화 시 구결정이 소멸되는 것을 확인하였다. 열적 특성은 용융온도, 결정화온도, 발열량이 열화가 진행됨에 따라 감소하는 경향이 관찰되며, 460oC 장시간 노출에서 결정구조가 소멸된 것을 확인하였다. 랩전단강도(Lap shear strength)시험 결과, 열화된 표면에서는 낮은 접합강도가 관찰되며, 접합면 분석에서 특정 면에서는 열에 의한 용융 특성이 나타나지 않았다. 결론적으로 CF/PEKK 복합재의 근적외선 고속가열 적용에 있어 특정 온도에서 열화 진행되며, 이에 구결정의 형태학적 변화와 열가소성 소재의 재용융 특성의 저하를 확인하였다.

Characterization of Thermal Products of Alpha-Tocopherol

Chung, Hee-Young The Korean Society of Food Science and Nutrition 2004 Preventive Nutrition and Food Science Vol.9 No.4

Alpha-tocopherol was thermally oxidized and degraded at high temperatures and the resulting products were chromatographically separated and identified by LC-MS. Alpha-tocopherol dissolved in glycerol was heated at 200^{\circ}C for 30 min. The thermal products were separated by hexane extraction and analyzed by HPLC using a reversed phase $\mu$-Bondapak $C_{18}-column$ with two kinds of elution solvents: a mixture of acetonitrile and methanol (3:2), and of acetonitrile, methanol, 2-propanol, chloroform and methylene chloride (3:2:5:0.5:0.5) in a gradient mode. The isolated thermal. products of alpha-tocopherol were more viscous than alpha-tocopherol, and dark brown in color. Major thermal degradation products of alpha-tocopherol were identified by LC-MS, and the structures of thermal products were proposed. Alpha-tocopherol and its thermal degradation products were degraded into fragments, mainly at the non-aromatic parts. The degradation products of alpha-tocopherol. were combined with oxidized product (tocopherylquinone) to make thermal. products through dimerization.

Performance Analysis of a Once-Through Steam Generator for Constant Thermal Power Operation

Hun Sik Han(한훈식),Juhyeon Yoon(윤주현),Young In Kim(김영인) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

A numerical study is made of the operation strategy of a once-through steam generator considering degradation in the thermal-hydraulic performance. The performance of the steam generator is gradually degraded as it experiences fouling, clogging, and plugging during its lifetime. To maintain the thermal power of the steam generator, therefore, its operating condition should be properly changed according to the degradation rate. Emphasis is given to the operation strategy of the steam generator to transport a constant thermal power regardless of the degradation rate. Comprehensive numerical solutions to the governing equations are acquired. It is found that a constant thermal power can be maintained by properly adjusting the secondary coolant outlet pressure with a variation of the superheat degree and secondary coolant pressure drop. A constant thermal power operation curve is obtained, and the thermal-hydraulic performance of the steam generator is analyzed according to the degradation rate in terms of the degree of superheat, secondary coolant pressure drop, temperature distribution, and quality distribution in the tube.

A Kinetic Study of Thermal Degradations of Chitosan/Polycaprolactam Blends

Liao, Shen-Kun,Hung, Chi-Chih,Lim, Ming-Fung The Polymer Society of Korea 2004 Macromolecular Research Vol.12 No.5

We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

Effects of heat and Gamma radiation on the degradation behaviour of fluoroelastomer in a simulated severe accident environment

송인영,이태현,류경하,김용진,김명성,박종원,김지현 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.12

In this study, the effects of heat and radiation on the degradation behaviour of fluoroelastomer under simulated normal operation and a severe accident environment were investigated using sequential testing of gamma irradiation and thermal degradation. Tensile properties and Shore A hardness were measured, and thermogravimetric analysis was used to evaluate the degradation behaviour of fluoroelastomer. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the structural changes of the fluoroelastomer. Heat and radiation generated in nuclear power plant break and deform the chemical bonds, and fluoroelastomer exposed to these environments have decreased CeH and functional groups that contain oxygen and double bonds such as CeO, C¼O and C¼C were generated. These functional groups were formed by auto oxidation by reacting free radicals generated from the cleaved bond with oxygen in the atmosphere. In this auto oxidation reaction, crosslinks were generated where bonded to each other, and the mobility of molecules was decreased, and as a result, the fluoroelastomer was hardened. This hardening behaviour occurred more significantly in the severe accident environment than in the normal operation condition, and it was found that thermal stability decreased with the generation of unstable structures by crosslinking.

지역난방 노후 축열조의 부식 건전성 평가 및 고찰

윤대호,채호병,김희산,김정구,김우철,하태백,장재혁,정준철,이수열 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.10

The thermal storage tank in a district heating system is a component that stores excess heat during normal operation and releases the stored heat to increase the efficiency of the system, when the heat source is stopped or additional demands occur. Recently, an obsolete thermal storage tank was dismantled for the first time since it began operation 30 years ago. In this work, the corrosion integrity of the obsolete thermal storage tank was evaluated by examining its appearance, thickness thinning, corrosion products, microstructure, and mechanical properties. Samples were taken at various locations (roof, shell, bottom) of the thermal storage tank, which enabled diagnosis of the respective environmental degradations. Severe corrosion was found in the roof edge plate due to corrosion under the insulation, and exhibited thinning exceeding ~49% of the designed thickness. In this location, the ferrite-pearlite band structure disappeared and deteriorated microstructures, such as decarburization and spheroidized pearlite, were measured, which resulted in a ~27% decrease in hardness. The inner surfaces of the bottom and shell plate were well covered with a magnetite film, and the degradation of the microstructure and mechanical properties showed a permissible limit in terms of ASTM A285/ A516. In addition, no particular drop in hardness was found in the weld zone of each plate.