Effect of air flow rate on preparation of boron carbide by sol-gel low-temperature pyrolysis system

Chengcheng Tian,Yang Li,Yuanxia Wang,Ying Shi,Li-Zhi Liu 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.2

The morphology and particle size of boron carbide in the sol-gel low-temperature pyrolysis system were controlled bychanging the air flow rate during the pyrolysis of boric acid glycerin system. Analyzed the infrared absorption propertiesof condensation products and pyrolysis products, as well as the carbon network structure of pyrolysis products and themicrostructure, phase composition, and particle size of boron carbide powder. The research results indicate that the airflowing in the pyrolysis atmosphere can accelerate the thermal decomposition efficiency of boric acid glycerol condensate andeffectively reduce the pyrolysis temperature. The faster the air flow rate during the pyrolysis process, the denser the carbonnetwork structure, smaller pore size, and more pores in the pyrolysis products, and the better the dispersion of boron oxide. Inthe boric acid glycerol system, with the increase of pyrolysis gas flow rate, the average particle size of boron carbide decreasesfrom 10 μm to about 2 μm. In addition, the morphology of boron carbide changes from a hexagonal diamond to a smoothermorphology. This indicates that by changing the air flow rate during the pyrolysis process, the carbon network structure ofthe pyrolysis products can be improved, thereby controlling the morphology and particle size of boron carbide. This paperprovides a new method for the study of the sol-gel low-temperature pyrolysis method to accurately control the morphology ofboron carbide.

폐플라스틱 열분해 유화공정 잔류물의 성상분석에 의한 재활용 가능성 평가

채호진(Ho Jin Che),이수출(Soo Chool Lee),박노국(No-Kuk Park),김세정(Se Jeong Kim),김태윤(Tae Yoon Kim),김태진(Taejin Kim) 한국에너지기후변화학회 2019 에너지기후변화학회지 Vol.14 No.2

The purpose of this study is to evaluate the recyclability of carbon-based solids released as residues of the waste plastic low-temperature pyrolysis process. Waste plastic low-temperature pyrolysis process is a process to produce hydrocarbon oil from waste plastic made of polypropylene (PP), polyethylene (PE), polystyrene (PS) among the household wastes by the pyrolysis liquefaction process at 350°C. The final products from the pyrolysis process are pyrolysis oils and carbon-rich solids. In general, the solids are all buried in landfills, which can cause environmental pollution in the long run. Therefore, this study investigated the recyclability of these solid residues by analyzing their element composition. Solid properties were analyzed using TGA, XRD, XRF and SEM. It was found that 30% of the residue discharged from the low-temperature pyrolysis process of waste plastic was composed of carbon, approximately 40% of recyclable hydrocarbons, and about 30% of metal oxides. Metal oxides were found to contain mainly calcium, titanium, iron, and silica etc. Because the residue includes various impurities, the residue itself is somewhat difficult to use as a high value-added recycled raw material, and it may be used as the adsorbents/absorbents for removing heavy metals and trace contaminants. In addition, when a large amount of residue is secured, it respected to can be used as a raw material for producing syngas or recycling oils through gasification or liquefaction.

저온열분해 시스템개발을 위한 농산부산물의 열분해속도 구명

정태상,박용대,민영봉 경상대학교 농업생명과학연구원 2015 농업생명과학연구 Vol.49 No.6

본 연구에서는 농산부산물의 추출물의 유효 성분 함유량을 최대화 하면서 경제적으로 생산할 수 있는 저온 열분해 탄화 시스템을 개발하기 위하여 왕겨 및 은행잎을 재료로 Thermo Gravimetric Analyzer(TGA;열중량분석기) 추출 실험을 실시하여 열분해속도를 구명하였다. 두 시료는 가열속도 5∼ 50℃/min에서, 가열온도 40∼70℃에서 탈휘발이 시작되어 200∼300℃까지 탈휘발이 활발히 진행되면 서 열분해 속도가 가장 높으며 약 300℃에서 열분해속도가 급감하여 400℃이내에서 열분해가 완료되는 것으로 나타났다. 가열 속도가 높아질수록 열분해가 시작되는 온도가 높아짐을 알 수 있었고, 최적 가 열속도는 30℃/min로 추정되며 이때 두 시료의 열분해속도는 9%/min로 동일하게 나타났다. 따라서 농 산부산물의 열분해가 완료되는 온도는 가열속도에 관계없이 400℃ 이내로 추정된다. The development of the environmentally friendly technology to use of agricultural by-products about 20% of the total production of the agricultural products as the useful clean resources is very important and urgent for the recycling of the resources, environmental protection and energy recovery. the low-temperature pyrolysis carbonization system of the agricultural by-products was used to maximize the useful ingredient content of the agricultural by-products and produce them economically. For the development of the system, TGA test of ginkgo and chaff to investigate the pyrolysis process speed of the agricultural by-products were performed. Under the heating rate of 5~50℃/min, the volatilization of two materials was started at the heating temperature of 40~70℃, proceeded actively to 200~300℃ and finished between 300~40 0℃. The pyrolysis starting temperature became higher with the heating rate becoming higher and the estimated optimum heating rate was 30℃/min and the pyrolysis process speed of ginkgo and chaff was represented to have 9%/min as same value of both. Thus the pyrolysis process of the agricultural by-products was estimated to finish below the temperature of 400℃.

CCA (Chromated Copper Arsenate)처리 목재의 저온 열분해와 CCA 유효 성분분리 특성

임기표 ( Kie Pyo Lim ),이종탁 ( Jong Tak Lee ),범정원 ( Jung Won Bum ) 한국목재공학회 2007 목재공학 Vol.35 No.1

폐타이어의 저온 열분해시 발생되는 오염물의 거동 특성

김상식(Sang-sik Kim) 대한환경공학회 2019 대한환경공학회지 Vol.41 No.8

목적: 폐타이어를 환경적으로 안전하게 처리할 수 있는 저온 열분해공정을 개발하는 데 있다. 방법: 폐타이어의 무게를 계량하여 열분해로에 장입한 후, 진공상태에서 저온으로 열분해하였다. 열분해로에서 발생되는 공해물질을 제거하기 위한 후 처리공정은 가스세정기, 응축기, 폐열보일러, 여과필터로 구성되었다. 본 연구를 위해 조사된 오염물질은 황화합물, 질소화합물, 암모니아 등 28개 대기오염물질과 복합악취, 12개의 지정악취물질, 다이옥신 그리고 응축수에 함유된 BOD 등 13개 수질오염물질이다. 결과 및 토의: 열분해로에 장입된 폐타이어는 100 Kg이며, 3회에 걸쳐 7시간 동안 진행되었다. 열분해로에서 폐타이어의 안정적 분해는 320℃ 전후에서 일어나며, 이는 열분해로의 배기가스를 통해서 확인할 수 있었다. 열분해로에서 폐타이어를 처리 시 발생되는 대기오염물질은 CO, HCl, NOx 등 10개 물질이 검출되었으며, 불소화합물, 페놀, 비소 등 18개 물질은 검출되지 않았다. 열분해로에서 발생되는 대기오염물질은 후처리공정에서 법 규제치 이하로 안정적으로 처리되었다. 폐타이어를 열분해로에서 처리할 때 발생되는 복합악취는 42,800 희석배수였다. 최종 배출구에서는 복합악취의 강도는 300 희석배수이며, 초기 발생농도 대비 99%가 저감되었다. 암모니아, 황화수소, n-발레르산 등 11개 지정악취 물질이 검출되었다. 이중 암모니아와 아세트알데히드는 가스세정기에서 각각 99.3%, 94.5%가 제거되었으며, 남은 물질은 여과필터에서 안정적으로 제거되었다. 최종배출구의 다이옥신농도는 0.002 ng-TEQ/S㎥로 배출허용기준인 5 ng-TEQ/S㎥ 보다 훨씬 낮은 농도로 나타났다. 결론: 28개의 대기오염물질중 10개가, 22개 지정악취물질 중 11개가 검출되었다. 열분해로에서 발생되는 NH₃ 농도는 후처리공정인 가스 세정기에서 97.2%가 저감되었으며, HCl농도는 여과필터를 통과한 후에 99.7%까지 저감되었다. 최종 배출구에서는 복합악취의 강도는 300 희석배수로 초기 발생농도 대비 99%가 저감되었다. 지정악취 물질인 암모니아와 아세트알데히드는 가스세정기에서 각각 99.3%, 94.5%가 제거되었다. 최종배출구의 다이옥신 농도는 0.002 ng-TEQ/S㎥로 조사되었으며, 법규제치 이하였다. Objectives: The purpose of this study is to develop environmentally stable treatment process by low temperature pyrolysis of waste tires. Methods : The weight of the waste tire was measured and charged to the pyrolysis furnace and pyrolyzed at a low temperature in a vacuum state. In order to remove the pollutants generated in the pyrolysis furnace, the post treatment process consisted of a gas scrubber, a condenser, a waste heat boiler, and a filter. The pollutants investigated for this study are 28 air pollutants such as sulfur compounds, nitrogen compounds, and ammonia, complex odor, 12 designated odorous substances, dioxin, and 13 water pollutants including BOD, CODMn contained in condensed water. Results and Discussion: The waste tire charged to the pyrolysis furnace was 100 kg, which was run three times for 7 hours. Stable decomposition of the waste tire in pyrolysis furnace occurred around 320℃, that could be confirmed by the exhaust gas of pyrolysis furnace. Out of 28 air pollutants, 10 substances such as CO, HCl and NOx were detected, and 18 substances such as fluorine compounds, phenol and arsenic were not detected. The air pollutants generated from the pyrolysis furnace were stably treated in the post-treatment process to below the legal limits. The complex odor generated when the waste tires were treated in the pyrolysis furnace was 42,800 dilution. At the final outlet, the intensity of the complex odor was 300 dilution, which was reduced by 99% compared to the initial concentration. 11 designated odor substances such as ammonia, hydrogen sulfide, and n-valeric acid were detected. Ammonia and acetaldehyde were 99.3 and 94.5% removed from the scrubber, respectively, and the remaining material was stably removed from the filter. The dioxin concentration at the final outlet was 0.002 ng-TEQ/S㎥, much lower than the emission limit of 5 ng-TEQ/S㎥. Conclusions : Ten out of 28 air pollutants and eleven out of 22 designated odorous substances were detected. The NH₃ concentration in the pyrolysis furnace was reduced by 97.2% in the scrubber, and the HCl concentration was reduced to 99.7% after passing through the filter. Ammonia and acetaldehyde, designated odor substances, were removed by 99.3% and 94.5% respectively in the gas scrubber. At the final outlet, the intensity of the complex odor was 300 dilutions, which is a 99% decrease compared to the initial concentration. The dioxin concentration at the final outlet was 0.002 ng-TEQ/S㎥, which was very allowable level to the legal.

폐전선으로부터 유가자원 회수를 위한 저온열분해(II)

한성국,김재용,Han, Seong-Kuk,Kim, Jae-Yong 한국공업화학회 2009 공업화학 Vol.20 No.5

본 연구의 목표는 열분해 기술의 문제점을 보완하여 유가자원의 회수와 폐기물 처리의 효율을 높이는데 있다. 우선 경제성을 높이기 위해 기존 열분해온도(보통 $500{\sim}1000^{\circ}C$)보다 낮은 $450^{\circ}C$에서의 저온열분해 반응을 시도하였다. 촉매를 사용하여 반응온도와 반응시간을 단축할 수 있었고, 무 산소 상태를 유지시키는데 유리하도록 간접열을 사용하였다. 결과적으로 유가자원인 구리와 합성연료유의 회수율을 증가시킬 수 있었고, 발생하는 부산물과 배가스의 처리효과가 뛰어남을 알 수 있었다. 배가스는 2단의 중화조를 통과시켜 다이옥신은 거의 발생되지 않았으며, 나머지 대기환경기준의 측정항목 또한 기준치 이하를 보였다. 이번 연구에서는 앞에서 말한 저온 열분해장치(GTPK-001)를 제작하였고, 경제적으로나 친환경적으로 상용화 개발이 가능함을 알 수 있었다. This research aims at the recovery of valuable resource and more efficient waste treatment through solving the problem of pyrolysis technique. At first, in order to raise the economical efficiency, the low temperature pyrolysis experiment was carried out at the temperature of $450^{\circ}C$, which is lower than the common pyrolysis temperature area ($500{\sim}1000^{\circ}C$). We could lower the reaction temperature and reduce the reaction time by using catalyst. Also we used indirect heat for the purpose of maintaining favorable anoxic condition. As a result, we could raise the recovery rate of the valuable copper and synthetic fuel oil. Furthermore, the by-products and flue gas could be treated more effectively as well. The flue gas passed through two stage neutralization tank, so that dioxin hardly occurs and other environment items are controlled fairly well to the environmental standard. Throughout this study, we produced the low temperature pyrolysis equipment (GTPK-001) as mentioned above, and we found out that the technique can be commercialized economically as well as environmentally friendly.

폐전선으로부터 유가자원 회수를 위한 저온열분해(1)

한성국 ( Seong Kuk Han ),김재용 ( Jae Yong Kim ) 한국공업화학회 2009 공업화학 Vol.20 No.2

폐진선으로부터 유가자원 회수를 위한 저온열분해(2)

한성국 ( Seong Kuk Han ),김재용 ( Jae Yong Kim ) 한국공업화학회 2009 공업화학 Vol.20 No.5

저온 소성 굴 패각의 피복에 의한 연안 오염 퇴적물의 성상 변화에 관한 연구

김형철,우희은,정일원,오석진,이성호,김경회 해양환경안전학회 2019 海洋環境安全學會誌 Vol.25 No.1

In this study, pyrolyzed oyster shells at a low temperature (350℃) were applied for a mesocosm experiment to confirm resulting changes in the properties of sediment. After creating a covering of oyster shells, an increase in ORP and decrease in ammonia in the overlying water was observed in an experimental case. The decrease of TOC in this experiment was due to the dilution of organic matter due to the addition of inorganic matter (pyrolyzed oyster shells). The decrease in the concentration of AVS was observed due to the adsorption of AVS by the surface of the oyster shells. From the results obtained in this experiment, it has been concluded that pyrolyzed oyster shells at a low temperature can be used for remediation of polluted sediment. 본 연구에서는 저온 소성 굴 패각의 재활용을 위한 기초적 연구로서 메조코즘 실험을 통해 저온 소성 굴 패각의 피복에 따른 연안 오염 퇴적물의 성상 변화를 조사하였다. 이를 위해 350°C에서 소성시킨 굴 패각을 연안 오염 퇴적물에 피복하여 직상수와 간극수의 성상변화를 분석하는 메조코즘 실험을 수행하였다. 실험 결과, 굴 패각의 피복에 의해 수층과 퇴적층이 분리되었기 때문에 직상수의 산화환원전위(ORP) 증가 및 DIN 중의 NH3-N의 비율의 감소가 실험구에서 관측되었다. 실험구의 DIP의 농도는 대조구와 비교하여 유의한 차이를 확인하기 어려웠다. 굴 패각의 피복에 의한 퇴적물의 총유기탄소(TOC)는 감소하였으며, 산휘발성황화물(AVS)은 저온 소성 굴 패각의 황화물 흡착 능력으로 인해 최대 50%까지 감소한 것으로 확인되었다. 본 연구의 결과로부터 저온 소성 굴 패각은 연안 오염 퇴적물의 정화를 위해 이용될 수 있는 재료인 것으로 결론 지을 수 있다.

A facile two-step preparation of compact and crystalline Sb2S3 thin film for efficient solar cells

Wu Di,Wu Yu,Wang Yanqing,Lv Kai,Shi Chengwu 한국물리학회 2021 Current Applied Physics Vol.29 No.-

The two-step preparation of compact and crystalline Sb2S3 thin films was firstly reported using the pyrolysis of the Sb-butyldithiocarbamate complex solution in DMF. The porous and amorphous Sb2S3 thin films were successfully prepared at 170 ◦C for 30 min, and then can be converted to compact and crystalline Sb2S3 thin films at 200 ◦C for 30 min or 300 ◦C for 2 min. The corresponding solar cells with the architecture of FTO/TiO2 compact layer/Sb2S3/spiro-OMeTAD/Au achieved the photoelectric conversion efficiency of 4.16% at 200 ◦C and 5.05% at 300 ◦C. The two-step preparation of the compact and crystalline Sb2S3 thin films can provide the feasible approach for the fabrication of various microstructure thin film solar cells and the low preparation temperature of 200 ◦C was also attractive to assemble the flexible Sb2S3 thin film solar cells.