Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Recovery of Lipids from Chlorella sp. KR-1 via Pyrolysis and Characteristics of the Pyrolysis Oil

Chlorella sp. KR-1 열분해에 의한 지질 회수 및 열분해 오일 특성 분석

  • Lee, Ho Se (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Jeon, Sang Goo (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Oh, You-Kwan (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Kim, Kwang Ho (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Chung, Soo Hyun (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Na, Jeong-Geol (Clean Fuel Department, Korea Institute of Energy Research) ;
  • Yeo, Sang-Do (Department of Chemical Engineering, Kyungpook National University)
  • 이호세 (한국에너지기술연구원 청정연료연구단) ;
  • 전상구 (한국에너지기술연구원 청정연료연구단) ;
  • 오유관 (한국에너지기술연구원 청정연료연구단) ;
  • 김광호 (한국에너지기술연구원 청정연료연구단) ;
  • 정수현 (한국에너지기술연구원 청정연료연구단) ;
  • 나정걸 (한국에너지기술연구원 청정연료연구단) ;
  • 여상도 (경북대학교 화학공학과)
  • Received : 2012.01.30
  • Accepted : 2012.03.20
  • Published : 2012.08.01
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Abstract

Lipids in microalgal biomass were recovered by using pyrolysis method. The pyrolysis experiments of two Chlorella sp. KR-1 samples, which have triglyceride contents of 10.8% and 36.5%, respectively were carried out at $600^{\circ}C$ to investigate the effects of lipid contents in the cells on the reaction characteristics. The conversion and liquid yield of the lipid-rich sample were higher than those of the lipid-lean sample since its carbon to hydrogen ratio was low. There were low molecular weight organic acids, ketones, aldehydes and alcohols in the liquid products from both KR-1 samples, but the pyrolysis oil of the lipid-rich sample was abundant in free fatty acids, particularly palmitic acid, oleic acid and stearic acid while the content of nitrogen containing organic compounds was low. The microalgal pyrolysis oil had two layers composed of the light hydrophobic fraction and the heavy hydrophilic fraction. The light fraction might be originated from triglycerides and the heavy fraction might be from carbohydrates and proteins. In the light fraction of the liquid products, there were considerable linear alkanes such as pentadecane and heptadecane as well as free fatty acids, implying that deoxygenation reaction including decarboxylation was occurred during the pyrolysis. The yield of the liquid products from the pyrolysis of the KR-1 sample having triglyceride content of 36.5% was 56.9% and the light fraction in the liquid products was 68.2%. Also more than 80% of the light fraction was free fatty acids and pure hydrocarbons, thus showing that most triglycerides could be extracted in the form of suitable raw materials for biofuels.

Chlorella sp. KR-1 바이오매스에 대한 열분해를 통하여 세포 내 지질을 회수하였다. 중성지질 함량이 10.8%와 36.5%인 두 종류의 KR-1 샘플에 대하여 $600^{\circ}C$에서 열분해를 수행함으로써 지질 함량이 열분해 오일 수율 및 품질 등 반응 특성에 미치는 영향을 살펴보았다. 열분해 결과, 중성지질 함량이 높아 C/H 비가 낮은 샘플이 열분해 전환율 및 오일 수율이 높았다. 저분자량의 유기산, 케톤, 알데히드, 알콜은 두 시료의 열분해에서 모두 발생하였으나 중성지질 함량이 높은 미세조류의 경우 palmitic acid와 oleic acid를 비롯한 유리 지방산의 함량이 높은 대신 질소 함유 유기화합물의 함량은 상대적으로 적었다. 미세조류 열분해 오일은 두 개의 층으로 분리되는데 상부의 경질 분획은 지질 분해에 의하여, 하부의 중질 분획은 당류나 단백질의 분해에 의하여 생성된 것으로 판단되었다. 상부의 경질 분획에는 중성지질의 분해 산물인 유리지방산 이외에 직쇄형 알칸도 상당 부분 포함되어 있었으며 이는 미세조류 열분해시 열분해와 함께 탈카르복실 반응을 비롯한 탈산소 반응이 동시에 일어났기 때문이다. GC 분석을 통하여 생성된 열분해 오일의 품질을 조사하고 지질 추출 방법으로서의 열분해 공정을 평가하였다. 중성지질 함량이 36.5%인 KR-1 샘플의 경우 열분해 수율이 56.9%이며 이 중 경질분획은 68.2%로서 경질분획 만의 수율은 38.8%였다. 또한, 경질분획의 80% 이상이 유리지방산과 순수 탄화수소로 구성되어있어 열분해를 통하여 대부분의 지질을 회수할 수 있음을 확인하였다.

Keywords

Acknowledgement

Supported by : 한국에너지기술연구원

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