Korean Chemical Engineering Research, Vol.46, No.1, 194-199, February, 2008
Amberlyst-15를 이용한 자트로파 오일의 에스테르화 반응 최적화 및 바이오디젤 생산
Optimization of Esterification of Jatropha Oil by Amberlyst-15 and Biodiesel Production
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초록
본 연구에서는 자트로파 오일로부터 바이오디젤을 생산하는데 적합한 유리지방산의 에스테르화 조건을 검토하였다. 자트로파 오일의 초기 산가는 11.5 mg KOH/g으로, 알칼리 촉매를 적용한 직접 전이에스테르화 공정은 바이오디젤 수율이 낮은 문제가 있어 유리지방산을 산촉매를 사용하여 에스테르화 후 전이에스테르화하는 2단계 반응공정의 적용이 필요하였다. 전처리 공정에 적합한 고체 산 촉매를 도출하기 위해 4가지 고체 산 촉매에 대한 성능 비교 연구를 수행하였으며 Amberlyst-15를 최적 촉매로 선정하였다. Amberlyst-15를 사용한 반응표면분석법(response surface method, RSM)에 의해 구한 최적 전처리 반응조건은 메탄올 6.79%, 촉매 17.14%로, 산가가 0.7 mgKOH/g으로 감소하였다. 전처리 후 알칼리 촉매 KOH를 이용한 전이에스테르화 반응을 가압 회분식 반응기에서 수행하여 바이오디젤을 생산하였다. 그 결과 지방산 메틸 에스터(fatty acid methyl ester, FAME) 함량 97.35%를 비롯하여 산화 안정성 8.17 h, 총 글리세롤 함량 0.125%, 저온필터막힘점(cold filter plugging point, CFPP) 0 ℃ 등으로 나타났으며 주요 바이오디젤 품질 규격을 모두 만족하였다.
In this study, the effective method to esterify the free fatty acids in jatropha oil was examined. Compared to other plant oils, the acid value of jatropha oil was remarkably high, 11.5 mgKOH/g. So direct transesterification by a base catalyst was not suitable for the oil. After the free fatty acids were esterified with methanol, jatropha oil was transesterified. The activities of four solid acid catalysts were tested and Amberlyst-15 showed the best activity for the esterification. After constructing the experiment matrix based on RSM and analyzing the statistical data, the optimal esterification conditions were determined to be 6.79% of methanol and 17.14% of Amberlyst-15. After the pretreatment, jatropha biodiesel was produced by the transesterification using KOH in a pressurized batch reactor. Jatropha biodiesel produced could meet the major specifications of Korean biodiesel standards; 97.35% of FAME, 8.17 h of oxidation stability, 0.125% of total glycerol and 0 ℃ of CFPP.
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