고온 반회분식 반응기에서의 팜 지방산 에스테르화 반응의 모델링

Abstract

바이오디젤은 경유와 유사한 특성을 지니며 동물성 기름 및 식물성 유지와 알코올을 반응시켜 얻는다. 바이오디젤은 연료로 사용시 유해 배출가스가 감소하는 등의 환경적인 장점이 있어서 대체 에너지원으로 각광받아 왔다. 본 연구에서는 기존의 바이오디젤 합성반응과는 달리 반회분식 반응기에서 팜 지방산(palm fatty acid distillate; PFAD)를 원료로 사용하는 에스테르화(esterification) 반응을 통하여 바이오디젤의 주성분인 유리 지방산 에스테르(free fatty acid ester; FAME)를 생성하는 반응에 대한 수학적인 모델링 및 모사연구를 수행하였다. 반응속도식으로서 유사 균일 2차 반응속도식을 적용하였으며, 경쟁관계에 있는 물과 메탄올의 반응과 증발을 고려하기 위하여 "반응 유효인자"를 도입하였다. 비선형 프로그래밍을 사용한 최적화 기법을 이용하여 실험값과 수치해석적 방법으로부터 얻은 값의 차이가 최소가 되는 동역학적 매개변수를 도출하였으며, 이를 바탕으로 반응의 겉보기 활성화 에너지 및 반응열이 각각 41.91 과 19.95 kJ/mol임을 확인하였다. 별도의 촉매를 첨가 하지 않아도 기존 연구와 유사한 활성화 에너지를 갖는 것은 온도 및 압력 조건에 따른 각 성분의 유전율 상수와 이온 전도의 변화로 인하여 발생되는 이온에 의한 산 촉매 효과에 따른 것으로 추정된다. 본 연구로부터 촉매의 첨가 없이 PFAD로부터 FAME계 바이오디젤의 효율적 생산이 가능함을 알 수 있었다.|Biodiesel has been spotlighted as one of the most promising substitute energy resources because of its biodegradable and nontoxic features as well as low emissions, compared to conventional petroleum diesel. The esterification reaction scheme performed under the non-catalytic and high temperature condition (230-290 oC) was quantitatively analyzed by using a mathematical modeling. Assuming that the esterification reaction is the pseudo homogeneous 2nd order reversible reaction rate, the "reaction effectiveness factor ( )" was introduced to take into account the simultaneous consumption of methanol by the reaction and evaporation. The nonlinear programing was utilized to derive optimal kinetic parameters for the purpose of minimizing the error between experimental data and the numerical values. Based on these parameters, the apparent activation energy and the heat of reaction were calculated to be 41.91 and 19.95 kJ/mol, respectively. The value of the activation energy of esterification without catalyst is similar to that of conventional reactions. This seems to be caused by the catalytic effect of ions depending on the dielectric constant and ionic conduction of each component affected by the temperature and pressure conditions. From the present work, we can see that efficient production of fatty acid methyl ester (FAME) biodiesel from palm fatty acid distillate (PFAD) is possible.; Biodiesel has been spotlighted as one of the most promising substitute energy resources because of its biodegradable and nontoxic features as well as low emissions, compared to conventional petroleum diesel. The esterification reaction scheme performed under the non-catalytic and high temperature condition (230-290 oC) was quantitatively analyzed by using a mathematical modeling. Assuming that the esterification reaction is the pseudo homogeneous 2nd order reversible reaction rate, the "reaction effectiveness factor ( )" was introduced to take into account the simultaneous consumption of methanol by the reaction and evaporation. The nonlinear programing was utilized to derive optimal kinetic parameters for the purpose of minimizing the error between experimental data and the numerical values. Based on these parameters, the apparent activation energy and the heat of reaction were calculated to be 41.91 and 19.95 kJ/mol, respectively. The value of the activation energy of esterification without catalyst is similar to that of conventional reactions. This seems to be caused by the catalytic effect of ions depending on the dielectric constant and ionic conduction of each component affected by the temperature and pressure conditions. From the present work, we can see that efficient production of fatty acid methyl ester (FAME) biodiesel from palm fatty acid distillate (PFAD) is possible.