Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Thermal Characteristics of LaMnO3 Non-isothermal Synthesis Reaction

LaMnO3 비등온 합성반응의 열적특성

  • Jeon, Jong Seol (Department of Chemical Engineering, Chungnam National University) ;
  • Lee, Jung Hun (Department of Chemical Engineering, Chungnam National University) ;
  • Yoon, Chang Hyeok (Department of Chemical Engineering, Chungnam National University) ;
  • Yoo, Dong Jun (Department of Chemical Engineering, Chungnam National University) ;
  • Lim, Dae Ho (Department of Chemical Engineering, Chungnam National University) ;
  • Kang, Yong (Department of Chemical Engineering, Chungnam National University)
  • 전종설 (충남대학교 화학공학과) ;
  • 이정훈 (충남대학교 화학공학과) ;
  • 윤창혁 (충남대학교 화학공학과) ;
  • 유동준 (충남대학교 화학공학과) ;
  • 임대호 (충남대학교 화학공학과) ;
  • 강용 (충남대학교 화학공학과)
  • Received : 2016.01.05
  • Accepted : 2016.01.22
  • Published : 2016.06.01
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Abstract

Thermal Characteristics and kinetic parameters of $LaMnO_3$ synthesis reaction were investigated by means of TGA (Thermogravimetric analysis) at non-isothermal heating conditions (5.0, 10.0, 15.0 and 20.0 K/min). The reaction was occurred rapidly at 450~600K (X=0.4~0.7) depending on the heating rate. Activation energy for the synthesis of $LaMnO_3$ from the precursor, which was determined by different method such as Friedman, Ozawa-Flynn-Wall and Vyazovkin methods, was in the range of 23~243 kJ/g-mol depending on the fractional conversion level and estimation method. The reaction order decreased with increasing heating rate and fractional conversional level. The average reaction order was 4.50 in case of X=0.1~0.3, while it was 1.87 in case of X=0.7~0.9, respectively. The value of frequency factor of reaction rate increased with inceasing heating rate and fractional conversion level. The aveage value of frequency factor was 205.6 ($min^{-1}$) when X=0.1~0.3, while it was 475.2 ($min^{-1}$) when X=0.7~0.9, respectively.

비등온의 열중량분석기(TGA)에 의해 nitrate-citrate 혼합물의 전구체로부터 $LaMnO_3$ 합성반응의 열적특성과 반응특성을 고찰하였다. TGA의 승온속도는 5.0, 10.0, 15.0, 20.0 K/min으로 조정하였다. $LaMnO_3$ 합성반응은 승온속도의 변화에 따라 450~600 K (X=0.4~0.7)에서 빠르게 진행되었다. $LaMnO_3$ 합성반응의 활성화에너지는 Friedman, Ozawa-Flynn-Wall 그리고 Vyazovkin의 방법으로 해석하였는데, 반응전환율의 변화에 따라 23~243 kJ/g-mol 범위 값을 나타내었다. 반응차수는 승온속도와 반응전환율이 증가함에 따라 감소하였다. 반응차수의 평균값은 반응전환율이 0.1~0.3의 범위인 반응초기에는 4.5이었으며, 반응전환율이 0.7~0.9 범위인 반응의 종결 부분에서는 1.87이었다. 반응속도의 빈도인자는 승온속도와 반응전환율의 증가에 따라 점차 증가하였다. 반응속도의 빈도인자(frequency factor)는 반응전환율이 0.1~0.3인 경우에는 205.6 ($min^{-1}$)이었으며 반응전환율이 0.7~0.9인 경우에는 475.2 ($min^{-1}$)이었다.

Keywords

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