기-고체 반응 모델을 이용한 Kideco탄의 이산화탄소 촉매 석탄가스화 반응 특성

Abstract

본 연구는 인도네시아 아역청탄인 키데코(Kideco)탄의 촤(char)-이산화탄소 촉매가스화 kinetic분석을 열중량분석기(thermogravimetric analysis, TGA)를 이용하여 수행하였다. 촉매는 탄산칼륨 및 탄산나트륨을 선정하였으며, 석탄과 촉매의 물리적 혼합을 통하여 촤를 제조하였다. 촤-이산화탄소 촉매가스화반응은 탄산나트륨 7 wt%, 850 ℃에서 이산화탄소 농도가 60 vol%일 때 가장 빠른 탄소전환율을 보여주었다. 750~900 ℃ 등온조건에서 촤-이산화탄소 촉매가스화 반응결과, 온도가 증가할수록 탄소전환율 속도가 빨라졌으며, 기-고체 반응모델 shrinking core model (SCM), random pore model (RPM), volumetric reaction model (VRM) 및 modified volumetric reaction model (MVRM)을 실험결과에 적용하였을 때, MVRM이 키데코탄의 가스화반응 거동을 잘 예측하였다. 또한 Arrhenius plot을 통한 활성화에너지는 탄산나트륨을 첨가한 촤가 탄산 칼륨을 첨가한 촤보다 더 우수한 촉매 활성을 보여주었다. In this study, we have investigated the kinetics on the char-CO₂ catalytic gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-CO₂ catalytic gasification of an Indonesian Kideco sub-bituminous. Na₂CO₃ and K₂CO₃ were selected as catalysts which were physically mixed with coal. The char-CO₂ catalytic gasification reaction showed a rapid increase of carbon conversion rate at 850 ℃, 60 vol% CO₂, and 7 wt% Na₂CO₃. At the isothermal conditions ranging from 750 ℃ to 900 ℃, the carbon conversion rates increased as the temperature increased. Four kinetic models for gas-solid reaction including the shrinking core model (SCM), random pore model (RPM), volumetric reaction model (VRM), and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM for the Kideco sub-bituminous. The activation energies for each char mixed with Na₂CO₃ and K₂CO₃ were found 55-71 kJ/mol and 69-87 kJ/mol.