- 期刊
- OpenAccess
氫氧化鈣與氟氣反應之晶粒模式反應動力研究
Grain Model for Simulating the Kinetic Reaction between Fluorine and Calcium Hydroxide
摘要
本研究以氫氧化鈣乾式反應半導體產業排放的含氟氣體之一：氟氣，主要探討此氣固相反應的反應動力，分別以冪次定律(power law)及阿瑞尼士方程式(Arrhenius equation)計算反應階數及反應活化能。結果顯示氫氧化鈣與氟氣的反應屬於一階反應，平均反應活化能為3.64 kJ/mole。晶粒模式(grain model)模擬結果顯示反應速率決定步驟為擴散阻力所控制，計算之氫氧化鈣轉化率，在低溫時(25℃)與實驗值相當接近；但是在較高的反應溫度下(115℃, 200℃)，反應初期時，因模式低估了擴散阻力導致轉化率模擬值偏高；但是到了反應後期，因為氟氣與氫氧化鈣反應釋放出氣體，降低了擴散阻力，導致模式的擴散阻力高估，使得模式所計算的氫氧化鈣轉化率逐漸低於實驗值，但綜合觀之，晶粒模式仍大致合適描述此一氣固相反應的動力行為。
並列摘要
Calcium hydroxide (Ca (OH)2) is used to removal fluorine that usually emitted from the IC industry in this study. According to the power law and Arrhenius equation, the reaction order and chemical reaction activation energy are calculated, as well as the results shows that the gas-solid reaction between Ca (OH)2 and F2 is belong to first order with an activation energy of 3.64 kJ/mol. By the evaluation of grain model, the reaction rate limiting step was controlled by the diffusion resistance that took place by passing F2 through the product layer (CaF2).The conversion of Ca (OH)2 calculated by grain model is similar with the experimental value at low reaction temperature (25℃). However, at a higher reaction temperature (115℃, 200℃), the modeling Ca(OH)2 conversion is higher than experimental value at the initial stage because the diffusion resistance is underestimated by assuming the reactant (F2) can be diffused uniformly on the surface of grain of Ca (OH)2. When the experiment has been carried out at the final stage, the modeling Ca (OH)2 conversion is higher than experimental value due to the diffusion resistance is overestimate. Because the reduction of diffusion resistance will decreased by the emission of produced gases (H2O and O2) resulting in the reduction of particle size and the increased of porosity. In sum, the grain model is suitable for the modeling of gas-solid reaction of fluorine and calcium hydroxide.