冷凝相NaCl的硫酸化动力学机理

Kinetic mechanism of sulfation of condensed sodium chlorides

为了解碱金属氯化物的硫酸化动力学机理,利用固定床研究了反应温度及反应气体SO2,O2和H2O的体积分数对NaCl异相硫酸化率的影响,并采用X射线衍射仪对试样中元素进行分析。结果表明:NaCl异相硫酸化反应产物为Na2SO4;气体SO2,O2和H2O的体积分数的增加均可促进NaCl异相硫酸化;当反应温度低于773K时,活化能为12kJ/mol,此时温度变化对NaCl异相硫酸化率没有显著影响,当反应温度高于773K时,活化能为92kJ/mol,此时NaCl异相硫酸化率随温度升高呈指数增加;同时NaCl异相硫酸化高、低温反应机理不同,可能是由于高温下会形成共熔体引起的。

Sulfation of alkali chlorides has great significance on relieving slagging and corrosion on heating surfaces of the boiler during combustion of alkali-and chloride-rich fuels.On a fixed bed,this paper experi-mentally investigated the effects of sulfation temperature and reactants （like SO2 ,O2 and H2 O）concentra-tion on the heterogeneous sulfation of NaCl.The products were analyzed by the X-ray diffractometer.The results show that,only Na2 SO4 was found in the products.The increase in volume fraction of SO2 ,O2 and H2 O enhanced the sulfation ratio of NaCl.At temperatures below 773 K,the activation energy of the sulfa-tion reaction was 12 kJ/mol,indicating the sulfation ratio of NaCl changed little at low temperatures.How-ever,at temperatures above 773 K,the activation energy of the sulfation reaction was 92 kJ/mol,and the sulfation rate of NaCl exhibited an exponential growth with the temperature.The sulfation mechanism of NaCl at high and low temperatures was different,may be it is caused by formation of the eutectic at high temperatures.