金属氧化物脱硫/固硫反应动力学中的补偿效应

Compensation Effect in Kinetics of Desulfurization and SO_2 Fixing by Metal Oxides

讨论了氧化锌中温脱硫、氧化钙高温固硫的补偿效应 .实验发现 ,脱除硫化氢和二氧化硫在反应过程中均先后在动力学控制区和粒子扩散控制区进行 .改变非硫气氛或添加催化组分 ,所得热重数据均可用有效粒子模型处理 .lnk0 Ea 及lnD0 ED 呈线性关系 .给出了补偿效应的理论解释 .指出晶粒表面及内部缺陷等的随机指数分布是出现该效应的主要原因 .计算了两反应体系的等动力学温度 .讨论了高于和低于该温度时 ,反应活性与活化能不同的变化规律 .

Compensation effect of ZnO desulfurization and SO 2 fixing by CaO at high temperatures is discussed. Experiments showed that both the H2S removal and SO2 fixing were first under surface reaction control be fore the eventual grain diffusion control. The thermal gravimetric data were obt ained during change of reaction atmosphere or additive used for a series of samp les and were well simulated by using equivalent grain model. There were linear r elationships between logarithms of the pre-exponential factor lnk0, lnD 0 and activation energies Ea, ED, respectively. Furthermore, the compensation effect could be explained based on assumption of exponential energ y distribution function over crystal surface and its inner as well. There existe d different kinetic behavior when operating temperature was above or below the isokinetic temperature TS. Above the isokinetic temperature TS, the greater the activation energy, the higher activity the desulfurizer/SO2 fixer had. It appeared that the grain diffusion of sulfur contained ion was very diffe rent from the molecule diffusion in pore.