粒度对多相反应动力学参数的影响

Effect of Particle Size on Kinetic Parameters of the Heterogeneous Reactions

以纳米氧化锌与硫酸氢钠溶液为反应体系,研究反应物粒度对动力学参数的影响规律.讨论了表观活化能降低的原因.结果表明:当反应物粒径、反应温度和搅拌速率一定时,纳米氧化锌与硫酸氢钠溶液的反应速率仅与反应物的浓度有关;反应物粒度对多相反应的反应级数、速率常数、表观活化能和指前因子均有较大的影响;随着反应物粒径的减小,表观活化能和指前因子减小,而反应级数和速率常数增大,并且速率常数和表观活化能与反应物粒径的倒数呈线性关系;反应物粒度是通过摩尔表面积、摩尔表面能和摩尔表面熵三个方面影响多相反应的动力学参数的.

Effects of particle size on kinetic parameters were studied by the reaction of nano-ZnO with solution of sodium bisulfate, and the cause of the apparent activation energy decreasing was discussed. The results show that the reaction rate is only related to the concentration of reactant when the partical size of reactant, the reaction temperation and the stirring rate are constant. The particle size has obvious effects on the reaction or-der, the rate constant, the activation energy and the pre-exponential factor. With decreasing the particle size, the rate constant and the reacture order increase, while the pre-exponential factor and the apparent activation energy decrease. There is a linear relation between the apparent activation energy and the reciprocal of the size, and the particle size exerts influences on kinetic parameters of a heterogeneous reaction through the mole surface area, the mole surface energy and the mole surface entropy.