钛酸锌脱硫剂硫化过程的动力学分析

利用固定床反应器对钛酸锌高温煤气脱硫剂硫化过程的动力学进行了研究，考察了硫化反应温度、H2S体积分数对脱硫反应过程的影响。结果表明，脱硫剂具有良好的脱硫反应活性，在400 ℃～600 ℃，脱硫剂的硫化反应速率随着硫化反应温度的升高、反应器入口H2S 体积分数的增大而增大。在实验数据的基础上，利用等效粒子模型对其反应动力学进行了分析，发现该脱硫剂的硫化反应主要受固体内扩散控制，固体内扩散活化能为 61.4 kJ/mol，相应的频率因子为 4.4×105 m2/min。硫化反应后脱硫剂比表面积、孔体积显著减小，脱硫剂表面有颗粒聚集物存在，进一步验证了该脱硫剂的硫化反应主要是通过产物层的体相扩散控制的。

Kinetics of zinc titanate desulfurization at high temperature

Sulfur compounds in coal gas must be removed before gas processing or burning to meet the chemical synthesis and environmental law. The developments of desulfurization sorbent and technologies at high temperature have been attracting world wide attention because of its importance to the advanced coal based power generation (e.g. IGCC). The existing problems for coal gas desulfurization technology at high temperature are the loss of effective component and the powdering of desulfurizer which considerably hinder the industrial application. Zinc titanate desulfurizer is regarded as a promising sorbent for its good chemical and mechanical performance. The effect of the concentration of H2S and desulfurization temperature on the desulfurization beheavior of zinc titanate (Zn2TiO4)sorbent and the kinetic model validation were investigated in a fixed bed reactor under atmospheric pressure. The results show that the sorbent has a very good desulfurization performance. The desulfuization rate of the sorbent increases with raising the sulfidation temperature in the range of 400 ℃ ～600 ℃ and the H2S concentration of inlet gas in the range of 3 g/m3～10 g/m3. Model tests show that the desulfurization process can be fitted by the equivalent grain model with the diffusion controlling in the product layer. The calculated values of diffusion activation energy and corresponding frequency factor are 61.4 kJ/mol and 4.4×105 m2/min, respectively. It suggests that the desulfurization process is controlled by solid grain diffusion instead of pore diffusion. It is found that specific surface area and pore volume of the sulfided sample decrease considerably and there are many congregating grains formed on the surface of sulfided sorbent by means of N2 adsorption analysis and SEM photos of surface morphology, which further validates that the desulfurization of Zn2TiO4 sorbent is controlled by the solid grain diffusion.