烟气脱硫中CaS与SO_2的反应机理研究

Research on Mechanism of Reaction Between CaS and SO_2 During Desulfurization Process

为了研究固硫反应中Ca S与SO2的反应机理,采用密度泛函理论中的B3LYP方法,在6-311G++(d,p)水平上优化得到反应物、中间体、过渡态和产物的稳定构型和相应的能量值。结果表明:Ca S与SO2反应时,先络合生成具有链状的中间体IM1,随后经过S原子与O原子成键,生成过渡态TS;TS经过分子重排和能量重新排布生成中间体IM2、IM3、IM4,最后生成产物Ca SO4和硫单质;由中间体IM4到产物P1的过程能垒最大,说明该步骤是反应的速率控制步骤。

To study the reaction mechanism between CaS and SO2 in desulfurization reaction, stable molecular configurations of reactants, intermediates, transition state, and products were optimized at the 6- 31 lG＋＋ （d ,p） level, using the B3LYP method in density fimctional theory, and the corresponding energy values of them were obtained. The results show that the reaction of SO2 and CaS forms chain intermediate IM1 firstly, then transient state TS is generated by S and O atoms forming chemical bond. Intermediates IM2, IM3 and IM4 are generated through molecular rearrangement and energy configuration of TS, product CaS04 and sulfur are finally generated. The energy barrier of intermediate IM4 to product P1 is the greatest, which shows that it is the rate-determining step.