化学链燃烧中H 2S与CuFe 2O 4载氧体的反应机理

Interaction Mechanism Between H2S and CuFe2O4 Oxygen Carrier in Chemical-Looping Combustion

基于密度泛函理论和周期性结构模型,在分子水平上研究了化学链燃烧中H 2S与CuFe 2O 4载氧体表面相互作用的微观反应机理。结果表明,H 2S分子解离的SH、S和H基团倾向于吸附在O 1原子顶位上。H 2S分子在CuFe 2O 4载氧体表面发生的反应主要包括3个步骤:H 2S分子吸附、H 2S脱氢和H 2O分子形成。首先H 2S吸附在CuFe 2O 4载氧体表面进而发生两步脱氢反应,随着反应的进行,产生的H 2O分子从载氧体表面脱附,CuFe 2O 4载氧体表面的S基团发生迁移并填入氧空位形成硫化表面。其中H 2O分子的形成需克服135.57 kJ/mol的反应能垒,为速控步骤。围绕Cu原子进行的反应路径是H 2S与CuFe 2O 4载氧体表面反应的主要路径,与实验结果吻合。

Based on density function theory and periodic structural model,the interaction mechanism between H 2S and CuFe 2O 4 surface was studied at the molecular level.The results show that SH,S and H species dissociated from H 2S molecule tend to be adsorbed on the most active O 1 atom.The interaction between H 2S and CuFe 2O 4 mainly consists of three steps:adsorption of H 2S molecule,dehydrogenation of H 2S,and H 2O molecule formation.H 2S molecule adsorbs on the CuFe 2O 4 surface firstly and then the two-step dehydrogenation of H 2S occurs.As the reaction proceeds,H 2O molecule desorbs form the CuFe 2O 4 surface,the S species migrates and fills in the oxygen vacancy to form vulcanized surface.The formation of H 2O molecule is the rate-determining step with an energy barrier being 135.57 kJ/mol.The pathway concentrated on the surface Cu atom is the main reaction pathway between H 2S and CuFe 2O 4,which is consistent with experimental results.