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煤化学链燃烧必然释放汞,汞与载氧体表面相互作用,影响表界面的氧化还原反应。本文采用密度泛函理论计算,研究汞(Hg0)在理想表面(Fe_2O_3[001])和一系列被还原表面(Fe_2O_(2.75)、Fe_2O_(2.5)、Fe_2O_(2.25)、Fe_2(O1.625)、Fe_2O_(0.875)、Fe_2O_(0.375)和Fe)的吸附,以及Hg0对Fe_2O_(1.625)、Fe_2O_(0.875)、Fe_2O_(0.375)和Fe等表面催化CO分解反应的协同作用机理。Hg0物理吸附在理想Fe_2O_3[001]表面。随着Fe_2O_3[001]表面不断被还原,Hg0发生化学吸附。Hg0吸附降低了CO与Fe_2O_3、Fe_2O_(2.75)、Fe_2O_(2.5)和Fe_2O_(2.25)等表面之间的相互作用,抑制O传递氧化CO为CO_2的反应;载氧体进一步还原过程中,Hg0吸附促进了CO与Fe_2O_(1.625)、Fe_2O_(0.875)、Fe_2O_(0.375)及Fe等表面之间的相互作用,进而促进了表面对CO的催化分解反应,加速了载氧体表面的积碳,降低了化学链燃烧效率。因此,合理控制载氧体的还原程度既可以减弱Hg0的吸附,也可以抑制积碳的形成,这对化学链燃烧的操作优化至关重要。
Coal chemical chain combustion inevitably release mercury, mercury and oxygen carrier surface interaction, affect the surface of the redox reaction. In this paper, density functional theory (DFT) calculations were used to study the effect of mercury on the ideal surface (Fe_2O_3 [001]) and a series of reduced surfaces (Fe_2O_2.75, Fe_2O_5, Fe_2O_2.25, Fe_2 (O1.625) , Fe_2O_ (0.875), Fe_2O_ (0.375) and Fe), and the synergistic action mechanism of HgO on the catalytic CO decomposition reaction of Fe_2O_ (1.625), Fe_2O_ (0.875), Fe_2O_ (0.375) Hg0 physically adsorbed on the ideal Fe_2O_3 [001] surface. With the Fe_2O_3 [001] surface is continuously reduced, Hg0 chemical adsorption. Hg0 adsorption reduces the interaction between CO and Fe_2O_3, Fe_2O_2.75, Fe_2O_ (2.5) and Fe_2O_ (2.25), and inhibits the reaction of O transfer and oxidation of CO to CO_2. During the further reduction of oxygen carrier, Hg0 adsorption Promoted the interaction between CO and Fe_2O_ (1.625), Fe_2O_ (0.875), Fe_2O_ (0.375) and Fe, and promoted the catalytic decomposition of CO on the surface and accelerated the carbon deposition on the surface of the oxygen carrier Chemical chain combustion efficiency. Therefore, a reasonable control of the degree of reduction of the oxygen carrier can not only weaken the adsorption of Hg0, but also inhibit the formation of carbon deposition, which is very important for optimizing the operation of the chemical chain combustion.