为阐明H2O2/Fe2(MoO4)3体系脱硝过程中H2O2吸附分解及NO氧化行为,基于DFT方法首次计算了H2O2和NO分子单独及二者同时在Fe2(MoO4)3表面的吸附构型,并通过考察吸附能、Mulliken电荷及氧化路径等特性揭示H2O2催化分解和NO氧化的微观机制。结果表明:H2O2在Fe2(MoO4)3表面易分解为活性自由基,而NO则以分子形式吸附;H2O2和NO共吸附时,H2O2优先吸附于催化剂表面并随后分解,NO则分别被H2O2分解产生的OH/O基团氧化为HNO2/NO2;氧化产物HNO2和NO2仅通过氢键与催化剂表面作用,易在流体扰动下进入主流烟气,从而降低了催化剂表面硝酸盐沉积的可能性。本研究阐明了Fe2(MoO4)3催化剂表面H2O2吸附分解及NO氧化的微观机制,为设计兼具高催化活性及优良稳定性的非均相类Fenton脱硝体系提供理论指导。

To elucidate the adsorption/ decomposition behavior of H2O2 and oxidation behavior of NO in H2O2 / Fe2(MoO4) 3 denitrificationsystem, density functional theory (DFT) calculations were performed to investigate the individual adsorption and co-adsorption characteristics of H2O2 and NO on Fe2(MoO4) 3 surface for the first time. The adsorption energies, Mulliken population, and oxidation pathwayswere systematically analyzed to reveal the mechanism of catalytical decomposition of H2 O2 and NO oxidation. The results show thatH2O2 can be easily decomposed into reactive radicals on Fe2(MoO4) 3 surface, while NO is adsorbed in molecular form. In the case of coadsorption, H2 O2 preferentially adsorbs on the catalyst surface and undergoes decomposition process. NO is subsequently oxidized toHNO2 / NO2 by the hydroxyl group/ oxygen atom generated from H2O2 decomposition. The oxidation products HNO2 / NO2 are only bonded tothe catalyst surface via hydrogen bond and can easily enter the mainstream flue gas under flow disturbance, thus reducing the depositionpossibility of nitrate on catalyst surface. This study unravels the micro mechanism of H2O2 adsorption/ decomposition and NO oxidation onFe2(MoO4) 3 surface, providing theoretical guidance for designing heterogeneous Fenton-like denitrification system with high catalytic activity and excellent stability.

0 引言

1 计算方法与模型

   1.1 计算方法

   1.2 计算模型

2 模拟结果与分析

   2.1 H2O2在Fe2(MoO4)3(001)表面的吸附分解特性

   2.2 NO在Fe2(MoO4)3(001)表面的吸附特性

   2.3 H2O2和NO同时在Fe2(MoO4)3(001)表面吸附氧化特性

3 结论