Currently, Pb poisoning of heterogeneous catalysts is considered to be a key area of interest in research involved with industrial NO_x reduction. As such, a series of Pb-poisoned V₂O₅-WO₃/TiO₂ catalysts were prepared by a wet impregnation method and the influence of SO₂ on the performance of these poisoned catalysts for NO_x reduction was assessed both experimentally and using theoretical calculations. As expected, the incorporation of Pb in these materials resulted in a significant reduction in their catalytic performance. The conversion of NO_x over the Pb-V₂O₅-WO₃/TiO₂ catalyst increased from approximately 50% to 90% in presence of SO₂ (2000 ppm) at 350 °C. It was postulated that in the absence of SO₂, Pb reacts with surface V-OH species, which ultimately results in the destruction of Brønsted acid sites; considered to be crucial for the catalytic conversion of NO_x. In the presence of SO₂ however, enhanced catalytic activity was observed which was suggested to be a result of the formation of additional Brønsted sites (S-OH) via a surface bidentate sulfate intermediate species. The formation of these species was attributed to the interaction of Pb with SO₂ and O₂ on the surface of the catalyst. Density functional theory (DFT) calculations based on a monolayer V model on TiO₂ (0 0 1) showed that SO₂ absorbed selectively onto Pb sites rather than V or Ti oxides. It was subsequently determined that NH₃ absorption proceeds through the formation of Pb-N species with Pb atom and H-O with SO₂. We believe that the present work provides new insights into the design and application of SCR catalysts with specific relevance for application in flue gas streams which contain high quantities of Pb content.

目前，非均相催化剂的中毒铅被认为是在涉及工业NO的研究兴趣的关键领域_X减少。这样，一系列的Pb-中毒V ₂ ø ₅ -WO ₃ /二氧化钛_2个催化剂通过湿浸渍法和SO的影响制备₂上为NO这些中毒催化剂的性能_X还原评估实验和使用理论计算。如所期望的，在这些材料中掺入铅导致其催化性能的显着降低。NO _x在Pb-V ₂ O ₅ -WO _3上的转化在350°C的SO ₂（2000 ppm）存在下，/ TiO ₂催化剂从大约50％增加到90％。据推测，在没有SO ₂的情况下，Pb与表面的V-OH发生反应，最终导致布朗斯台德酸位点的破坏。被认为对于NO _x的催化转化至关重要。然而，在SO ₂的存在下，观察到增强的催化活性，这被认为是通过表面二齿硫酸盐中间物质形成额外的布朗斯台德位点（S-OH）的结果。这些物质的形成归因于Pb与SO ₂和O ₂的相互作用在催化剂表面上。基于在TiO ₂（0 0 1）上的单层V模型的密度泛函理论（DFT）计算表明，SO ₂选择性地吸收到Pb部位，而不是V或Ti氧化物。随后确定通过形成具有Pb原子的Pb-N物种和形成SO _2的HO来进行NH ₃吸收。我们认为，当前的工作为SCR催化剂的设计和应用提供了新的见解，与在含大量Pb含量的烟道气中的应用具有特定的相关性。