A coprecipitation approach was used to prepare vanadium–molybdenum composite oxide catalysts, which were then calcined at 300, 400, 500, 600, and 700 °C. The vanadium–molybdenum catalyst, under calcination at 500 °C, possesses abundant surface defects and acid species. As a result, it showed an outstanding active window, achieving over 90% NO_x conversion efficiency within the temperature range of 220–340 °C. Compared with other catalysts, the vanadium–molybdenum catalyst with the calcination at 500 °C resulted in the formation of polymeric vanadate with the most active oxygen, which was conducive to the high catalytic efficiency for the NH₃-SCR reaction. Based on our in-depth understanding gained from in situ DRIFTS experiments, we proposed that the NH₃-SCR reaction occurred on the vanadium–molybdenum catalyst via an Eley–Rideal pathway. This mechanism involves the initial adsorption of ammonia on the catalytic surface, followed by its interaction with weakly adsorbed or gaseous NO to form an activated complex. Furthermore, the presence of molecular oxygen (O₂) serves to augment the adsorption and activation of nitric oxide over the catalytic surface. The augmentation arises from the generation of adsorbed NO₂ species or nitrates, which possess pronounced oxidizing capabilities. Notably, the significant impact of NH₃ and NO in the denitration reaction was elucidated, providing valuable insights that can guide the adjustment and optimization of practical operational conditions. This understanding is crucial for enhancing the efficiency and effectiveness of the denitration process, thereby contributing to improved environmental qualities.

中文翻译：

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焙烧温度对钒钼催化剂NH3选择性催化还原NOx的影响

采用共沉淀法制备钒钼复合氧化物催化剂，然后在300、400、500、600和700℃下煅烧。钒钼催化剂在500℃下煅烧后，具有丰富的表面缺陷和酸物种。因此，它表现出出色的活性窗口，在 220-340 °C 的温度范围内实现了超过 90% 的 NO _x转化效率。与其他催化剂相比，钒钼催化剂在500 ℃下煅烧后形成了活性氧最多的聚合钒酸盐，有利于NH ₃ -SCR反应的高催化效率。基于我们对原位DRIFTS实验的深入了解，我们提出NH ₃ -SCR反应通过Eley-Rideal途径在钒-钼催化剂上发生。该机制涉及氨在催化表面上的初始吸附，随后与弱吸附或气态 NO 相互作用形成活化复合物。此外，分子氧（O ₂ ）的存在有助于增强催化表面上一氧化氮的吸附和活化。这种增强作用是由于吸附的NO ₂物质或硝酸盐的产生而产生的，它们具有显着的氧化能力。值得注意的是，阐明了NH ₃和NO在脱硝反应中的显着影响，为指导实际操作条件的调整和优化提供了有价值的见解。这种理解对于提高脱硝过程的效率和有效性至关重要，从而有助于改善环境质量。