CuCr2O4催化剂形貌特征与其SCR脱硝性能的关系

分别制备形貌为多面体状、颗粒状、球状的尖晶石型CuCr₂O₄催化剂，测试对比不同形貌CuCr₂O₄催化剂的SCR脱硝性能. 结果表明，多面体状CuCr₂O₄的催化活性最好，且在157 ℃时脱硝效率达到50%，在225~320 ℃脱硝效率超过99%，具有良好的抗硫、抗水性能. 脱硝活性由大到小依次为多面体状CuCr₂O₄、颗粒状CuCr₂O₄、球状CuCr₂O₄. 采用表征技术分析微观形貌对CuCr₂O₄脱硝性能的影响. N₂吸附-脱附结果显示，多面体状CuCr₂O₄具有最大的比表面积(25.5 m²/g)和最大的孔容积(0.154 cm³/g)；X射线光电子能谱(XPS)结果显示，多面体状CuCr₂O₄相较于其他形貌拥有更高比例的表面活性氧(49.5%)和Cu⁺(16.2%)；NH₃-程序升温脱附(NH₃-TPD)结果显示，多面体状CuCr₂O₄拥有最高表面酸浓度(0.12 mmol/g)及酸强度；H₂-程序升温还原(H₂-TPR)结果显示，多面体状CuCr₂O₄表面活性物种最易还原且数量最多(3.69 mmol/g)，使得SCR反应在低温段更易进行. 多面体状CuCr₂O₄的高表面酸性与氧化还原性，使其具有良好的脱硝性能.

Relationship between morphology characteristics of CuCr2O4catalyst and its SCR denitrification activity

The SCR denitrification activities of CuCr₂O₄ catalysts with various morphologies were tested and compared. The spinel-type CuCr₂O₄ catalysts with polyhedral, granular and spherical shapes were prepared, respectively. The results showed that polyhedral CuCr₂O₄ showed the best catalytic activity, with the de-NO_x activity reaching 50% at 157 ℃ and maintaining above 99% at 225-320 ℃, and it exhibited good resistance against water vapor and SO₂. The de-NO_x activities follow the sequence of polyhedral CuCr₂O₄ > granular CuCr ₂O₄>spherical CuCr₂O₄. The effects of morphology on the denitrification performance of CuCr₂O₄ were analyzed by a series of characterization techniques. N₂ sorption-desorption results showed that polyhedral CuCr₂O₄ had the highest specific surface area (25.5 m²/g) and the largest pore volume (0.154 cm³/g); X-ray photoelectron spectroscopy (XPS) results showed that polyhedral CuCr₂O₄ possessed the highest ratio of surface reactive oxygen species (49.5%) and Cu⁺(16.2%); NH₃-programmed temperature desorption (NH₃-TPD) showed that polyhedral CuCr₂O₄ had the highest surface acid concentration (0.12 mmol/g) and intensity; H₂-programmed temperature reduction (H₂-TPR) showed that polyhedral CuCr₂O₄ had the most reducible and abundant surface active species (3.69 mmol/g), which facilitated the SCR reaction in the low-temperature range. The enhanced surface acidity and redox properties of polyhedral CuCr₂O₄ makes it exhibit better de-NO_x performance.