Tix-Ni1-x-MOFs的制备及其CO选择性催化还原NOx研究

采用溶剂热法和微波法合成了不同比例的Ti_x-Ni_1-x-MOFs材料,并用于以CO为还原剂的选择性催化脱硝反应。结果表明,双金属Ti_x-Ni_1-x-MOFs的NO还原率显著高于单金属Ni-MOF,且反应温度窗口更宽,其中,Ti_0.2-Ni_0.8-MOF表现出最佳的脱硝效率,在200~400^oC温度范围达到100%的转化率。通过XRD,FT-IR,SEM,TGA,XPS,N₂吸脱附等表征手段发现,Ti掺杂Ni-MOF后有利于改善原子分散性,Ti、Ni间金属的相互作用有利于产生丰富的高效Ni-O-Ti位点,加强Ni²⁺+Ti⁴⁺↔Ni³⁺+Ti³⁺氧化还原循环,从而明显提高了NO+CO催化反应性能。与溶剂热法相比,微波法制备Ti_0.2-Ni_0.8-MOF具有合成效率高、结晶度好、晶粒细小均匀的优势,并进一步提高了其低温脱硝效果。

Preparation of Tix-Ni1-x-MOFs and their selective catalytic reduction of NOx by CO

Ti_x-Ni_1-x-MOFs catalysts with different proportions were successfully synthesized by solvothermal method and microwave method, applied for selective catalytic reduction reaction of NO_x with CO. The doping of Ti significantly improved NO_x reduction performance of Ni-MOF catalysts and widened reaction temperature window. Ti_0.2-Ni_0.8-MOF showed the best denitration efficiency and reached 100% conversion in the temperature range of 200~400℃. Multiple characterizations were conducted to ascertain the properties of bimetallic Ti_x-Ni_1-x-MOFs materials (e.g., TGA, XRD, SEM, FT-IR, XPS and BET). Ti-doping in Ni-MOF can improve the atomic dispersion, and indicate a strong metal-metal interaction between Ti and Ni which was conducive to produce more efficient Ni-O-Ti sites and oxygen vacancies, strengthen the Ni²⁺+Ti⁴⁺ ↔ Ni³⁺+Ti³⁺ redox cycle, and thus improve the catalytic performance of NO reduction reaction by CO. Compared with solvothermal method, the preparation of Ti_0.2-Ni_0.8-MOF by microwave method exhibits the advantages of high synthesis efficiency, good crystallinity, fine and uniform grains, which further enhancing its low-temperature denitration effect.