负载型Pt/CeO_(2)催化剂上N_(2)O的生成机理

Mechanism of N_(2)O Formation over Supported Pt/CeO_(2) Catalysts

以水热法结合固相研磨法制备了Pt/CeO_(2)催化剂粉体,探究了笑气(N_(2)O)的生成机理及贵金属负载量对笑气产率的影响。研究结果表明,随着Pt负载量的增加,N_(2)O选择性先增加后下降,其中负载0.5wt%Pt的催化剂的N2O选择性最高,在275℃时达到85.1%。通过包括程序升温还原(TPR)及程序升温脱附(TPD)等方法对催化剂结构和性能的表征发现,反应遵循Langmuir-Hinshelwood机理,催化剂的氧化能力、NH_(3)和NO_(X)的吸附能力是影响N2O选择性的关键因素。在最佳气氛条件下:[NH_(3)]=600mg/Nm^(3),[NO]=535mg/Nm^(3),[O_(2)]=5vol.%,生成的N2O浓度可达970mg/Nm^(3)。

Laughing gas(N2O)has been widely used in fields of medicine,food,chemical and military industry.Pt/CeO2 catalysts were prepared by the combination of hydrothermal method and solid phase grinding method for N2O synthesis.The N2O formation mechanism and effects of Pt loading on the N2O production were investigated.The results indicated that with the increase of Pt loading,the selectivity of N2O increased first and then decreased.The catalyst with 0.5wt%Pt showed the highest catalytic efficiency and the selectivity of N2O reached 85.1%at 275℃.The catalyst structure and property were characterized experimentally,which revealed that the reaction follows the Langmuir-Hinshelwood route,and the oxidability,NH3 and NOX adsorptivity of the catalyst play important roles on the N2O selectivity.The optimal reaction conditions for N2O preparation were found to be:[NH3]=600mg/Nm3,[NO]=535 mg/Nm3,[O2]=5vol.%,and the N2O concentration can reach 970mg/Nm3.