利用3种不同的有机胺[乙胺(EA)、乙二胺(EDA)、三乙胺(TEA)]调节溶液的pH,通过共沉淀法制备3种具有不同表面氧空位浓度的二氧化铈(CeO₂)载体,通过优化载体的合成条件以及添加不同种类助剂进一步提升其构筑催化剂的氨合成性能。结果表明,利用EDA调节溶液的pH≈11、铈源以逐滴的方式加入、前驱体焙烧温度为500℃时,制备的载体CeO₂-EDA-500-11-j所构筑的钌基催化剂性能最佳,在加入4%的Cs助剂后,催化剂4% Cs-2.5% Ru/CeO₂-EDA-500-11-j在450℃、3 MPa、n(H₂)/n(N₂)=3(60 mL/min)的测试条件下,氨合成的催化活性可达25.5 mmol/(g·h)。XPS和H₂-TPR测试结果表明,2.5% Ru/CeO₂-EDA-500-11-j催化剂中的CeO₂具有较高的Ce³⁺浓度、较多的氧空位和适当的碱位密度,是获得较高氨合成活性的重要因素。

Through using ethylamine (EA),ethylenediamine (EDA),and triethylamine (TEA) respectively to adjust the pH of solution,and three kinds of cerium dioxide (CeO₂) carriers with different surface oxygen vacancy concentrations are prepared by co-precipitation method.In addition,the performance of the catalyst in ammonia synthesis is further improved by optimizing the synthetic conditions of the carriers and adding different additives into the catalyst.It is found that Ru-based catalyst has the best performance as it is supported by CeO₂-EDA-500-11-j prepared under the conditions that the pH of the solution is adjusted to around 11 by EDA,cerium source is added drop by drop,and the precursor is calcined at 500℃.The catalytic activity of 4% C_S-2.5% Ru/CeO₂-EDA-500-11-j in ammonia synthesis reaches 25.5 mmol/(g·h) under the conditions of 450℃,3 MPa,and n(H₂)/n(N₂)=3 (60 mL·min^-1).XPS and H₂-TPR test results show that CeO₂ in 2.5% Ru/CeO₂-EDA-500-11-j catalyst has higher concentration of Ce³⁺,more oxygen vacancies and appropriate base density,which are important factors for obtaining higher activity in ammonia synthesis.