Ru基氨合成催化剂石墨化炭载体的制备

Preparation of Graphitic Carbon as Support of Ru-Based Catalyst for Ammonia Synthesis

采用X射线衍射、N2物理吸附和程序升温脱附-质谱等表征手段考察了活性炭经Ar气保护下高温石墨化、O2-N2混合气氧化和HNO3处理后孔结构及表面基团的变化.结果表明,活性炭在惰性气氛中高温处理能够部分石墨化,且温度越高,石墨化程度越高.高温处理后的活性炭纯度和稳定性提高,但其比表面积大幅度减小.进一步的氧化扩孔处理能在一定程度上恢复石墨化活性炭的比表面积和孔结构.随后的HNO3处理可以使石墨化活性炭表面的含氧基团增加,改变载体的浸润性能,有利于催化剂活性组分的分散及催化活性的提高.

Activated carbon （AC）as a support of Ru-based catalyst for ammonia synthesis was graphitized at high temperature in argon and then oxidized with a O2-N2 mixture and HNO3. Its structure, texture, and surface oxygenous groups were investigated by N2-physisorption and temperature-programmed desorption. The results showed that the graphitization process could eliminate the carbon impurities and improve the support stability. However, after the thermal treatment, the specific surface area of AC decreased sharply, and its texture was destroyed. The surface area and porosity could be recovered partially by oxidation treatment with a O2-N2 mixture. In further treatment with HNO3, the amount of surface oxygenous groups was increased, and the surface polari- ty was transformed from hydrophobic to hydrophilic. HNO3 treatment led to a significant increase in the catalyst activity with an ammonia concentration in the exit being more than 19 % （ under the conditions of GHSV = 10 000 h^- 1, dation with p = 10 MPa, and θ = 400 ℃ ）. Thus, the AC graphitized at suitable temperature followed by oxiO2-N2 and HNO3 was a good support of Ru-based catalyst for ammonia svnthesis.