Abstract: 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 polarity 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=10000 h-1, p=10 MPa, and θ=400 ℃). Thus, the AC graphitized at suitable temperature followed by oxidation with O2-N2 and HNO3 was a good support of Ru-based catalyst for ammonia synthesis.

Key words: ruthenium, supported catalyst, support, activated carbon, graphitization, ammonia synthesis