Effect of carbon and chlorine on the performance of carbon-covered alumina supported Ru catalyst for ammonia synthesis

Uniformly carbon-covered alumina (CCA), which was prepared by pyrolysis of sucrose. was used as support of ruthenium catalyst. Carbon did not significantly influence on the ammonia synthesis activities of Ru catalysts by changing their Ru particle sizes or Ru 3d(5/2) binding energies. Residual chlorine severely suppressed ammonia synthesis by decreasing the amount of hydrogen with the desorption peak at medium temperatures. Carbon also inhibited the adsorption of this hydrogen species for chlorine-free Ru catalysts, but did not change their activities. On the other hand, carbon can increase the ammonia synthesis activities of containing-chlorine Ru catalysts by decreasing the disadvantageous effect of chlorine on H(2) adsorption. (C) 2011 Elsevier B.V. All rights reserved.