Evidence of ammonia synthesis by bulk diffusion in cobalt molybdenum particles in a CLAS process

Abstract

For the first time ammonia-synthesis-on-nitridation has been reported in CoMo during a chemical looping ammonia synthesis experiment. The observation lends evidence to the existence of a dynamic surface, a shrinking core and counter diffusion. The Mars-van Krevlen mechanism involving surface and bulk exchange has been established for the CoMo system under H2:N2 atmospheres was extended into the CLAS domain and complicated by the existence of an unreacted oxide core containing molybdenum bronzes, HxMoO3. This OH−1 diffuses outward as the core is stabilized by N−3, resulting in the observation of gas phase H2O and NH3 in the absence of gaseous H2.

Keywords

• Nitride
• Chemical looping
• Ammonia synthesis
• Cobalt molybdenum