An alternative process for nitric oxide and hydrogen production using metal oxides

Abstract

A new process employing metal oxide is proposed for the production of nitric oxide and hydrogen which are precursors to the production of nitric acid. There have only been a few studies reporting the oxidation of ammonia by metal oxides, but the ammonia–metal oxide reactions for the simultaneous production of NO and H2 have not yet been reported. The reaction of ammonia with different metal oxides is investigated in detail, including thermodynamic feasibility calculations. The salient feature of the proposed reaction is the production of H2 in addition to NO. Experiments are performed for the most feasible metal oxides in a semi batch reactor. These experiments confirm the feasibility of the ammonia–metal oxide reaction for cupric oxide (CuO), ferric oxide (Fe2O3) and cobalt oxide (Co3O4) at 825°C, 830°C and 530°C, respectively. The maximum yields of NO are around 90% for each metal oxide. The effect of varying the different parameters such as temperature, ammonia concentration, and particle size on the yield of nitric oxide is reported for the case of CuO and a reaction mechanism is proposed to explain these results. These results are used to develop two different chemical looping based processes for NO and H2 production depending on the mode of regeneration of metal oxides.