Bimetallic (Co, Fe, Ni)MgAlO layered double hydroxides based catalysts for the process of ammonia decomposition

In this work, monometallic MMgAlO and bimetallic MMMgAlO (M – Co,Fe, Ni) layered double hydroxides based catalysts were synthesized by the coprecipitation method. It was found that the samples dried at 110°C are layered double hydroxides with a hydrotalcite structure. After calcination at 550°C, the samples form mixed oxides with a specific nanostructure, intermediate between the NaCl and spinel type structures. The samples are characterized by a high specific surface area (105–209 m/g). The catalytic activity was studied in the ammonia decomposition process. Among all the catalysts, the CoNiMgAlO catalyst has the highest activity: at 550°C and GHSV 72000 mL h g ammonia conversion was 32%, which corresponds to H productivity of 25.7 mmol g min. According to the TEM, it was found that the average size of metal particles in the CoNiMgAlO catalyst is 10–14 nm. The CoNiMgAlO catalyst showed stable activity during the all testing period in the ammonia decomposition process (~40 h).