Ammonia partial cracking over low-cost Ni catalysts for enhancing combustion

Partial cracking is a feasible strategy to improve ammonia (NH3) combustion. The nickel (Ni) based catalysts have become promising non-noble metal NH3 decomposition catalysts owing to the low cost and decent performance. In order to meet the demand of reducing cost and expanding production, a batch of Ni catalysts were obtained by using low-cost supports and traditional impregnation preparation method. It was found that the Al2O3 was the optimal support for Ni catalysts by comparing the catalytic performance. On the basis of Ni/Al2O3 catalysts, the catalytic activity was further improved by introducing cerium (Ce) modification. The catalytic performance of Ce-doped catalysts enhanced at first and then decreased with the rise of Ce contents. Among all of catalysts in this work, the Ni/Al0.5Ce0.5Ox catalysts possessed the highest activity and the lowest apparent activation energy. The characterization results suggested that the addition of Ce could destroy the pore structure of Al2O3 supports, but it might promote the formation of more B5 active sites. The NH3 temperature programmed desorption (NH3-TPD) results implied that the introduction of Ce strengthened the strong interactions between meatal and support, which improved the activity and stability of the Ce-doped catalysts. The Ni/Al0.5Ce0.5Ox catalysts were proved to possess excellent resistance to the high temperature sintering through the 32 h's thermal stability test. This study provides a feasible path for preparing low-cost Ni catalysts for NH3 decomposition.