▎ 摘　　要

NOVELTY - A catalyst comprises a support comprising a monocrystalline material having a hexagonal structure, and a catalyst metal supported on the support. USE - Catalyst used for ammonia dehydrogenation and ammonia synthesis (all claimed). ADVANTAGE - The catalyst has excellent catalytic activity, turnover frequency, high active point, and improved performance, and is not decomposed and stable under industrial conditions, and is stably maintained without the problem of methanation, and improves the efficiency of hydrogen production because the conversion frequency for the ammonia conversion reaction is very excellent compared to the known catalysts. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacture of the catalyst, which involves impregnating a catalyst metal precursor solution into support, drying the impregnated product, heat-treating the dried product to obtain a catalyst having catalyst metal supported and controlling at least one of the shape and size of the catalyst metal by heat-treating the dried product under specific conditions.