An ammonia storage cartridge includes an ammonia storage member having a storage material capable of absorbing or adsorbing ammonia. The storage member extends along a longitudinal axis. A heating element heats the storage member, and a hermetic tank houses the storage member. A tubular ammonia circulation element is arranged coaxially to the storage member, and includes a first surface at least partially delimiting, with an element chosen from among the heating element and the hermetic tank, a circulation duct for the fluid ammonia. A second surface is arranged at least partially in contact with the storage member, and at least one orifice passes radially through, allowing the circulation of fluid between the circulation duct and the storage member.