Methods and systems for decomposing ammonia in a gasifier are provided. The system includes a gasifier including a pressure vessel and an injection nozzle extending through the pressure vessel and including a nozzle tip at a distal end of the injection nozzle, the injection nozzle further includes a passage configured to direct a fluid stream including ammonia proximate the nozzle tip such that the fluid stream including ammonia facilitates reducing a temperature of at least a portion of the nozzle tip.