Ammonia decomposition catalyst systems

A method for forming hydrogen, the method comprising:

• contacting an ammonia decomposition catalyst system with an ammonia source at a reaction temperature of about 450° C. or lower to form hydrogen,
• wherein the catalyst system comprising a support material and a trimetallic catalyst component carried on the support material and within a reactor, wherein the trimetallic catalyst component includes no more than three metals comprising a first metal being ruthenium, a second metal selected from the group consisting of magnesium, calcium, hafnium, scandium, rhenium, strontium, and yttrium, and a promoter comprising an alkali metal, wherein the ruthenium and the second metal are present in a weight ratio to one another of from about 8:1 to about 1:8, wherein the ruthenium is present in an amount of less than 4 wt. % of the catalyst system and the promoter is present in an amount of from about 5 wt. % to about 20 wt. % of the catalyst system, wherein the reactor is fluidly connected to the ammonia source such that ammonia flows from the ammonia source to the reactor;
• a first heat exchanger located between the ammonia source and the reactor and configured to heat the ammonia;
• and
• a hydrogen selective membrane fluidly connected to the catalyst system such that reaction product from the catalyst system.