Ammonia (NH3) is a gas at room temperature, so the question of drying it is typically related to removing any moisture present in an ammonia gas stream.

Common methods for drying ammonia gas include:

* Calcium oxide (CaO): Calcium oxide is a strong desiccant (drying agent) that readily absorbs water. It is often used in industrial settings.

* Silica gel: Silica gel is another common desiccant that can be used to dry ammonia. It is a porous material that absorbs water vapor.

* Molecular sieves: These are highly porous materials with specific pore sizes that can trap water molecules. They are effective for drying gases, including ammonia.

* Phosphorous pentoxide (P2O5): This is a powerful desiccant but it is highly reactive and must be handled with caution.

The choice of drying agent depends on several factors, including:

* The required purity of the ammonia

* The operating temperature and pressure

* The cost of the drying agent

It is important to note that some drying agents can react with ammonia, so it's crucial to choose a suitable and compatible material for the specific application.

Let me know if you would like more information on any of these drying methods!