**Separating hydrogen from other gases is notoriously difficult.**
In 9th grade Science Class, we separated Hydrogen and Oxygen from water using a 9 volt radio battery. The only problem would be scaling it for larger amounts.
Of course in the context of my post the separation would be separating Hydrogen gas from other gases while in the gaseous state.
The only two ways I know of doing this is through distillation which is the way industrial gases are made which is refrigerating the gases essentially making liquid hydrogen. The other is gaseous diffusion which is forcing gasses through a series of membranes which is easier for hydrogen to do than other gasses until you have only hydrogen remaining. As far as I know no one uses diffusion.