Hydrogen Membrane Separation Techniques

Dense Metal Technique

• The technique for hydrogen gas separation using a metal membrane is also referred to as solution-diffusion, says IOP Science. Dense metal technique involves hydrogen transportation through a metal membrane in various proceedings, which include the adsorption of hydrogen gas on the membrane, its dissociation into ions and electrons and its dissolution into the metal and consequent diffusion through the metal. The metal membrane is dense enough to restrict other gaseous molecules to diffuse through the metal, thus separating only hydrogen. This technique produces extremely pure hydrogen gas.

Non-Porous Organic Polymer Technique

• This technique also involves a solution-diffusion mechanism like the dense metal technique, but it does not involve the hydrogen dissociation step. Non-porous organic polymer membranes are made or rubbery or glassy materials, and require temperatures of 212 to 392 degrees Fahrenheit to operate, reports IOP Science. The major disadvantage of this technique is carbon dioxide is also permeable in polymeric membranes, and thus the hydrogen gas produced is not expected to be pure.

Porous Materials Technique

• According to an article published on Industrial and Engineering Chemical Research, porous materials such as ceramic membranes offer advantages over other hydrogen separation techniques. They are non-permeable to some poisonous gases such as carbon monoxide and hydrogen sulfide, unlike some polymeric membranes. However, the levels of purity in hydrogen gas production are less than 95 percent. Hydrogen is a very small molecule, and the porous materials technique involves the selection of molecules by size, thus favoring hydrogen selection, says IOP Science.