Look, no wires
15 Jan 2000
American researchers are developing a new catalyst system which, they claim, could produce nitric acid at a far lower cost than current systems.
Currently, nitric acid is made by oxidising ammonia to NO, reacting this with air to form NO2 and then mixing this with water to give HNO3. The problematic stage is the first the ammonia oxidation requires a platinum catalyst, in the form of a wire gauze. Not only is this expensive to produce, it's consumed slowly by the reaction.
The new system, developed by Kentucky-based United Catalysts, uses a metal-coated porous ceramic support. This is soaked in a solution of alumina, zirconium oxide and cerium nitrate, then heated above 800 C. This process is repeated with a bath of cobalt nitrate, cerium nitrate and zirconium acetate, and then with platinum oxalate.
This catalyst can be simply dropped into existing plants, where it converts ammonia to NO at half the temperature of the solid catalyst, and with no metal loss, the researchers claim.
