Office of Technology Transfer – University of Michigan

Ion Exchanged Pillared Clays for Selective Catalytic Reduction of Nitric Oxide

Technology #1615

Pillared Interlayered Clay Catalysts for Selective Reduction of Nitrogen Oxide Pollutants. This technology is capable of selectively reducing nitrogen oxides (NOx), potent greenhouse gases, that are produced during combustion of fossil fuels. The catalyst, by employing, pillared interlayered clay structures, more efficiently reduces nitrogen oxides and is more compatible with sulfur-containing fuels than the vanadia based commercial catalysts currently available.
Nitrogen oxides are produced during the combustion of fossil fuels and emitted in the resulting exhaust gas streams. They are potent greenhouse gases and considered a toxic pollutant. Selective reduction of NOx compounds is typically performed with commercial vanadia-based catalysts; however, this system is prone to oxidizing sulfur dioxide (i.e. SO2) to sulfur trioxide (i.e. SO3), a primary component in acid rain and also a potent pollutant. Consequently, catalysts capable of selective NOx reduction have been limited to process industries that use fossil fuels with low or no sulfur content.

Pillared Interlayered Clay Catalysts Increase Efficiency and Reduce Undesirable Byproducts.

By doping pillared interlayered clay catalysts with various metals and using ammonia, this technology takes advantage of the ability of ammonia to reduce NOx compounds selectively. Researchers in the Department of Chemical Engineering have demonstrated that this technique is three times more efficient at reducing NOx compounds than the commercial product and reduces the undesirable production of sulfur trioxide compounds by 85%. Moreover, the production of nitrous oxide (i.e. N2O and also a potent greenhouse gas) was reduced to less than 1% of the product compared to 9% of the product found when using the commercial catalysts. The end result is a more efficient, less costly, and less toxic catalyst system.

Applications - Selective reduction of Nitrogen Oxide products - Removal of Nitrogen Oxide pollutants in fossil fuel exhaust streams. Advantages - Three times more efficient than vanadia-based catalysts - Reduces production of toxic byproduct sulfur trioxide compounds - Enables selective reduction of nitrogen oxides in sulfur containing fuels - Reduces the passage of unreacted ammonia (i.e. ammonia slip)