Application of a new color detection based method for the fast parallel screening of DeNOx catalysts

A new fast parallel detection method for stage I screening of solid catalysts has been developed. This method is based on the color change of organic dyes in the presence of either educts or reaction products in a reaction gas flow. As an example, NO decomposition and NO reduction with propylene under lean or rich conditions were studied. The presence of NO in a gas stream was detected by the color change from colorless to blue-green of filter paper impregnated with an organic dye, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), which was placed in the gas stream after the catalyst bed. The catalyst library was made up of mixed metal oxides, synthesized by impregnation of activated carbon with metal oxide precursor solutions and subsequent combustion of the carbon matrix. Catalytic activity of these metal oxides was compared to platinum on y-alumina as a reference catalyst. The most active compounds were then studied in detail for their DeNO(x) properties in a high precision parallel flow test rig under a stationary and cyclic lean/reach operation. A new promising NOx storage catalyst was discovered.