Nitrogen Oxide (NO) and carbon monoxide (CO) are major pollutants in the exhaust streams of automobiles, power plants, and other combustion processes. The growing concerns for the environment have resulted in increasingly restrictive emission standards. The removal of NO and CO from exhaust gases is a challenging task.
One method for harmful gas removal is using a catalyst for dissociation. This work explored an alternative method for catalytic reduction of NO. Polymer solutions with palladium catalyst and ceramic precursors were electrospun to form polymer nanofibers. These nanofibers were heated to form ceramic nanofibers with catalyst
nanoparticles and were mixed with microfibers to form a nonwoven fibrous catalyst support structure. The concentration of the polymer was varied to create nanofibers with diameters ranging from 100 to 700 nm with a constant mass of catalyst particles per mass of fiber. The effect of the fiber diameter on the corresponding catalyst structure performance was tested. A surface area comparison test was completed to determine whether the reactions occur strictly on the surface of the catalyst or if diffusion occurs. An aging comparison was also completed which tested 1 week old catalytic filters compared to 6 months old. A conventional catalytic converter was tested to verify the performance was similar to the catalytic fibrous filter media containing only palladium.
Experiments were carried out using a lab reactor to expose the media to a mixture of gases simulating an exhaust stream at room temperature to a maximum of 450°C. The reactor exhaust concentrations are measured using gas chromatography (GC) to determine the catalyst performance. Results indicated that the catalytic reaction performance was about the same for fiber sizes ranging from 100 to 700 nm on a mass basis with a reduction temperature of 325 – 350°C. The surface area comparison filter reduced at 275°C which showed that both surface catalyst particles and particles within the fibers are available for reaction. Furthermore, a conventional catalytic converter reduced at approximately 325°C which exhibits comparable catalytic performance with the catalytic filters. Model theory and equations were also developed for decomposition reactions of NO and CO using elementary reactions.