Determining the role of the catalyst support in the reduction of NO to N2 in engine exhaust

In current NOX chemistry models developed for catalytic converters, the focus is on the precious metal (Pt, Rh and Pd) component activity and chemistry over the precious metal site. Any chemistry associated with the support material is ignored. However, in modeling both literature data and results obtained from preliminary work obtained at UW, there are indications that the support material plays a significant role in some steps of the chemistry. Since the literature does not contain results focused on the support role, we propose to investigate at a fundamental level the ongoing NOX chemistry on key support materials and then the effects of adding the active metal species. In approaching this in a step-wise manner we can isolate the impacts of each component and determine their relative significance.

We propose to fabricate six sets of catalyst samples. After this stage, platinum will be added to each and the same chemistry studied. Via comparing the NO oxidation and reduction data with and without Pt, the conditions where the support oxide chemistry will be relevant can be evaluated and the support chemistry isolated. Lastly, infra-red spectroscopy analysis (DRIFTS) will be used to analyze the chemical states of the NOX species interacting with the materials as a function of temperature. Therefore, for 6 catalysts, NO and NO2 adsorption, TPD after adsorption and NO oxidation and reduction with H2 as a function of temperature will be evaluated.

This work is being performed in collaboration with an industrial partner, a Tier I automobile manufacturer with a significant research presence in India. The data obtained will be directly provided to the vehicle manufacturer as input for their modeling efforts. The student will design and perform the experiments described above. In order to accomplish the objectives, the student will learn to operate the Catlab micro-reactor system, learn the fundamentals of mass spectrometry (MS), learn to analyze MS data, learn to operate a DRIFTS reactor and learn to analyze DRITS data. This will also require substantial literature review for the DRIFTS analysis, so that the data obtained can be readily analyzed.  Prior to the experiments being performed, the student is also required to author and submit a safety report focused on the reactors to be used, including the gases and their potential hazards.

Rohit Jaini
Faculty Supervisor: 
Dr. William Epling