Internal combustion engines, catalytic reactors, selective reduction, nitrogen oxides, air pollution

The paper presents a comparison of test results conducted on platinum reactors containing different platinum loadings, in terms of evaluating their ability to convert nitrogen oxides using ammonia. The paper includes the results of physical and chemical studies of the active surface structure of the reactors performed using an SEM microscope.Topography images of the active surface and point analysis of its chemical composition are presented. The study contains the results of calculations for NOX and NO conversion and the share of NO in NOX as a function of reactor operating temperature, along with determined characteristic operating parameters. The article includes the results of ammonia slip measurements taken after the tested reactors. The obtained test results demonstrated the possibility of using platinum reactors for the reduction of nitrogen oxides with ammonia only within a narrow temperature range. The influence of increasing the platinum loading on the increase in achieved NOX conversion levels and the reduction of ammonia slip was demonstrated. Currently, one of the fundamental problems that must be solved regarding the reduction of harmful substance emissions in compression-ignition engines is the development of a highly effective catalytic system that reduces the concentration of nitrogen oxides in exhaust gases to the levels specified in the Euro 5 standard and those planned for the future for Euro 6. In compression-ignition engines, effective reduction of nitrogen oxides is limited due to the presence of high concentrations of oxygen in the exhaust gases. (…)

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