Investigation of degradation of catalyst performance due to phosphorus poisoning in practical catalysts

Although exhaust gas regulations for internal combustion engines have been in place for quite some time, they are still getting stricter every year. Motorcycles are no exception. Exhaust gas regulations for after-degradation durability have already been applied, and the next regulation is expected to require vehicles in use in the market to meet the exhaust gas regulation values. Technology to comply with exhaust gas regulations mainly deals with catalyst performance degradation. The main issues are metal sintering and poisoning. In particular, it is difficult to clearly explain the change in catalyst performance due to poisoning alone, as it is necessary to distinguish it from sintering and to determine the distribution of deterioration. However, phosphorus poisoning from oil cannot be ignored unless oil consumption is reduced to zero. In order to understand the change in practical catalyst performance due to poisoning with a distribution of degradation, it is necessary to explain the distribution of poisoning substances and to understand the performance change at each point while separating poisoning and sintering. In this report, we attempt to show the distribution of poisoning substances on the catalyst from individual durability histories based on a simple adsorption mechanism hypothesis. Furthermore, we investigated the performance change at each point of the poisoning substance distribution. To this end, we prepared a catalyst in which it is believed that there was almost no sintering distribution within the catalyst during degradation durability. We investigated samples that were divided as finely as possible in the flow direction. By using the rear end part of the catalyst, which is almost unpoisoned, as a reference, we can obtain the change in catalyst performance relative to the amount of poisoning. These results will be used to consider the performance change of practical catalyst due to poisoning.