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Stringent NOx emission legislation accelerates the study of NOx aftertreatment. Urea-SCR system which is one of promising NOx reduction measures has been widely studied and been put to practical use not only for heavy duty vehicles but also passenger cars. As SCR catalyst, although use of zeolite ion-exchanged with transition metals (M/zeolite) has been under intense investigation, in particular, NOx conversion performance at low temperatures are still a challenging problem. Increasing the number of active sites is one of countermeasures to solve the problem. In this study, a catalytic honeycomb substrate mainly comprised of M/zeolite (NCH structure) and a conventional wash coated type catalyst(conventional structure) were prepared, respectively. To clarify the advantage of NCH structure, a relationship between NH3 adsorption and NOx conversion of the NCH structure and of the conventional structure were evaluated in both synthetic gas bench and engine bench.

In Europe, where diesel engine cars enjoy widely popularity, the major diesel-engine car manufacturers have already announced that they will equip their diesel engine vehicles with DPF systems. Silicon carbide(SiC) has good fundamental properties. And the crack problem during regeneration could be successfully controlled by using split-type DPF which consists of multiple filter segments. The functional characteristics were focused on. For DPF, a model test by which events that may actually occur on vehicles can be produced is said to have not yet been established. From this point of view, in this study, SiC-DPF functions are characterized and evaluated under a regeneration system, and their correlation is discussed.