A catalytic converter unit includes walls defining a treatment zone, first and second transfer zones and at least one through-flow zone, which zones are adjacent each other. The walls include a partition wall that divides the treatment zone into first and second segments. The first transfer zone is plugged upstream of the partition wall and the second transfer zone is plugged downstream of the partition wall. A catalytic converter element is disposed in the first segment of the treatment zone, spaced from the partition wall. The first segment of the treatment zone is in flow communication with the first transfer zone and the second segment of the treatment zone is in flow communication with the second transfer zone.