Method for operating a catalytic converter used for purifying the exhaust gas of an internal combustion engine and a device for implementing the method

A device for operating a catalytic converter used for purifying exhaust gas of an internal combustion engine, the device comprising:

• means for introducing into an exhaust duct, upstream of the catalytic converter, a reagent needed in the catalytic converter;
• means for controlling a reagent fill level of the catalytic converter to a predefined storage setpoint value, wherein the predefined storage setpoint value is adjusted by a setpoint control element as a function of a measure for a temperature of the catalytic converter;
• wherein the setpoint control element continuously reduces, below an operating-temperature range of the catalytic converter toward lower temperatures, the temperature-dependent storage setpoint value;
• and
• wherein the setpoint control element reduces, after a maximum lying within an operating-temperature range of the catalytic converter toward higher temperatures, the temperature-dependent storage setpoint value.