Control method for reductant generation device, exhaust purification method, reductant generation system, and exhaust purification system

A reductant generation system, the reduction generation system comprising:

• a reductant generation device comprising:
• a sprayer capable of spraying a reductant precursor;
• and a heater comprising a ceramic substrate, the heater being arranged on a downstream side of the sprayer and capable of heating the reductant precursor to generate a reductant;
• and
• a control device comprising:
• a reductant precursor spray control unit for controlling spraying of the reductant precursor from the sprayer;
• and a heater control unit for controlling heating of the reductant precursor by the heater,
• wherein the reductant precursor spray control unit generates a control signal for spraying the reductant precursor from the sprayer when the heater is not heated, and controls the reductant generation system such that the ceramic substrate can be permeated with the reductant precursor.