Methods and systems are provided for regulating exhaust flow through an exhaust system of an engine. In one example, a method may include directing exhaust from downstream of a catalytic converter to a compressor storage tank in response to an engine air-fuel ratio deviating from stoichiometry. The stored exhaust may be released from the compressor storage tank to recirculate through the catalytic converter to atmosphere after adjusting an air-fuel ratio of the exhaust in the storage tank and when the catalytic converter is at a target operating temperature.