The rate at which the catalyst heats up is an important factor in the control of the start-up emissions of an engine.
The beneficial impact on reducing cold start emissions via thermal management has led to numerous improvements to
the exhaust system components up stream of the converter in order to retain as much heat as possible in the exhaust
gases. A number of measures have been used to improve this such as Moving the catalyst closer to the exhaust valve
outlets - close coupled; Insulation of the exhaust manifold; Insulation of the downpipe; Insulation of the catalyst.
Exhaust system manufacturers have been working together with catalyst companies to develop ways to heat up the
catalyst as quickly as possible. A catalytic converter thermal management system (TMS) using variable-conductance
vacuum insulation and phase-change thermal storage can maintain the converter temperature above its operating
temperature for many hours, thus having minimal "cold-start" emissions.