Cold start emissions constitute around 60% to 80% of all the hydrocarbon & CO emissions in present day vehicles. The time taken to achieve the catalyst light-off temperature in a three-way catalytic converter significantly affects the emissions and fuel efficiency. The current work aims at development of a method to retain heat in catalytic converter, thus avoiding the need for light-off and reducing cold start emissions effectively. Various techniques under study involve recovering heat from exhaust gases downstream of catalyst bricks, composite insulation with different materials and geometry optimization of the phase change material around the catalyst bricks to increase the heat absorption rate and storage capacity for prolonged cool down periods. Analytical models were developed and the variants were tested using real-world cycle data. Two variants were studied in particular with modifications made to the thickness of the insulation layer and PCM layer. Furthermore, a target heat transfer curve was estimated and a set of simulations were performed to identify the physical properties of the PCM that would closely imitate the target curve and this was used to search for alternate PCM materials that favour this particular application.