Natural　gas　(NG)　is　a　possible　pathway　for　developing　countries　to　reduce　transportation　carbon　footprint.　However,　its　high　exhaust　temperature　decreases　the　thermal　efficiency　of　NG　engines　and　accelerates　the　thermal　aging　of　three-way　catalyst　(TWC).　This　study　proposes　to　place　an　organic　Rankine　cycle　waste　heat　recovery　(ORC-WHR)　system　between　an　NG　engine　and　its　TWC　to　recover　exhaust　energy　and　extend　the　useful　life　of　TWC.　The　feasibility　of　this　design　concept　is　confirmed　by　the　simulation　results　of　an　experimentally　validated　1D　NG　engine　model　combined　with　an　ORC-WHR　model　at　three　TWC　working　temperatures　representing　field-average,　modern,　and　future　TWC　technologies.　Results　show　that　the　decrease　in　the　outlet　temperature　of　the　ORC-WHR　system　benefits　the　availability　of　exhaust　energy,　improving　the　overall　efficiency　of　the　engine　plus　ORC-WHR　system　and　extending　the　useful　life　of　the　TWC.　Hence,　more　advanced　catalyst　technologies,　which　can　achieve　high　conversion　efficiency　at　lower　temperatures,　are　deemed　more　favorable　for　ORC-WHR　coupling.　The　cost-effectiveness　of　such　combinations　is　better　due　to　more　exhaust　energy　recovered　and　less　noble　metal　catalyst　needed　to　be　added.