Journal of Global Ecology and Environment

Catalytic converters are critical emission control devices employed in internal combustion engine vehicles to mitigate the release of harmful exhaust pollutants, including carbon monoxide (CO), unburned hydrocarbons (HC), and nitrogen oxides (NOx). By facilitating catalytic reactions that convert these toxic compounds into less harmful substances, catalytic converters play a vital role in reducing the environmental and public health impacts associated with vehicular emissions. This paper presents a comprehensive review of catalytic converter technologies, with particular emphasis on three-way catalytic converters (TWCs), which remain the predominant emission control technology in modern gasoline-powered vehicles. The study examines the fundamental aspects of catalyst materials, structural configurations, reaction mechanisms, and key operational parameters that influence catalytic converter performance. A systematic review of relevant literature published between 2003 and 2025 is conducted to evaluate recent developments in exhaust emission control technologies, highlighting advances in catalyst design, thermal management strategies, modelling approaches, and efforts to reduce dependence on costly noble metals. Furthermore, the review identifies major challenges affecting catalytic efficiency under real-world driving conditions, including catalyst ageing, thermal degradation, and cold-start emissions. Finally, potential future research directions are discussed, focusing on the development of cost-effective, thermally stable, and environmentally sustainable catalytic systems that can support increasingly stringent emission regulations, particularly within developing economies.