Most cars today are equipped with a Three - way catalytic converter. The term 3 - way refers to the three emissions it helps to reduce, carbon monoxide, hydrocarbons or volatile organic compounds (VOCs) and NOx molecules. 3-way converters use two different types of catalysts, a reduction catalyst and oxidization catalyst. Both types consist of a base structure coated with a catalyst such as platinum, rhodium and/or palladium. The scheme is to create a structure that expose the maximum surface area of the catalyst to the exhaust flow, while also minimize the amount of catalyst required.