In order to achieve the requirements on emissions of harmful substances in exhaust gases, when the engine runs
with stoichiometric mixture, it is advisable to use a special multifunctional three-way catalyst, specifically
designed for complex conversion of exhaust gases produced by a natural gas-powered ICE. A number of
catalysts for engine exhaust aftertreatment were identified, which are able to oxidize methane and reduce
nitrogen oxides efficiently in a wide temperature range. The key components of three-way catalysts for exhaust
gases of natural gas engines are precious metals with Ce, Ce-Zr and other additives to improve efficiency and
thermal stability of the contact. Experimental studies have shown that efficient (over 90%) conversion of gas
engine exhaust components takes place in the range of excess air ratio from 0.99 to 1.01.