Ihe ntụgharị nke catalytic bụ ngwaọrụ dị ọcha dị n'èzí arụnyere na sistemu iyuzucha, nke nwere ike gbanwee gas na-emerụ ahụ dị ka CO, HC na NOx site na ikuku iyuzucha ka ọ bụrụ carbon dioxide na-adịghị emerụ ahụ, mmiri na nitrogen site na oxidation na mbelata.Mgbe elu-okpomọkụ ọdụ gas na-agafe site na ịdị ọcha unit, na-asachapụ gị n'ụlọnga na catalyst ga-eme ka ọrụ nke CO, HC na NOx na-akwalite ha na-ebu a ụfọdụ oxidation Mbelata chemical mmeghachi omume, nke CO na-oxidized na-enweghị colorless na ikuku carbon dioxide na-adịghị egbu egbu na oke okpomọkụ;Ogige HC oxidized na mmiri (H20) na carbon dioxide na elu okpomọkụ;A na-ebelata NOx ka ọ bụrụ nitrogen na oxygen.Igwe ọkụ atọ ndị ahụ na-emerụ ahụ na-aghọ gas na-adịghị emerụ ahụ, nke mere na gas ọdụ nwere ike sachaa.

Akụkụ nke na-ebu ihe na-eme ka ọ bụrụ ihe na-emepụta ihe bụ seramiiki porous, nke a na-etinye na ọkpọkọ ikpochapu pụrụ iche.A na-akpọ ya ụgbọelu n'ihi na ọ naghị etinye aka na mmeghachi omume catalytic, ma kpuchie ya na platinum, rhodium, palladium na ọla ndị ọzọ dị oké ọnụ ahịa.Ọ nwere ike ịgbanwe HC na CO na iyuzucha gas na mmiri na CO2, na decompose NOx n'ime nitrogen na oxygen.HC na CO bụ gas na-egbu egbu.Ikuku ume dị ukwuu ga-eduga ọnwụ, ebe NOX ga-eduga ozugbo na anwụrụ ọkụ photochemical.

N'okpuru ọnọdụ ọrụ nkịtị nke onye ntụgharị catalytic, n'ihi oke mmeghachi omume mmeghachi omume sitere na mmeghachi omume oxidation, arụmọrụ nke ntụgharị catalytic nwere ike ikpe site na ntụnyere ọdịiche okpomọkụ.Okpomọkụ ọpụpụ nke ihe ntụgharị catalytic ga-adị ma ọ dịkarịa ala 10 ~ 15% dị elu karịa okpomọkụ mbata.Maka ọtụtụ ndị ntụgharị catalytic nkịtị, okpomoku mwepu nke ihe ntụgharị catalytic ga-adị 20 ~ 25% dị elu karịa okpomọkụ mbata.

Honeycomb metal substrate catalyst nwere uru nke ọkụ ngwa ngwa, obere olu, ike dị elu, okpomọkụ na-eguzogide, wdg. A na-ejikarị ya eme ihe na ọgba tum tum na ụgbọ (petrol engine na diesel engine) iyuzucha usoro.Anyị nwere ike iru ọkọlọtọ Euro II, Euro III, Euro IV, Euro V, EPA na CARB.