Catalyst for treating motor vehicle exhaust gas - using preformed nickel alloy substrate coated with copper and heated to form oxides

摘要

A composite catalytic structure is obtd. by forming a coating contg. Cu on a substrate contg. Ni plus 10 wt. % min. of Cr, the coating contg. less Ni than the substrate. The coated substrate is heated in a protective atmos. to above the m. pt. of Cu to obtain a catalytic structure contg Ni, Cr, and Cu with a stratified surface or which after heating in an atmos. contg. O2 or during its use, develops stratified layers of oxide and an oxidised sub-layer rich in chromium. Used for sepn. of NOx, CO and hydrocarbons in motor vehicle exhaust gas. Provides an inexpensive method of mfg. the catalyst structure by starting from a preformed metal substrate.