CATALYST FOR PURIFICATION OF EXHAUST GAS

摘要

PURPOSE: To enhance selectivity for a reduction reaction of NOx and to attain a high rate of removal of NOx by depositing an active metal on Ti-contg. zeolite and using the resultant catalyst for reduction and removal of NOx with hydrocarbons from exhaust gas contg. excess oxygen. CONSTITUTION: An active metal is deposited on Ti-contg. zeolite to obtain the objective catalyst for reduction and removal of NOx with hydrocarbons from exhaust gas contg. NOx and hydrocarbons as well as excess oxygen. The Ti-contg. zeolite is not a simple mixture of zeolite with titanium oxide but zeolite obtd. by incorporating Ti atoms into part of the skeleton structures of zeolite crystals or surface-modified zeolite obtd. by tightly bonding or sticking titania to the surface of zeolite. When the active metal is deposited on the Ti-contg. zeolite, combustion reactions of hydrocarbons in an oxygen-contg. atmosphere are decelerated, a reduction reaction of NOx with hydrocarbons is accelerated and selectivity to the reduction reaction is enhanced especially at high temp.