MESOPOROUS OXIDE MOLECULAR SIEVE FOR ABSORBING NITROGEN OXIDE IN OXIDATIVE EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To enhance the NOx absorptivity of a material subjected to sol-gel treatment. SOLUTION: The mesoporous oxide molecular sieve is prepared by a sol-gel process using a neutral surfactant as well as an alcoholate, water and an alcohol for forming an aluminum oxide material having a mutually connected pore structure of a medium pore size. The catalyst is useful for absorbing NOx emitted by a lean burning engine that may be a gasoline or diesel engine when exhaust gas is oxidative. When exhaust gas is made rich, NOx is released and reduced on a noble metal with reducing species contained in the gas such as hydrocarbons. The alcoholates may include heterogeneous alcoholates of metals such as aluminum and alkali metals or alkaline earth metals and lanthanides may be included. The alcohol used for preparing the oxide is a 4C alcohol, preferably s-butanol.