EXHAUST GAS PURIFICATION CATALYST AND DEVICE FOR PURIFYING EXHAUST GAS

摘要

PURPOSE:To efficiently remove NOx in a lean burning region or the region from a lean burning region to a stoichiometric (theoretical fuel-air ratio) region. CONSTITUTION:A transition metal such as Co, Cu or Ni and antimony are incorporated into zeolite to obtain an NOx catalyst 1 for lean burning and NOx is removed using this catalyst 1 from oxygen-contg. exhaust gas from an internal-combustion engine. The catalyst 1 for removal of NOx in a region above a stoichiometric region may be used in combination with a ternary catalyst 3 acting in a stoichiometric region or an adsorbent adsorbing NOx in a lean burning region and desorbing NOx in a stoichiometric region may be used in addition to the catalysts 1, 3.