ABSORPTION/REDUCTION TYPE CATALYST FOR NOX REMOVAL

摘要

A catalyst free from drawbacks of absorption/reduction type NOx removal catalysts, such as poor NOx-removing performance at low temperatures and insufficient SOx-eliminating performance. The catalyst is characterized by comprising support particles having a catalyst ingredient deposited thereon and NOx absorbent particles mixed with the support particles. Preferably, the support particles include acid support particles, and the particulate NOx absorbent is a metal oxide having basic sites, especially zirconia containing a rare earth metal. In conventional catalysts, the strongly basic NOx absorbent such as an alkali metal causes the catalyst ingredient, which is present on the same support, to be exposed to basic conditions and thereby reduces the catalyst performance. In the catalyst of the invention, since the NOx absorbent and the support are separate particles, the catalyst ingredient can show its intrinsic catalyst performances. As a result, low-temperature NOx-removing performance and SOx-eliminating performance are improved.