| 摘要 |
<p>A subject for the invention is to provide a highly heat-resistant SCR catalyst which has an NOx reduction percentage of 40% or higher at 200°C after a hydrothermal durability treatment. The invention relates to use of ²-type zeolite which has an SiO 2 /Al 2 O 3 molar ratio of 20 or higher but less than 30 and a crystallite diameter before a hydrothermal durability treatment of 20 nm or larger, shows a change in crystallite through the hydrothermal durability treatment of less than 10%, and has a fluorine content lower than 0.1 %. The ²-type zeolite can be crystallized from a liquid reaction mixture containing a secondary and/or a tertiary alkylamine having 5 or more carbon atoms.</p> |
