| abstract |
PROBLEM TO BE SOLVED: To provide an SCR catalyst having high purification performance and an exhaust gas purification catalyst system provided with the SCR catalyst. An exhaust gas purification catalyst system includes an internal combustion engine that exhausts exhaust gas, a DOC3, a DPF4, a urea addition valve that adds urea water into an exhaust passage (exhaust pipe 5), an SCR catalyst 7, and ASC catalyst 8 is included. The catalyst for SCR contains an iron ion exchange zeolite and a solid acid. SCR catalysts described above, ammonia temperature programmed desorption acid amount obtained from the desorption amount at 300 to 700 ° C. as measured by (NH 3 -TPD) is a catalyst volume 112mmol more per 1L 160 mmol or less. [Selection] Figure 1 |