| 摘要 |
PURPOSE:To obtain a catalyst having a high nitrogen oxide removal ratio even at high temp. by setting the metal oxide forming enthalpy of metal mordenite having a specific composition to a definite value or more. CONSTITUTION:The composition formula of a metal substituted mordenite catalyst is set to MA.H (X-Z-B).Na(Z-C) [(AlO2)X.(SiO2)y]mH2O. A metal M is a multivalent metal whose valence is (B+C/A), oxide forming enthalpy Hf deg. is 80kcal/oxygen gram atom or more and a mol ratio A/X is set to 0.3 or more. By this method, good catalytic reaction, where the oxidizing power of the active point formed by the metal M to NH3 is controlled and N2 is easily formed, is obtained. Further, a mol ratio (Z-C)/X is set to 0.35 or less and y/X is set to 5 or more. As a result, inverse reaction wherein ammonia is oxidized is suppressed and the heat resistance of mordenite is enhanced and reaction at high temp. is made possible. |
