EXHAUST GAS CLEANING CATALYST

摘要

An exhaust gas cleaning catalyst, particularly a catalyst for cleaning exhaust gas containing nitrogen oxides, carbon monoxide and hydrocarbons, which has excellent durability and exhibits denitrification performances in a lean atmosphere which are not deteriorated even in a high-temperature lean atmosphere. The catalyst has a specified X-ray diffraction pattern and comprises at least one metal selected from among platinum group elements and rare earth elements supported on a crystalline silicate having the following chemical formula in terms of the molar ratio of the oxide components in an anhydrous form: (1 +/- 0.8)R2O<.> [aM2O3<.>bM'O<.>cAl2O3]<.>ySiO2 wherein R represents an alkali metal ion and/or a hydrogen ion; M represents at least one element ion selected from among group VIII elements, rare earth elements, titanium, vanadium, chromium, niobium, antimony and gallium; M' represents an alkaline earth metal ion such as magnesium, calcium, strontium or barium ion; and a > 0, 20 > b >/= 0, a + c = 1 and 3,000 > y > 11.