Catalyst for purifying exhaust gas from internal combustion engine and process for purifying exhaust gas using the same

摘要

An Object of the patent is to remove highly reducing hydrocarbon exhausted during acceleration period, and to remove efficiently hydrocarbon even after contacting with highly reducing hydrocarbon. By using a catalyst having a higher proportion of palladium having surface charge of 2-valence or 4-valence supported than that of 0-valence by supporting palladium together with magnesium oxide, hydrocarbon exhausted from an internal combustion engine especially during acceleration period can be efficiently removed.

主权项

1. A catalyst for treating an exhaust gas from an internal combustion engine, which comprises a catalyst active component comprising at least both palladium and magnesium, wherein said palladium includes palladium that has a surface charge of 2-valence, 4-valence, or both, and the proportion of the palladium that has a surface charge of 0-valence is less than 0.5, said proportion being calculated by 0-valence/(0-valence+2-valence+4-valence), and said catalyst active component is supported on a refractory inorganic oxide powder that comprises activated alumina, zeolite, titania, zirconia, silicon oxide, or a composite oxide thereof and, optionally, further comprises a rare-earth metal other than cerium.