Patent ID: 8168559
Filing Date: 2012-05-01
Classification: B01D,B01J

Abstract:
1. A production method of an oxidation catalyst device for exhaust gas purification which purifies an exhaust gas from an internal combustion engine by oxidizing particulates contained therein with a catalyst composed of a composite metal oxide, comprising steps of: calcining a mixture of a plurality of metal compounds served as components of the composite metal oxide, an organic acid and water to prepare a catalyst precursor; grinding a mixture of the prepared catalyst precursor, water and a binder to prepare a slurry; coating the slurry to a porous filter carrier; and calcining the porous filter carrier coated with the slurry to convert the catalyst precursor into the composite metal oxide to form a porous catalyst layer supported on the porous filter carrier; wherein the slurry includes plural kinds of slurries which contain the catalyst precursors prepared from mutually different organic acids, respectively, wherein the porous catalyst layer is formed by repeating for each kind of slurry selected from the plural kinds of slurries an operation which includes coating the selected kind of slurry on the porous filter carrier and calcining the porous filter carrier coated with the selected kind of slurry; wherein the plural kinds of slurries contain the catalyst precursors prepared from citric acid, malic acid and glutamic acid, respectively; a first slurry containing a first catalyst precursor prepared from citric acid is coated on the porous filter carrier and a first porous catalyst layer is formed by calcining the porous filter carrier coated with the first slurry; a second slurry containing a second catalyst precursor prepared from malic acid is coated on the first porous catalyst layer and a second porous catalyst layer is formed by calcining the porous filter carrier coated with the second slurry; and a third slurry containing a third catalyst precursor prepared from glutamic acid is coated on the second porous catalyst layer and a third porous catalyst layer is formed by calcining the porous filter carrier coated with the third slurry.