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Oxidation Catalyst and Exhaust-Gas Purification System Using the Same

a technology of oxidation catalyst and purification system, which is applied in the direction of metal/metal-oxide/metal-hydroxide catalyst, machine/engine, arsenic compound, etc., can solve the problem of complex system, insufficient purification effect of nitrogen oxides and particulates, and so on. achieve the effect of efficient promotion of the reaction of a substan

Inactive Publication Date: 2008-05-29
ICT CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]Therefore an object of the present invention is to provide an oxidation catalyst for efficiently promoting oxidation of NO to NO2 even in a low temperature range.
[0013]Another object of the present invention is to provide an exhaust-gas purification system and method for efficiently removing nitrogen oxides or particulate matters even in a low temperature range.
[0014]The present inventors have found, after having intensively studied a way to solve the above problem, that an oxidation catalyst containing platinum and palladium as catalytically active components which contains 1 to 55% by weight of the palladium relative to 100% by weight of the platinum, efficiently promotes oxidation of NO to NO2 even in a low temperature range, and completed the present invention.
[0019]Since the oxidation catalyst of the present invention can form NO2 even when an exhaust gas is at low temperature, it can efficiently promote a reaction of a substance to be reacted with NO2 even when an exhaust gas is at low temperature.

Problems solved by technology

However, the reaction of formula (5) is so slow under a low temperature condition even when the Pt catalyst disclosed in the above U.S. Pat. No. 4,902,487 or US-A-2002-039550 is used that sufficient effect for purifying nitrogen oxides and particulate matters has not been obtained.
In addition, when the temperature of exhaust gases is low, it has been necessary in a conventional method to elevate the temperature of the exhaust gas, which sometimes has made a system complicated.
Further, installation of an apparatus for separately forming NO2 as described in US-A-2004-168429 requires a plasma-generating device and its peripheral devices to be installed, which poses a problem of high equipment cost and power cost and makes it unsuitable to be used for vehicles due to a sufficient installation space to be required.

Method used

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  • Oxidation Catalyst and Exhaust-Gas Purification System Using the Same
  • Oxidation Catalyst and Exhaust-Gas Purification System Using the Same
  • Oxidation Catalyst and Exhaust-Gas Purification System Using the Same

Examples

Experimental program
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Effect test

example 1

[0071]20.4 g of an aqueous solution of dinitrodiammine platinum corresponding to 2.32 g of platinum, 1.1 g of an aqueous solution of palladium nitrate corresponding to 0.15 g of palladium and 80 g of activated alumina (γ-Al2O3, BET specific surface area: 200 m2 / g, mean primary particle diameter: 6 μm) were subjected to wet milling by a ballmill to prepare 300 g in total of an aqueous slurry (A). A cylindrical honeycomb carrier made of cordierite of 24 mm in diameter and 50 mm in length having 400 cells per square inch of cross-sectional area was coated (wash coat) with this slurry, dried at 120° C. for 8 hours and then calcined at 500° C. for an hour to obtain catalyst A so that the sum of platinum, palladium and alumina is 82.47 q per liter of the honeycomb carrier.

example 2

[0072]19.8 g of an aqueous solution of dinitrodiammine platinum corresponding to 2.25 g of platinum, 1.57 g of an aqueous solution of palladium nitrate corresponding to 0.22 g of palladium and 80 g of activated alumina (γ-Al2O3, BET specific surface area: 200 m2 / g, mean primary particle diameter: 6 μm) were subjected to wet milling by a ballmill to prepare 300 g in total of an aqueous slurry (B). A cylindrical honeycomb carrier made of cordierite of 24 mm in diameter and 50 mm in length having 400 cells per square inch of cross-sectional area was coated (wash coat) with this slurry, dried at 120° C. for 8 hours and then calcined at 500° C. for an hour to obtain catalyst B so that the sum of platinum, palladium and alumina is 82.47 g per liter of the honeycomb carrier.

example 3

[0073]14.4 g of an aqueous solution of dinitrodiammine platinum corresponding to 1.64 g of platinum, 5.92 g of an aqueous solution of palladium nitrate corresponding to 0.83 g of palladium and 80 g of activated alumina (γ-Al2O3, BET specific surface area: 200 m2 / g, mean primary particle diameter: 6 μm) were subjected to wet milling by a ballmill to prepare 300 g in total of an aqueous slurry (C). A cylindrical honeycomb carrier made of cordierite of 24 mm in diameter and 50 mm in length having 400 cells per square inch of cross-sectional area was coated (wash coat) with this slurry, dried at 120° C. for 8 hours and then calcined at 500° C. for an hour to obtain catalyst C so that the sum of platinum, palladium and alumina is 82.47 g per liter of the honeycomb carrier.

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Abstract

An oxidation catalyst that efficiently promotes oxidation of NO to NO2 even in a low temperature range, and an exhaust-gas purification system and method that efficiently removes exhaust-gas components even in a low temperature range are provided. This invention provides an oxidation catalyst comprising platinum and palladium as catalytically active components, which promotes oxidation of nitrogen monoxide to nitrogen dioxide, wherein the oxidation catalyst comprises 1 to 55% by weight of the palladium relative to 100% by weight of the platinum.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an oxidation catalyst and an exhaust-gas purification system using the same, and in particular, to an exhaust-gas purification system having excellent performance in purifying particularly nitrogen oxides from an internal combustion engine such as a diesel engine.[0003]2. Description of Related Art[0004]As a method for purifying nitrogen oxides discharged from an internal combustion engine such as a diesel engine, a method of installing a reduction catalyst along the flow of an exhaust gas and purifying NOX on a reduction catalyst by a reducing agent supplied from front of the reduction catalyst has drawn attention. Ammonia (NH3), urea ((NH2)2CO), a hydrocarbon such as light oil, and the like are used as the reducing agent. It is known that the reaction for purifying NOX proceeds via NO2 using any of the above reducing agents. It is known, for example, that the reaction for purifying nit...

Claims

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Application Information

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IPC IPC(8): B01D53/56B01J23/42
CPCB01D53/9418Y02T10/24B01D53/9477B01D2251/2062B01D2255/1021B01D2255/1023B01D2258/01B01J23/44B01J23/745B01J35/0006B01J35/04B01J35/10B01J37/0036B01J37/0246B01J37/0248F01N3/206F01N2240/40B01D53/944
Inventor IKEDA, MASANORIKATO, NAOHIRO
Owner ICT CO LTD
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