Close coupled catalyst

A catalyst and close-coupled technology, applied in the field of close-coupled catalysts and their preparation, can solve the problems of volume shrinkage, catalyst specific surface area loss, active component sintering and catalytic activity decline, etc. Effect

Inactive Publication Date: 2006-07-12
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

(3) The limited conversion of CO, the strong exotherm of CO oxidation causes the sintering of the catalyst, reducing the life of the close-coupled catalyst
[0009] Because close-coupled catalysts are exposed to exhaust gases above 1000°C, the carrier currently used as close-coupled catalysts is γ-Al 2 o 3 or La-Al 2 o 3 , both exist at high temperatures, especially at high temperatures in the presence of water vapor (there is about 10% H in the tail gas 2 The volume shrinkage caused by the phase transition of O) leads to the loss of the specific surface area of ​​the catalyst, the sintering of the active components and the decrease of the catalytic activity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Take 112 grams of Al in different phases 2 o 3 Powder Al 2 3 g, where γ-Al 2 o 3 , La-γ-Al 2 o 3 , δ-Al 2 o 3 and La-θ-Al 2 o 3 Each accounts for 25% by weight. Impregnate with a palladium nitrate solution containing 2.24 grams of Pd, dry at 120°C for 4 hours, and bake at 550°C for 3 hours to obtain Pd-containing alumina. Pd-containing alumina and strontium nitrate (containing SrO5 grams), lanthanum nitrate (containing La 2 o 3 7 g), zirconium nitrate (containing ZrO 2 7 g) neodymium nitrate (containing Nd 2 o 3 4 grams) and an appropriate amount of water spheres are ground into a coating solution with a solid content of 40% (weight). Take a 400cpsi cordierite substrate and immerse it in the coating solution. After taking it out, blow off the excess coating solution with compressed air, dry it at 120°C for 3 hours, and bake it at 500°C for 4 hours to obtain catalyst C1. Pd content is 2.24 g / L, 112 g / L Al 2 o 3 , 5 g / L SrO, 7 g / L La 2 o 3 , 8 g / L ZrO...

Embodiment 2

[0033] The preparation method is the same as in Example 1, except that the Al in different phases 2 o 3 In, θ-Al 2 o 3 , La-γ-Al 2 o 3 , YSZ-γ-Al 2 o 3 La-δ-Al 2 o 3 25% each. Catalyst C2 is obtained

Embodiment 3

[0035] The preparation method is the same as in Example 1, except that the Al in different phases 2 o 3 Medium, La-δ-Al 2 o 3 Accounting for 15%, YSZ-γ-Al 2 o 3 20%, La-γ-Al 2 o 3 45%, γ-Al 2 o 3 20%. Catalyst C3

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Abstract

The invention relates to a close-coupled catalyst with high activity and thermal stability to purify the tail gas of cold start of motor. Said close-coupled catalyst comprises at least three kinds of alumina in different physical phased as catalyst carrier; the Pd as active component; at least one of rare-earth oxides as Y2O3, La2O3, Nd2O3 and Sm2O3; at least one of alkaline earth oxides as SrO, BaO and CaO; and ZrO2.

Description

1. Technical field [0001] The invention relates to a close-coupled catalyst for effectively reducing the emission of HC pollutants during engine cold start and a preparation method thereof. 2. Background technology [0002] In recent years, the research on catalysts for purifying harmful substances HC, CO and NOx in automobile exhaust has been very active. With the increasingly stringent environmental emission regulations, it is extremely important to address HC emissions during engine cold start. [0003] A cold start is the brief moment when the engine starts from ambient temperature. The cold start process depends on the ambient temperature, engine type, engine control system and how the engine works. A typical cold start process is within the first two minutes after the engine is started from ambient temperature, and the FTP-75 test method considers a cold start to be within 505 seconds after the engine is started from ambient temperature. The FTP-75 test method is cu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/44B01J23/56B01J21/04B01J32/00B01J37/02B01D53/94
Inventor 史忠华陈耀强龚茂初赵明
Owner SICHUAN UNIV
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