Exhaust gas purification catalyst and method for producing the same

A technology of exhaust gas purification and catalyst, which is applied in the direction of catalyst activation/preparation, physical/chemical process catalyst, catalyst carrier, etc., can solve the problem of lack of exhaust gas purification performance, etc., and achieve the effect of excellent purification performance

Active Publication Date: 2021-10-26
CATALER CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, in conventional exhaust gas purification catalysts as described above, the catalyst layer itself is formed on a base material that does not have exhaust gas purification performance, for example, a honeycomb base material made of cordierite.

Method used

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  • Exhaust gas purification catalyst and method for producing the same
  • Exhaust gas purification catalyst and method for producing the same
  • Exhaust gas purification catalyst and method for producing the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0165] (1) Formation of the lower layer

[0166] Use 50g as CeO of the 1st CZ 2 :ZrO 2 = 35:65 (mass ratio), ceria-zirconia composite oxide with a secondary particle diameter of 1 μm, 50 g of CeO as the second CZ 2 :ZrO 2 =35:65 (weight ratio), ceria-zirconia composite oxide having a secondary particle diameter of 30 μm, 100 g of alumina, and 300 g of water were mixed to prepare a slurry for the lower layer.

[0167] This underlayer slurry was applied to a substrate, and heated at 250° C. for 1 hour to form a lower layer on the substrate (coating amount: 200 g / L).

[0168] (2) Formation of the upper layer

[0169] Use 50g of CeO as the upper layer with CZ 2 :ZrO 2 =20:80 (weight ratio), the ceria-zirconia composite oxide that the secondary particle diameter is 1 μ m is immersed in the aqueous solution that contains the rhodium nitrate of 0.2g / L equivalent, is then heated at 250 ℃ for 1 hour, and then heated at 500 ℃ for 1 hour to obtain Rh-loaded CZ.

[0170] 50 g of R...

Embodiment 2～16 and comparative example 6～12

[0209] (1) Preparation of catalyst

[0210] As the first CZ and the second CZ, CZ having the particle diameters described in Table 2 or Table 3 were used respectively, and the usage ratio of the two was set according to Table 2 or Table 3, and it was formed on the substrate in the same manner as in Example 1. Lower layer (coating amount: 200g / L).

[0211] Next, CZ carrying Rh was prepared in the same manner as in Example 1 except that CZ having the particle diameters described in Table 1 was used as CZ for the upper layer, and CZ carrying Rh was formed in the same manner as in Example 1 using this CZ carrying Rh. An upper layer (coating amount: 100 g / L) was formed on the base material of the lower layer, thereby preparing an exhaust gas purification catalyst.

[0212] (2) Evaluation

[0213] Using the exhaust gas purification catalyst prepared above, the measurement of the particle size of the oxide particles and the evaluation of the exhaust gas purification performance wer...

Embodiment 17

[0215] In this example, the effect of loading a small amount of Rh on the second CZ in the lower layer was investigated.

[0216] (1) Formation of the lower layer

[0217] As the 2nd CZ, use CeO 2 :ZrO 2 =35:65 (weight ratio), ceria-zirconia composite oxide with a secondary particle diameter of 30 μm, 50 g of the second CZ is immersed in an aqueous solution containing 0.25 g / L equivalent of rhodium nitrate, and then heated at 250° C. After 1 hour, further firing at 500° C. for 1 hour, the second CZ carrying Rh was obtained.

[0218] Use 50g as CeO of the 1st CZ 2 :ZrO 2 = 35:65 (weight ratio), ceria-zirconia composite oxide with a secondary particle diameter of 1 μm, 50 g of the above Rh-loaded 2nd CZ as the 2nd CZ, 50 g of alumina, and 200 g of water were mixed to prepare a slurry for the lower layer .

[0219] This underlayer slurry was applied to a substrate, and heated at 250° C. for 1 hour to form a lower layer on the substrate (coating amount: 150 g / L).

[0220] (...

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Abstract

An exhaust gas purification catalyst comprising a lower layer and an upper layer, wherein the lower layer contains cerium oxide-based oxide particles, and the upper layer contains metal oxide particles and a noble metal supported on the metal oxide particles, wherein the exhaust gas purification catalyst is characterized in that , the Rh content in the lower layer is 0.25 g / L or less, and the particle size distribution of the cerium oxide-based oxide particles contained in the lower layer observed by scanning electron microscopy has a first peak and a second peak, so The first peak has a peak top in the region of 0.90 to 6.50 μm, and the second peak has a peak top in the region of 9.50 to 34.0 μm.

Description

technical field [0001] The present invention relates to an exhaust gas purifying catalyst and a manufacturing method thereof. Background technique [0002] A three-way catalyst in which a noble metal is supported on an inorganic oxide is known as an exhaust gas purification catalyst used for treating exhaust gas from automobiles or the like. Three-way catalysts are widely used as catalysts capable of effectively removing hydrocarbons (HC), nitrogen oxides (NOx) and carbon monoxide (CO) simultaneously. Exhaust gas purification catalysts typified by three-way catalysts often contain rhodium (Rh) excellent in NOx purification activity. [0003] The exhaust gas removal performance of the exhaust gas purification catalyst is most efficient when the air-fuel ratio is a stoichiometric air-fuel ratio (so-called "stoichiometric ratio") near 14.6. However, cars often don't drive at an air-fuel ratio close to stoichiometric. It is known that when the air-fuel ratio is varied by engi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J23/63B01D53/94B01J37/02F01N3/10
CPCB01J23/63B01D53/945B01D2255/1023B01D2255/1025B01D2255/2065B01D2255/407B01D2255/9022B01D2255/9202B01D2258/01F01N3/2803F01N2330/30F01N2370/02F01N2510/06F01N2510/0684B01J37/0244B01J23/10B01J35/023B01J35/002B01J35/0073B01D53/94B01J37/02F01N3/10B01J35/0006F01N3/101
Inventor 三隅宝松枝悟司
Owner CATALER CORP
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