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Two-section type catalyst for diesel vehicle exhaust treatment and preparation method of catalyst

A tail gas treatment and catalyst technology, applied in physical/chemical process catalysts, gas treatment, molecular sieve catalysts, etc., can solve the problems of unable to eliminate particulate matter, poisoning can withstand space velocity, and reduced catalytic activity, achieving excellent N2 selectivity, urea The effect of decomposing and eliminating escaped NH3 and simple preparation process

Active Publication Date: 2017-10-10
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, there are still some problems in using it for diesel vehicle exhaust treatment, such as: narrow temperature window, high temperature N 2 Poor selectivity, with N 2 O formation and NH 3 oxidation, and TiO 2 At high temperature, the crystal structure will change, which will reduce the catalytic activity. At the same time, vanadium is poisonous to the environment and can withstand low space velocity.
The SSZ-13 molecular sieve catalyst used in the prior art for automobile exhaust treatment is BASF's SSZ-13 molecular sieve catalyst. Although the temperature window is relatively wide and it is resistant to high space velocity, its low-temperature activity is not high and particulate matter cannot be eliminated; while the particulate matter emission in diesel vehicle exhaust It is very harmful to people when exposed to the air

Method used

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  • Two-section type catalyst for diesel vehicle exhaust treatment and preparation method of catalyst
  • Two-section type catalyst for diesel vehicle exhaust treatment and preparation method of catalyst
  • Two-section type catalyst for diesel vehicle exhaust treatment and preparation method of catalyst

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preparation example Construction

[0056] The present invention also provides a method for preparing the two-stage catalyst described in the above technical solution, comprising the following steps:

[0057] a) Hydrothermal reaction of cerium source, X' source and triethylamine in the first solvent to obtain CeO 2 -X nanoparticles; the X' source is selected from a copper source, an iron source or a manganese source;

[0058] b) Co-precipitate M' source, cerium source and ammonia water in the second solvent to obtain M@CeO 2 Core-shell nanoparticle; The M' source is selected from a rhodium source, a platinum source or a palladium source;

[0059] c) the CeO obtained in step a) 2 -X nanoparticles and M@CeO obtained from step b) 2 Nanoparticles with core-shell structure are respectively loaded with molecular sieves to obtain Catalyst A and Catalyst B respectively;

[0060] d) Catalyst A is arranged at the intake end, and catalyst B is arranged at the outlet end to obtain a two-stage catalyst for diesel vehicle...

Embodiment 1

[0078] (1) Preparation of CeO 2 -Fe 2 o 3 Nanoparticles:

[0079] Weigh 5.4g of polyvinylpyrrolidone (PVP-K30) and dissolve it in 360mL of absolute ethanol; after the PVP is completely dissolved, add 0.7422g of cerium nitrate and 0.0218g of ferric nitrate into the solution, stir until completely dissolved, then add 1.82g of triethylamine dropwise , stirred for another 10 minutes, then transferred to the reactor, and reacted hydrothermally at 180° C. for 24 hours. After the reaction, the solution was taken out to a constant volume (0.0008 g / mL) for use.

[0080] The CeO 2 -Fe 2 o 3 TEM images of the nanoparticles as figure 1 shown by figure 1 It can be seen that CeO 2 -Fe 2 o 3 The average particle diameter of the nanoparticles is 3nm-5nm.

[0081] (2) Preparation of Rh@CeO 2 Core-shell nanoparticles:

[0082] Add 7.5mg of potassium bromide to a beaker with 20mL of deionized water, stir and dissolve in a water bath at 60°C, then add 0.417mL of 0.03M rhodium nitrate...

Embodiment 2

[0090] (1) Preparation of CeO 2 -Fe 2 o 3 Nanoparticles:

[0091] Weigh 5.4g of polyvinylpyrrolidone (PVP-K30) and dissolve it in 360mL of absolute ethanol; after the PVP is completely dissolved, add 0.4661g of cerium nitrate and 0.0186g of ferric nitrate into the solution, stir until completely dissolved, and then dropwise add 1.22g of triethylamine , stirred for another 10 minutes, then transferred to the reactor, and reacted hydrothermally at 180° C. for 24 hours. After the reaction, the solution was taken out to a constant volume (0.0008 g / mL) for use.

[0092] (2) Preparation of Rh@CeO 2 Nanoparticles with core-shell structure: the same as in Example 1.

[0093] (3) Preparation of CeO 2 -Fe 2 o 3 / ZSM-5: Same as Example 1.

[0094] (4) Preparation of Rh@CeO 2 / ZSM-5: Same as Example 1.

[0095] (5) 25mg catalyst A is arranged at the inlet end of the tubular fixed bed reactor, and 25mg catalyst B is arranged at the gas outlet end of the tubular fixed bed reactor ...

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Abstract

The invention provides a two-section type catalyst for diesel vehicle exhaust treatment. The catalyst comprises a catalyst A at a gas inlet end and a catalyst B at a gas outlet end, wherein the catalyst A has the general formula: CeO2-X / molecular sieve, and X is selected from CuO, Fe2O3 or MnO2; the catalyst B has the general formula: M@CeO2 / molecular sieve, and M is selected from Rh, Pt or Pd. Compared with the prior art, the two-section type catalyst for diesel vehicle exhaust treatment has a high elimination effect and selectivity for nitric oxides in a relative wide temperature range, can eliminate particulate matter in a certain degree and also has the function of eliminating escaping ammonia. The catalyst B at the gas outlet end also has the functions of a DOC catalyst. Experimental results indicate that the two-section type catalyst has the nitric oxide conversion activity higher than 80%, good stability and excellent N2 selectivity at the high temperature of 150-550 DEG C and at the high space velocity of 240,000 h<-1>, and can eliminate carbon particles in exhaust at about 450 DEG C.

Description

technical field [0001] The invention relates to the technical field of catalysts, in particular to a two-stage catalyst used for treating diesel vehicle exhaust and a preparation method thereof. Background technique [0002] Nitrogen oxides (NO x ) mainly refers to NO and NO 2 , of which NO accounts for 95%. Nitrogen oxides are one of the main air pollutants, and their direct contact with air and water can cause many hazards, such as acid rain, photochemical smog, stratospheric ozone depletion, global climate change, etc. Nitrogen oxides in the atmosphere mainly come from mobile sources (motor vehicles) and stationary sources (mainly thermal power plants, industrial combustion devices), among which, 95% of the world's nitrogen oxides come from motor vehicle emissions (49%) and power plant emissions (46%). With the growth of energy consumption and the rapid increase of the number of motor vehicles, more and more acidic substances such as nitrogen oxides are discharged int...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/44B01J29/46B01J29/48B01J29/74B01J29/76B01J29/78B01J35/02B01D53/94B01D53/56B01J35/00
CPCB01D53/9413B01J29/44B01J29/46B01J29/48B01J29/7415B01J29/7476B01J29/7615B01J29/7676B01J29/7815B01J29/7876B01D2258/012B01J35/396B01J35/40
Inventor 杨向光易婷张一波
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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