Preparation of Diesel Oxidation Catalyst Via Deposition of Colloidal Nanoparticles

a technology of colloidal nanoparticles and catalysts, which is applied in the direction of physical/chemical process catalysts, separation processes, arsenic compounds, etc., can solve the problems of difficult to support only the precious metal of a desired cluster size on the oxide support, and the structure of the supported catalyst often provides limited control over the resulting materials

Inactive Publication Date: 2011-02-10
BASF CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Though simple, conventional impregnation methods used for the preparation of supported catalysts often provide limited control over the structure of the resulting materials (i.e. average particle size, particle composition and location of the active components).
However, the limited stability of such clusters on the surfaces of various supports, as well as difficulties in their synthesis and handling makes the use of cluster-derived catalysts problematic for large-scale applications.
It has therefore been extremely difficult to support only the precious metal of a desired cluster size on the oxide support.
However, this method is not free from problems in which the precious metal must be introduced into the pores of the hollow carbon material, which results in low productivity.
However, when a compound is used as the reducing agent in the method described above, there is a problem that an element or elements are contained in the compound mix as impurities in the final precious metal particles.
When hydrogen is used as the reducing agent, problems occur in that the particle diameter of the resulting precious metal particles becomes large and the particles are odd-shaped.

Method used

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  • Preparation of Diesel Oxidation Catalyst Via Deposition of Colloidal Nanoparticles
  • Preparation of Diesel Oxidation Catalyst Via Deposition of Colloidal Nanoparticles
  • Preparation of Diesel Oxidation Catalyst Via Deposition of Colloidal Nanoparticles

Examples

Experimental program
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Effect test

example 1

[0109]10.2 g of an H2PtCl6 solution containing 5.1*10−2 moles of Pt per liter of solution were diluted in 400 ml of water and an opportune amount of a PVP solution containing 10 mg of PVP per ml of solution was added in order to achieve a Pt / PVP weight ratio equal to 1. After letting the solution stir at room temperature in air for 1 hour, NaBH4 was added to the solution at room temperature. The amount of NaBH4 was chosen in order to have a Pt / NaBH4 weight ratio of 1 / 2. Following stirring for 1 hour in air of the obtained mixture, an appropriate amount of alumina powder was added to the solution in order to achieve a total metal loading of 1% wt / wt and the pH adjusted to a value of 2.4 with an HCl solution containing 15% HCl in weight. After 30 minutes of stirring the solution was filtered and the solid powder recovered.

example 2

[0110]The same process and quantities of reagents were used as in Example 1 with the exception of the PVP addition. Here an opportune amount of PVP solution containing 10 mg of PVP per mg of solution was added in order to achieve a Pt / PVP weight ratio equal to 2.

example 3

[0111]The same process and quantities of reagents were used as in Example 2 with the exception that 6.6 g of an H2PtCl6 solution containing 5.1*10−2 moles of Pt per liter of solution were diluted in 400 ml of water together with 110 mg of K2PdCl4.

[0112]As one can see from FIG. 1, the precious metal nanoparticles comprise both platinum and palladium and the composition is the same as one would expect from the relative ratio of platinum and palladium when calculated based on the mol of precious metal.

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Abstract

The present invention relates to a process for preparing a catalyst, at least comprising the steps of adding a protecting agent to an aqueous solution of a metal precursor to give a mixture (M1), adding a reducing agent to mixture (M1) to give a mixture (M2), adding a support material to mixture (M2) to give a mixture (M3), adjusting the pH of mixture (M3), and separating the solid and liquid phase of mixture (M3). Furthermore, the present invention relates to the catalyst as such and its use as diesel oxidation catalyst.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This patent application claims the benefit of pending U.S. provisional patent application Ser. No. 61 / 231,427 filed on Aug. 5, 2009, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates to a production method of a precious metal catalyst. Furthermore, the present invention relates to the catalyst as such and its use as diesel oxidation catalyst.BACKGROUND OF THE INVENTION[0003]Exhaust gas emitted from an internal combustion engine such as an automobile engine contains carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and so forth. These detrimental substances are generally purified by an exhaust gas purification catalyst in which a catalyst component mainly consisting of a precious metal such as platinum (Pt), rhodium (Rh), palladium (Pd), iridium (Ir), etc., is supported by an oxide support such as alumina.[0004]To support the precious metal of the cat...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D53/94B01J23/44B01J23/42
CPCB01D53/944B01D53/94B01D2255/1023B01D2255/1025B01D2255/104B01D2255/106B01J21/04B01J23/38B01J23/42B01J23/44B01J23/48B01J35/0013B01J35/002B01J35/006B01J37/0203B01J37/04B01J37/16B01D2255/1021B01D53/9418B01D53/9422B01D53/9436B01D2258/012F01N3/2803F01N2570/10B01J37/02
Inventor SIANI, ATTILIOMULLER-STACH, TORSTENNEUBAUER, TORSTENWEI, XINYI
Owner BASF CORP
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