Iron-zeolite chabazite catalyst for use in NOx reduction and method of making

A catalyst and zeolite-type technology, applied in the direction of catalyst activation/preparation, molecular sieve catalysts, chemical instruments and methods, etc., can solve problems such as insufficient thermal stability and damage to exothermic reactions of catalysts

Inactive Publication Date: 2015-08-19
FORD GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Such catalysts provide good NO at high temperature x reduction, but suffers from other disadvantages
For example, beta zeolite has insufficient thermal stability for prolonged use at high temperatures and tends to adsorb large amounts of hydrocarbons, which can lead to exothermic reactions that can damage the catalyst
[0004] Although it is desirable to incorporate a metal such as iron into a chabazite-type zeolite to achieve high activity and improved thermal stability, the use of traditional ion exchange methods to incorporate iron into a chabazite-type zeolite—such as SSZ-13— —Medium is difficult because of the small pore openings of the chabazite structure

Method used

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  • Iron-zeolite chabazite catalyst for use in NOx reduction and method of making
  • Iron-zeolite chabazite catalyst for use in NOx reduction and method of making
  • Iron-zeolite chabazite catalyst for use in NOx reduction and method of making

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Effect test

Embodiment 1

[0046] Chabazite samples were synthesized according to the procedure detailed above. The iron content was determined to be 1.2 wt% for both samples. One sample was ion exchange with ammonium ions to convert chabazite to the ammonium form. The sodium content in the non-exchanged sample was determined to be 6.3 wt%, whereas the sodium content after ammonium ion exchange was 390 ppm. Na and NH 4 The chabazite samples were then degreened at 750°C for 4 hours. Two samples were then used containing NO x The simulated vehicle exhaust device is tested. The samples were tested in a bench-top continuous reactor using simulated diesel engine exhaust from 13% O 2 , 5% CO 2 , 4.5%H 2 O, 350ppm NO, 350ppm NH 3 and balance N 2 composition. 3.0 grams of each sample was placed on an airflow of 9.65 SLPM (standard liters per minute). This corresponds to a space velocity of 30,000 / hour on the washed monolith. except N 2 and O 2 All other components were analyzed simultaneously by F...

Embodiment 2

[0049] Three different samples of the catalyst were prepared and tested. The first two samples were synthesized according to the procedure detailed above. For both samples, the iron content was determined to be 1.2 wt%. Both samples were then ion exchanged with ammonium ions to convert the chabazite to the ammonium form. The sodium content was greatly reduced after ammonium ion exchange. Two chabazite samples were then degreened at 750°C for 4 hours. A second chabazite sample was then subjected to accelerated aging at 800°C for 80 hours. A third sample comprised a conventional copper-based SCR catalyst obtained from BASF that had been degreened at 750°C for 4 hours. All samples were then used to contain NO x simulated vehicle exhaust for testing. After initial degreening at 750° C. for 4 hours, samples were tested in a benchtop continuous reactor. The simulated diesel exhaust is composed of 13% O 2 , 5% CO 2 , 4.5%H 2 O, 350ppmNO, 350ppmNH 3 , and the balance N 2 c...

Embodiment 3

[0052] The aged chabazite catalyst prepared according to the embodiment of the present invention was tested along with the degreened traditional copper-based SCR monolithic catalyst. The catalysts were tested individually and in combination with chabazite particulate catalyst positioned immediately upstream of the copper-based SCR monolith catalyst. Samples were tested in a benchtop continuous reactor after initial degreening at 750 °C for 4 hours. The simulated diesel exhaust is composed of 13% O 2 , 5% CO 2 , 4.5%H 2 O, 350ppm NO, 350ppm NH 3 , and the balance N 2 composition. 3.0 grams of chabazite pellets and 1.18in 3 The copper-based SCR monolith catalyst was placed on an airflow of 9.65 SLPM, corresponding to a space velocity of 30,000 / hour on each component. except N 2 and O 2All other gas species are analyzed simultaneously by FTIR. From Figure 5 It can be seen that the performance of the combined chabazite catalyst and copper-based catalyst is superior to ...

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Abstract

An iron-zeolite chabazite (CHA) catalyst is provided as an SCR catalyst for reducing nitrogen oxides (NOx) from vehicle engine exhausts. The catalyst is formed by incorporating iron during synthesis of the chabazite zeolite, which eliminates the need for a post-synthesis ion-exchange step and which results in the incorporation of iron into the (CHA) zeolite crystal lattice structure. The resulting catalyst exhibits good high temperature activity at temperatures greater than 550° C. and exhibits good thermal stability.

Description

Background technique [0001] Embodiments described herein relate to the preparation and use of iron zeolite catalysts in the reduction of nitrogen oxides (NOx) from vehicle exhaust, and more particularly, to an iron-zeolite-type rhombohedron for nitrogen oxide reduction as an SCR catalyst Zeolite (CHA) catalyst. [0002] In recent years, U.S. government regulations have limited nitrogen oxides (NO x ) emissions. This necessitates the use of catalysts in vehicle exhaust systems that stimulate NO x restoration. A number of catalysts are currently used to convert these exhaust components into environmentally acceptable compounds. Selective catalytic reduction catalysts (SCR) are used to reduce NO x converted to N 2 , and typically contain metal-promoted zeolites, and utilize an ammonia reductant typically produced by thermal decomposition of aqueous urea injected in the tail gas stream. SCR catalysts should be able to maintain good catalytic activity over a wide range of te...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/76B01D53/94B01D53/56
CPCB01J29/88B01D53/9418B01D2255/20738B01D2255/50B01J29/763B01J35/0006B01J37/0246C01B39/065Y02T10/12Y02A50/20
Inventor 克利福德·诺曼·蒙特勒伊
Owner FORD GLOBAL TECH LLC
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