# US 5,705,136 A · Catalyzed decomposition of nitrogen oxides on metal oxide supports

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- Number: US 5,705,136 A
- Document ID: US5705136A
- Status: Granted
- Kind: A
- Application number: 08/555,646
- Filed: 1995-11-13
- Granted: 1998-01-06
- Earliest claimed: 1995-11-13
- Assignees: University of Florida Research Foundation, Inc.
- Inventors: Russell S. Drago; Krzysztof Jurczyk
- Web page: https://patentgrep.com/patent/US5705136A

## CPC

- C01B 21/02: Preparation of nitrogen (by decomposition of ammonia C01B3/047)
- B01D 53/8628: {Processes characterised by a specific catalyst}
- B01J 23/002: {Mixed oxides other than spinels, e.g. perovskite}
- B01J 23/02: of the alkali- or alkaline earth metals or beryllium
- C01B 13/0203: {from inorganic compounds}
- B01J 2523/00: Constitutive chemical elements of heterogeneous catalysts
- Y02C 20/10: of nitrous oxide (N2O)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

This invention is a nitrogen oxide decomposition process and catalyst employed therein. The catalyst is a metal oxide, such as CoO, on a basic metal oxide-containing support, such as a MgO support.

## Claims

### Claim 1

A process for the decomposition of nitrogen oxides, comprising contacting a nitrogen oxide with a mixed oxide catalyst under conditions effective to decompose the nitrogen oxide to nitrogen and oxygen, wherein the catalyst comprises a first metal oxide selected from the oxide of Mn, Fe, Co, Ni, Cu, Zn, or mixtures thereof on a metal oxide support consisting essentially Of MgO, CaO, ZnO, TiO.sub.2, MoO.sub.3 --CoO--Al.sub.2 O.sub.3, ZnO--Al.sub.2 O.sub.3, TiO.sub.2 --MgO, Al.sub.2 O.sub.3 --ZnO, TiO.sub.2 --Al.sub.2 O.sub.3, TiO.sub.2 --ZnO, MgO--CuO and MgO--NiO or mixtures thereof, and wherein the catalyst is prepared by contacting the support with the nitrate salt of said first metal oxide, and wherein the catalyst is calcined prior to use under conditions effective to decompose to metal oxide said nitrate salt of said first metal oxide without sintering or intercalation of the catalyst.

### Claim 2 (depends on 1)

The process of claim 1 wherein the catalyst is calcined at a temperature between about 500.degree. C. and about 800.degree. C.

### Claim 3 (depends on 1)

The process of claim 1 wherein the contacting occurs at a temperature between about 400.degree. C. and about 800.degree. C. and at a GHSV of at least 1,000 h.sup.-1.

### Claim 4 (depends on 2)

The process of claim 2 wherein the contacting temperature is between about 500.degree. C. and about 700.degree. C. and at a GHSV of at least 4000 hr.sup.-1.

### Claim 5 (depends on 3)

The process of claim 3 wherein the support contains a metal oxide selected from the group consisting of MgO, CaO and mixtures thereof.

### Claim 6 (depends on 3)

The process of claim 3 wherein the first metal oxide is MnO, CuO, NiO, CoO, or mixture thereof.

### Claim 7 (depends on 3)

The process of claim 3 wherein the mixed oxide catalyst consists essentially of MnO, CuO, NiO, CoO, or mixture thereof in combination with MgO, CaO, or mixture thereof.

### Claim 8 (depends on 3)

The process of claim 3 wherein the mixed oxide catalyst consists essentially of CuO/2MgO, 3NiO/5MgO, MnO/2MgO, CoO/2CaO, or 2MgO/CuO.

### Claim 9 (depends on 3)

The process of claim 3 wherein the catalyst comprises cobalt oxide or copper oxide in an amount of from about 1 to about 10 weight percent based on the total weight of the catalyst.

### Claim 10 (depends on 1)

The process of claim 1 wherein the nitrogen oxide is N.sub.2 O.

### Claim 11 (depends on 1)

The process of claim 1 wherein the nitrogen oxide is present during contacting in a feed in a concentration of from about 1,000 to about 300,000 ppm.

### Claim 12

A mixed oxide catalyst composition useful in a process for the decomposition of nitrogen oxides, wherein the composition comprises a first metal oxide selected from the oxide of Mn, Fe, Co, Ni, Cu, Zn, or mixtures thereof on a metal oxide support consisting essentially of MgO, CaO, ZnO, TiO.sub.2, MoO.sub.3 --CoO--Al.sub.2 O.sub.3, ZnO--Al.sub.2 O.sub.3, TiO.sub.2 -MgO, Al.sub.2 O.sub.3 --ZnO, TiO.sub.2 --Al.sub.2 O.sub.3, TiO.sub.2 --ZnO, MgO--CuO and MgO--NiO or mixtures thereof, and wherein the catalyst is prepared by contacting the support with the nitrate salt of said first metal oxide, and wherein the catalyst is calcined prior to use under conditions effective to decompose to metal oxide said nitrate salt of said first metal oxide without sintering or intercalation of the catalyst.

### Claim 13 (depends on 12)

The catalyst of claim 12 wherein the catalyst is calcined at a temperature between about 500.degree. C. and about 800.degree. C.

### Claim 14 (depends on 12)

The catalyst of claim 12 wherein the support contains a metal oxide selected from the group consisting of MgO, CaO and mixtures thereof.

### Claim 15 (depends on 12)

The catalyst of claim 12 wherein the first metal oxide is MnO, CuO, NiO, CoO, or mixture thereof.

### Claim 16 (depends on 12)

The catalyst of claim 12 wherein the mixed oxide catalyst consists essentially of MnO, CuO, NiO, CoO, or mixture thereof in combination with MgO, CaO, or mixture thereof.

### Claim 17 (depends on 12)

The catalyst of claim 12 wherein the mixed oxide catalyst consists essentially of CuO/2MgO, 3NiO/5MgO, MnO/2MgO, CoO/2CaO, or 2MgO/CuO.

### Claim 18 (depends on 12)

The catalyst of claim 12 wherein the first metal oxide is cobalt oxide or copper oxide and is present in an amount of from about 1 to about 10 weight percent.

### Claim 19 (depends on 12)

The catalyst of claim 12 wherein the catalyst has a structure characterized by an x-ray photoelectric spectroscopy signature containing an oxygen 1s peak that can be resolved into three different component peaks, said peaks reflecting the presence of hydroxyl functionalities on the catalyst and the absence of spinnel or related structures.

### Claim 20

A process for the decomposition of nitrogen oxides, comprising contacting a gaseous feed containing one or more nitrogen oxides with a mixed oxide catalyst under conditions effective to decompose nitrogen oxide components to nitrogen and oxygen, wherein the catalyst is selected from the group consisting of Cu.sub.3 Mg.sub.5 Al.sub.2 (OH).sub.20 CO.sub.3.yH.sub.2 O; Ni.sub.3 Mg.sub.5 Al.sub.2 (OH).sub.20 CO.sub.3.yH2O; Mn.sub.3 Mg.sub.5 Al.sub.2 (OH).sub.20 CO.sub.3.yH.sub.2 O or Co.sub.3 Ca.sub.5 Al.sub.2 (OH).sub.20 CO.sub.3.yH.sub.2 O and is prepared by adding a base to an aqueous composition containing cobalt nitrate, calcium nitrate, and aluminum nitrate such that a gel forms; drying the gel; and calcining the dry gel to form the mixed metal oxide.

### Claim 21 (depends on 20)

The process of claim 20 wherein said contacting is at temperatures from about 450.degree. C. to about 850.degree. C.

### Claim 22 (depends on 20)

The process of claim 20 wherein said contacting is at temperatures from about 500.degree. C. to about 700.degree. C.

### Claim 23 (depends on 20)

The process of claim 20 wherein the mixed metal oxide catalyst has a lifetime of at least about 120 hours in feed concentrations of nitrogen oxide up to about 250,000 ppm, and has a lifetime of at least about 100 hours in feed concentrations of nitrogen oxide up to about 350,000 ppm.

### Claim 24 (depends on 20)

The process of claim 20 wherein the contacting occurs at a GHSV of at least 1000 h.sup.-1.

### Claim 25 (depends on 20)

The process of claim 20 wherein the nitrogen oxide is N.sub.2 O.

### Claim 26 (depends on 20)

The process of claim 20 wherein feed concentration of the nitrogen oxide in the gas is about 1,000 to about 300,000 ppm.