# US 10,864,501 B2 · Metal ferrite oxygen carriers for conversion of CO2 to CO and fuel to syngas or CO

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- Number: US 10,864,501 B2
- Document ID: US10864501B2
- Status: Granted
- Kind: B2
- Application number: 16/550,747
- Filed: 2019-08-26
- Published: 2020-03-12
- Granted: 2020-12-15
- Earliest claimed: 2017-05-19
- Assignees: U.S. Department of Energy
- Applicants: United States Department of Energy
- Inventors: Ranjani V. Siriwardane
- Web page: https://patentgrep.com/patent/US10864501B2

## CPC

- B01J 23/78: with alkali- or alkaline earth metals
- C01B 3/42: using moving solid particles, e.g. fluidised bed technique
- C01B 3/40: characterised by the catalyst
- C01B 2203/0238: the reforming step being a carbon dioxide reforming step
- C01B 2203/066: with fuel cells
- C01B 2203/1047: Group VIII metal catalysts
- C01B 2203/1241: Natural gas or methane
- Y02P 20/52: using catalysts, e.g. selective catalysts
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The invention provides a use of metal ferrite oxygen carrier for converting carbon dioxide to carbon monoxide or synthesis gas via three processes: catalytic dry reforming of methane, chemical looping dry reforming of fuel and promoting coal gasification with CO2. The metal ferrite oxygen carrier comprises MzFexOy, where MzFexOy is a chemical composition with 0<x≤4, z>0 and 0<y≤6 and M is one of Ca, Ba, and/or combinations thereof. For example, MzFexOy may be one of CaFe2O4, BaFe2O4, MgFe2O4, SrFe2O4 and/or combinations thereof. In catalytic dry reforming, methane and carbon dioxide react in the presence of metal ferrites generating a product stream comprising at least 50 vol. % CO and H2. In another embodiment, chemical looping dry reforming process where metal ferrite is reduced with a fuel and then oxidized with carbon dioxide is used for production of CO from carbon dioxide. In another embodiment, the metal ferrite is used as a promoter to produce CO continuously from coal gasification with CO2.

## Claims

### Claim 1

A method for chemical looping dry reforming of methane comprising:
delivering a metal ferrite oxygen carrier comprising MzFexOy to a fuel reactor, where 0<x≤4, z>0 and 0<y≤6, and where M is at least one of Mg, Ca, Ba, Sr or combinations thereof;
delivering a fuel stream to the metal ferrite oxygen carrier in the fuel reactor and maintaining the fuel reactor at a reducing temperature, where the reducing temperature is sufficient to reduce some portion of the metal ferrite oxygen carrier and oxidize some portion of the fuel stream, and generating gaseous products containing H2, CO or CO2 gas in the fuel reactor;
delivering the reduced metal ferrite to an oxidation reactor;
oxidizing the reduced carrier by contacting the reduced carrier and carbon dioxide at an oxidizing temperature, where the oxidizing temperature is sufficient to generate an oxidizing reaction, where reactants of the oxidizing reaction comprise some portion of the carbon dioxide, some portion of the M component, and some portion of a FecOd component, where c>0 and d≥0 and where a product of the oxidizing reaction is CO and a re-oxidized carrier, where the re-oxidized carrier comprises some portion of the MzFexOy; and
withdrawing a product stream CO from the oxidation reactor, where the gaseous products comprise the product stream, and where at least >50 vol. % of the product stream consists of CO.

### Claim 2 (depends on 1)

The method of claim 1 where the reducing temperature ranges from about 500° C. to about 1100° C.

### Claim 3 (depends on 1)

The method of claim 1 where 2>z>0, 2≤x≤3 and 3≤y≤5.

### Claim 4 (depends on 1)

The method of claim 1 where the MzFexOy comprises at least 30 wt. % of the metal ferrite oxygen carrier.

### Claim 5 (depends on 1)

The method of claim 1 where the metal ferrite oxygen carrier further comprises an inert support, where the inert support comprises from about 5 wt. % to about 70 wt. % of the metal ferrite oxygen carrier.

### Claim 6 (depends on 1)

The method of claim 1 wherein the inert support contains at least one of alumina, silica, zirconia, clay, titania, monolith or combinations thereof.

### Claim 7 (depends on 1)

The method of claim 1 where the mixing the fuel stream and the metal ferrite oxygen carrier in the fuel reactor step generates a reduced carrier, where the reduced carrier comprises an M component and an FecOd component, where the M component comprises some portion of the M comprising the MzFexOy, and MO and where the FecOd component comprises some portion of the Fe comprising the MzFexOy, where c>0 and d≥0.

### Claim 8 (depends on 7)

The method of claim 7 where the FecOd component comprises Fe0, FeO, Fe3O4 or Fe2O3 and M component comprises MO or MCO3.

### Claim 9 (depends on 1)

The method in claim 1 where the fuel in the fuel reactor is coal, methane or bio mass.

### Claim 10 (depends on 9)

The method of claim 9 wherein the methane concentration may be greater than 5 vol %.

### Claim 11 (depends on 1)

The method of claim 1 wherein oxidization of the reduced carrier occurs in an oxidizing reactor, and further comprising:
transferring the reduced carrier from the fuel reactor to the oxidizing reactor; supplying the carbon dioxide containing gas stream to the oxidizing reactor, thereby
generating the re-oxidized carrier, producing carbon monoxide;
transferring the re-oxidized carrier from the oxidizing reactor to the fuel reactor; and
repeating the delivering the metal ferrite oxygen carrier to the fuel reactor, introducing methane or coal to the metal ferrite oxygen carrier in the fuel reactor, and the withdrawing the product stream from both the fuel reactor and the oxidizing reactor.

### Claim 12 (depends on 11)

The method of claim 11 where the oxidizing temperature ranges from about 500° C. to about 1100° C.

### Claim 13 (depends on 11)

The method of claim 11 wherein the carbon dioxide gas stream may be provided by carbon dioxide separated from fuel combustion streams with air or fuel chemical looping combustion streams.