Catalytic oxidation of NOx/SOx in flue gases with atmospheric oxygen as the oxidation reagent

Patent metadata

Field	Value
Publication number	US-10946335-B2
Application number	US-201816628028-A
Country	US
Kind code	B2
Filing date	Jul 18, 2018
Priority date	Jul 20, 2017
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

A NO x and SO x oxidation with atmospheric oxygen to remove NO x and SO x from flue gases. The combined system for catalytic oxidation and wet-scrubbing of NO x and SO x from a flue gas and manufacturing fertilizers includes: an air separation unit for separating atmospheric oxygen from air and producing an air stream enriched with atmospheric oxygen, an adsorption and oxidation reactor containing an oxidation catalyst and carrying out the catalytic oxidation of NO x and SO x by said oxygen to yield nitric and sulphuric acids, a separator and reactor control unit for separation of products and liquids and controlling the reaction; and a vessel containing ammonia streaming said ammonia into the reactor or into the control unit to react with the nitric and sulphuric acids and to yield the fertilizers.

First claim

The invention claimed is:

1. A combined system for catalytic oxidation and wet-scrubbing of simultaneously both nitrogen oxides (NO x ) and sulphur oxides (SO x ) from a flue gas, and for manufacturing fertilisers comprising:
a) An air separation unit for separating atmospheric oxygen from air and thereby producing an air stream substantially enriched with atmospheric oxygen for oxidation of NO x and SO x ;
b) An adsorption and oxidation reactor containing a dry oxidation catalyst or an adsorbing dispersion containing the oxidation catalyst, and designed to receive the air stream substantially enriched with atmospheric oxygen and a flue gas stream containing NO x and SO x , to adsorb said streamed gases, and then to carry out the catalytic oxidation of said NO x and SO x by said oxygen to yield nitric and sulphuric acids;
c) A separator and reactor control unit for separation of products and liquids and controlling said catalytic oxidation and wet-scrubbing; and
d) A vessel containing gas or liquid ammonia, connected to said adsorption and oxidation reactor or to said separator and reactor control unit, and having an inlet streaming said ammonia into the adsorption and oxidation reactor or into the separator and reactor control unit to react with the nitric and sulphuric acids and to yield ammonium nitrate and ammonium sulphate fertilisers, thereby wet-scrubbing NO x and SO x from the flue gas and producing said fertilisers.

2. The system of claim 1 , wherein said adsorption and oxidation reactor is dry and packed with inert solids promoting a better contact between said oxygen stream and said flue gas stream.

3. The system of claim 1 , wherein said adsorption and oxidation reactor is wet containing a liquid circulating inside.

4. The system of claim 1 , wherein said adsorption and oxidation reactor is selected from a bubble column, packed bed and spray tower.

5. The system of claim 4 , wherein said adsorption and oxidation reactor is a spray tower equipped with spray means capable of spraying into said spray tower: (i) water or mother liquor onto the dry oxidation catalyst particles, thereby forming floating drops of the adsorbing dispersion directly inside the spray tower, or (ii) the adsorbing dispersion prepared in advance and comprising the oxidation catalyst particles.

6. The system of claim 5 , wherein said spray means comprise one or more spray nozzles arrayed within the spray tower along the flue gas flow path and configured to spray said water, mother liquor or adsorbing dispersion into the vessel.

7. The system of claim 1 , wherein said adsorbing dispersion is an aqueous suspension of the oxidation catalyst particles.

8. The system of claim 7 , wherein said oxidation catalyst comprises the mixture of an aqueous solution of a metal salt precursor with silica gel particles and used for catalysing the oxidation reaction of NO x and SO x in the flue gas.

9. The system of claim 8 , wherein the metal salt precursor is a water-soluble inorganic salt of a transition metal selected from cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu) and chromium (Cr).

10. The system of claim 9 , wherein the metal salt precursor is cobalt chloride (CoCl 2 ), and the oxidation catalyst comprises an aqueous suspension of cobalt oxide/hydroxide particles supported on silica gel particles.

11. The system of claim 1 , wherein said separator and reactor control unit comprises at least one of the following processing units: a phase separator, crossflow separator, mixer-settler, decanter, tricanter or filter.

12. The system of claim 11 , further comprising a crystallisation vessel connected to the processing unit and configured to receive from said processing unit an aqueous solution containing the dissolved ammonium nitrate and ammonium sulphate products, said crystallisation vessel is capable of crystallising and precipitating the ammonium nitrate and ammonium sulphate from the aqueous solution.

13. The system of claim 1 , wherein said adsorbing dispersion is an oil-water emulsion, and said separator and reactor control unit comprises an oil-water phase separator configured to receive said oil-water emulsion from the adsorption and oxidation reactor and to separate gross amounts of oil (organic phase) from water (aqueous phase).

14. The system of claim 13 , wherein the oil-water emulsion comprises a filtered aqueous solution and an organic phase, said organic phase comprises elemental sulphur in saturated heavy mineral oil, said sulphur is capable of catalysing the oxidation reaction of NO x and SO x in the flue gas.

15. The system of claim 14 , wherein said organic phase further comprises activators added to the sulphur oil solution to increase solubility of the elemental sulphur.

16. The system of claim 1 , further comprising a separate oxidation chamber connected to the air separation unit and configured to receive the air stream substantially enriched with atmospheric oxygen and a stream of the flue gas containing NO x and SO x , said oxidation chamber is filled with the oxidation catalyst capable of catalysing oxidation of NO x and SO x by said atmospheric oxygen.

17. The system of claim 16 , wherein said oxidation chamber is dry and packed with inert solids promoting a better contact between said oxygen stream and said flue gas stream, or said oxidation chamber is wet containing a liquid circulating inside.

18. A process of removing simultaneously nitrogen and sulphur oxides from a flue gas containing said oxides, said process comprises:
I. Separating atmospheric oxygen from air, thereby producing an air stream substantially enriched with atmospheric oxygen for oxidation of NO x and SO x ;
II. Catalytic oxidation of the NO x and SO x contained in the flue gas by the atmospheric oxygen in said air stream, thereby producing the oxidised NON and SON streamed with the flue gas; and
III. Wet-scrubbing of the oxidised NO x and SO x streamed in the flue gas with an adsorbing dispersion comprising a solid oxidation catalyst suspended in water, an oxidation catalyst soluble in organic solvent and emulsified in water, or combination thereof, thereby removing the NO x and SO x from the flue gas.

19. The process of claim 18 , further comprising the steps of contacting the oxidised NO x and SO x dissolved in said adsorbing dispersion with ammonia to produce ammonium nitrate (NH 4 NO 3 ) and ammonium sulphate ((NH 4 ) 2 SO 4 ), separating, crystallising end collecting said NH 4 NO 3 and (NH 4 ) 2 SO 4 and recycling water from mother liquor, said mother liquor is left after precipitation of said NH 4 NO 3 and (NH 4 ) 2 SO 4 .

20. The process of claim 18 , wherein said process is carried out at the temperature of 50-90° C. and pH 4-7.

Assignees

• Ariel Scient Innovations Ltd

Inventors

• Pinhasi Gad A
• Zidki Tomer
• Cohen Haim

Classifications

• Y02A50/20

  Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters · CPC title

• C05C3/00

  Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor · CPC title

• C05C1/00

  Ammonium nitrate fertilisers · CPC title

• B01D53/8693

  After-treatment of removed components · CPC title

• B01D53/8653

  characterised by a specific device · CPC title