WE CLAIM:
1. Process for treating a waste gas stream containing nitrogen oxides
(NOx) and contaminants selected from the group consisting of heavy metals,
acid gases (such as S02, S03, H3P04, HCl, HI, HBr, and/or HF) and
5 combinations thereof, said waste gas stream originating from a combustion process, said treating process comprising:
injecting an alkali sorbent comprising a compound selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium sesquicarbonate (trona), quick lime, hydrated lime, limestone, and combinations thereof;
10 contacting at least a portion of the contaminants with the alkali sorbent to
remove at least a portion of the contaminants from the waster gas stream,
injecting an ammonia source into the waste gas stream;
injecting a catalyst into the waste gas stream; and
converting, in the presence of O2, by reduction with NH3 of at least a 15 portion of the NOx in the waste gas stream to N2 and water at a temperature of at least 100°C and preferably at most 600°C,
wherein the catalyst comprises an active catalyst component deposited on a porous support;
wherein said active catalyst component comprises copper, copper oxide, or 20 combination thereof; and
wherein said porous support comprises at least 60 wt % of a calcium-deficient hydroxyapatite having a calcium to phosphate molar ratio (Ca/P) of less than 1.67, preferably more than 1.5 and less than 1.67.
2. A blend comprising an alkali sorbent and a catalyst,
25 said alkali sorbent comprising a compound selected from the group
consisting of sodium bicarbonate, sodium carbonate, sodium sesquicarbonate (trona), quick lime, hydrated lime, limestone, and combinations thereof,
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wherein the blend comprises
- at least 0.1 wt%, or at least 0.2 wt%, or at least 0.5 wt%, or at least 1
wt%, or at least 3 wt%, or at least 5 wt%, of the catalyst, and/or
- at most 20 wt%, or at most 15 wt%, or at most 12 wt%, or at most 10
5 wt%, of the catalyst;
said catalyst comprising an active catalyst component deposited on a porous support; wherein said active catalyst component comprises copper, copper oxide, or combination thereof;
wherein said porous support comprises at least 60 wt % of a calcium-10 deficient hydroxyapatite having a calcium to phosphate molar ratio (Ca/P) of less than 1.67, preferably more than 1.5 and less than 1.67.
3. The process according to claim 1 or blend according to claim 2, wherein
the porous support of the catalyst further comprises calcium carbonate in an
amount of less than 20 wt% and more than 0 wt%, preferably from 1 wt% to 19
15 wt%, more preferably from 2 wt% to 18 wt%, even more preferably from 5 wt% to 15 wt%, yet even more preferably from 7 wt% to 13 wt%, most preferably from 8 wt% to 12 wt%.
4. The process according to any of the preceding claims or blend according
to claim 2 or 3, wherein the porous support of the catalyst comprises less than 1
20 wt% of calcium dihydroxide Ca(OH)2, preferably less than 0.5 wt% calcium dihydroxide Ca(OH)2, more preferably less than 0.3 wt% calcium dihydroxide Ca(OH)2, even more preferably less than 0.2 wt% calcium dihydroxide Ca(OH)2, most preferably being substantially free of calcium dihydroxide Ca(OH)2.
5. The process according to any of the preceding claims or blend according
25 to any of claims 2-4, wherein the porous support of the catalyst further comprises
water in an amount of less than 20 wt% and more than 0 wt%, preferably from 1 wt% to 18 wt%, more preferably from 2 wt% to 15 wt%, even more preferably from 4 wt% to 12 wt%, yet even more preferably from 5 wt% to 11 wt% most preferably from 6 wt% to 11 wt%.
30 6. The process according to any of the preceding claims or blend according
to any of claims 2-6, wherein the porous support of the catalyst comprises a Ca/P
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molar ratio greater than the Ca/P molar ratio of the calcium-deficient
hydroxyapatite.
7. The process according to any of the preceding claims or blend according
to any of claims 2-5, wherein the porous support of the catalyst comprises a Ca/P
5 molar ratio of 1.60 or more, preferably of 1.65 or more, preferably of 1.67 or more, more preferably of 1.68 or more.
8. The process according to any of the preceding claims or blend according
to any of claims 2-7, wherein the porous support of the catalyst comprises :
- at least 65 wt%, preferably at least 70 wt%, more preferably at least 75
10 wt%, yet more preferably at least 80 wt%, yet most preferably at least 85
wt%, of the calcium-deficient hydroxyapatite,
and/or comprises
- at most 99 wt%, preferably at most 98 wt%, more preferably at most 97
wt%, yet more preferably at most 95 wt%, even more preferably at most
15 93 wt%, most preferably at most 91 wt% of the calcium-deficient
hydroxyapatite.
9. The process according to any of the preceding claims or blend according
to any of claims 2-8, wherein the porous support has a specific BET surface area
of at least 110 m2/g and a pore volume of at least 0.5 cm3/g after a heat
20 treatment at 200 °C
10. The process according to any of the preceding claims or blend
according to any of claims 2-9, wherein the catalyst has a BET specific surface
area measured after being calcined at 400 °C of at least 65 m2/g and/or at most
100 m2/g.
25 11. The process according to any of the preceding claims or blend
according to any of claims 2-10, wherein the catalyst has a pore volume measured after being calcined at 400 °C of:
- at least 0.3 cm /g, preferably of at least 0.41 cm /g, and/or
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- at most 1.1 cm /g, preferably of at most 1.0 cm /g, more preferably of at
most 0.9 cm /g. most preferably of at most 0.8 cm /g.
12. The process according to any of the preceding claims or blend
according to any of claims 2-11, wherein the active catalyst component
5 comprises:
- at least 0.1 wt%, preferably at least 0.5 wt%, more preferably at least 1.0
wt%, most preferably at least 1.5 wt%, of copper, copper oxide, or
combination thereof;
and/or
10 - at most 15 wt%, preferably at most, more preferably at most 13 wt%,yet
more preferably at most 12 wt%, most preferably at most 11 wt%, of copper, copper oxide, or combination thereof.
13. The process according to any of the preceding claims or blend
according to any of claims 2-12, wherein the active catalyst component is
15 deposited on the porous support by ion exchange or impregnation using a copper precursor selected from the group consisting of copper nitrate, copper acetate, copper chloride, copper acetylacetonate, and any mixture thereof.
14.The process according to any of the preceding claims or blend according to any of claims 2-13, wherein the alkali sorbent comprises or consists 20 of a compound selected from the group consisting of trona, sodium bicarbonate, and mixture thereof.
15. The process according to any of the preceding claims or blend according to any of claims 2-14, wherein the alkali sorbent contains an ammonia source.
25 16. The process according to any of the preceding claims or blend
according to any of claims 2-15, wherein the weight ratio of the catalyst to said alkali sorbent is
- at least 0.001, or at least 0.005, or at least 0.010, or at least 0.020, or at
least 0.030, or at least 0.045; and/or
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- at most 1.00, or at most 0.50, or at most 0.40, or at most 0.30.
17. The process according to any of the preceding claims, wherein the
alkali sorbent and the catalyst are mixed to form a blend to be injected
simultaneously into the waste gas stream, and wherein the blend comprises
5 - at least 0.1 wt%, or at least 0.2 wt%, or at least 0.5 wt%, or at least 1
wt%, or at least 3 wt%, or at least 5 wt%, of the catalyst, and/or
- at most 20 wt%, or at most 15 wt%, or at most 12 wt%, or at most 10
wt%, of the catalyst.
18. The process according to any of claims 1-15, wherein the alkali sorbent
10 and the catalyst are injected sequentially into the waste gas stream flowing
through a duct, and wherein the alkali sorbent is injected in a duct at a location upstream of where the catalyst is injected.
19. The process according to any of claims 1-18, wherein the ammonia
source and the catalyst are injected simultaneously into the waste gas stream.
15 20. Process for treating a waste gas stream containing nitrogen oxides
(NOx) and contaminants selected from the group consisting of heavy metals, acid gases (such as S02, S03, H3P04, HCl, HI, HBr, and/or HF) and combinations thereof, said waste gas stream originating from a combustion process, said treating process comprising:
20 injecting the blend according to any of Claims 2-16 into the waste gas
stream;
removing at least a portion of the contaminants from the waste gas stream with the alkali sorbent, and
converting, in the presence of O2, by reduction with NH3 of at least a 25 portion of the NOx in the waste gas stream to N2 and water at a temperature of at least 100°C and preferably at most 600°C.
21. The process according to any of the preceding claims, wherein the temperature is at least 105°C, preferably at least 120°C, more preferably at least
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180°C; and/or at most 400°C, preferably at most 350°C, more preferably at most 300°C.
Dated this 27 day of June 2019
- Digitally signed -
(Anand Barnabas)
Reg. No.: IN/PA - 974
Of De Penning & De Penning
Agent for the Applicants
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