Regenerable high capacity sorbent for removal of mercury from flue gas
A regenerable, high-capacity sorbent for removal of mercury from flue gas and processes and systems for making and using the sorbent. A phyllosilicate substrate, for example vermiculite or montmorillinite, acts as an inexpensive support to a thin layer for a polyvalent metal sulfide, ensuring that more of the metal sulfide is engaged in the sorption process. The sorbent is prepared by ion exchange between the silicate substrate material and a solution containing one or more of a group of polyvalent metals including tin (both Sn(II) and Sn(IV)), iron (both Fe(II) and Fe(III)), titanium, manganese, zirconium and molybdenum, dissolved as salts, to produce an exchanged substrate. Controlled reaction of a sulfide ion source with the one or more polyvalent metals that are exchanged on the silicate substrate produces the sorbent. The sorbent is used to absorb elemental mercury or oxidized mercury species such as mercuric chloride from flue gas containing acid gases (e.g., SO 2 , NO and NO 2 , and HCl) and other gases over a wide range of temperatures.
1. A sorbent particle comprising:
a vermiculite having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a product of a plurality of thiocarbonate ions having chemically reacted with at least some of said polyvalent metal ions;
wherein said sorbent particle has a largest dimension of less than about twenty micrometers and said sorbent particle is operative to capture at least ninety percent of the ionic and elemental mercury present in a flue gas containing acid gases to which it is exposed.
2. A sorbent particle comprising:
a montmorillonite having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a product of a plurality of thiocarbonate ions having chemically reacted with at least some of said polyvalent metal ions;
wherein said sorbent particle has a largest dimension of less than about twenty micrometers and said sorbent particle is operative to capture at least some of the ionic and elemental mercury present in a flue gas containing acid gases to which it is exposed.
3. A sorbent particle comprising:
a cryptocrystalline phyllosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a product of a plurality of thiocarbonate ions having chemically reacted with at least some of said polyvalent metal ions;
wherein said sorbent particle is operative to capture at least some of the ionic and elemental mercury present in flue gas to which it is exposed.
4. A sorbent comprising:
a phyllosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a product of a plurality of thiocarbonate ions having chemically reacted with at least some of said polyvalent metal ions;
wherein said sorbent operative to accomplish removal of the ionic and elemental mercury present in an acidic flue gas to which it is exposed.
5. A sorbent comprising:
a non-zeolitic, amorphous aluminosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a product of a plurality of thiocarbonate ions having chemically reacted with at least some of said polyvalent metal ions;
wherein said sorbent is essentially devoid of copper and polysulfides.
6. A concrete additive comprising:
a fly ash containing the adsorbent composition of claim 5 that has been used to remove mercury from a gas stream and is mercury laden.
7. A composition of matter consisting essentially of:
a hydrated laminar magnesium aluminum ironsilicate having a plurality of ion-exchange sites;
a polyvalent metal ion derived from a highly acidic solution exchanged at some of said ion-exchange sites; and
a plurality of thiocarbonate ions chemically reacted with some of said polyvalent metal ions.
8. A composition of matter made by combining:
phyllosilicate substrate material having a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions derived from a highly acidic solution that are exchanged at some of said ion-exchange sites; and
a plurality of thiocarbonate ions which are chemically reactable with some of said polyvalent metal ions.
9. A composition made by combining:
means for supporting having a first layered structure and a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions which are reversibly substituted at some of said ion-exchange sites; and
a plurality of thiocarbonate ions which are chemically reacted to some of said polyvalent metal ions to produce a second layered structure having an inter-layer spacing of about five nanometers;
wherein said composition is capable of removing mercury from a gas stream containing trace amounts of acid gases.
10. A composition made by combining:
a montmorillinite having a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions in a highly acidic solution which are reversibly substituted at some of said ion-exchange sites; and
a plurality of thiocarbonate ions which are chemically reacted to some of said polyvalent metal ions;
wherein said composition is capable of sorbing mercury from a gas.
11. A concrete made by combining:
a cement;
an aggregate; and
a fly ash containing the composition of claim 8 that has been used to remove mercury from a gas stream.
12. A composition made by combining:
a synthetic montmorillinite having a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions in a highly acidic solution which are reversibly substituted at some of said ion-exchange sites; and
a plurality of thiocarbonate ions which are chemically reacted to some of said polyvalent metal ions;
wherein said composition is essentially devoid of polysulfide ions and is capable of sorbing mercury from a gas.
13. A sorbent particle comprising:
a cryptocrystalline phyllosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a plurality of inorganic polysulfide ions chemically reacted to at least some of said polyvalent metal ions;
wherein said sorbent particle is essentially devoid of polysulfides said sorbent particle is operative to capture at least some of the ionic and elemental mercury present in flue gas to which it is exposed.
14. A sorbent comprising:
a non-zeolitic, amorphous aluminosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a plurality of inorganic polysulfide ions chemically reacted to at least some of said polyvalent metal ions;
wherein said sorbent is essentially devoid of copper and polysulfides.
15. A composition made by combining:
means for supporting having a first layered structure and a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions which are reversibly substituted at some of said ion-exchange sites; and
a plurality of polysulfide ions which are chemically reacted to some of said polyvalent metal ions to produce a second layered structure having an inter-layer spacing of about five nanometers;
wherein said composition comprises essentially no polysulfides and is capable of removing mercury from a gas stream containing trace amounts of acid gases.
16. A composition made by combining:
a montmorillinite having a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions that are other than copper ions in a highly acidic solution which are reversibly substituted at some of said ion-exchange sites; and
a plurality of polysulfide ions or thiocarbonate ions which are chemically reacted to some of said polyvalent metal ions;
wherein said composition is essentially devoid of polysulfides and is capable of sorbing mercury from a gas.
17. A sorbent particle comprising:
a cryptocrystalline phyllosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a plurality of polysulfide ions or thiocarbonate ions chemically reacted to at least some of said polyvalent metal ions;
wherein said sorbent particle is operative to capture at least some of the ionic and elemental mercury present in flue gas to which it is exposed.
18. A sorbent comprising:
a non-zeolitic, amorphous aluminosilicate having a plurality of ion-exchange sites;
a plurality of polyvalent metal ions exchanged at some of said ion-exchange sites; and
a plurality of polysulfide ions or thiocarbonate ions chemically reacted to at least some of said polyvalent metal ions.
19. A composition made by combining:
means for supporting having a first layered structure and a plurality of ion-exchange sites at which cations are exchangeable;
a plurality of polyvalent metal ions which are reversibly substituted at some of said ion-exchange sites; and
a plurality of polysulfide ions or thiocarbonate ions which are chemically reacted to some of said polyvalent metal ions to produce a second layered structure;
whereby said composition is capable of removing mercury from a gas stream containing trace amounts of acid gases.
20. A concrete additive comprising:
a fly ash containing the composition of claim 19 that has been used to remove mercury from a gas stream and is mercury laden.