Absorbents

1. An absorbent composition for removing mercury, arsenic or antimony from a fluid stream having a total metal sulphide content, comprising 5-50% by weight of a particulate sulphided copper compound and 30-90% by weight of a particulate support material, bound together by 5-20% by weight of two or more binders comprising a first binder and a second binder, wherein the first binder is a cement binder and the second binder is a high aspect ratio binder having an aspect ratio >2 and wherein the total metal sulphide content of the absorbent, other than copper sulphide, is ≦5% by weight.

2. An absorbent according to claim 1 wherein the sulphided copper compound is sulphided basic copper carbonate, sulphided copper hydroxide, sulphided copper oxide or mixtures of these.

3. An absorbent according to claim 1 wherein the first binder is a calcium aluminate cement binder.

4. An absorbent according to claim 1 wherein the second binder is an aluminosilicate clay.

5. An absorbent according to claim 1 wherein the second binder is an Attapulgite clay.

6. An absorbent according to claim 1 wherein the relative amounts of the first and second binder are in the range 1:1 to 3:1 (first to second binder).

7. An absorbent according to claim 1 wherein the total metal sulphide content, other than copper sulphide, is ≦0.5% wt.

8. An absorbent according to claim 1 wherein the total metal sulphide content, other than copper sulphide, is ≦0.1% wt.

9. An absorbent according to claim 1 wherein the density of the absorbent, expressed as the sulphur density, is in the range 50 to 200 kg S/m 3 .

10. A method for making the absorbent according to claim 1 comprising the steps of:

i) forming a composition comprising a particulate copper compound capable of forming copper sulphide, a particulate support material and binders comprising a first binder and a second binder, wherein the first binder is a cement binder and the second binder is a high aspect ratio binder having an aspect ratio >2,

ii) shaping the composition to form an absorbent precursor,

iii) drying the absorbent precursor material to form a dried absorbent precursor, and

iv) sulphiding the precursor to form the absorbent.

11. A method according to claim 10 wherein the sulphiding step is performed by reacting a sulphur compound selected from hydrogen sulphide, carbonyl sulphide, mercaptans and polysulphides with the metal compound capable of forming a metal sulphide in the dried absorbent precursor.

12. A process for removing mercury, arsenic or antimony from a process fluid comprising contacting said fluid with an absorbent according to claim 1 .

13. A mercury removal process according to claim 12 wherein the mercury containing fluid contains water in an amount in the range 0.02 to 5% vol.

14. A mercury removal process according to claim 12 wherein the fluid is a hydrocarbon stream.

15. A mercury removal process according to claim 13 wherein the fluid is an off-shore hydrocarbon stream or a regeneration stream from a hydrocarbon dehydration unit.

16. A method according to claim 10 wherein the sulphiding step is performed on the dried absorbent precursor ex-situ in a sulphiding vessel through which a sulphiding agent is passed, or in situ in a vessel in which the absorbent is used to absorb mercury compounds using a sulphiding agent stream, or a mercury-containing stream that also contains sulphur compounds.

17. A method according to claim 10 , wherein the particulate support material is an alumina, hydrated alumina, titania, zirconia, silica or aluminosilicate, or a mixture of two or more of these.

18. An absorbent precursor composition for preparing an absorbent according to claim 1 , comprising a copper compound capable of forming copper sulphide a particulate support material, bound together by two or more binders comprising a first binder and a second binder, wherein the first binder is a cement binder and the second binder is a high aspect ratio binder having an aspect ratio >2, and wherein a sulphidable metal content of the absorbent precursor, other than copper, is below 5% by weight as oxide.

19. An absorbent according to claim 1 wherein the particulate support material is an alumina, hydrated alumina, titania, zirconia, silica or aluminosilicate, or a mixture of two or more of these.

20. An absorbent according to claim 1 wherein the total metal sulphide content, other than copper sulphide, is ≦1% wt.