CHEMICAL ABSORBENT COMPOSITION

Abstract

A particulate composition said composition comprises a metal carbonate and/or a metal bicarbonate and a compound of aluminium, characterised in that the weight ratio of metal carbonate plus metal bicarbonate compounds to said compound of aluminium is at least 3:1. The composition is useful for removing halogenated compounds from a hydrocarbon-containing process stream.

Claims

1. A particulate composition for removing halogenated compounds from a hydrocarbon-containing process stream, said composition comprising a metal carbonate and/or a metal bicarbonate and a compound of aluminium that is an alumina or a hydrated alumina, wherein the weight ratio of metal carbonate plus metal bicarbonate compounds to said compound of aluminium is at least 3:1, and the amount of metal carbonate in the total amount of metal carbonate plus metal bicarbonate is 0-75% by weight.

2. The particulate composition of claim 1, wherein the weight ratio of metal carbonate plus metal bicarbonate compounds to said compound of aluminium is at least 4:1.

3. The particulate composition of claim 1, wherein the metal carbonate is potassium carbonate, calcium carbonate or sodium carbonate.

4. The particulate composition of claim 1, wherein the metal bicarbonate is potassium bicarbonate or sodium bicarbonate.

5. The particulate composition of claim 1, wherein the composition contains a mixture of a metal bicarbonate and a metal carbonate.

6. (canceled)

7. The particulate composition of claim 1, wherein the amount of metal carbonate in the total amount of metal carbonate plus metal bicarbonate is 20-60% by weight.

8. (canceled)

9. The particulate composition of claim 1 further comprising a binder.

10. A method of forming a particulate composition of claim 1 comprising the steps of mixing together a. metal carbonate and/or metal bicarbonate compounds, b. a compound of aluminium and c. optionally a binder, in the presence of water and forming the mixture into particles.

11. The method of claim 10, further comprising the step of drying the formed particles at less than 120 C.

12. The method of claim 11, wherein the drying is carried out a temperature in the range of 25-90 C.

13. The method of claim 10, wherein the mixture is formed into particles by granulation, tabletting or extrusion.

14. The method as claimed in of claim 10, wherein the particles have an average size (diameter or equivalent dimension) of at least 0.2 mm.

15. A process for removing halogenated compounds from a hydrocarbon-containing process stream using a particulate composition of claim 1.

16. The method of claim 10, wherein the particles have an average size (diameter or equivalent dimension) of at least 0.8 mm.

17. The method of claim 10, wherein the particles have an average size (diameter or equivalent dimension) of at least 1 mm.

Description

EXAMPLE 1

[0015] Granules of a composition according to the invention were prepared by mixing powders of sodium bicarbonate, alumina trihydrate (gibbsite) and a binder (attapulgite clay) in the weight ratio 6:1:1. The powders were formed into granules using a planetary (Hobart) mixer by adding water. The resulting granular material was dried in air in an oven at 25 C. (or at 90 C. see Table 1). The granules were then sieved to a size fraction of 2-4.8 mm and tested for chloride capacity as described in Example 4 below.

EXAMPLE 2

[0016] Granules of a composition according to the invention were prepared by mixing powders of sodium bicarbonate, sodium carbonate, alumina trihydrate (gibbsite) and a binder (attapulgite clay) in the weight ratio 6:3:2:1. The powders were formed into granules using a planetary (Hobart) mixer by adding water. The resulting granular material was dried in air in an oven at 30 C. (or at 90 C. see Table 1). The granules were then sieved to a size fraction of 2.8-4.8 mm and tested for chloride capacity as described in Example 4 below.

EXAMPLE 3 (COMPARATIVE)

[0017] Granules of a composition according to the invention were prepared by mixing powders of sodium bicarbonate, alumina trihydrate and a binder in the ratio 55:45:11. The powders were formed into granules using a Hobart mixer and adding water. The resulting granular material was dried in air in an oven at 25 C. (or at 90 C. see Table 1). The granules were then sieved to a size fraction of 2-4.8 mm and tested for chloride capacity as described in Example 4 below.

EXAMPLE 4: CHLORIDE SATURATION TEST

[0018] 10 ml samples of each of the absorbent granules made in Examples 1 and 2 were tested separately for HCl absorption characteristics by passing hydrogen containing 1% HCl by volume at atmospheric pressure and about 20 C. for 22 hours through the sample. The gas flow rate was set to 45 litres/hour, giving a GHSV of 4,500 hr.sup.1. The samples are then ground up and tested for chloride content using a commercially available chloride analyser (Sherwood Scientific Ltd). Prior to analysis the ground samples are reacted in nitric acid/water mixture to prevent the formation of Ag salts which would otherwise interfere with the chloride analysis.

TABLE-US-00001 TABLE 1 Sample Drying T ( C.) Cl.sup. (%) Example 1 25 40.4 Example 1 90 28.3 Example 2 30 39.1 Example 2 90 33.6 Example 3 (comp) 25 26.3 Example 3 (comp) 90 12.7