Desulphurisation material comprising copper supported on zinc oxide

Abstract

A particulate desulphurization material includes one or more copper compounds supported on a zinc oxide support material, wherein the desulphurization material has a copper content in the range 0.1 to 5.0% by weight and a tapped bulk density 1.55 kg/l. The material is obtained by (i) mixing a powdered copper compound with a particulate zinc support material comprising zinc oxide and one or more precursors that form zinc oxide upon calcination, and one or more binders to form a copper-containing composition, (ii) shaping the copper-containing composition by granulation, and (iii) drying and calcining the resulting granulated material.

Claims

1. A method of making a particulate desulphurisation material comprising one or more copper compounds supported on a particulate zinc oxide support material, wherein the desulphurisation material is in the form of granules consisting of one or more powdered copper compounds, zinc oxide, zinc oxide formed by calcination of one or more zinc oxide precursors, and one or more binders, wherein the desulphurisation material has a copper content, expressed as CuO, in the range 0.1 to 5.0% by weight and a tapped bulk density 1.55 kg/l, comprising the steps of: (i) mixing one or more powdered copper compounds with a particulate zinc oxide support material comprising zinc oxide, one or more precursors that form zinc oxide upon calcination, and one or more binders to form a copper-containing composition, (ii) shaping the copper-containing composition by granulation, and (iii) drying and calcining the resulting granulated material to form the particulate desulphurization material.

2. The method according to claim 1, wherein the copper compound in the copper-containing composition is selected from the group consisting of copper oxide, copper hydroxide, and copper hydroxycarbonate.

3. The method according to claim 1, wherein the copper compound, zinc oxide support material, and one or more zinc oxide precursors are combined with one or more binders and granulated to form agglomerated spheres with a diameter in the range 1 to 10 mm.

4. The method according to claim 1, wherein the copper compound, zinc oxide support material, and one or more zinc oxide precursors are combined with one or more binders and granulated to form agglomerated spheres with a diameter in the range 1.5 to 7.5 mm.

5. The method according to claim 1, wherein the copper compound, zinc oxide support material, and one or more zinc oxide precursors are combined with one or more binders and granulated to form agglomerated spheres with a diameter in the range 2.5 to 5.0 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The invention will now be further described by reference to the following examples.

(2) Tapped bulk density (TBD) was measured by filling a 1 liter measuring cylinder with particulate desulphurisation material and tapping its walls until a constant volume was achieved. The tapped volume was recorded. The material was then weighed and its density calculated.

(3) The sulphur content of the used desulphurisation materials was determined using a LECO SC632 instrument.

(4) The BET surface areas were measured using Micromeritics ASAP 2420 and Micromeritics Tristar 3000 equipment. The samples were outgassed at 140 C. for at least 1 hr with dry nitrogen purge. All instruments comply with ASTM D3663-03 (N2 BET area) and ASTM D4222-03 (N2 ads/des isotherm).

(5) Pore volumes were derived from mercury porosimetry using a Micromeritics AutoPore 9520 mercury porosimeter designed to comply with ASTM D4284-03. The samples were dried at 115 C. overnight before analysis. Pore volumes measured at 60 000 psia after inter-particle intrusion had been removed.

(6) Densitometry: Pore volumes were calculated from the skeletal and geometric densities of the samples. Skeletal densities were measured using a Micromeritics AccuPyc 1330 helium pycnometer. Geometric densities were measured using an in-house mercury pycnometer. Again the samples were dried at 115 C. overnight before analysis. Both methods comply with ASTM D6761-02

EXAMPLE 1

Comparative

(7) In a first test, a 60 ml sample of KATALCO.sub.JM 32-5 (2.8-4.75 mm, 91.5 wt % ZnO) was loaded into a 19 mm ID glass reactor tube. The sample was subsequently heated in flowing nitrogen to 370 C. Once at temperature the gas feed was then switched to 5 vol % H.sub.2S+95 vol % H.sub.2 delivered at 42 l/hr and atmospheric pressure. The H.sub.2S level exit the absorbent bed was then monitored periodically using Dragger tubes until such time as the exit H.sub.2S level exceeded 100 ppmv. At this point the test was discontinued. The sulphided absorbent was subsequently discharged in 6 discrete layers. The sulphur pick-up on each layer was measured using a LECO instrument. The results obtained were subsequently used to determine a bed-averaged sulphur pick-up (average of the six sub-bed sulphur measurements). The result obtained is reported in Table 1 in units of kg S/l.

(8) The corresponding tapped bulk density, BET surface area, mercury porosimetry and densitometry data for fresh KATALCO.sub.JM 32-5 are provided in Table 2.

EXAMPLE 2

Comparative

(9) To 75 parts of ZnO were added 25 parts of basic zinc carbonate and 7.0 parts of a calcium aluminate binder. The resulting powder was thoroughly mixed and then granulated with appropriate water addition using an orbital planetary mixer. The produced granules were then sieved and the on-size fraction (2.8-4.75 mm) calcined. The ZnO loading in the finished product was measured by XRF and found to be 92.7 wt %. An accelerated sulphiding test was subsequently carried out on this material under conditions identical to those specified in Example 1. Again the results obtained are reported in Table 1 in units of kg S/l.

(10) The corresponding tapped bulk density, BET surface area, mercury porosimetry and densitometry data for fresh material are again provided in Table 2.

EXAMPLE 3

Inventive

(11) To 75 parts of ZnO were added 25 parts of zinc hydroxycarbonate, 7.0 parts of a calcium aluminate binder and 2.2 parts of copper hydroxycarbonate. The resulting powder was thoroughly mixed and then granulated with appropriate water addition using an orbital planetary mixer. The produced granules were then sieved and the on-size fraction (2.8-4.75 mm) calcined. The CuO and ZnO loadings in the finished product were measured by XRF and found to be 1.7 wt % and 92.1 wt % respectively. An accelerated sulphiding test was subsequently carried out on this material under conditions identical to those specified in Example 1. Again the results obtained are reported in Table 1 in units of Kg S/l.

(12) The corresponding tapped bulk density, BET surface area, mercury porosimetry and densitometry data for fresh material are again provided in Table 2.

(13) TABLE-US-00001 TABLE 1 Accelerated sulphiding test results. CuO ZnO Fresh Sulphur ZnO loading loading TBD pick-up coversion (wt %) (wt %) (kg/l) (kgS/I) to ZnS (%) Example 1 0.0 91.5 1.40 0.197 46 Example 2 0.0 92.7 1.69 0.198 38 Example 3 1.7 92.1 1.64 0.298 59

(14) TABLE-US-00002 TABLE 2 Nitrogen physisorption and mercury porosimetry data Corrected Surface intrusion Mean pore area (BET) volume Entrapment diameter (m.sup.2/g) (cm.sup.3/g) (% v/v) () Example 1 29 0.24 26 583 Example 2 17 0.17 33 716 Example 3 19 0.18 36 856 Densitometry data Skeletal Geometric (He) density (Hg) density Pore volume (g/cm.sup.3) (g/cm.sup.3) (cm.sup.3/g) Example 1 4.99 2.23 0.25 Example 2 5.06 2.67 0.18 Example 3 5.07 2.57 0.19

(15) In comparing the results of Examples 1 and 2, it is clear that just increasing the density of a ZnO absorbent is not in itself an effective strategy for improving the sulphur pick-up of the product. Although the material in Example 2 contained significantly more ZnO on a unit volume basis than in Example 1, because of the low surface area and porosity of the high density product, it was not able to effectively utilise this additional ZnO for further sulphur capture (the ZnO conversion efficiency at the point of 100 vppm H.sub.2S breakthrough dropped from 46% to 38% between these two cases under the conditions of the test). In contrast, when copper promotion is combined with increased density, as in Example 3, although the porosity and surface area of the product are reduced, the material is able to more effectively utilise the available ZnO for sulphur absorption, which leads to a considerable increase in sulphur capture per unit volume of absorbent.

(16) This is surprising as normally it may be presumed that increasing the density and so reducing the pore volume and surface area would lead to a reduction in absorption of the sulphur compounds.

EXAMPLE 4

Comparative

(17) Two 85 cm.sup.3 capacity samples baskets containing KATALCO.sub.JM 32-5 were placed in an industrial desulphuriser vessel operating, at elevated temperature, in lead-lag mode. One basket was placed at the inlet of the vessel and one at the exit. After a period of time on line, the baskets were removed and the sulphur uptakes measured using a LECO instrument. The results obtained are reported in Table 3.

EXAMPLE 5

Inventive

(18) The details of Example 4 were repeated with the exception that sample baskets, again placed at both the inlet and the exit of the vessel, were filled with a desulphurisation material prepared as described in Example 3 above. The results obtained are reported in Table 3.

(19) TABLE-US-00003 TABLE 3 CuO ZnO Fresh Sulphur ZnO loading loading TBD pick-up coversion (wt %) (wt %) (kg/l) (kgS/I) to ZnS (%) Industrial reactor sulphur pick-up results: Inlet baskets Example 4 0.0 91.5 1.40 0.350 75 Example 5 1.7 92.1 1.64 0.468 84 Industrial reactor sulphur pick-up results: Exit baskets Example 4 0.0 91.5 1.40 0.091 22 Example 5 1.7 92.1 1.64 0.139 27

(20) Examples 4 and 5 were tested simultaneously in the same desulphuriser vessel for the same length of time on line. Examples 4 and 5 show that the improved performance discussed above is also observed under real plant conditions.