Manganese Oxide Containing Alumina Composition, A Method for Manufacturing the Same and Use Thereof

Abstract

The present invention is concerned with a manganese oxide alumina containing composition with high resistance against SOx, to a method for making the composition and to use of the composition as a catalyst carrier. The composition comprises an alumina based material, manganese oxide, and silica.

Claims

1. A composition comprising: a support material comprising an alumina based support material and manganese oxide, the content of the manganese oxide in the support material being between 0.1 and 20 wt. % of the total support material calculated as MnO.sub.2, the support material further comprising SiO.sub.2 and optionally oxides of zirconium, titanium, rare-earth elements or combinations thereof, the SiO.sub.2 being either incorporated into the support material or the SiO.sub.2 being a coating of the support material or both; i) wherein where the SiO.sub.2 is incorporated into the support material, the SiO.sub.2 content is greater than 5 wt % relative to the alumina based support material, if no oxides of zirconium, titanium, rare-earth elements or combinations thereof are incorporated into the support material or; ii) wherein where the SiO.sub.2 is incorporated into the support material the SiO.sub.2 content is at least 5 wt % relative to the alumina based support material, if oxides of zirconium, titanium, rare-earth elements or combinations thereof are incorporated into the support material or; iii) wherein the SiO.sub.2 coats the support material, the SiO.sub.2 coating makes up at least 0.2 wt. % of the support material relative to the alumina based support material.

2. The composition of claim 1, wherein the alumina based support material is alumina, silica-alumina or a mixture thereof.

3. The composition of claim 1, wherein the support material comprises oxides of zirconium.

4. The composition of claim 1, wherein the manganese oxide content is between 1 and 10 wt. %, calculated as MnO.sub.2, of the support material.

5. The composition of claim 1, wherein the SiO.sub.2 coating is 0.2 to 5 wt. % relative to the alumina based support material.

6. The composition of claim 1, wherein where the SiO.sub.2 is incorporated into the support material without oxides of zirconium, titanium, rare-earth elements or combinations thereof, the support material comprises a SiO.sub.2 content of at least 10 wt % relative to the alumina based support material.

7. The composition of claim 1, wherein where the support material includes ZrO.sub.2, then at least 5 wt. % of SiO.sub.2 and at least 5 wt. % ZrO.sub.2 is incorporated into the support, each relative to the alumina based support material.

8. A method to prepare a composition the method comprising the following steps with steps ii) to iv) being in any order: i) providing an alumina based support material; ii) optionally adding oxides of zirconium, titanium, rare-earth elements or combinations thereof to the alumina based support material or to the manganese oxide impregnated support material or to both; iii) impregnating the alumina based support material with a manganese oxide salt solution to form a manganese oxide impregnated support material; and iv) adding SiO.sub.2 into the alumina based support material or into the manganese oxide impregnated support material by: a. coating the manganese oxide impregnated support material with a SiO.sub.2 solution to form a SiO.sub.2 coating around the manganese oxide impregnated support material, the SiO.sub.2 coating forming at least 0.2 wt. % relative to the alumina based support material; or b. incorporating SiO.sub.2 into the support material, wherein where the SiO.sub.2 is incorporated into the alumina based support material the SiO.sub.2 content is greater than 5 wt % relative to the alumina based support material, if no oxides of zirconium, titanium, rare-earth elements or combinations thereof are incorporated into the support material; or c. incorporating SiO.sub.2 into the support material, wherein where the SiO.sub.2 is incorporated into the alumina based support material the SiO.sub.2 content is at least 5 wt % relative to the alumina based support material, if oxides of zirconium, titanium, rare-earth elements or combinations thereof are incorporated into the support material.

9. The method of claim 8, wherein the alumina based support material is either alumina, silica-alumina or a mixture thereof.

10. The method of claim 8, wherein oxides of zirconium are incorporated into the alumina based support material.

11. The method of claim 8, wherein where the manganese oxide impregnated support is coated with SiO.sub.2, the SiO.sub.2 coating is 0.2 to 5 wt. %, relative to the alumina based support material.

12. The method of claim 8, wherein the manganese oxide impregnated support material is coated with silicic acid.

13. The method of claim 8 wherein, where the SiO.sub.2 is incorporated into the support material without oxides of zirconium, the support material comprises a SiO.sub.2 content of at least 10 wt % relative to the alumina based support material.

14. The method of claim 8 wherein, where the support material includes ZrO.sub.2, then at least 5 wt % of SiO.sub.2 and at least 5 wt % ZrO.sub.2 is incorporated into the support, relative to the support material.

15. (canceled)

Description

[0071] The invention will now be described with reference to the following non-limiting examples and Figures, where:

[0072] FIG. 1 represents a plot of the amount of SOx uptake relative to the wt. % of SiO.sub.2 coating as per the invention; and

[0073] FIG. 2 represents a plot of the amount of SOx adsorption relative to the wt. % of SiO.sub.2 incorporated into the support material.

EXAMPLES

[0074] SOx Tolerance Test

[0075] The SOx tolerance was determined by measuring the SOx uptake capacity of the composition. Ca. 80 mg of the material were placed in a tubular quartz microreactor and were heated at a constant rate (10? C./min) under N.sub.2 (total flow 0.5 l/min) until 300? C. Adsorption experiments were conducted under isothermal condition at 300? C. in O.sub.2/SO.sub.2/N.sub.2 gas mixture (10% O2 v/v+200 ppm SO.sub.2, balance N2; total flow 0.5 l/min), up to saturation of the sample. Then the temperature was cooled down to 100? C. and the gas mixture was changed to N.sub.2 (total Flow 0.5 l/min) until SO.sub.2 Concentration signal went back to zero. The outlet gas composition (i.e. SO.sub.2) was measured by using FT-IR gas analyzers (MultiGas 2030, MKS).

ExperimentsSiO.SUB.2 .Coating

Comparative Example 1

[0076] A state-of-the-art Mn oxide impregnated support material was prepared by impregnating a commercially available alumina having a BET surface area of 150 m.sup.2/g and a pore volume of 0.8 ml/g (measured by N.sub.2 adsorption) with manganese acetate solution by incipient wetness impregnation yielding a total loading of 5% MnO.sub.2 relative to the manganese oxide impregnated support material followed by a calcination at 550? C. for 3 h.

Example 1

[0077] The Mn oxide impregnated support material as prepared in Comparative Example 1 was impregnated with an aqueous solution of silicic acid under incipient wetness impregnation conditions. Subsequently the material was calcined at 550? C. for 3 h. The final amount of coated SiO.sub.2 was 1 wt. % based on the total Mn oxide impregnated support material.

Comparative Example 2

[0078] A state-of-the-art Mn oxide impregnated support material was prepared by impregnating a commercially available silica-alumina containing 5 wt. % SiO.sub.2 and having a BET surface area of 180 m.sup.2/g and a pore volume of 0.7 ml/g (measured by N.sub.2 adsorption) with manganese acetate solution by incipient wetness yielding a total loading of 5% MnO.sub.2 relative to the manganese oxide impregnated support material followed by a calcination at 550? C. for 3 h.

Example 2

[0079] The Mn oxide impregnated support material as prepared in Comparative Example 2 was impregnated with an aqueous solution of silicic acid under incipient wetness impregnation conditions. Subsequently the material was calcined at 550? C. for 3 h. The final amount of coated SiO.sub.2 was 0.2 wt. % based on the total Mn oxide impregnated support material.

Example 3

[0080] The material was prepared as in Example 2 but the amount of SiO.sub.2 coating was 0.5 wt. % based on the total composition.

Example 4

[0081] The material was prepared as in Example 2 but the amount of SiO.sub.2 coating was 1 wt. % based on the total composition.

[0082] The results of the Examples and Comparative Examples are included in Table 1. From Table 1 it is clear that the uptake of SOx is greatly reduced by the present invention when compared to the Comparative Examples.

TABLE-US-00001 TABLE 1 Effect of SiO.sub.2 coating on SOx uptake capacity Alumina based Amount Mn Amount SOx support material (MnO.sub.2 SiO.sub.2 coated uptake composition wt. %) (wt. %) (mg/g) Comparative Al.sub.2O.sub.3 (100%) 5 0 32.9 Example 1 Example 1 Al.sub.2O.sub.3 (100%) 5 1 11.9 Comparative Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 0 20.9 Example 2 Example 2 Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 0.2 4.8 Example 3 Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 0.5 3.3 Example 4 Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 1 1.7

Experiments SiO.SUB.2 .Incorporated into the Support

Example 5

[0083] A silica-alumina containing 10 wt. % SiO.sub.2 and having a BET surface area of 250 m.sup.2/g was prepared by adding silicic acid to an aluminium compound that was formed by the hydrolysis of an aluminium alkoxide, followed by spray drying and a subsequent calcination at 900? C. for 3 h. The silica-alumina was impregnated with manganese acetate solution by incipient wetness impregnation yielding a total loading of 5% MnO.sub.2 relative to the manganese oxide impregnated support material followed by calcination at 550? C. for 3 h.

Example 6

[0084] The material was prepared as in Example 5 but the amount of SiO.sub.2 added to the aluminium compound was adjusted to obtain a silica-alumina containing 25 wt. % SiO.sub.2 with a BET surface area of 321 m.sup.2/g and a pore volume of 1.07 ml/g after calcination at 1000? C. for 3 h.

Example 7

[0085] An aqueous solution of Zr Acetate was added to a mixture of silicic acid and an aluminium compound that was formed by the hydrolysis of an aluminium alkoxide and the mixture was spray dried and calcined at 900? C. for 3 h to obtain a ZrO.sub.2 containing silica-alumina based support material having a BET surface area of 156 m.sup.2/g and a pore volume of 0.8 ml/g (measured by N.sub.2 adsorption). The percentage of ZrO.sub.2 added and SiO.sub.2 added is each 5% (relative to the alumina based support material). The alumina based support material was further impregnated with a manganese acetate solution by incipient wetness impregnation yielding a total loading of 5% MnO.sub.2 relative to the manganese oxide impregnated support material followed by calcination at 550? C. for 3 h.

[0086] The results of the experiments are included in Tables 2 and 3 hereunder:

TABLE-US-00002 TABLE 2 Effect of SiO.sub.2 content in support material on SOx uptake capacity Alumina based support Amount Mn SOx uptake material (MnO.sub.2 wt. %) (mg/g) Comparative Al.sub.2O.sub.3 (100%) 5 32.9 Example 1 Comparative Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 20.9 Example 2 Example 5 Al.sub.2O.sub.3 90%/SiO.sub.2 10% 5 1.5 Example 6 Al.sub.2O.sub.3 75%/SiO.sub.2 25% 5 0.3

[0087] Again, from the Tables it is clear that the uptake of SOx is greatly reduced by the present invention when compared to the Comparative Examples.

TABLE-US-00003 TABLE 3 Effect of ZrO2 in support material on SOx uptake capacity Alumina based support Amount Mn SOx uptake material (MnO.sub.2 wt. %) (mg/g) Comp. Al.sub.2O.sub.3 95%/SiO.sub.2 5% 5 20.9 Example 2 Example 7 Al.sub.2O.sub.3 90%/SiO.sub.2 5%/ 5 6.3 ZrO.sub.2 5%