INORGANIC POROUS FRAMEWORKLAYERED DOUBLE HYDROXIDE CORESHELL MATERIALS

Abstract

Core @ layered double hydroxide shell materials of the invention have the formula:

T.sub.p@{[M.sup.z+.sub.(1x)M.sub.x.sup.y+(OH).sub.2].sup.a+(X.sup.n).sub.a/n.Math.bH.sub.2O.Math.c(AMO-solvent)}.sub.q

wherein T is a solid, porous, inorganic oxide-containing framework material, M.sup.z+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z=1 or 2; y=3 or 4; 0<x<0.9; b is 0 to 10; c is 0.01 to 10; p>0; q>0; X.sup.n is an anion; with n>0; a=z(1x)+xy2; and AMO-solvent is an organic solvent which is completely miscible with water.

Also disclosed are the products obtained by calcining the core @ layered double hydroxide shell materials which calcination products are core @ mixed metal oxide materials having the formula

T.sub.p@[{M.sup.z+.sub.1xM.sup.y+.sub.xO.sub.w].sub.p]

wherein T is a solid, porous, inorganic oxide-containing framework material, M.sup.z+.sub.1xM.sup.y+.sub.xO.sub.w is a mixed metal oxide, or mixture of mixed metal oxides, which may be crystalline or non-crystalline, wherein M.sup.z+ and M.sup.y+ are different charged metal cations; M.sup.z+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z is 1 or 2; y is 3 or 4; 0<x<0.9; w>0; p>0 and q>0; is the residue of an X.sup.n anion in which n>0.

Claims

1. A core @ layered double hydroxide shell material having the formula
T.sub.p@{[M.sup.z+.sub.(1x)M.sub.x.sup.y+(OH).sub.2].sup.a+(X.sup.n).sub.a/n.Math.bH.sub.2O.Math.c(AMO-solvent)}.sub.q wherein T is a solid, porous, inorganic oxide-containing framework material, Mz.sup.+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z=1 or 2; y=3 or 4; 0<x<0.9; b is 0 to 10; c is 0.01 to 10; p>0; q>0; X.sup.n is an anion; with n>0; a=z(1x)+xy2; and AMO-solvent is an organic solvent which is completely miscible with water.

2. A material according to claim 1, wherein T is a molecular sieve material selected from silicate, aluminium silicate, vanadium silicate, iron silicate, silicon-aluminium phosphate (SAPO) and aluminium phosphate (AIPO), preferably an aluminium silicate having a silicon:aluminium ratio of from 1 to 100, more preferably of 1 to 50, most preferably 1 to 40.

3. A material according to claim 1, wherein the aluminium silicate has a framework structure selected from zeolite types LTA, FAU, BEA, MOR and MFI and preferably the aluminium silicate has a framework structure containing non-framework organic and/or inorganic cations, more preferably the non-framework organic and inorganic cations are selected from NR4.sup.t, where R is an optionally-substituted alkyl group, Na.sup.+, K.sup.+ and Cs.sup.+.

4. A material according to claim 1, wherein the aluminium silicate is a crystalline aluminosilicate zeolite having a composition in terms of mole ratios of oxides as follows:
M.sup.n+.sub.2/nO:Al.sub.2O.sub.3:SiO.sub.2:H.sub.20 wherein M.sup.n+ is at least one cation having a valence n, =0.90.2; is at least 2 and is between 0 and 40.

5. A material according to claim 1, wherein M is Al or Fe and/or M is Li, Mg, Ca, Co, Cu, Ni, or Cr or a mixture of two or more thereof and/or X.sup.n is selected from CO.sub.3.sup.2, OH.sup., F.sup., Cl.sup., Br.sup., SO.sub.4.sup.2, NO.sub.3.sup. and PO.sub.4.sup.3, preferably from CO.sub.3.sup.2, Cl.sup. and NO.sub.3.sup., or a mixture of two or more thereof.

6. A material according to claim 1, wherein M is Mg, M is Al and X.sup.n is CO.sub.3.sup..

7. A material according to claim 1, wherein the core @ layered double hydroxide shell material has the general formula Id
T.sub.p@{[M.sup.z+.sub.(1x)M.sup.y+.sub.x(OH).sub.2].sup.a+(X.sup.n).sub.a/n.Math.bH.sub.2O.Math.c(ethanol)}.sub.q (Id) wherein, T is; i) an aluminium silicate with a framework structure selected from zeolite types LTA, FAU, BEA, MOR or MFI; ii) an aluminophosphate; iii) a silicoaluminophosphate; or iv) a mesoporous silicate, wherein the aluminium silicate has a silicon:aluminium ratio of from 1 to 50, more preferably of 1 to 40, most preferably of 1 to 30; and the aluminium silicate has a framework structure containing non-framework organic and/or inorganic cations, more preferably the non-framework organic and inorganic cations are selected from NR.sub.4.sup.+, where R is an optionally-substituted alkyl group, Na.sup., K.sup.+ and Cs.sup.+; M.sup.z+ is selected from Li.sup.+, Ca.sup.2+, Cu.sup.2+, Zn.sup.2+, Ni.sup.2+ or Mg.sup.2+, and M.sup.y+ is Al.sup.3+, Ga.sup.3+, In.sup.3+, Fe.sup.3+; 0<x<0.9; b is 0 to 10; c is 0.01 to 10; p>0, q>0; X.sup.n is is selected from CO.sub.3.sup.2 or NO.sub.3.sup.; with n>0 (preferably 1-5) a=z(1x)+xy2.

8. A method of making a core @ layered double hydroxide shell material according to claim 1, having the formula
T.sub.p@{[M.sup.z+.sub.(1x)M.sub.x.sup.y+(OH).sub.2].sup.a+(X.sup.n).sub.a/n.Math.bH.sub.2O.Math.c(AMO-solvent)}.sub.q wherein T is a solid, porous, inorganic oxide-containing framework material, M.sup.z+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z=1 or 2; y=3 or 4; 0<x<0.9; b is 0 to 10; c is 0.01 to 10; p>0; q>0; X.sup.n is an anion; with n>0; a=z(1x)+xy2; and AMO-solvent is an organic solvent which is completely miscible with water; which method comprises the steps: (a) contacting a metal ion-containing solution containing metal ions M.sup.z+ and M.sup.y+ and particles of the framework material in the presence of a base and an anion solution; and (b) optionally treating the product with AMO-solvent and recovering the solvent treated material to obtain the core @ layered double hydroxide material.

9. A method according to claim 8, wherein T is a molecular sieve material selected from silicate, aluminium silicate, vanadium silicate, iron silicate, silicon-aluminium phosphate (SAPO) and aluminium phosphate (AIPO).

10. A method according to claim 8, wherein T is a molecular sieve material which is an aluminium silicate having a silicon:aluminium ratio of from 1 to 100, preferably 1 to 50, more preferably 1 to 40.

11. A method according to claim 8, wherein the aluminium silicate is a crystalline aluminosilicate zeolite having a composition in terms of mole ratios of oxides as follows:
M.sup.n+.sub.2/nO:Al.sub.2O.sub.3:SiO.sub.2:H.sub.20 wherein M.sup.n+ is at least one cation having a valence n, =0.90.2; is at least 2 and is between 0 and 40.

12. A core @ mixed metal oxide material having the formula
T.sub.p@{[M.sup.z+.sub.1xM.sup.y+.sub.xO.sub.w].sub.p] wherein T is a solid, porous, inorganic oxide-containing framework material, M.sup.z+.sub.1xM.sup.y+.sub.xO.sub.w is a mixed metal oxide, or mixture of mixed metal oxides, which may be crystalline or non-crystalline, wherein M.sup.z+ and M.sup.y+ are different charged metal cations; M.sup.z+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z is 1 or 2; y is 3 or 4; 0<x<0.9; w>0; p>0 and q>0; is the residue of an X.sup.n anion in which n>0.

13. A method of making a core @ mixed metal oxide according to claim 12, which method comprises subjecting a core @ layered double hydroxide shell material having the formula
T.sub.p@{[M.sup.z+.sub.(1x)M.sub.x.sup.y+(OH).sub.2].sup.a+(X.sup.n).sub.a/n.Math.bH.sub.2O.Math.c(AMO-solvent)}.sub.q wherein T is a solid, porous, inorganic oxide-containing framework material, to heat treatment wherein M.sup.z+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M.sup.y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z=1 or 2; y=3 or 4; 0<x<0.9; b is 0 to 10; c is 0.01 to 10; p>0; q>0; X.sup.n is an anion; with n>0; a=z(1x)+xy2; and AMO-solvent is an organic solvent which is completely miscible with water.

14. A method according to claim 13, wherein the core @ layered double hydroxide shell material is subjected to heat treatment at a temperature of from 100 to 1000 C., preferably from 400 to 550 C.

15. A method according to claim 13, wherein the heat treatment is carried out in specific atmosphere, preferably in air or a nitrogen atmosphere or hydrogen atmosphere.

Description

FIGURES

[0161] FIG. 1. TEM images of (a) zeolite HY5.1 and (b) HY5.1 @ AMO-LDH

[0162] FIG. 2. Thermal analysis data for the zeolite @ layered double hydroxide shell material (HY5.1 @ AMO-LDH) showing the thermal events on heating. [0163] LeftThermogravimetric Analysis (TGA), where (a) is HY 5.1, (b) is HY 5.1 @ LDA-A and (c) is LDH-A. [0164] Rightderivative Thermogravimetric Analysis (dTGA), where (a) is HY 5.1, (b) is HY 5.1 @ LDA-A and (c) is LDH-A. [0165] LDH-A denotes AMO-synthesised LDH using acetone treatment.

[0166] FIG. 3. Pore size distribution of HY5.1 and HY5.1 @ AMO-LDH after calcination at 300 C., where (a) is HY5.1 and (b) is HY5.1 @ LDH-A and LDH-A denotes AMO-synthesised LDH.

[0167] FIG. 4. TEM images of HY5.1 @ LDH top shows water-washed product bottom shows acetone-washed product LDH-W denotes conventionally-synthesised LDH, LDH-A denotes AMO-synthesized LDH.

[0168] FIG. 5. X-ray powder diffraction of HY5.1 @ LDH

[0169] Lefta comparison with starting material, where (a) is HY5.1, (b) is HY5.1 @ LDH-A and (c) is LDH-A. [0170] Righta comparison between water- and acetone-washed samples, where (a) is HY5.1 @ LDH-W and (b) is HY5.1 @ LDH-A. LDH-W denotes conventionally synthesised LDH, LDH-A denotes AMO-synthesised LDH.

[0171] FIG. 6. Thermal analysis data for the zeolite @ layered double hydroxide shell material, HY5.1 @ LDH, showing the thermal events on heating. [0172] LeftThermogravimetric Analysis (TGA), where the solid line is HY(5.1) @ LDH-W and the dashed line is HY(5.1) @ LDH-A. [0173] Rightderivative Thermogravimetric Analysis (dTGA), where the solid line is HY(5.1) @ LDH-W and the dashed line is HY(5.1) @ LDH-A. [0174] LDH-W denotes conventionally-synthesised LDH, LDH-A denotes AMO-synthesised LDH with acetone treatment.

[0175] FIG. 7. TEM images of HY @ AMO-LDH. AMOST method treatment using acetone as the AMO solvent.

[0176] FIG. 8. TEM images of HY30 @ AMO-LDH. AMOST method treatment using acetone as the AMO solvent.

[0177] FIG. 9. TEM images of HY15 @ AMO-LDH. AMOST method treatment using acetone as the AMO solvent.

[0178] FIG. 10. TEM images of ZSM5 @ AMO-LDH. AMOST method treatment using acetone as the AMO-solvent.

[0179] FIG. 11. TEM images of ZSM5-23 @ LDH at a rate of 60 ml/hr drop rate.

[0180] FIG. 12. TEM images of ZSM5-40 @ LDH at rates of 60 ml/hr, 40 ml/hr and 20 ml/hr drop rates.

[0181] FIG. 13. Thermal analysis data for the zeolite @ layered double hydroxide shell material, ZSM5-23 @ LDH, showing the thermal events on heating. [0182] LeftThermogravimetric Analysis (TGA), where the solid line is LDH-A, the dashed line is ZSM-5(23) @ LDH-A and the dotted line is ZSM-5(23). [0183] Rightderivative Thermogravimetric Analysis (dTGA), where the solid line is LDH-A, the dashed line is ZSM-5(23)@LDH-A and the dotted line is ZSM-5(23). [0184] AMOST method treatment using acetone as the AMO-solvent. LDH-A denotes AMO-synthesised LDH using acetone treatment.

[0185] FIG. 14. Thermal analysis data for the zeolite @ layered double hydroxide shell material, ZSM5-23 @ LDH, [0186] Leftacetone-washed, where the squared line is ZSM-5(23), the circled line is ZSM-5(23) @ LDH-A and the triangular line is LDH-A [0187] Rightwater-washed, where the squared line is ZSM-5(23), the circled line is ZSM-5(23) @ LDH-W and the triangular line is LDH-W [0188] LDH-A denotes AMO-synthesised LDH using acetone treatment and LDH-W denotes conventionally synthesised LDH.

[0189] FIG. 15. Represents the different BET values at various calcination temperatures using HY5.1 @ LDH demonstrating no particular change.

[0190] FIG. 16. TEM image of HY5.1 @ Mg.sub.2AlNO.sub.3LDH-A. LDH-A denotes AMO-synthesised LDH, [0191] left1 m scale zoom [0192] right500 nm scale zoom.

[0193] FIG. 17. X-Ray powder diffraction of HY5.1 @ Mg2A1-NO3 LDH-A. LDH-A denotes AMO-synthesised LDH.

[0194] FIG. 18. Thermogravimetric Analysis (TGA) of (a) HY5.1, (b) HY5.1 @ Mg.sub.2AlNO.sub.3 LDH-A and (c) LDH-A. LDH-A denotes AMO-synthesised LDH.

[0195] FIG. 19. Two TEM images of HY5.1 @ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH-A. LDH-A denotes AMO-synthesised LDH.

[0196] FIG. 20. X-Ray powder diffraction of HY5.1 @ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH-A. LDH-A denotes AMO-synthesised LDH.

[0197] FIG. 21. Thermogravimetric Analysis (TGA) of (a) HY5.1, (b) HY5.1@ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH-A and (c) LDH-A. LDH-A denotes AMO-synthesised LDH.

[0198] FIG. 22. Two TEM images of HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A. LDH-A denotes AMO-synthesised LDH.

[0199] FIG. 23. X-Ray powder diffraction of HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A. LDH-A denotes AMO-synthesised LDH.

[0200] FIG. 24. Thermogravimetric Analysis (TGA) of (a) HY5.1, (b) HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A and (c) LDH-A. LDH-A denotes AMO-synthesised LDH.

[0201] FIG. 25. X-Ray powder diffraction of MSN @ LDH (a) MCM-41 @ AMO-LDH (b) SBA-15 @ AMO-LDH.

[0202] FIG. 26. TEM images of (a, b) MCM-41 @ AMO-LDH and (c, d) SBA-15 @ AMO-LDH.

[0203] FIG. 27. X-Ray powder diffraction of Microporous Aluminophosphate @ LDH: (a)ALPO-5 @ AMO-LDH, (b)SAPO-5 @ AMO-LDH.

[0204] FIG. 28. Two TEM images of SAPO-5 @ AMO-LDH.

[0205] FIG. 29. Two TEM images of ALPO-5 @ AMO-LDH.

EXAMPLES

[0206] Experimental Methods [0207] 1. General Details [0208] 1.1 Powder X-Ray Diffraction [0209] Powder X-ray diffraction (XRD) data were collected on a PANAnalytical XPert Pro diffractometer in reflection mode and a PANAnalytical Empyrean Series 2 at 40 kV and 40 mA using Cu K radiation (1=1.54057 , 2=1.54433 , weighted average=1.54178 ). Scans were recorded from 50 70 with varying scan speeds and slit sizes. Samples were mounted on stainless steel sample holders. The peaks at 43-44 are produced by the XRD sample holder and can be disregarded. [0210] 1.2 Thermogravimetric Analysis [0211] Thermogravimetric analysis (TGA) measurements were collected using a Netzsch STA 409 PC instrument. The sample (10-20 mg) was heated in a corundum crucible between 30 C. and 800 C. at a heating rate of 5 C. min.sup.1 under a flowing stream of nitrogen. [0212] 1.3 Transmission Electron Microscopy [0213] Transmission Electron Microscopy (TEM) analysis was performed on a JEOL 2100 microscope with an accelerating voltage of 200 kV. Particles were dispersed in water or ethanol with sonication and then cast onto copper grids coated with carbon film and left to dry. [0214] 1.4 Brunauer-Emmett-Teller Surface Area Analysis [0215] Brunauer-Emmett-Teller (BET) specific surface areas were measured from the N.sub.2 adsorption and desorption isotherms at 77 K collected from a Quantachrome Autosorb surface area and pore size analyser. [0216] General Method of Synthesis [0217] Zeolite was dispersed in deionised water using ultrasound treatment. After 30 minutes, sodium carbonate was added to the solution and a further 6 minutes of sonication was carried out to form solution A. An aqueous solution containing magnesium nitrate hexahydrate and aluminium nitrate nonahydrate was added at a rate to solution A under vigour stirring. The pH of the reaction solution was controlled with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. Optionally, the obtained solid was collected and then re-dispersed in deionised water and stirred for 1h. The samples (Zeolite @ LDH) were then dried under vacuum. The Zeolite @ AMO-LDH was synthesized using the same procedure. However, before final isolation, the solid was treated with AMOST method, which was washed with acetone and then re-dispersed in a fresh acetone under stirring for certain time. The solid was then dried under vacuum for materials characterization. [0218] Using this general method, zeolite @ LDH shell materials were synthesised using the different zeolite types HY5.1, HY30, HY15, syn-ZSM5, ZSM5-23 and ZSM5-40. [0219] Experimental Methods [0220] Example Method of HY5.1 @ LDH [0221] HY5.1 (100 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 30 minutes, sodium carbonate was added to the solution and a further 6 minutes of sonication was carried out to form solution A. An aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate and aluminium nitrate nonahydrate was added at a rate of 60 ml/h to solution A under vigour stirring. The pH of the reaction solution was controlled with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. Optionally, the obtained solid was collected and then re-dispersed in deionised water (40 mL) and stirred for 1 h. The collection and re-dispersion was repeated once. The samples (HY5.1 @ LDH) were then dried under vacuum. The HY5.1 @ AMO-LDH was synthesized using the same procedure. However, before final isolation, the solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in a fresh acetone (40 mL) under stirring for overnight. The solid was then dried under vacuum for materials characterization. [0222] The zeolite @ LDH shell materials obtained using these different zeolite types were characterised and/or studied according to the following. [0223] Characterisation of HY5.1 @ LDH [0224] The zeolite HY5.1 was used to attempt the synthesis of the first Zeolite @ AMO-LDH. FIGS. 1 and 2 highlight the synthesis and characterisation of HY5.1 @ AMO-LDH. Acetone was used as the AMO-solvent. The AMO-LDH can fully coat the surface of HY5.1 with open hierarchical structure. The content of LDH is around 61.5% according to the TGA result. After thermal treatment at 300 C., the total surface area of HY5.1 @ AMO-LDH is similar to that of pure HY5.1 as shown in Table 1. The external surface area increased close to three times (70 to 201 m.sup.2/g) and the accumulate volume increased from 0.07 to 0.66 cc/g. While the micropore surface area dropped from 625 to 497 m.sup.2/g. [0225] Comparison Between HY5.1 @ AMO-LDH and HY5.1 @ LDH [0226] A similar procedure was used to synthesise and characterise zeolite @ LDH core-shell using conventionally synthesised LDH, HY5.1 @ LDH, FIG. 4. The morphology of HY5.1 @ LDH-W and HY5.1 @ LDH-A are similar. [0227] FIG. 5 and FIG. 6 are the XRD and TGA results from conventional and AMO-synthesised HY5.1 @ LDH. Both samples show similar crystallinity and weight loss. [0228] Variation of Si/Al ratio in HY @ AMO-LDH [0229] FIG. 7 shows the increased affinity for LDH with increased aluminium content, providing a better Al.sup.3+ source for LDH growth. [0230] Variation of Other Parameters Using HY30 @ LDH [0231] The coating of LDH on the HY30 surface did not increase by changing temperature and Mg/Al ratio. However, a change in pH and Na.sub.2CO.sub.3 soaking time demonstrated a small improvement in affinity of LDH on the surface.

[0232] Variation of Zeolite to LDH Ratio in HY15 @ AMO-LDH [0233] FIG. 9 shows that for HY15, 200 mg seems to possess the best coating of the three. 90% of HY15 has been coated with dense LDH layer when using 200 mg. [0234] Variation of Si/Al Ratio in ZSM5 @ LDH [0235] LDH can easily grow on the surface of ZSM5 regardless of the Si/Al ratio. [0236] Variation of Zeolite to LDH Ratio in ZSM5-23 @ LDH [0237] By increasing the amount of ZSM5-23, the free LDH was reduced. However, less ZSM5 was coated with LDH. [0238] Variation of the Drop Rate in ZSM5-40 @ LDH [0239] Change in the drop rate has no significant effect. [0240] Characterisation of ZSM5-23 @ AMO-LDH [0241] FIG. 13 shows around 50% LDH in the sample ZSM5-23 @ AMO-LDH.

TABLE-US-00001 TABLE 1 Summary data from N.sub.2 adsorption and desorption BET External Micropore Micropore Cumulative SSA SSA SSA volume Volume Samples (m.sup.2/g) (m.sup.2/g) (m.sup.2/g) (cc/g) (cc/g) HY5.1 813 72 740 0.28 0.08 HY5.1@LDH-W 565 164 401 0.17 0.60 HY5.1@LDH-W 698 497 LDH-W 11 0.4 11 0.004 0.04 LDH-A 281 252 29 0.01 1.08 ZSM5-23 424 45 379 0.15 0.05 ZSM5-23@LDH- 167 54 113 0.04 0.33 W ZSM5-23@LDH-A 339 140 199 0.08 0.05 HY5.1 300 C. 695 70 625 0.30 0.07 HY5.1@LDH-A 698 201 497 0.23 0.66 300 C. [0242] LDH-W means the LDH was prepared by the conventional method in water. [0243] LDH-A means the LDH was treated with acetone.

[0244] FIG. 15 represents the different BET values at various calcination temperatures using HY5.1 @ LDH demonstrating no particular change. [0245] FURTHER CORE @ LAYERED DOUBLE HYDROXIDE SHELL MATERIALS [0246] Variation of the Anion of the LDH [0247] Example Method of HY5.1 @ Mg.sub.2AlNO.sub.3 LDH-A [0248] HY5.1 (100 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 36 minutes, an aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate and aluminium nitrate nonahydrate was added at a rate of 60 mL/h to HY5.1 solution under vigour stirring. The pH of the reaction solution was controlled to 10 with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. The obtained solid was collected and then re-dispersed in deionised water (40 mL) and stirred for 1 h. The collection and re-dispersion was repeated once. The solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in a fresh acetone (40 mL) under stirring for overnight. The solid was then dried under vacuum oven for materials characterization. [0249] Characterisation [0250] HY5.1 @ Mg.sub.2AlNO.sub.3 LDH [0251] The same synthesis method is applied to LDH-NO.sub.3. The TEM (FIG. 16) show that the Mg.sub.2AlNO.sub.3 LDH-A can grow on the surface of HY5.1. However, the amount of LDH on the surface is less, compared to LDHCO.sub.3 when using the same conditions. The XRD (FIG. 17) indicates that HY5.1 @ Mg.sub.2AlNO.sub.3 LDH-A has both characterization peaks of HY5.1 and LDH. TGA (FIG. 18) shows that HY5.1 @ Mg.sub.2AlNO.sub.3 LDH-A exhibits the typical three decompose stage of LDH. [0252] Variation of the Metal of the LDH [0253] Example Method of HY5.1 @ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH-A [0254] HY5.1 (100 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 36 minutes, an aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate, iron nitrate nonahydrate and aluminium nitrate nonahydrate (Mg:Al:Fe 2:0.8:0.2) was added at a rate of 60 mL/h to HY5.1 solution under vigour stirring. The pH of the reaction solution was controlled to 10 with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. The obtained solid was collected and then re-dispersed in deionised water (40 mL) and stirred for 1 h. The collection and re-dispersion was repeated once. The solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in a fresh acetone (40 mL) under stirring for overnight. The solid was then dried under vacuum oven for materials characterization. [0255] Characterisation [0256] HY5.1 @ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH [0257] The TEM (FIG. 19) show that the Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH can grow on the surface of HY5.1. The XRD (FIG. 20) indicates that HY5.1 @ Mg.sub.2Al.sub.0.8Fe.sub.0.2CO.sub.3 LDH-A has both characterization peaks of HY5.1 and LDH. TGA (FIG. 21) shows that HY5.1 @ Mg.sub.2Al.sub.0.8Fe0.2CO.sub.3 LDH-A exhibits the typical three decompose stage of LDH. [0258] Example Method of HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A [0259] HY5.1 (100 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 36 minutes, an aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate, nickel nitrate hexahydrate and aluminium nitrate nonahydrate (Mg:Al:Ni 1.8:1:0.2) was added at a rate of 60 mL/h to HY5.1 solution under vigour stirring. The pH of the reaction solution was controlled to 10 with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. The obtained solid was collected and then re-dispersed in deionised water (40 mL) and stirred for 1 h. The collection and re-dispersion was repeated once. The solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in a fresh acetone (40 mL) under stirring for overnight. The solid was then dried under vacuum oven for materials characterization. [0260] Characterisation [0261] HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH [0262] The TEM (FIG. 22) show that the Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A can grow on the surface of HY5.1. The XRD (FIG. 23) indicates that HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A has both characterization peaks of HY5.1 and LDH. TGA (FIG. 24) shows that HY5.1 @ Mg.sub.1.8AlNi.sub.0.2CO.sub.3 LDH-A exhibits the typical three decompose stage of LDH. [0263] Mesoporous Silica Based Materials [0264] Example Method of MSN @ Mg.sub.3AlCO.sub.3 LDH [0265] Generally, MCM-41 (50 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 30 minutes, the sodium carbonate was added to the solution and a further 6 minutes of sonication was carried out to form solution A. An aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate and aluminium nitrate nonahydrate was added at a rate of 60 mL/h to solution A under vigorous stirring. The pH of the reaction solution was controlled with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. The obtained solid was collected and then re-dispersed in deionised water (40 mL) and stirred for 1 h. The collection and re-dispersion was repeated once. Before final isolation, the solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in acetone (40 mL) under stirring for overnight. The samples (MCM-41 @ AMO-LDH) were then dried under vacuum. The other MSN @ AMO-LDH (such as SBA-15 @ AMO-LDH) was synthesized using the same procedure. [0266] Characterisation [0267] MSN @ Mg.sub.3AlCO.sub.3 LDH [0268] According to X-ray diffraction (XRD) pattern (FIG. 25) of MSN @ LDH, the core of MCM-41 has a mean pore diameter about 3 nm and SBA-15 has a mean pore diameter about 9 nm. The XRD pattern of low angle (FIG. S25 inset) showed that the samples had an high ordered hexagonal structure and high crystallinity, these Bragg peaks can be indexed as (100), and overlapped (110) of the two-dimensional hexagonal mesostructure (space group p6m). Since MCM-41 and SBA-15 consists of amorphous silica, it has no crystallinity at the atomic level. Therefore, only the typical peaks of LDH have been observed at higher degrees. We can observe from the TEM images (FIG. 26) that LDH-nanosheet can grow on the Mesoporous Silica Nanoparticles surface. [0269] Microporous Molecular Sieves @ LDH [0270] Example Method of ALPO-5/SAPO-5 @ LDH [0271] Generally, ALPO-5(100 mg) was dispersed in deionised water (20 mL) using ultrasound treatment. After 30 minutes, the sodium carbonate was added to the solution and a further 6 minutes of sonication was carried out to form solution A. An aqueous solution (19.2 mL) containing magnesium nitrate hexahydrate and aluminium nitrate nonahydrate was added at a rate of 60 mL/h to solution A under vigorous stirring. The pH of the reaction solution was controlled with the addition of 1 M NaOH by an autotitrator. The obtained suspension was stirred for 1 h. The collection and re-dispersion was repeated once. Before final isolation, the solid was treated with AMOST method, which was washed with acetone (40 mL) and then re-dispersed in acetone (40 mL) under stirring for overnight. The samples (ALPO-5 @ AMO-LDH) were then dried under vacuum. The SAPO-5 @ AMO-LDH was synthesized using the same procedure. [0272] SAPO5 @ Mg.sub.3AlCO.sub.3 LDH & ALPO5 @ Mg.sub.3AlCO.sub.3 LDH [0273] XRD (FIG. 27) shows typical peaks of ALPO-5/SAPO-5 which is an AFI-type. On the other hand, typical peaks of LDH have been also observed at higher degrees. TEM images (FIGS. 28 and 29) show that LDH can grow on the surface of ALPO and SAPO. However, the thickness is depended on the composites of materials and synthesis method. For example, ALPO with higher Al content could have thicker layer of LDH, comparing SAPO.

[0274] While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.