Method for Preparation of a Group 4 Metal Silicate and Use Thereof

Abstract

The invention provides a method for the preparation of an amorphous silicate of at least one metal from the Group 4 of the Periodic Table of Elements with a total pore volume of at least 0.3 mL/g. The method of preparation involves the use of pore shaping conditions, which can be the use of a pore shaper and optionally an increased precipitation temperature, e.g. at least 60 C. The silicate of the invention is especially suitable in catalytic reactions such as esterifications, Michael additions, transesteritications, (ep)oxidations, hydroxylations, or in absorbance of small inorganic and organic molecules e.g. CO.sub.2 or aromatic compounds.

Claims

1. A catalyst or adsorbent composition comprising a mesoporous and/or macroporous amorphous Group 4 metal silicate of formula
M.sup.v+.sub.wT.sub.xSi.sub.yO.sub.2x+2y+0.5vw, wherein M is selected from the group consisting of a proton, ammonium, a metal cation and combinations thereof, v is the valence of M being a positive integer, is at least one of the Group 4 metals, x, y and w are molar ratios: x is 1; y is from 0.01 to 99; w is from 0.01 to 50; and wherein said silicate has a total pore volume of at least 0.3 mL/g as measured by liquid nitrogen adsorption.

2. The composition according to claim 1, wherein M is selected from the group consisting of a proton, ammonium, Na, Li, K, Cs, Ca, Mg, Sr, Ba, Fe, Sn, Ce, La, Nb, Ni, V, W, Mo, Al, Ag, Zn, Cu, Mn cations, and combinations thereof.

3. The composition according to claim 1, wherein T is selected from the group consisting of Ti, Zr and Hf, and mixtures thereof.

4. The composition according to claim 1 in the form of a powder, tablet, granule or extrudate.

5. The composition according to claim 1 in the form of a tablet or extrudate.

6. A method of performing a chemical reaction under catalytic conditions, the method comprising employing the composition according to claim 1 as a catalyst.

7. The method according to claim 6 wherein the chemical reaction is an esterification, Michael addition, transesterification, oxidation, epoxidation or an hydroxylation.

8. The method according to claim 6 wherein the chemical reaction is a transesterification.

9. A method for adsorption and/or removal of radionuclides from a contaminated aqueous stream, the method comprising contacting the stream with the composition of claim 1.

10. The method according to claim 9 wherein the radionuclides are selected from the group consisting of Sr and actinides.

11. A method for selective adsorption and desorption of metal cations under physiological conditions, the method comprising contacting an aqueous solution at physiological pH with the composition of claim 1.

12. The method according to claim 11, wherein the metals are selected from the group consisting of Pt, Pd, Gd, Hg, Cd, Au, Ho and combinations thereof.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0064] FIG. 1 is a graph of pore diameter () vs. dV/dlog(D) pore volume (cm3/g-) for each of Examples 1-10.

EXAMPLES

General

[0065] Physical adsorption of nitrogen at 196 C. using a Micromeritics ASAP 2420 apparatus was used to determine the textural properties of the example including the pore volume, pore size distribution, average pore diameter and the BET surface. The BET surface area and pore size distributions were determined by BET and BJH methods, respectively. The presence of micropores was determined from a t-plot analysis. Prior to the measurements, all samples were degassed under vacuum until a pressure lower than 10 m Hg at 180 C.

[0066] Powder X-ray diffraction (XRD) patterns were obtained with a Bruker D8 ADVANCE (Detector: SOL'X, Anode: Copper, wavelength: 1.542 , Primary Soller slit: 4, Secundary Soller slit: 4, Detector slit: 0.2 mm, Spinner: 15 RPM, Divergence slit: variable V20, Antiscatter slit: variable V20, Start: 10 2 theta, Stop: 100 2 theta, Stepsize: 0.05 2 theta, Time/step: 8 sec, Sample preparation: Front loading).

Example 1

TiSi Without Washing

[0067] In a vessel containing 95 g of demi-water there were dissolved 36 g of a 30% NaOH solution, 13.6 mL of a 27% Na.sub.2SiO.sub.3 solution. The solution in this vessel is called solution A. In another vessel containing 110 g of demi-water, 17 mL of a 35% TiOCl.sub.2 solution was added. The solution in this vessel is called solution B. Then, solution A is added to solution B in 5 minutes with vigorous stirring. After the addition is complete, the mixture is allowed to continue mixing for an additional 10 minutes. The pH of the solution should fall between 7.5 and 7.9; if necessary, the pH is adjusted with dilute HCl or dilute NaOH. The sample is then allowed to age for at least 4 hours. The slurry was filtered and the remaining substance was dried in the oven overnight at 110 C. The resulting white solids were granulated, sieved through a 400 m sieve, reslurried in water and stirred for 1 h at a pH 2.00 using diluted nitric acid. Subsequently, the slurry was filtered, washed with demi-water until the conductivity of the wash water was below 50 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 12 grams of white solids were produced by this method.

[0068] The resulting material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.05:1:0.95, a total pore volume 0.33 mL/g, BET-SA 403 m.sup.2/g, average pore diameter 46 .

Example 2

Addition of Extra NaCl

[0069] A similar procedure as described in Example 1 was used but to solution B 10 g of NaCl was added before the precipitation. After the mixing of solutions A and B and pH adjustment, the resulting precipitate was filtered and dried at 110 C. overnight. Then the material was granulated to below 400 microns, reslurried in water and stirred for 1 h at room temperature. Then the slurry was filtered, washed until the conductivity was below 20 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 14 grams of white solids were produced by this method. The resulting material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.36:1:0.96, a total pore volume 0.54 mL/g, BET-SA 389 m.sup.2/g, average pore diameter 59 .

Example 3

Addition of NaHCO.SUB.3

[0070] A similar procedure as described in Example 1 was used but now right after the completion of mixing solution A and B and pH adjustment to 7.5, 20 g of NaHCO.sub.3 was added to the slurry. The resulting precipitate was filtered and dried at 110 C. overnight. Then the material was granulated to below 400 microns, reslurried in water and stirred for 1 h at room temperature. Then the slurry was filtered, washed until the conductivity was below 20 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 13.5 g of white solids were produced by this method. The resulting material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.38:1:0.94, a total pore volume 0.53 mL/g, BET-SA 170 m.sup.2/g, average pore diameter 118 .

Example 4

Addition of HHDMA

[0071] A similar procedure as described in Example 2 was used, except that the 10 g of NaCl were replaced by 20 mL of hexadecyl(2-hydroxyethyl)dimethyl ammonium dihydrogenphosphate solution in water (30%). The work-up of the resulting precipitate was similar to Example 2. The resulting material was amorphous by XRD and was calcined at 450 C. The calcined material was also amorphous and had a Na:Ti:Si molar ratio 0.38:1:0.94, a total pore volume 0.50 mL/g, BET-SA 238 m.sup.2/g, average pore diameter 69 .

Example 5

Addition of BaCl.SUB.2

[0072] A similar procedure as described in Example 1 was used up to the part of the ageing of the precipitate. Then the precipitate was washed with demi-water until the conductivity was below 50 S/cm. The resulting substance was reslurried in 200 mL demi-water and 26.2 g of barium chloride was added as a solid. The resulting slurry was heated to 80 C. and stirred for an additional 90 minutes. Then the slurry was filtered and washed with demi-water until no Cl could be detected (by AgNO.sub.3 addition). The resulting substance was dried in an oven overnight at 105 C. The resulting material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.00:1:0.61, contained 17 wt % Ba and had a total pore volume of 0.40 mL/g, BET-SA 330 m.sup.2/g, average pore diameter 60 .

Example 6

Use of High Temperatures During Precipitation

[0073] A similar procedure as described in Example 1 but now solution A and B were heated to before they were mixed. After ageing, the resulting precipitate was washed with demi-water until the conductivity was below 50 S/cm. The precipitate was dried in an oven at 110 C. overnight. The resulting dried material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.27:1:0.49, a total pore volume 0.40 mL/g, BET-SA 262 m.sup.2/g, average pore diameter 71 .

Example 7 (Comparative)

Comparative TiSi Preparation

[0074] Titanium silicate powder was made in accordance with Example 9 of U.S. Pat. No. 5,053,139. Two litres of a 1.5 M titanium chloride solution (solution A) were made by adding 569.11 g TiCl.sub.4 to enough deionized water to make 2 litres. Two litres of 1.5M sodium silicate solution (solution B) are made by dissolving 638.2 g of Na.sub.2SiO.sub.3.5H.sub.2O in enough 3M NaOH to make 2 litres. Solution B is added to solution A at a rate of 16 cc/minute with extremely vigorous stirring. After addition is complete, the mixture is allowed to continue mixing for an additional 15 minutes. The pH of the solution should fall between 7.5 and 7.9; if this is not the case, the pH is adjusted with dilute HCl or dilute NaOH, The sample is then allowed to age 2-4 days. After aging, any water on top of the substance is decanted off. The sample is then filtered, washed with 1 litre deionized water per litre of substance, reslurried in 4-6 litres of deionized water, filtered, and finally rewashed in 2 litres of water per litre of substance.

[0075] For efficiency reasons, the sample was then dried at 105 C. for 24 hours (until LOI is below 10). At no time during the synthesis procedure is the substance allowed to contact any metal; polypropylene and glass labware are used throughout the preparation.

[0076] The solids produced from this method were granulated and sieved to particles below 400 micron and the resulting material had a silicon-to-titanium molar ratio of 1:1 and a total pore volume around 0.14 mL/g, BET-SA 364 m.sup.2/g, average pore diameter 31 . The resulting material was amorphous by XRD.

Example 8

Use of TiSi in Transesterification

[0077] 0.2 grams of TiSi material from Example 7 was placed in a 20 mL vial. To this a mixture of refined rapeseed oil (8.9 mL) and n-butanol (6.1 mL) was added. The mixture was heated to 110 C. for 20 h. After 2011, the reaction mixture was analysed by GC. The reaction product showed 20.7% conversion of the rapeseed oil. A comparative reaction without a catalyst showed only 1.2% conversion.

Example 9

Use of Large Pore TiSi in Transesterification

[0078] 0.2 grams of TiSi material from Example 6 was placed in a 20 mL vial. To this a mixture of refined rapeseed oil (8.9 mL) and n-butanol (6.1 mL) was added. The mixture was heated to 110 C. for 20 h. After 20 h, the reaction mixture was analysed by GC. The reaction product showed 53.5% conversion of the rapeseed oil. A comparative reaction without a catalyst showed only 1.2% conversion.

Example 10

Removal of Halides with Na.SUB.2.SO.SUB.4

[0079] A similar procedure as described in Example 1 was used, but after ageing the slurry was filtered and the remaining substance was washed with a Na.sub.2SO.sub.4 solution in demi-water (200 g Na.sub.7SO.sub.4 in 1000 mL demi-water). Analysis of the collected wash water showed that virtually all of the chloride was removed from the wet filter cake. The remaining white Cl-free material was dried in the oven overnight at 110 C. The resulting white solids (39.6 g) were granulated, sieved through a 400 m sieve, reslurried in 250 mL water and stirred for 3 h at a pH 2.00 using diluted nitric acid. Subsequently, the slurry was filtered, washed with demi-water until the conductivity of the wash water was below 50 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 12 grams of white solids were produced by this method.

[0080] The resulting material was amorphous by XRD and had a Na:Ti:Si molar ratio 0.05:1:0.95, a total pore volume 0.31 mL/g, BET-SA 324 m.sup.2/g, average pore diameter 68 .

Example 11

Use of Na.SUB.2.SO.SUB.4 .Washed TiSi in Transesterification

[0081] 0.2 grams of TiSi material from Example 10 was placed in a 20 mL vial. To this, a mixture of refined rapeseed oil (8.9 mL) and i-decanol (8.0 mL) was added. The mixture was heated to 140 C. for 24 h. After 24 h, the reaction mixture was cooled to room temperature and was analysed by GC. The reaction product showed 34.3% conversion of the rapeseed oil. A comparative reaction with the catalyst from Example 7 showed only 17.9% conversion. A comparative experiment without a catalyst showed only 8.0% conversion.