Titanium stannate silicate, method of preparation and use thereof

Abstract

The present invention relates to an amorphous titanium stannate silicate with the general formula: M.sup.v+.sub.wTi.sub.xSi.sub.ySn.sub.zO.sub.2x+2y+2z+0.5vw, wherein M is proton, ammonium, a metal or a mixture of metals, wherein v is the valence of M being a positive integer, and wherein x, y, z and w are molar ratios: x is 1, y is from 0.01 to 99, z is from 0.01 to 99, and w is from 0.01 to 50. The described titanium stannate silicates are particularly useful in catalysis and adsorption.

Claims

1. Amorphous titanium stannate silicate with the general formula:
M.sup.v+.sub.wTi.sub.xSi.sub.ySn.sub.zO.sub.2x+2y+2z+0.5vw, wherein M is at least one of a proton, ammonium, a metal or a mixture of metals, v is the valence of M being a positive integer and wherein x, y, z and w are molar ratios: x is 1, y is from 0.1 to 5, z is from 0.03 to 1, and w is from 0.01 to 10, and wherein said titanium stannate silicate has an average pore diameter of at least 40 , determined by liquid nitrogen adsorption.

2. The titanium stannate silicate according to claim 1, wherein M is at least one of proton, ammonium, Na, Li, K, Cs, Ca, Mg, Sr, Ba, Fe(II), Fe(III), Sn(II), Ce, La, Nb, Ni, V, W, Mo, Al, Zn, Cu, Mn.

3. The titanium stannate silicate according to claim 1, wherein w is in the range 0.1-10.

4. The titanium stannate silicate according to claim 1, wherein said titanium stannate silicate has a pore volume of at least 0.3 mL/g, determined by liquid nitrogen adsorption.

5. The titanium stannate silicate according to claim 1 having a form of powder, tablets, granules or extrudate.

6. A method for titanium stannate silicate preparation, the method comprising: reacting a soluble silicate source, a soluble stannate source and a soluble titanium source in an aqueous medium to form titanium stannate silicate, precipitating the titanium stannate silicate, and isolating the titanium stannate silicate, the titanium stannate silicate having the general formula:
M.sup.v+.sub.wTi.sub.xSi.sub.ySn.sub.zO.sub.2x+2y+2z+0.5vw, wherein M is at least one of a proton, ammonium, a metal or a mixture of metals, v is the valence of M being a positive integer and wherein x, y, z and w are molar ratios: x is 1, y is from 0.1 to 5, z is from 0.03 to 1, and w is from 0.01 to 10, and wherein said titanium stannate silicate has an average pore diameter of at least 40 , determined by liquid nitrogen adsorption.

7. The method according to claim 6, further comprising ion exchanging with a cation selected from proton, ammonium, Na, Li, K, Cs, Ca, Mg, Sr, Ba, Fe(II), Fe(III), Sn(II), Ce, La, Nb, Ni, V, W, Mo, Al, Zn, Cu, Mn ions, and combinations thereof.

8. The method according to claim 6, wherein the titanium stannate silicate is further calcined at a temperature of above 200 C.

9. A method comprising: introducing into a chemical reaction an amorphous titania stannate silicate with the general formula:
M.sup.v+.sub.wTi.sub.xSi.sub.ySn.sub.zO.sub.2x+2y+2z+0.5vw, wherein M is at least one of a proton, ammonium, a metal or a mixture of metals, v is the valence of M being a positive integer and wherein x, y, z and w are molar ratios: x is 1, y is from 0.1 to 5, z is from 0.03 to 1, and w is from 0.01 to 10, and wherein said titania stannate silicate has an average pore diameter of at least 40 , determined by liquid nitrogen adsorption.

10. The method according to claim 9, wherein the chemical reaction is a reaction of esterification, Michael addition, transesterification, oxidation, epoxidation, or hydroxylation.

11. A method for adsorption and desorption of metals from a metal-contaminated waste stream and ground water, the method comprising: introducing an amorphous titania stannate silicate having the general formula:
M.sup.v+.sub.wTi.sub.xSi.sub.ySn.sub.zO.sub.2x+2y+2z+0.5vw, wherein M is at least one of a proton, ammonium, a metal or a mixture of metals, v is the valence of M being a positive integer and wherein x, y, z and w are molar ratios: x is 1, y is from 0.1 to 5, z is from 0.03 to 1, and w is from 0.01 to 10; and contacting the amorphous titania stannate silicate with a metal contaminated stream, wherein said titania stannate silicate has an average pore diameter of at least 40 , determined by liquid nitrogen adsorption.

12. The method of claim 11 further comprising selectively adsorbing and desorbing metals in the metal contaminated stream.

13. The method according to claim 12, wherein the metals comprise Pt (II), Pt(IV), Pd, Gd, Hg, Cd, Au or Ho.

14. The method according to claim 11, wherein y is in the range of 0.2-5.

15. The method according to claim 11, wherein z is in the range of 0.05-1.

16. The method according to claim 11, further comprising adsorbing and removing radionuclides.

17. The method of claim 16, wherein the radionuclides comprise .sup.90Sr or actinides.

Description

EXAMPLE 1

Preparation of Na:Ti:Si:Sn with Molar Ratios of 0.29:1:1.02:0.06

(1) In a vessel containing 95 g of demi-water there were dissolved 27.6 mL of a 30% NaOH solution, 10 mL of a 27% Na.sub.2SiO.sub.3 solution and 6.8 mL of a 13.5 wt % solution of Na.sub.2SnO.sub.3. The solution in this vessel is called solution A. In another vessel containing 112 g of demi-water, 16 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 more than 4 hours (up to 4 days). 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 425 m sieve, reslurried in water and stirred for 1 h. Subsequently, the slurry was filtered, washed with demi-water until the conductivity of the wash water was below 200 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 12.5 g of white solids were produced by method.

(2) The material is amorphous (XRD) and had a Na:Ti:Si:Sn ratio of 0.29:1:1.02:0.06 and a pore volume of 0.47 mL/g, BET-SA=430 m.sup.2/g, average pore diameter=52 .

EXAMPLE 2

Preparation of Na:Ti:Si:Sn with Molar Ratios of 0.23:1:0.34:0.18

(3) A similar procedure as described in Example 1 was used but with different amounts of starting materials. Solution A contained 95 g of demi-water, 26.7 mL of a 30% NaOH solution, 3.4 mL of a 27% Na.sub.2SiO.sub.3 solution and 20 mL of a 13.5 wt. % solution of Na.sub.2SnO.sub.3. Solution B was similar to example 1. Approximately 10.8 g of white solids were produced.

(4) The material is amorphous (XRD) and had a Na:Ti:Si:Sn molar ratio of 0.23:1:0.34:0.18 and a pore volume of 0.48 mL/g. BET-SA=431 m2/g, average pore diameter=51 .

EXAMPLE 3

Preparation of a H+ Exchanged Material

(5) A similar procedure as described in example 1 was used but with different amounts of starting materials. Solution A contained 380 g of demi-water, 105 mL of a 30% NaOH solution, 13.7 mL of a 27% Na.sub.2SiO.sub.3 solution and 80.8 mL of a 13.5 wt. % solution of Na.sub.2SnO.sub.3. Solution B was prepared by adding 64.5 mL of a 35% TiOCl.sub.2 solution to 450 g of demi-water. Then, solution A is added to solution B in 10 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. To the mixture 40 g of NaCl was added (optional). The sample is then allowed to age for more than 4 hours. The slurry was filtered and the remaining substance was dried in the oven overnight at 110 C. After drying, the white solids were granulated, sieved through a 425 m sieve, reslurried in water and stirred for 1 h at a pH 2.0 (pH adjustment with 10% HCl). Subsequently, the slurry was filtered, washed with demi-water until the conductivity of the wash water was below 200 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 40.7 g of white solids were produced by method.

(6) The material is amorphous as confirmed by XRD, and had a Na:Ti:Si:Sn molar ratio of 0.01:1:0.34:0.16 and a pore volume of 0.50 mL/g. BET-SA=384 m.sup.2/g, average pore diameter=55 .

EXAMPLE 4

Preparation without Si

(7) A similar procedure as described in example 1 was used but with different amounts of starting materials. Solution A contained 90 g of demi-water, 24.3 mL of a 30% NaOH solution and 25 mL of a 13.5 wt. % solution of Na.sub.2SnO.sub.3. Solution B was containing 100 g of demi-water and 15 mL of a 35% TiOCl.sub.2 solution. 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 this is not the case, the pH is adjusted with dilute HCl or dilute NaOH. To the mixture 10 g of NaCl was added (optional). The sample is then allowed to age for more than 4 hours (up to 4 days). 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 425 m sieve, reslurried in water and stirred for 1 h at a pH 2.0 (pH adjustment with 10% HCl). Subsequently, the slurry was filtered, washed with demi-water until the conductivity of the wash water was below 200 S/cm. The resulting white material was dried in the oven overnight at 110 C. Approximately 8.2 g of white solids were produced by method.

(8) The material is crystalline as confirmed by XRD, and had a Na:Ti:Si:Sn molar ratio of 0.01:1:0:0.24 and a pore volume of 0.30 mL/g, BET-SA=256 m.sup.2/g, average pore diameter=39 .

Calcination of Examples 1, 2, 3 and 4

(9) The samples prepared by Example 1, 2, 3 and 4 were calcined in air at 450 C. for 2 hours. After calcination all samples remained amorphous, except the material from Example 4 that remained crystalline.

EXAMPLE 5

TiSi Traditional Synthesis

(10) 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.

(11) 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.

(12) The solids produced from this method were granulated and sieved to particles below 250 micron and the resulting had a sodium:titanium:silicon molar ratio of 0.35:1:0.96 and a pore volume around 0.14 mL/g, BET-SA=364 m.sup.2/g, average pore diameter=31 .

(13) FIG. 1 shows the pore size distribution of the products obtained in Examples 2 and 5. It can be seen that the presence of Sn built in the structure (Example 2) results in a significantly larger pore volume in comparison with a compound without Sn (Example 5).

EXAMPLE 6

Cation Exchange by TiSi Modification with SnCl.SUB.2

(14) In a glass beaker 50.0 g of titanium silicate prepared according to Example 5 was slurried in 450 mL demi-water. To this slurry was added 29.34 g SnCl.sub.2.2H.sub.2O as a solid. The colour of the mixture changes from white to yellow. The pH of the slurry changed from 8.80 to 1.60. The mixture was allowed to stir for an additional 2 hours at room temperature. After 2 hours the slurry was filtered and washed with demi-water until the conductivity of the filtrate was below 20 microSiemens/cm. The yellowish filtercake was dried in an oven overnight at 110 C. yielding 48.2 g of a yellow powder. The resulting material was amorphous by XRD.

(15) The material had a Na:Ti:Si:Sn molar ratio of 0.01:1:1.27:0.19. The pore volume measured is 0.14 mL/g, the BET surface is 229 m.sup.2/g, the average pore diameter is 32 .

EXAMPLE 7

Preparation of Tablets

(16) The material of Example 3 was mixed with graphite and was tableted to a size of 1.51.5 mm. The resulting tablets were calcined @ 500 C. for 2 hours.

EXAMPLE 8

Use of TiSi in Simultaneous Esterification and Transesterification

(17) 10 mL of titanium silicate tablets were made from the material prepared according to Example 5 but in which the Na content was lowered by HCl treatment at pH 2.00. After filtration, washing and drying the material contains 0.8 wt. % Na. This material was tableted into 1.5*1.5 mm tablets. The tablets were loaded in a fixed bed reactor. The reactor was continuously fed with MeOH (1.73 mL/h) and rapeseed oil (3.47 mL/h) whereto 5 wt. % dodecanoic acid had been added. Reaction conditions were 180 C., 28 bars N.sub.2 back pressure, LHSV rapeseed oil 0.347 h.sup.1 (3.47 mL/h), LHSV MeOH 0.173 h.sup.1 (1.73 mL/h).

(18) Conversion of the triglyceride to fatty acid methyl esters was 46% and 99.1% of the dodecanoic acid was converted into the corresponding methyl ester.

EXAMPLE 9

Use of TiSiSn in Simultaneous Esterification and Transesterification

(19) 10 mL of titanium stannate silicate tablets prepared from material prepared according to Example 3. The tablets were loaded in a fixed bed reactor. The reactor was continuously fed with MeOH (1.73 mL/h) and rapeseed oil (3.47 mL/h) whereto 5 wt % dodecanoic acid had been added. Reaction conditions were 180 C., 28 bar N.sub.2 back pressure, LHSV rapeseed oil 0.347 h.sup.1 (3.47 mL/h), LHSV MeOH 0.173 h.sup.1 (1.73 mL/h).

(20) Conversion of the triglyceride to fatty acid methyl esters was 60% and 99.8% of the dodecanoic acid was converted into the corresponding methyl ester.