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, transesterifications, (ep)oxidations, hydroxylations, or in adsorbance of small inorganic and organic molecules e.g. CO.sub.2 or aromatic compounds.

Claims

1. Method for the preparation of a mesoporous and/or macroporous amorphous Group 4 metal silicate with the general 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, T 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, comprising the steps of: (a) providing a metal source of at least one metal of Group 4, a silicate source and optionally a pore shaper in an aqueous medium; (b) carrying out a precipitation reaction by combining the metal and the silicate sources and having a pH range of 7-8.5, whereby a substance of the metal silicate and a soluble salt are formed; and (c) drying the substance to remove water, wherein the preparation is performed under pore shaping conditions, wherein said pore shaping conditions consists of the use of a pore shaper before the drying step (c), wherein a halide salt of M is formed in the precipitation reaction or is added before, during or after the precipitation reaction in step (b), which halide salt is then replaced by a non-halide salt before drying, which non-halide salt is allowed to accumulate in the substance during step (c).

2. The method according to claim 1, wherein the pore shaping conditions further consists of the use of a temperature of at least 60° C. during the precipitation in step (b).

3. The method according to claim 1, wherein the pore shaper is a soluble salt of M, wherein M is selected from the group consisting of a proton, ammonium, a metal cation and combinations thereof.

4. The method according to claim 3, 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.

5. The method according to claim 1, wherein said non-halide salt is selected from the group consisting of phosphate, biphosphate, phosphite, biphosphite, sulfate, bisulfate, sulfite, bisulfite, nitrate, nitrite, carbonate, bicarbonate, formate, acetate and citrate.

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

7. The method according to claim 1, wherein the metal source of at least one metal of Group 4 is a soluble salt, wherein said salt is a halide salt or a non-halide salt.

8. The method according to claim 1, wherein the metal source of at least one metal of Group 4 is a titanium source selected from the group consisting of TiCl.sub.4, titanium(IV) oxychloride, titanium(IV) bromide, titanium(IV) fluoride, titanium(IV) iodide, titanium(IV) alkoxides, TiO-alkoxides and Ti(III) compounds.

9. The method according to claim 1, wherein the silicate source is a soluble metal silicate or an organic silicate.

10. The method according to claim 1, comprising a calcination step of the metal silicate.

11. The method according to claim 1, wherein after step (c), the salt is then removed from the metal silicate in a washing step followed by a further drying step.

12. The method according to claim 1, wherein said method comprises an ion exchange step before or after drying step (c), and wherein said ion exchange step is performed with cations.

Description

EXAMPLES

(1) General

(2) 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 μm Hg at 180° C.

(3) Powder X-ray diffraction (XRD) patterns were obtained with a Bruker D8 ADVANCE (Detector: SOL'X, Anode: Copper, wavelength: 1.542 Å, 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

(4) TiSi Without Washing

(5) 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 μm 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 μS/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.

(6) 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 Å.

Example 2

(7) Addition of Extra NaCl

(8) 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 μS/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 Å.

Example 3

(9) Addition of NaHCO.sub.3

(10) 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 μS/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 Å.

Example 4

(11) Addition of HHDMA

(12) 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 Å.

Example 5

(13) Addition of BaCl.sub.2

(14) 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 μS/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 Å.

Example 6

(15) Use of High Temperatures During Precipitation

(16) A similar procedure as described in Example 1 but now solution A and B were heated to 80° C. before they were mixed. After ageing, the resulting precipitate was washed with demi-water until the conductivity was below 50 μS/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 Å.

Example 7 (Comparative)

(17) Comparative TiSi Preparation

(18) Titanium silicate powder was made in accordance with Example 9 of U.S. Pat. No. 5,053,139. Two liters 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 liters. Two liters 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 liters. 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 liter deionized water per liter of substance, reslurried in 4-6 liters of deionized water, filtered, and finally rewashed in 2 liters of water per liter of substance.

(19) 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.

(20) 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 Å. The resulting material was amorphous by XRD.

Example 8

(21) Use of TiSi in Transesterification

(22) 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 20 h, 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

(23) Use of Large Pore TiSi in Transesterification

(24) 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

(25) Removal of Halides with Na.sub.2SO.sub.4

(26) 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.2SO.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 μm 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 μS/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.

(27) 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 Å.

(28) The FIGURE shows the pore size distribution of Examples 1-7 and 10.

Example 11

(29) Use of Na.sub.2SO.sub.4 Washed TiSi in Transesterification

(30) 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.