WO1999065822A1

WO1999065822A1 - New process to make mesoporous crystalline materials, and materials made by such process

Info

Publication number: WO1999065822A1
Application number: PCT/US1999/013389
Authority: WO
Inventors: Alexander Kuperman; Geoffrey A. Ozin; Deepa Khushalani
Original assignee: The Dow Chemical Company
Priority date: 1998-06-18
Filing date: 1999-06-14
Publication date: 1999-12-23
Also published as: AU4682399A

Abstract

A novel process to make a mesoporous crystalline material comprises the steps of: (1) forming a layered composition that contains: (a) at least one complex of a polyol with suitable inorganic elements and (b) a surfactant; (2) simultaneously or sequentially: (a) hydrolyzing the complex in the layered composition and (b) dehydrating the hydrolysis product to form a cross-linked oxide of the suitable inorganic elements; and (3) calcining the product of Step (2) under conditions sufficient to produce an inorganic mesoporous crystalline material. The process can make both known mesoporous crystalline materials, and materials which conventional processes do not make.

Description

NEW PROCESS TO MAKE MESOPOROUS CRYSTALLINE MATERIALS, AND MATERIALS MADE BY SUCH PROCESS

Background of the Invention The present invention relates to the art of mesoporous crystalline materials and processes to make them.

Known mesoporous crystalline materials and processes to make them are described in detail in several patents, including: Kresge, U.S. Patent 5,098,684 (March 24, 1992); Kresge, U.S. Patent 5,102,643 (April 2, 1992); Beck, U.S. Patent 5,057,296 (October 15, 1991 ); Chu, et at., U.S. Patent 5,104,515 (April 14, 1992); Beck, U.S. Patent 5,108,725 (April 28, 1992); Kresge, U.S. Patent 5,198,203 (March 30, 1993); Kresge, U.S. Patent 5,211 ,934 (May 18, 1993); Chu, et al., U.S. Patent 5,215,737 (June 1 , 1993); Kresge, et al., U.S. Patent 5,250,282 (October 5, 1993); Kresge, et al., U.S. Patent 5,300,277 (April 5, 1994); Beck, et al., U.S. Patent 5,304,363 (April 19, 1994); and Beck, et al., U.S. Patent 5,334,368 (August 2, 1994), which are incorporated herein by reference.

These known mesoporous crystalline materials are porous inorganic solids having relatively uniform pore sizes of about 13 A to 500 A. They are illustrated by Formula 1

1 M^WAYAO.) wherein: "W" is one or more divalent elements such as manganese, cobalt, iron and/or magnesium;

"X" is one or more trivalent elements such as aluminum, boron or gallium;

"Y" is one or more tetravalent elements such as silicon or germanium;

"Z" is one or more pentavalent elements, such as phosphorus; "M" is a charge-balancing counter-ion, such as ammonium;

"n" is the charge of the composition, excluding M, expressed as oxides;

"q" is the is the weighted molar average valence of M;

"n/q" is the mole fraction of M;

"a", "b", "c" and "d" are mole fractions of W, X, Y and Z, respectively; "h" is a number from 1 to 2.5; and

(a + b + c + d) = 1

The pore size of known mesoporous crystalline materials is usually about 13 A to about 500 A, and most often about 15 A to about 100 A. The known mesoporous crystalline materials have a narrow pore size distribution. The mesoporous crystalline materials have a relatively large surface area (about 750 m²/g to 1400 m²/g), as demonstrated by their capacity to absorb more than 15 g of benzene per 100 g of material at 50 torr and 25°C. The pores are typically arranged in an ordered manner, and form deep channels through a particle of the material.

The large number of pores and relatively uniform pore size which mesoporous crystalline materials provide is unique for materials with this pore size, and makes the mesoporous crystalline materials particularly useful for many different applications. The materials are useful as catalysts, as support for catalysts, as adsorbents, and as sieving materials.

The known processes to make mesoporous materials contain the following three steps:

1. forming a mixture which contains:

(a) inorganic oxides of W, X, Y and Z,

(b) a surfactant,

(c) a source of counter-ions (M), and (d) a solvent which is preferably water;

2. crystallizing an organic-containing precursor from the mixture at a temperature of 25°C to 250°C; and

3. optionally calcining the precursor material at a temperature of at least 400°C for a time of 1 minute to 20 hours. Although Formula 1 suggests that known mesoporous crystalline materials may contain a broad range of different elements, the known processes actually are only able to make a limited range of mesoporous crystalline compositions. Achievable compositions usually contain predominantly silicon and oxygen with only small proportions of other elements. For example, the table in Kresge, U.S. Patent 5,102,643 (April 2, 1992) at column 7 shows that the ratio of X_jO/YO,, used to make mesoporous crystalline material has a useful range of only 0 to 0.05. This useful range permits only very limited concentrations of the trivalent element (X).

It would be desirable to develop a new process that is able to make a broader range of compositions. Summary of the Invention The present invention is a process that permits manufacture of mesoporous crystalline materials which contain a broad range of oxides of suitable inorganic elements. For the purposes of this application, the "suitable inorganic elements" are a group of any one or more elements from the transition metals or Groups MA to IVA plus antimony and bismuth, but excluding carbon, chosen such that:

(1) The suitable inorganic elements form covalent bonds with oxygen that link two or more atoms of the metallic and/or semiconducting elements together, when the suitable inorganic elements are in oxide form.

(2) The suitable inorganic elements, as a group, have an average valence greater than 2. Individual elements within the group may have a valence of 2 or less, but the average valence must be greater than 2 so that the oxide of the group is cross- linked.

(3) The suitable inorganic elements form soluble, hydrolyzable complexes with a polyol.

One aspect of the present invention is a process to make a mesoporous crystalline material, comprising the steps of:

(1 ) forming a layered composition having discrete layers of:

(a) at least one surfactant and

(b) at least one complex of one or more suitable inorganic elements with one or more polyols; (2) simultaneously or sequentially:

(a) hydrolyzing the complex in the layered composition; and

(b) dehydrating the hydrolysis product to form a cross-linked oxide of the suitable inorganic elements; and

(3) calcining the product of Step (2) under conditions sufficient to produce an inorganic mesoporous crystalline material.

A second aspect of the present invention is mesoporous crystalline material having a composition expressed as in Formula 2:

2 M_f(Q X_bJ_cSi_eZ_dO_h) wherein Q, X, J, Si and Z together meet the definition of "suitable inorganic elements" and are chose such that:

"Q" is one or more divalent elements; "X" is one or more trivalent elements;

"J" is one or more tetravalent elements, other than carbon or silicon; "Si" is silicon;

"Z" is one or more elements having a valence higher then 4; and

"M" is a charge-balancing counter-ion;

"f" is a mole fraction of M which is sufficient to balance charges in the material; "a", "b", "c", "d" and "e" are mole fractions of Q, X, J, Z and Si, respectively; "h" is a number from 1 to 3; (a + b + c + d + e) = 1 ; and characterized in that (a + b + c) is at least 0.12.

A third aspect of the present invention is a layered composition that contains discrete layers of:

(a) at least one surfactant; and (b) at least one complex of suitable inorganic elements with a polyol wherein no more than 50% weight percent of the suitable inorganic elements are silicon. Detailed Description of the Invention

The process of the present invention comprises three steps:

(1) forming layered composition having discrete layers of: (a) a complex of at least one polyol and at least one suitable inorganic element; and

(b) a surfactant;

(2) simultaneously or sequentially:

(a) hydrolyzing the complex in the layered composition from Step (1); and (b) dehydrating the hydrolysis product to form a cross-linked oxide of the suitable inorganic elements; and

Step (1 ): Reagents. Process and Product Step (1) of the process is the formation of a layered composition that contains alternating layers of a complex and a solvent.

The complex contains a polyol and at least one suitable inorganic element. Suitable complexes and processes to make them are known in the art. For instance, suitable processes are described in B. Herreros, et al., 98 J. Phys. Chem. 4570 (1994) and

Gainsford, et al., 34 Inorg, Chem. 746 (1995), which are incorporated herein by reference.

The suitable inorganic element(s) in the complex are chosen in proportions desired for the final mesoporous material. Criteria for selection and suitable elements are well known. The elements form covalent bonds with oxygen to form chain or cross-linked structures. Individual inorganic elements in the mixture may have a valence of 2, but the average valence of suitable inorganic elements in the mixture should be greater than 2, in order to provide cross-linking in the final mesoporous structure. The average valence of the suitable inorganic elements is preferably at least about 2.5 and more preferably at least about 3; it is preferably no more than about 4. The suitable inorganic elements should be capable of forming stable complexes with the polyol when oxidized. Examples of suitable inorganic elements include silicon, titanium, aluminum, boron, iron, gallium, germanium, tantalum, vanadium, manganese, chromium, copper, molybdenum, tungsten, zirconium and niobium.

The polyol in the complex preferably contains on average between about 2 and about 12 carbon atoms, more preferably contains on average between about 2 and about 8 carbon atoms, and most preferably contains on average between about 2 and about 6 carbon atoms. It preferably contains about 2 to about 4 hydroxyl groups per molecule, more preferably about 2 to about 3 hydroxyl groups per molecule and most preferably about 2 hydroxyl groups per molecule. The hydroxyl groups are preferably not geminal hydroxyl groups. They are more preferably vicinal hydroxyl groups. Examples of suitably polyhydric alcohols include ethylene glycol, propylene glycol, glycerol, and catechol.

The layered structure also contains a surfactant, which is described in the prior art as an "organic directing agent". The surfactant is adequately described in Kresge, et al., U.S. Patent 5,102,643 (April 7, 1992) at column 7, line 56 to column 8, line 30, which is incorporated herein by reference. It preferably comprises an ammonium or phosphonium ion that contains at least one long carbon chain (about 6 to about 36 carbon atoms).

The molar ratio of surfactant to complex should be selected to form the layered structure. The optimum ratio varies depending on the selection of complex and surfactant.

The molar ratio of surfactant to complex is preferably at least 0.25:1 , more preferably at least about 0.5:1 and most preferably at least about 1 :1. It is preferably less than about 10:1 , more preferably no more than about 4:1 , and most preferably no more than about 3:1.

The layered structure forms when the complex and surfactant are in the correct ratios and the correct concentrations in the mixture. In very dilute solutions, the complex and surfactant form an unorganized mixture. In higher concentrations, they form spherical micelles. In higher concentrations, they form a hexagonal structure, which contains oriented cylidrical micelles. In even higher concentrations they form a layered structure. Mesoporous materials form when the inorganic oxide forms in Step (2) of the process (hydrolysis of the complex and crosslinking) in a hexagonal phase. In our invention, the reaction mixture is in a more concentrated, layered phase prior to step (2), and achieves the hexagonal phase during or just prior to step (2).

A preferred method to form the layered structure contains the steps of:

(A) Reacting the polyol with an oxide, hydroxide, alkoxide or aryloxide of the suitable inorganic element(s), in the presence of a base and optionally a solvent in an essentially non-aqueous solution, whereby the complex is formed;

(B) Simultaneously or sequentially with (A), mixing the surfactant into the mixture; and

(C) Removing excess organic components (such as polyol, surfactant and solvent), whereby a layered structure is formed.

In Step (1 )(A), a polyol reacts with an oxide, hydroxide, alkoxide or aryloxide of the suitable inorganic element(s). It preferably reacts with an oxide. Examples of suitable oxides that are useful to make the complex include: silicon dioxide, QO, X₂0₃, J0₂, Z₂0₅ Z0₃, A m ZO n wherein:

Q is a divalent metallic element. Q is preferably magnesium or a first row transition metal; is more preferably titanium, manganese, iron, copper, vanadium, molybdenum, tungsten, niobium, zirconium or tantalum, or a mixture thereof; and is most preferably titanium. (Prior art references use the character "W" to designate this divalent metallic element. We have substituted the character "Q" in order to prevent confusion with the element tungsten.)

X is a trivalent element. It is preferably aluminum, boron, iron, gallium or a mixture thereof, and is most preferably aluminum.

J is a tetravalent element other than carbon or silicon. It is preferably germanium or titanium or both, and is more preferably titanium. (Prior art references use the character "Y" to designate the tetravalent element. We have substituted the character "J" in order to prevent confusion with the element yttrium.)

Z is an element having a valence higher than 4, which is preferably phosphorus, vanadium, manganese or chromium. A is an alkali metal.

"n" is a number of oxygen atoms greater than 2.

"m" is a number greater than or equal to one.

Suitable oxides are well known and commercially available.

The proportions of oxides should reflect the desired proportions of suitable inorganic elements in the mesoporous crystalline material. If

"a" represents the molar proportion of WO among the oxides;

"b" represents the molar proportion of X₂0₃ among the oxides;

"c" represents the molar proportion of J0₂ among the oxides;

"d" represents the aggregate molar proportion of Z₂0₅ Z0₃, and A_mZO_n among the oxides; and

"e" represents the molar proportion of Si0₂ among the oxides, then each of "a", "b", "c", "d" and "e" is from 0 to 1 , and

(a + b + c + d + e) equals about 1. The oxide components may be expressed as:

(aQO + bX₂0₃ + cJ0₂ + d[Z₂0₅ + A_mZO_n + Z0₃] + eSi0₂) wherein all characters have the meaning previously given.

In one preferred embodiment, (a + b + c) is at least about 0.12, more preferably at least about 0.2, more highly preferably at least about 0.25, and most preferably at least about 0.5. The proportions of (a + b + c) may optionally be as high as 1. "e" may be as high as 1 or as low as 0. In one preferred embodiment, "e" is no more than about 0.88, more preferably no more than about 0.8, and most preferably no more than about 0.75. "e" is preferably at least about 0.25 and more preferably at least about 0.5. "d" is preferably 0 to 0.5.

As an alternative, one or more of the oxides may be replaced by an equivalent hydroxide, alkoxide or aryloxide species. Examples of suitable reagents include: Q(OR)₂, X(OR)₃ and J(OR)₄, wherein R is hydrogen, a lower (C,-C₆) alkyl group, or an aryl group, and is preferably a lower alkyl group. For example, tetraethyl-ortho-silicate and tetra-isopropyl- ortho-titanate can be substituted for silicon dioxide and titanium dioxide, respectively. (For the sake of convenience, we shall use the term "oxide" to refer to the oxides and to hydroxides, aryl oxides and aryl oxides that can replace them.) Optionally, the mixture may further contain the acid of a Group VA or Group VIA element, such as phosphoric acid or sulfuric acid. The Group VA or VIA element from the acid becomes incorporated as an element (Z) in the mesoporous material. The acid reacts with base in the reaction mixture to form an A_mZO_n component, although (depending upon Z) it may not form a complex with the polyol. Preferably, the polyol serves both as a reagent to make the complex and as a solvent for the mixture in Step (1 )(A). In this case, the reaction of oxide with polyol preferably occurs in a substantial molar excess of polyol over the oxide. The molar ratio of polyol to oxide is preferably at least about 6:1 , more preferably at least about 10:1 and most preferably at least about 20:1. The maximum ratio is not critical and is governed by practical considerations, such as waste of polyol and maximizing capacity of equipment. The best molar ratio of polyol to oxide is usually less that 100:1 and most often less than 50:1.

If the mixture in Step (1)(A) will contain a solvent other than the polyol, then the concentration of polyol in the reaction mixture should at least be high enough to form the complex. The optimum quantity varies depending upon the reagents selected. In most cases, the molar ratio of polyol to oxide is preferably at least 2:1 and more preferably at least 3:1.

The reaction of polyol and oxide takes place in the presence of a base. Examples of suitable bases include alkali metal hydroxides, ammonium hydroxide, and Lewis bases such as ammonia. The base is preferably an alkali metal hydroxide or ammonium hydroxide, which has a formula of:

M-OH wherein M is an alkali metal or ammonium cation. The concentration of base is preferably suitable to hydrolyze the oxide. The concentration of base in the mixture is preferably at least about 1 mole per mole of oxide and more preferably at least about 2 moles per mole of oxide. It is preferably no more than about 10 moles per mole of oxide, and more preferably no more than about 5 moles per mole of oxide. In Step (1)(B), the complex is mixed with a surfactant and optionally an organic solvent. This step may be carried out simultaneously or sequentially with Step (1 )(A). The solvent is preferably excess polyol. If the mixture contains a separate organic solvent, it should be sufficiently polar to dissolve the complex, the surfactant and the base, but not so polar that it competes with the polyol for complexing with the suitable inorganic elements. The concentration of solvent is preferably minimized. Most preferably, the mixture contains essentially no solvent other than the polyol.

The mixture in Step (1 )(B) preferably contains no substantial amount of water. For the purposes of this application, "no substantial amount of water" means insufficient water to hydrolyze the complex or break up the layered phase. The mixture preferably contains no more than about 5 mole percent water (based on the quantity of complex), more preferably no more than about 2 mole percent water. It most preferably contains about 0 weight percent water.

In Step (1 )(C), the mixture of Step (1 )(B) is converted to the layered composition by removing excess polyol and surfactant and solvent. We theorize, without intending to be bound by the theory, that the excess organic components (polyol, surfactant and/or solvent) dilute the mixture in Step (1 )(A) to the point that layered structure in Step (1)(C) does not form. Removal of the excess organic component causes the complex and surfactant to form a layered structure as illustrated in Figure A. The excess organic components are preferably removed by washing the mixture with water. The quantity of water is important for the correct practice of the invention. The quantity of water should be sufficient to remove the excess organic components, so that the layered structure forms. (Of course, it is not practical to remove 100 percent of the excess organic components. However, it is possible and practical to remove enough so that the layered structure forms.) On the other hand, the quantity of water should be low enough so that the complex does not substantially hydrolyze. Optimum quantities of water vary, depending upon the quantity and identity of the excess organic components in the mixture, but such optimum quantities can be determined without undue experimentation.

Other common methods to remove excess organic compounds, such as distillation under heat or vacuum or both, may also be useful.

The conditions for Step (1)(C) should be selected to prevent undue hydrolysis of the complex. The temperature is preferably at least about 0°C and more preferably at least about 10°C. It is preferably no more than about 100°C and more preferably no more than about 50°C. The pressure is not critical as long as the reagents remain liquid and capable of forming the desired structure. The pressure is preferably at least about 0.01 atm and preferably no more than about 100 atm.

In an alternative process to form the layered product, the concentration and proportions of reagents in Steps 1 (A) and 1 (B) may be selected such that the layered product forms with aging. In this alternative process, no Step 1 (C) is necessary. The necessary concentrations and proportions vary depending upon the selection of reagents, and can be determined without undue experimentation.

The product of Step (1 )(C) is a unique layered material having discrete layers of surfactant and oxide-containing complex. Figure A, below shows an example of a layered structure that is formed using titanium, ethylene glycol, and an ammonium-based surfactant. Of course, other oxides, polyols and surfactants may be substituted for each of those components, as described above.

Figure A

The layers which contain the complex preferably reflect the selection and proportions of oxide(s) and polyol(s) that were used to make the mixture in Step (1 )(A). Likewise, the surfactant layers reflect the surfactants used in Step (1 )(A). The molar ratio of surfactant to complex is preferably at least than 0.25:1 , more preferably at least about 0.5:1 and most preferably at least about 1 :1. It is preferably less than about 10:1 , more preferably no more than about 4:1 , and most preferably no more than about 3:1.

One preferred layered composition is a layered silica-surfactant composition comprising silicon dioxide, a polyol and a surfactant, characterized in that:

(1 ) the X-ray diffraction pattern of the composition exhibits essentially no reflections greater than 30 degrees Θ, and

(2) the ²⁹Si nuclear magnetic resonance spectrum of the composition exhibits substantial Q₂ or Q₃ peaks or both. The X-ray diffraction pattern preferably exhibits essentially no reflection greater than 15 degrees, and more preferably essentially no reflections greater than 12 degrees. The ²⁹Si nuclear magnetic resonance spectrum preferably exhibits a Q₂ peak. The area of the Q₂ peak is preferably at least 20 percent of the area of the Q₃ peak.

Step (2): Reagents. Process and Products In Step (2), the layered material is converted to a crystalline precursor for the mesoporous material by:

(a) hydrolyzing the complex in the layered composition; and

(b) dehydrating the hydrolysis product to form a cross-linked, crystalline oxide of the suitable inorganic elements. For some suitable inorganic elements, such as silicon, the dehydration reaction occurs spontaneously after the complex is hydrolyzed. For other suitable inorganic elements, such as titanium, the dehydration reaction must be carried out separately, under different reaction conditions after the hydrolysis is at least partially complete. The dehydration reaction does not need to be complete before moving on to Step (3), the calcination step, since additional dehydration and cross-linking usually occur in Step (3). However, the crystalline material must contain sufficient cross-linking to prevent collapse of the pores during calcination.

The hydrolysis reaction is preferably carried out by contacting the layered composition with excess water, in the presence of a catalytic amount of base. The quantity of water is preferably greater than 6 moles per mole of complex, more preferably at least about 10 moles per mole of complex, and most preferably at least about 20 moles per mole of complex. The quantity of water should be selected such that the complex froms a hexagonal phase prior to hydrolysis and dehydration. The maximum quantity of water is usually not more than about 100 moles of water per mole of complex.

The layered product usually contains sufficient residual base from Step (1)(A) to catalyze the reaction. If it does not, more base may be added. The temperature is preferably at least about 25°C and more preferably at least about

50°C. It is preferably no more than about 200°C, more preferably no more than about 175°C, and most preferably no more than about 150°C. The pressure is not critical.

The second reaction in Step (2) is the dehydration of hydrolyzed product to form a cross-linked, crystalline solid oxide of the suitable inorganic elements. Cross-linking is important to give the crystalline material structural strength prior to calcination. Otherwise, the pores may collapse during the calcination step. In compositions that contain relatively high concentrations of silicon (e = 0.5 or greater), this reaction usually occurs spontaneously under hydrolysis conditions.

When the composition contains less silicon, the reaction may require stronger dehydrating conditions. For instance, the hydrolysis product may be heated under reduced pressure. The temperature is preferably at least 75°C and more preferably at least 100°C. The pressure is preferably no more than atmospheric, more preferably no more than 0.5 atm, and most preferably no more than 0.1 atm. The time necessary to dehydrate the crystalline material varies depending upon the temperature and pressure used. In most cases, the material is preferably dried for at least 30 minutes and more preferably at least an hour. Temperatures in excess of 250°C and times in excess of 48 hours are seldom necessary.

Crystalline materials having particularly low silicon content may also be heated in the presence of a cross-linking agent, such as Si₂H₆, TiCI₄, Ti(OR)₄ or Nb(OR)₅, to improve cross-linking after free water is substantially removed from the material and before calcination begins. The preferred temperatures are similar to those used in the dehydration. The pressure of a gaseous cross-linking agent is preferably at least about 0.1 atm, more preferably at least about 0.5 atm, and most preferably at least about 1 atm. The maximum pressure is not critical and is governed by practical considerations. It is preferably no more than 100 atm. After cross-linking, the mesoporous material will contain elements from the cross-linker within its structure. The resulting material is a crystalline solid that contains oxides of the metal(s) and/or semiconducting elements(s). It has pores, but residual organic material, such as surfactant and polyol, fills those pores.

The product of Step (2) preferably meets Formula 3: rRM_f(Q_aX_bJ_cSi_eZ_dO_h) wherein:

Q, X, J, Si, Z, a, b, c, d, e, and h all have the meanings and preferred embodiments set out previously.

M is a counterion which balances charges within the mesoporous crystalline material. M is preferably an alkali metal cation or a halogen anion, and more preferably a sodium action or a chlorine anion. Examples of suitable M counterions are described in Kresge, et al., U.S. Patent 5,098,684 (March 24, 1992) at col. 6, lines 14-28, which are incorporated herein by reference.

T is a quantity of M that is sufficient to approximately balance the charges in the mesoporous material. T is preferably approximately equal to n/q wherein:

"n" is the charge of the composition, excluding M; and

"q" is the weighted molar average valence of M.

R is the residual organic component. It typically comprises residual polyol, surfactant and solvent. "r" is the molar fraction of R in the mesoporous crystalline material.

Step (3): Process and Product

Calcination destroys the organic content of the mesoporous material by heating to high temperature in the presence of an oxidizing gas. In some materials, calcination may also cause further dehydration and cross-linking. The temperature of calcination is preferably at least about 400°C. The maximum temperature depends in a known way on the composition of the material. Silica may be calcined at temperatures up to about 1000°C, whereas titania is preferably calcined at a temperature as low as possible. The atmosphere should be an oxidizing atmosphere, such as air or oxygen. It is conveniently air. The pressure is not critical; it may be atmospheric, subatmospheric or superatmospheric. It is conveniently atmospheric. The time is preferably at least one minute and more preferably at least about one hour. The time is preferably no more than 20 hours and more preferably no more than 10 hours.

The calcined mesoporous crystalline material preferably meets Formula II. In Formula II, M, Q, X, Z, J, a, b, c, d and e all have the limits and preferred embodiments that were described previously.

The mesoporous crystalline material is porous. As described in Kresge, et al., U.S. Patent 5,098,684 (March 24, 1992) at column 6, lines 41 to 45, a material is considered porous if it adsorbs at least one gram of nitrogen per 100 grams of solid. The material preferably adsorbs at least 10 grams of nitrogen per 100 grams of material at 760 torr and 25°C. It more preferably adsorbs at least 25 grams and most preferably adsorbs at least 50 grams.

The average internal diameter of the pores is preferably at least about 13 A, more preferably at least about 20 A, and most preferably at least about 30 A. It is preferably no more than 500 A, more preferably no more than 200 A, and most preferably nor more than about 100 A. The standard deviation of the pore size within a single sample is preferably no more than +/- 25%, more preferably no more than +/- 15%, and most preferably no more than +/- 10%.

The mesoporous crystalline material is useful as an adsorbent or as a catalyst, for example as described in Kresge, et al., U.S. Patent 5,098,684 (March 24, 1992) at col. 13, line 58 to column 16, line 56, which is incorporated herein by reference.

Examples

The following examples are for illustrative purposes only. They should not be taken as limiting the scope of either the specification or the claims.

Example 1. Mesoporous Silicate Material. Two grams of sodium hydroxide is dissolved in 50 mL. of ethylene glycol. The mixture is heated to 40°C, and 10 grams of cetyltrimethylammonium bromide is added. A 1.5 gram quantity of Cab-O-Sil EH-5 silica is stirred into the mixture. The mixture is maintained at 80°C for 5 days. The resulting product is a silica glycolate complex.

The silica glycolate product is converted to a layered silica surfactant product by washing with 800 mL. of water at room temperature.

A 2 gram quantity of the layered product is converted to a mesoporous material by heating with 2 grams of water at 70°C for 8 hours. The material is calcined by heating at a temperature of 550°C for 12 hours to yield a mesoporous material.

Example 2. Alternative Third Step.

A 0.5 gram quantity of layered material from Example 1 is heated to 100°C under vacuum. After 2 hours at 100°C, 200 torr of disilane is added. The sample is maintained at 100°C under disilane atmosphere for 10 hours. The material is calcined as in Example 1 to yield a mesoporous silica.

Example 3. Synthesis of Titanate Mesoporous Product.

A quantity of disodium titanium triglycolate (Na₂Ti(gly)₃) is synthesized according to the procedure described in G.J. Gainsford, et al., 34 Inorganic Chemistry746 (1995). A mixture containing 25 mL. ethylene glycol, 1.1 grams sodium hydroxide, and 2.0 grams cetyltrimethylammonium bromide is heated to 80°C. A 6.5 gram quantity of the sodium titanium glycolate is stirred into the mixture, and the mixture is aged for 5 days at 80°C, to form a layered phase. After 5 days the mixture is cooled to room temperature. Two hundred mL. of deionized water is added with stirring, and the mixture is aged at room temperature for 3 hours under quiescent conditions. The mixture is filtered and the precipitate is washed with water, then dried under ambient conditions.

A 1.0627 gram quantity of the precipitate is dehydrated under a vacuum for 15 hours at 100°C. After dehydration, the sample weighs 823.2 mg. The dried sample is heated with 95.9 mg. of disilane at 100°C for 24 hours. 883.4 grams of product are recovered. EDX analysis shows that the recovered product contains 66.4% titanium, 26.4% silicon, 7% sodium, and 0.2% other elements.

The product is calcined by heating from 25°C to 500°C for 10 hours. At the end of calcination, the net weight of the product is about 0.4 grams. EDX analysis of the product shows that it contains 72.4% titanium, 23% silicon, 4.3% sodium, and 0.3% other elements.

Example 4. Mesoporous Material Contain a Mixture of Silicon and Titanium.

Disodium titanium triglycolate is made according to the process in Example 3. Disodium disilicon pentaglycolate is made according to the process described in Herreros, et al., 98 J. Phys. Chem. 4570 (1994). A mixture containing 25 mL. of ethylene glycol, 1.1 grams of sodium hydroxide and

2.0 grams of cetyltrimethylammonium bromide is heated to 80°C. A 3.8 gram quantity of disodium disilicon pentaglycolate and a 2.5 gram quantity of disodium titanium triglycolate are added sequentially to the mixture. The resulting gel is aged for 5 days at 80°C and then cooled to room temperature. A 200 mL. quantity of deionized water is added to the cooled gel, and the mixture is aged at room temperature for 3 hours. The resulting precipitate is filtered and washed with water, then dried under ambient conditions. It is heated to 500°C and calcined for 10 hours.

Example 5. Synthesis of Niobate Mesoporous Product

A mixture containing 6.0 g of niobium pentethoxide and 1.2 g of sodium hydroxide dissolved in 50 mL of ethylene glycol is refluxed under nitrogen for 5 hours at 195°C. Excess ethylene glycol is distilled, and the product is cooled to yield white crystals of niobium glycolate complex. The crystals are washed with acetonitrile.

A mixture containing 20 mL of ethylene glycol, 0.3 g of sodium hydroxide and 2.3 g of cetyltrimethylammonium bromide is heated to 80°C. A 3.6 g quantity of the niobium glycolate complex is stirred into the mixture, and the mixture is aged for 5 days at 80°C. The mixture is cooled to room temperature, 200 mL of deionized water is added, and the mixture is aged at room temperature for 5 hours. The mixture is filtered, and the precipitate is washed with water and then dried.

A 684.6 mg quantity of the product is dehydrated under vacuum for 4 hours at 80°C, after which it weighs 460.0 mg. It is heated with 85.4 mg disilane at 125°C for 40 hours, and 507.5 mg product are recovered. The product is heated to 500°C for 10 hours to calcine, and weighs 250 mg after calcination is complete. An EDX analysis of the product shows that it contains 58.1 parts niobium per 41.9 parts silicon.

Example 6. Synthesis of Zirconate Mesoporous Product

A mixture containing 5.0 g of zirconium tetraethoxide and 1.5 g of sodium hydroxide dissolved in 31 mL of ethylene glycol is refluxed under nitrogen for 5 hours at 195°C. Excess ethylene glycol is distilled, and the product is cooled to yield yellow oil. The oil is dissolved in 25 mL of methanol, and mixed with 10 mL of acetonitrile. The mixture is cooled at -10°C for 48 hours to yield the zirconium glycolate complex.

A mixture containing 25 mL of ethylene glycol, 1.3 g of sodium hydroxide and 3 g of cetyltrimethylammonium bromide is heated to 80°C. A 3.3 g quantity of the zirconium glycolate complex is stirred into the mixture, and the mixture is aged for 5 days at 80°C. The mixture is cooled to room temperature, 200 mL of deionized water is added, and the mixture is aged at room temperature for 5 hours. The mixture is filtered, and the precipitate is washed with water and then dried.

A 647.8 mg quantity of the product is dehydrated under vacuum for 4 hours at 80°C, after which it weighs 327.0 mg. It is heated with 236.7 mg disilane at 125°C for 40 hours, and 337.3 mg product are recovered. The product is heated to 500°C for 10 hours to calcine, and weighs 150 mg after calcination is complete. An EDX analysis of the product shows that it contains 57 parts zirconium per 43 parts silicon.

Claims

WHAT IS CLAIMED IS:

1. A process to make a mesoporous crystalline material, comprising the steps of:

(1) forming a mixture having: (a) at least one surfactant, and

(b) at least one complex of at least one polyol and at least one suitable inorganic element selected from any one or more elements from the transition metals or Groups IIA to IVA plus antimony and bismuth, but excluding carbon ;

(2) simultaneously or sequentially: (a) hydrolyzing the complex in the layered composition; and

(b) dehydrating the hydrolysis product to form a cross-linked oxide of the suitable inorganic element(s); and

(3) calcining the product of Step (2) under conditions sufficient to produce an inorganic mesoporous crystalline material, characterized in that the mixture in step (1) forms a layered composition having discrete layers of surfactant and complex.

2. A process as described in Claim 1 wherein the reaction mixture in step (2) forms a hexagonal phase mixture.

3. A process as described in any of Claims 1 or 2 wherein the Step (1) is carried out by:

(A) reacting the polyol with one or more oxides, hydroxides, alkoxides or aryloxides of the suitable inorganic element(s) in the presence of a base optionally a solvent in an essentially non-aqueous solution, whereby the complex is formed;

(B) Simultaneously or sequentially with (A), mixing the surfactant into the mixture; and5 (C) Removing excess organic components (such as polyol, surfactant and solvent), whereby a layered structure is formed.

4. A process as described in Claim 3 wherein the mixture of Step (1 )(A) contains no more than 2 weight percent water.

5. A process as described in any of Claims 3 or 4 wherein Step (1 )(B) is carried o out at a temperature of about 15⁹C to about 50⁹C.

6 A process as described in any of Claims 1-5 wherein the hydrolysis reaction of Step (2) is carried out in the presence of a catalytic amount of base.

7. A mesoporous crystalline material having a composition expressed as in Formula 2:

M₍(Q_aX_bJ_cSi_eZ_dO_h) wherein Q, X, J, Si and Z are suitable organic elements to make a mesoporous crystalline material selected such that:

"Q" is one or more divalent elements;

"X" is one or more trivalent elements; "J" is one or more tetravalent elements, other than carbon or silicon;

"Si" is silicon;

"Z" is one or more pentavalent elements;

"Q", "X", "J", "Si" and "Z" form covalent bonds with oxygen when in oxide form and have an average valence greater than 2; and

"M" is a charge-balancing counter-ion;

T is a mole fraction of M which is sufficient to balance charges in the material;

"a", "b", "c", "d" and "e" are mole fractions of Q, X, J, Z and Si, respectively;

"h" is a number from 1 to 2.5; and (a + b + c + d + e) = 1 characterized in that (a + b + c) is at least 0.12.

8. A process as described in any of the foregoing claims wherein the suitable inorganic element(s) contain no more than about 75 mole percent silicon.

9. A layered composition that contains discrete layers of: (a) at least one surfactant and

(b) at least one complex of suitable inorganic elements with a polyol wherein at no more than 50% weight percent of the suitable inorganic elements are silicon.

10. A process as described in any of the foregoing claims wherein the suitable inorganic element(s) are any one or more of: titanium, aluminum, boron, iron, gallium, germanium, vanadium, manganese, chromium, copper, molybdenum, tungsten, niobium or zirconium.