Patent Grant
6843978
The present invention is encompassed in the field of catalytic materials and, more specifically, in the field of zeolitic catalytic materials.
In the epoxidation of olefins methods are known in which organic hydroperoxides are utilised and which are carried out employing catalysts based on titanium anchored on siliceous supports (U.S. Pat. No. 3,923,843, 1975). An adequate selection of the reagent on titanium and also of the anchoring conditions permit catalysts to be obtained in which the titanium centres are separated and immobilised, reducing or rather cancelling the possibilities of deactivation of the catalyst through dimerisation of the titanium species. However, these catalysts can, during the catalytic process, suffer a loss of titanium content by extraction during the reaction which leads to the activity of the catalyst diminishing with time.
To overcome this drawback, it has been proposed that the titanium species be anchored on mesoporous silicas (T. Maschmeyer et. Al., Nature, 378, 159 (1995)). In this case, determined amounts of titanium of the order of 8% by weight can be anchored presenting good results as catalysts in epoxidation of olefins using organic peroxides as oxidising agents. Unfortunately the amorphous nature of these mesoporous silicas and the high concentration and proximity of silinol groups result in these materials being of low stability and to achieve adequate dispersions of the active titanium species on the surface of the mesoporous material proves to be problematic.
U.S. Pat. No. 4,975,258 discloses a crystalline material designated SUZ-2 having an empirical formula:
m(M2/aO):Xxz/2:yYO2
U.S. Pat. No. 6,469,226 discloses a delaminated microporous solid, called ITQ-6, which has a similar chemical structure with the material of the present invention, but it has a different chemical composition.
Finally, CN-1113454 discloses a crystalline molecular sieve having a framework isomorphous with zeolite beta and containing Si and Ti, but essentially no framework Al, useful in the epoxidation of olefins with hydrogen peroxide as oxidant.
The methods and materials of the state of the art therefore suffer from a series of drawbacks that it would be convenient to overcome.
The object of the present invention is to overcome the drawbacks in the state of the art, by means of a catalyst and by means of a procedure for the preparation thereof, making use of a material with an external high surface area and which shows in its structure active species, as for example, titanium and/or zirconium in tetrahedral positions which have been incorporated directly during the synthesis without carrying out any post-synthesis anchoring treatment, the activity and selectivity obtained in oxidation reactions being very high.
Likewise, the present invention has a further object a modification of the surface area which gives rise to the formation of organic species bound to the surface which notably improve the activity and selectivity of these materials when they are used as catalysts.
The objects of the invention are achieved, on one hand, by means of a delaminated ferrierite zeolitic TIQ-6 material with a chemical composition corresponding to the formula, expressed as oxides, SiO2:zZO2:mMO2:xX2O3:aH2O where
Moreover, the objects of the present invention also by means of a microporous METIQ-6 material with a chemical composition represented by the formula
SiO2:yYRpO2-P/2:zZO2:mMO2:xX2O3:aH2O
wherein R is selected between hydrogen, alkyl groups with 1 to 22 carbon atoms, aryl groups with 6 to 36 carbon atoms, polyaromatic groups with 6 to 36 carbon atoms, said groups being selected from among non-functionalised groups and functionalised groups with functional groups selected between acid, amino, thiol, sulphonic and tetra-alkyl ammonium groups,
Preferably both the zeolitic TIQ-6 material and the microporous METIQ-6 material, can have a specific external surface area greater than 500 m2g−1, a pore volume greater than 0.5 cm3g−1, and a charge transfer band in the visible-ultraviolet spectrum in the range between 200 and 230 nm.
According to the invention, the TIQ-6 material may or may not be subsequently modified by means of a treatment with reagents selected among organogermanes, organosilanes, organometals and combinations thereof, in order to produce organic species anchored on the surface of the materials described, giving rise to the METIQ-6 material.
The TIQ-6 material can be obtained from laminar precursors of zeolites synthesised with titanium and/or zirconium which is incorporated directly into its structure. More specifically, a delaminated TIQ-6 material ia obtained, similar to the material ITQ-6, both proceeding from the laminar precursor of Ferrierite (FER), the preparation of which is indicated in the Spanish Patent P9801689 (1998) and in the patent application PCT/GB99/02567 (1999). The catalytic material obtained has Si—O—M bonds (M═Ti or Zr), the active species of titanium or zirconium being distributed in a homogeneous manner in order that they be functional in selective oxidation processes of organic compounds with organic or inorganic peroxides, and in general in processes which involve the use of Lewis acid centres.
Thus, in accordance with the invention, the TIQ-6 material can be prepared by means of a procedure which comprises
In this process, the laminar precursor can be prepared by means of
In the procedure described above, preferably use is made of a source of silica as pure as possible. Adequate silica sources are commercially available, for example under the trade names of AEROSIL (DEGUSSA AG), CAB-O-SIL (SCINTRAN BDH), LUDOX (DU PONT PRODUCTS); use can also be made of tetraethylorthosilicate (TEOS) and also combinations of various different sources of silica.
The titanium source can be selected among TiCl4, tetraethylorthotitanate (TEOTi) and combinations thereof, and the zirconium is selected from between ZrCl4, zirconyl chloride and combinations thereof.
As fluoride salt and acid, it is possible to use ammonium fluoride, hydrogen fluoride or combinations thereof.
The structure director organic compound is selected preferably between 1,4-diaminobutane, ethylendiamine, 1,4-dimethylpiperazine, 1,4-diaminocyclohexane, hexamethylen imine, pirrolidine, piridine and preferably 4-amino-2,2,6,6-tetramethylpiperidine and combinations thereof.
In accordance with the invention, the zeolitic METIQ-6 material can be obtained by means of a reaction with reagents selected among organogermanes, organosilanes, and organometals selected among organotitanium or organotin in order to produce organic species anchored on the surface of the materials described, at a reaction temperature between 0 and 400° C., preferably in gas phase between 50 and 200° C., of the TIQ-6 material, for so to produce organic species anchored on the surface of the materials described. Thus, for said reaction to produce organic species anchored on the surface an agent can be employed selected among R1R2R3(R′)Y, R1R2(R′)2Y, R1(R′)3Y, R1R2R3Y—NH—YR1R2R3, and combinations thereof, wherein
According to the invention, the reaction to produce organic species anchored on the surface can be carried out in the absence of solvents, but also by dissolving the TIQ-6 material in a solvent selected between organic solvents and inorganic solvents. Likewise the silanisation can be carried out in the absence of catalysts or in the presence of at least one catalyst which favours a reaction of an alkylsilane, alkylgermane or organometallic compound in general with Si— groups.
In accordance with the invention, the zeolitic material TIQ-6 may be prepared as follows: in a first step the synthesis of the laminar precursor is carried out by mixing in an autoclave a source of silica like for example AEROSIL, CAB-O-SIL, LUDOX, tetraethylorthosilicate (TEOS), or any other known; a source of titanium and/or zirconium like for example TiCl4, tetraethylorthotitanate (TEOTi), ZrCl4, zirconyl chloride or any other known; some fluoride compounds like for example ammonium fluoride and hydrogen fluoride; an organic compound like 1,4-diaminobutane, ethylendiamine, 1,4-dimethylpiperazine, 1,4-diaminocyclohexane, hexamethylenimine, pirrolidine, piridine and preferably 4-amino-2,2,6,6-tetramethylpiperidine and water in adequate proportions. The synthesis takes place at temperatures between 100 and 200° C., with constant stirring of the gel and lasting 1 to 30 days, preferably between 2 and 15 days. At the end of this time, the reaction product, a white solid, is washed with distilled water, filtered and dried.
The sheets of the obtained precursor, which contain titanium and/or zirconium in their framework, are separated by intercalating voluminous organic species such as alkyl ammoniums, amines, esters, alcohols, dimethylformamide, sulphoxides, urea, chlorohydrates of amines, alone or mixtures thereof in solution. The solvent is generally water, but other organic solvents can also be used such as alcohols, esters, alkanes, alone or mixtures thereof in absence or in presence of water.
More specifically, when cetyltrimethylammonium bromide (CTMA+Br−) is employed for example, as swelling agent, the intercalation conditions are as follows: the laminar precursor is dispersed in an aqueous solution of CTMA+Br− and a tetra-alkyl ammonium hydroxide or an alkaline or alkaline-earth hydroxide, being preferred tetra-alkyl ammonium hydroxides like tetrapropylammonium hydroxide (TPA+OH−), the pH of the mixture being greater than 11. The resulting dispersion is heated to temperatures between 5 and 200° C. during periods between 0.5 and 90 hours whilst the suspension is vigorously stirred. The suspension resulting is dispersed in an excess of water, being stirred with a metal paddle of the Cowles type or any other known at speeds lying between 20 and 2000 rpm during periods not less than 1 hour. These conditions are sufficient to carry out the delamination of the precursor material. However, it is possible to employ other delamination methods such as for example treating the sample with ultrasounds, liophilisation and spray-drying.
Once the delamination has been carried out, the solids are separated and thoroughly washed in order to eliminate the excess CTMA+Br−. The obtained product is dried and is calcinated at a temperature sufficient to eliminate the organic matter occluded in the material, or at least the organic matter present on the material surface.
The materials obtained are characterised in that they have a high external surface area greater than 500 m2g−1 and a pore volume greater than 0.5 cm3g−1. They are likewise characterised in that they have a highly hydroxylated surface as may be deduced from the presence of a very intense band in the IR spectrum centered at about 3745 cm−1. Moreover the ultraviolet-visible spectrum of the TIQ-6 materials which contain Ti or Zr are characterised by the presence of an MIV-O charge transfer band between 200 and 220 nm.
This product containing Ti and/or Zr is active and selective in oxo-transference reactions and more specifically for epoxidation of olefins, oxidation of alkanes and alcohols, hydroxylation of aromatics, ammoximation of ketones, oxidation of organic sulphides and sulphoxides with organic or inorganic peroxides. Thus for example, the material termed TIQ-6 prepared from a laminar precursor of ferrieritic type, containing between 0.125 and 3% by weight of TiO2 is capable of epoxidating the 1-hexane at 50° C. with conversions of 20% and selectivities to the epoxide of 96% after seven hours of reaction using hydrogen hydroperoxide (H2O2) as oxidant, acetonitryl and/or methanol as solvent and 2% by weight of TIQ-6 as catalyst.
On the other hand, to obtain the microporous METIQ-6 material from the zeolitic TIQ-6 material, the TIQ-6 material can be treated with reagents selected among organogermanes, organosilanes, and organometals selected among organotitanium or organotin. By means of this process to produce organic species anchored on the surface it is possible to add one or more groups which incorporate carbon-tetravalent element bonds in the zeolitic material. This reaction for incorporating these groups is carried out using compounds with formula R1R2R3(R′)Y, R1R2(R′)2Y, R1(R′)3Y or R1R2R3Y—NH—YR1R2R3 in which R1, R2 and R3 are organic groups identical to or different from each other, and can be H or the alkyl or aryl groups mentioned earlier and Y is a metal among which Si, Ge, Sn or Ti are preferred. The procedures to produce organic species anchored on the surface are well known in the state of the art, in this manner the greater part of the Si-OH and M-OH groups present in the TIQ-6 material are functionalised.
The TIQ-6 and METIQ-6 materials can be employed as catalysts in
Thus for example, a METIQ-6 material containing between 0.125 and 3% by weight of TiO2 is capable of epoxidating the 1-hexene at 50° C. with conversions of 18% and selectivities to the epoxide of 99% after seven hours of reaction using hydrogen hydroperoxide (H2O2) as oxidant, acetonitryl and/or methanol as solvent and 2% by weight of METIQ-6 as catalyst.
The following examples illustrate characteristics applicable to the preparation of the TIQ-6 and METIQ-6 materials and of their applications as catalysts in oxidation processes.
Preparation of the Laminar Precursor of the TIQ-6 Material
10 g of silica (AEROSIL 200, Degussa) are added to an aqueous solution containing 9.2 g of ammonium fluoride (NH4F, Aldrich 98% purity), 3.4 g of hydrofluoric acid (HF, 48.1% purity) 26 g. of 4-amino-2,2,6,6-tetramethylpiperidine (FLUKA, 98% purity), 0.8 g of titanium tetraethoxide (Alfa, 98% purity) and 20.2 g of deionised water (MilliQ Quality of Millipore). The synthesis gel pH is 9. This reactive mixture is vigorously stirred for two hours at room temperature before placing it into an autoclave at 135° C. for 10 days. The resulting solid is filtered, thoroughly washed with water to a pH close to 7 and dried at 60° C. for 12 hours. The obtained laminar precursor shows a Si/Ti ratio of 50 measured by chemical analysis.
1 g of the laminar precursor described in example 1 is dispersed in a solution containing 4 g of MilliQ water, 20 g of cetyltrimethyl ammonium hydroxide and 6 g of tetrapropyl ammonium hydroxide, and the final pH is 12.5. These hydroxides were prepared by ion exchange of their respective bromide salts using DOWEX SBR resin. The bromide exchange level in both cases was approximately 70%.
The resulting dispersion was heated to 80° C. for 16 hours with constant, vigorous stirring to favour the separation of the sheets making up the precursor material. Once this time has elapsed, the resulting suspension is filtered to remove the excess of CTMA+Br− and the solid is dispersed in an excess of water and subjected to an ultrasounds treatment for one hour. HCl is then added (6M) to pH=3 to favour the solid's flocculation. The latter is recovered by centrifuging and thoroughly washed with distilled water. The final solid is dried at 60° C. for 12 hours and roasted at 580° C. in a nitrogen atmosphere for 3 hours, the heat treatment being extended for 7 more hours in air, and all organic material hidden in the solid's pores is completely eliminated. The product gives a Si/Ti ratio of 100 measured by chemical analysis.
This material (TIQ-6) shows a specific area of approximately 650 m2g−1 and a pore volume of 0.7 cm3g−1.
Silanization of the TIQ-6 material, giving rise to the material called METIQ-6, is carried out by making organosilane compounds to react on the surface of a material like that described in example 2. This process is usually performed in the following manner: 3 g of the TIQ-6 material described in example 2 are dehydrated at 300° C. and vacuum of 10−3 torr for 2 hours. A solution is added to this solid, containing 1.9 g of trimethylchlorosilane in 27 g of chloroform. The resulting suspension is vigorously shaken for 1 hour under an argon atmosphere, and then 1.28 g of triethylamine dissolved in 3 g of chloroform are added. This suspension is stirred for 1 hour at room temperature and is filtered, washed with dichloromethane and dried at 60° C. for 12 hours.
This material shows no significant nor structural nor textural differences with the TIQ-6 material described in example 2. The visible ultraviolet spectrum of this material shows a narrow band of 220 nm assigned to the formation of monomeric titanium species. The presence of Si—CH3 groups is evidenced by the presence of a band in the IR spectrum at 1410 cm−1 and a resonance line in the spectrum of 29Si-MAS-RMN at 15 ppm.
The catalytic activity of the material prepared in example 2 for 1-hexene epoxidation is described in this example.
300 mg of the material described in example 2 are placed into a glass reactor at 50° C. which contains 1420 mg of 1-hexene, 450 mg of H2O2 (at 35% P/P) and 11800 mg of acetonitryl or methanol as a solvent. The reaction mixture is stirred and a reaction sample is taken after 7 hours. Under these conditions, the conversion of 1-hexene achieved with respect to the maximum possible is 20% with a 96% epoxide selectivity.
The catalytic activity of the material prepared in example 2 for 2-norbornene epoxidation is described in this example.
300 mg of the material described in example 2 are placed into a glass reactor at 60° C. which contains 1550 mg of 2-norbornene, 500 mg of H2O2 (at 35% P/P) and 11800 mg of acetonitryl or methanol as a solvent. The reaction mixture is stirred and a reaction sample is taken after 7 hours. The conversion of 2-norbornene with respect to the maximum possible is 90% with a 94% epoxide selectivity.
The catalytic activity of the material prepared in example 2 for terpinolene epoxidation is described in this example.
300 mg of the material described in example 2 are placed into a glass reactor at 60° C. which contains 2200 mg of terpinolene, 500 mg of H2O2 (at 35% P/P) and 11800 mg of acetonitryl or methanol as a solvent. The reaction mixture is stirred and a reaction sample is taken after 7 hours. The conversion of terpinolene compared to the maximum possible is 46% with a 70% epoxide selectivity.
The catalytic activity of the material prepared in example 2 for cyclohexene epoxidation is described in this example.
300 mg of the material described in example 2 are placed into a glass reactor at 60° C. which contains 4500 mg of cyclohexene and 1538 mg of tertbutylhydroperoxide. The reaction mixture is stirred and a reaction sample is taken after 5 hours. The conversion of cyclohexene with respect to the maximum possible is 81% with a 94% epoxide selectivity.
The catalytic activity of the material prepared in example 3 for 1-hexene epoxidation is described in this example.
300 mg of the material described in example 3 are placed into a glass reactor at 50° C. which contains 1420 mg of 1-hexene, 450 mg of H2O2 (at 35% P/P) and 11800 mg of acetonitrile or methanol as a solvent. The reaction mixture is stirred and a reaction sample is taken after 7 hours. The conversion of 1-hexene with respect to the maximum possible is 18% with a 99% epoxide selectivity.
The catalytic activity of the material prepared in example 3 for cyclohexene epoxidation is described in this example.
300 mg of the material described in example 2 are placed into a glass reactor at 60° C. which contains 4500 mg of cyclohexene and 1538 mg of tertbutylhydroperoxide. The reaction mixture is stirred and a reaction sample is taken after 5 hours. The conversion of cyclohexene with respect to the maximum possible is 88% with a 98% epoxide selectivity.
The catalytic activity of the material prepared in example 3 for terpinolene epoxidation is described in this example.
150 mg of the material described in example 3 are placed into a glass reactor at 60° C. which contains 1135 mg of cyclohexene and 1380 mg of tertbutylhydroperoxide. The reaction mixture is stirred and a reaction sample is taken after 7 hours. The conversion of terpinolene with respect to the maximum possible is 56% with a 78% epoxide selectivity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 9902655 | Nov 1999 | ES | national |
This is a continuation of Application No. PCT/ES00/00456, filed Nov. 24, 2000.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3923843 | Wulff | Dec 1975 | A |
| 3966883 | Vaughan et al. | Jun 1976 | A |
| 4016245 | Plank et al. | Apr 1977 | A |
| 4578259 | Morimoto et al. | Mar 1986 | A |
| 4975258 | Barri | Dec 1990 | A |
| 5374747 | Saxton et al. | Dec 1994 | A |
| 6469226 | Chica Lara et al. | Oct 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| WO 9717290 | May 1997 | WO |
| WO 0034181 | Jun 2000 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20020193239 A1 | Dec 2002 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCTES00/00456 | Nov 2000 | US |
| Child | 10155564 | US |
