HYBRID MATERIAL AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The invention relates to a material in the form of a cellular solid monolith consisting of an inorganic oxide polymer. Said monolith comprises macropores which have an average size d.sub.A of 4 μm to 50 μm, mesopores that have an average size d.sub.E of 20 to 30 Å, and micropores which have an average size d.sub.1 of 5 à 10 Å, said pores being interconnected. The inorganic oxide polymer has organic groups R of formula —(CH.sub.2).sub.n—R.sup.1, wherein 0≤n≤5, and R.sup.1 is selected from among a thiol group, a pyrrole group, an amino group having one or more optional, optionally substituted alkyl, alkylamino, or aryl substituents, an alkyl group, or a phenyl group optionally having an alkyl-type substituent R.sup.2. The disclosed material can be used as a substrate for a metal catalyst and for decontaminating liquid or gaseous media.

Claims

1. A material in the form of a solid cellular monolith comprising a polymer of an inorganic oxide, wherein: said cellular monolith has macropores having a mean size d.sub.A from 4 μm to 50 μm, mesopores having a mean size d.sub.E from 20 to 30 Å and micropores having a mean size d.sub.I from 5 to 10 Å, said pores being interconnected; the inorganic oxide polymer carries organic R groups corresponding to the formula —(CH.sub.2).sub.n—R.sup.1 in which 0≤n≤5, and R.sup.1 represents a thiol group, a pyrrolyl group, an alkyl group, an amino group that may carry one or more possibly substituted alkyl, alkylamino or aryl substituents, or a phenyl group that may carry an alkyl substituent.

2. The material as claimed in claim 1, wherein the inorganic oxide is an oxide of one or more elements, at least one of these elements being of the type capable of forming an alkoxide.

3. The material as claimed in claim 2, wherein at least one of the metals is chosen from Si, Ti, Zr, Th, Nb, Ta, V, W and Al.

4. The material as claimed in claim 2, wherein the oxide is a mixed oxide additionally containing B and Sn.

5. The material as claimed in claim 1, wherein the inorganic polymer is a polymer of silicon oxide or a mixed oxide of silicon.

6. The material as claimed in claim 1, wherein R.sup.1 is an alkyl group having 1 to 5 carbon atoms.

7. The material as claimed in claim 1, wherein the inorganic oxide polymer carries a single type of R group.

8. The material as claimed in claim 1, wherein the inorganic oxide polymer carries at least two different types of R group.

9. The material as claimed in claim 1, wherein the organic group R is a 3-mercaptopropyl group, a 3-aminopropyl group, a 3-pyrrolylpropyl group, an N-(2-aminoethyl)-3-aminopropyl group, a 3-(2,4 dinitrophenylamino)propyl group, a phenyl group, a benzyl group or a methyl group.

10. A method for preparing a material as claimed in claim 1, wherein an emulsion is prepared by adding an oily phase to an aqueous solution of surfactant, at least one tetra-alkoxide (TAM) precursor of the inorganic oxide polymer is added to the aqueous surfactant solution, before or after preparing the emulsion, the reaction mixture is allowed to stand until the precursor condenses, and then the mixture is dried so as to obtain a monolith, wherein within said method at least one precursor alkoxide carrying an organic R group (compound AMR) is added.

11. The method as claimed in claim 10, wherein the alkoxide AMR is introduced into the aqueous surfactant solution before the oily phase is added.

12. The method as claimed in claim 10, wherein the alkoxide AMR is introduced into the oil phase that is then added to the aqueous TAM solution to form the emulsion.

13. The method as claimed in claim 10, wherein the inorganic monolith obtained from the aqueous surfactant solution and TAM after drying is impregnated with a solution of AMR.

14. The method as claimed in claim 11, wherein the hybrid monolith obtained at the end of the drying step is subjected to a heat treatment.

15. The method as claimed in claim 10, wherein the mass ratio (alkoxide AMR/tetra-alkoxide TAM) is less than 20/80.

16. The method as claimed in claim 10, wherein the tetra-alkoxide TAM is a silicon tetraethoxysilane.

17. The method as claimed in claim 16, wherein the tetra-alkoxide TAM is tetramethoxysilane or tetraethoxysilane.

18. The method as claimed in claim 10, the alkoxide AMR is a trialkoxysilane chosen from: 3-mercaptopropyl)trimethoxysilane, 3-aminopropyl)triethoxysilane, N-(3-trimethoxysilylpropyl)pyrrole, 3-(2,4 dinitrophenylamino)propyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, phenyltriethoxysilane; and methyltriethoxysilane.

19. The method as claimed in claim 10, wherein the oily phase is chosen from dodecane or a silicone oil.

20. The method as claimed in claim 10, wherein the surfactant compound is a cationic surfactant and the reaction medium is brought to a pH below 3.

21. The method as claimed in claim 10, wherein the surfactant compound is an anionic surfactant and the reaction medium is brought to a pH above 10.

22. The method as claimed in claim 10, wherein the surfactant compound is a non-ionic surfactant and the reaction medium is brought to a pH above 10 or below 3.

23. A use for a material as claimed in claim 1 for the elimination of benzene, toluene or xylene contained in a liquid or gaseous medium.

24. A catalytic system comprising a support and a metal catalyst, wherein the support is a material as claimed in claim 1.

25. The catalytic system as claimed in claim 24, wherein the metal catalyst is in the form of nanoparticles.

26. A use for a catalytic system as claimed in claim 24, for the catalysis of a carbon-carbon coupling reaction to form a biphenyl compound according to the Mitzoroki-Heck reaction or according to the Suzuki-Myaura reaction.

Description

DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1a is a photograph by transmission electron microscopy (TEM) of the general appearance of an SiO.sub.2 monolith containing 3-pyrrolylpropyl groups denoted by pyrrole-SiO-1a.

[0070] FIGS. 1b to 1g represent photographic plates obtained by TEM, for pyrrole-SiO-1a, methyl-SiO-1a, Benzyl-SiO-2a and Mercapto-SiO-1a monoliths containing respectively 3-pyrrolylpropyl groups (plate 1b) methyl groups (plate 1c), 3-(2,4-dinitrophenylamino) propyl groups (plate 1d), benzyl groups (plate 1e), and 3-mercaptopropyl groups (plates 1f and 1g).

[0071] FIGS. 2a to 2e represent differential intrusion (in ordinates, expressed in ml/g/nm) as a function of the diameter of the intermacropore windows (in abscissas, expressed in nm), respectively for pyrrole-SiO-1a, methyl-SiO-1a, DNP-amino-SiO-1a, Benzyl-SiO-2a, Mercapto-SiO-1a, and g-amino-SiO monoliths.

[0072] FIGS. 3a and 3e are transmission electron microscope (TEM) photographic plates and FIGS. 3f to 3e are SAXS diffusion profiles respectively for pyrrole-SiO-1a, methyl-SiO-1a, DNP-amino-SiO-1a, Benzyl-SiO-2a and Mercapto-SiO-1a monoliths.

[0073] FIGS. 3ka to 3kb are SAXS diffusion profiles produced on the g-amino-SiO and g-mercapto-SiO monoliths.

[0074] FIGS. 4a to 4e represent the pore size distribution determined by the DFT (Differential Functional Theory) method. The results are presented in FIGS. 4a to 4e, respectively for the Pyrrole-SiO-1a, Methyl-SiO-1a, DNP-amino-SiO-1a, Benzyl-SiO-2a, Mercapto-SiO-1a, g-amino-SiO and g-mercapto-SiO monoliths. The pore width (in A) is indicated as abscissas, and the differential surface area (in m.sup.2/g) is indicated in ordinates.

[0075] FIG. 5 represents from top to bottom, the NMR spectrum of methyl-SiO-1a, mercapto-SiO-1a, benzyl-SiO-1a, pyrrole-SiO-1a and DNP-amino-1a monoliths.

[0076] FIG. 6 represents the IR spectra that show signals corresponding respectively to the N-(3-propyl)pyrrole group (1360 cm.sup.−1 and 1650 cm.sup.−1, FIG. 6a), to the methyl group (2856 cm.sup.−1 and 2932 cm.sup.−1, FIG. 6b), to the 3-(2,4 dinitrophenylamino)propyl group (1338 cm.sup.−1 and 1622 cm.sup.−1, FIG. 6c) to the benzyl group (4 bands between 1450 and 1650 cm.sup.−1, FIG. 6d) and to the 3-mercaptopropyl group (690 cm.sup.−1, FIG. 6e).

[0077] FIGS. 7a to 7f represent the TEM plates for catalytic systems consisting of a monolith and palladium, respectively for the Pd@g-AE-amino-SiO, Pd@g-Amino-SiO, @-Mercapto-SiO, Pd@g-Mercapto-SiO, Pd@mercapto-SiO-1a, Pd@g-DNP-amino-SiO and Pd@g-pyrrole-SiO systems.

[0078] FIGS. 8a and 8b represent the XPS diagrams of monoliths carrying N-(2-aminoethyl)3-amino-propyl) groups and Pd particles generated by heterogeneous nucleation. FIG. 8b is an enlargement of the X-ray emission bands specific to palladium.

[0079] FIG. 9 represents the XPS diagram of a Pd@g-amino-SiO monolith carrying N-(2-aminoethyl) 3-amino-propyl), groups and Pd particles generated by heterogeneous nucleation.

[0080] FIGS. 10a to 10f show the degree of conversion obtained in a Suzuki-Myaura reaction with each of the following catalytic systems: Pd@g-AE-amino-SiO (10a), Pd@g-Mercapto-SiO (10b), Pd@g-Mercapto-SiO (10c), Pd@g-pyrrole-SiO (10d), Pd@g-AE-amino-SiO (10e) and Pd@g-Amino-SiO (10f).

[0081] FIG. 11 shows the degree of conversion obtained for the same Suzuki-Myaura reaction with a Pd catalyst of the prior art on active carbon.

[0082] FIG. 12 shows the change in the rate of conversion C in %, during time T (in minutes), when the catalyst is used for successive cycles in the Mitzoroki-Heck reaction, for the catalysts Pd@g-amino-SiO (curve indicated by a square □), Pd@g-mercapto-SiO (curve indicated by a black circle •), Pd@mercapto-SiO (curve indicated by a triangle Δ) and Pd@g-amino-SiO (curve indicated by a circle ◯).

[0083] FIG. 13 is a curve that represents in ordinates the percentage impregnation of a monolith as a function of time in minutes (indicated as abscissas).

[0084] The present invention is illustrated by the concrete examples described hereinafter, to which it is however not limited.

[0085] Examples A1 to A 3 concern the preparation of hybrid materials according to the invention, example A4 describes the characterization of the materials obtained, examples B1 to B2 describe the preparation of supported catalysts from materials according to the invention, example C1 and C2 describe catalytic tests, and examples D1 and D2 described decontamination treatment tests.

Example A1

[0086] Preparation of an SiO.sub.2 Monolith Carrying R Groups, with R=Benzyl

[0087] This example illustrates the first variant of the method.

[0088] 4.05 g of tetraethoxysilane (TEOS) and 1 g of benzyltriethoxysilane were added to 16.01 g of a 35% by weight aqueous solution of tetradecyltrimethylammonium bromide (TTAB). 5.87 g of 37% HCl were then added. In order to permit hydrolysis of the compounds before the oily phase was added, the solution prepared in this way was left with stirring for 5 minutes. The oily phase, consisting of 40.06 g of dodecane, was then added dropwise, and the system was then emulsified by hand with a mortar. The emulsion prepared in this way was placed in a closed plastic container in order to allow the precursors to condense. The condensation step proceeded over a period of one week. The oily phase was then extracted by immersing the compound in a THF/acetone solvent (80/20 by volume) for 24 hours. This washing step was repeated three times, before the immersed compound was left for one hour in an acetone solution. The compound was then dried by leaving it in air in a beaker with a non-airtight lid on top, in order to prevent too violent or rapid evaporation of the washing solvent that would bring about the formation of crack zones in the monolith prepared in this way. Finally, the compound was treated for 6 hours at 180° C. (temperature rise rate of 2° C. per minute), so as to sinter it slightly and in this way to improve its mechanical strength.

Preparation of SiO.SUB.2 .Monoliths Carrying Other R Groups

[0089] Other trialkoxysilanes could also be used for the preparation of SiO.sub.2 hybrid monoliths, by following the same operating mode as described above according to the first variant of the method according to the invention. They consisted of the following AMR compounds: methyltriethoxysilane, (3-mercaptopropyl)trimethoxysilane, (3-aminopropyl) triethoxysilane, 3-(2,4-dinitrophenylamino)propyltriethoxysilane, N-(2-aminoethyl)-3 aminopropyltrimethoxysilane and N-(3-trimethoxysilylpropyl) pyrrole.

[0090] Table 1 gives, for each preparation, the weights (in grams) of tetraethoxysilane (TEOS), of the AMR compound, of TTAB, of dodecane and of the HCl used.

TABLE-US-00001 TABLE 1 Reagent Monolith R TEOS AMR TTAB Dodecane HCl obtained Methyl 4.04 1.03 16.03 40.02 5.87 Methyl- SiO-1a N-(3- 4.05 1.00 16.05 40.03 5.9 Pyrrole- propyl)pyrrole SiO-1a 3- 4.01 1.02 16.03 40.06 5.89 Mercapto- mercaptopropyl SiO-1a (3- 4.03 1.01 16.03 40.02 5.89 Amino- aminopropyl) SiO-1a 3-(2,4 4.03 1.01 16.06 40.06 5.9 DNP- dinitrophenyl- amino- amino)propyl SiO-1a N-(2- 4.04 1.02 14.01 40.04 7.86 AE- aminoethyl)-3 amino- aminopropyl SiO-1a

Example A2

[0091] Preparation of an SiO.sub.2 Monolith Carrying R Groups with R=3-Mercaptopropyl

[0092] This example illustrates the second variant of the method.

[0093] 4.02 g of TEOS were added to 16.01 g of a 35% by weight aqueous solution of tetradecyltrimethylammonium bromide (TTAB). 5.87 g of 37% hydrochloric acid were then added. In order to permit hydrolysis of the TEOS before the oily phase was added, the solution prepared in this way was left with stirring for 3 minutes. The oily phase, consisting of 40.06 g of dodecane containing 1.02 g of (3-mercaptopropyl)trimethoxysilane) was added dropwise, and the system was then emulsified by hand with a mortar. The emulsion prepared in this way was placed in a closed plastic container in order to allow the precursors to condense. The condensation step proceeded over a period of one week. The oily phase was then extracted by immersing the compound in a THF/acetone solvent (80/20 by volume) for 24 hours. This washing step was repeated three times, before the immersed compound was left for one hour in an acetone solution. The compound was then dried by leaving it in air in a beaker with a non-airtight lid on top. The compound was then treated for 6 hours at 180° C. (temperature rise rate of 2° C. per minute), so as to sinter it slightly and in this way to improve its mechanical strength.

Preparation of SiO.SUB.2 .Monoliths Carrying Other R Groups

[0094] Other trialkoxysilanes were also used for the preparation of SiO.sub.2 hybrid monoliths, following the same operating mode as described above according to the second variant of the method according to the invention. They consisted of the following AMR compounds: methyltriethoxysilane, benzyltriethoxysilane, (3-aminopropyl)triethoxysilane, 3-(2,4-dinitrophenylamino)propyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and N-(3-trimethoxysilylpropyl)pyrrole.

[0095] Table 2 gives, for each preparation, the weights (in grams) of tetraethoxysilane (TEOS), of the AMR compound, of TTAB, of dodecane and of the HCl used.

TABLE-US-00002 TABLE 2 Reagent Monolith R TEOS AMR TTAB Dodecane HCl obtained Methyl 4.05 1.03 16.01 40.03 5.9 Methyl- SiO-2a Benzyl 4.00 1.04 16.02 40.02 5.89 Benzyl- SiO-2a N-(3- 4.03 1.01 16.07 40.02 5.9 Pyrrole- propyl)pyrrole SiO-2a (3- 4.08 1.01 16.00 40.01 5.98 Amino- aminopropyl) SiO-2a 3-(2,4 4.02 1.00 16.05 40.03 5.99 DNP- dinitrophenyl- amino- amino)propyl SiO-2a N-((2- 4.04 1.12 14.02 40.04 7.8 AE- aminoethyl)3- amino- aminopropyl SiO-2a

Example A3

[0096] Preparation of an SiO.sub.2 Monolith Carrying R Groups with =3-Pyrrolylpropyl. This Example Illustrates the Third Variant of the Invention.

[0097] The SiO.sub.2 monolith was first prepared. To this end, 6.1 g of hydrochloric acid were introduced into 16.07 g of a 35% by weight TTAB solution. 5.01 g of TEOS were then added dropwise as well as 40.02 g of decane, while emulsifying by hand by means of a mortar. The condensation step for the precursor proceeded for a period of one week and the oily phase was then extracted by immersing the monolith obtained in THF for hours, this step being repeated three times. The monolith was then carefully dried, so as to avoid too violent evaporation of THF. The monolith was then calcined at 600° C. in air for 6 hours, so as to sinter it slightly and to release the mesoporosity (induced by TTAB micelles). The material constituting the monolith thus obtained is called hereinafter “native silica”.

[0098] In a second step, 3-pyrrolylpropyl groups were grafted onto the SiO.sub.2 monolith synthesized in the first step, by proceeding in the following way: 3.1 g. of N-(3-trimethoxysilylpropyl)pyrrole were introduced into 150.40 g of chloroform. 1.2 g of the SiO.sub.2 monolith were then immersed in this solution. In order to increase the diffusion kinetics, the beaker containing the solution and the monolith was placed in a chamber under vacuum until the monolith fell to the bottom of the beaker. It could be ensured in this way that the monolith was completely impregnated by the reaction medium. This step lasted between 5 and 10 minutes. The beaker was then taken out of the vacuum chamber and then closed and allowed to stand for 24 hours. The compound obtained was then placed for one hour in a beaker containing acetone. The monolith was then dried in air in a beaker having a non-airtight lid on top.

Grafting of Other Compounds on an SiO.SUB.2 .Monolith

[0099] Other trialkoxysilanes were also used to prepare hybrid SiO.sub.2 monoliths, by following the same operating mode as that described above, according to the third variant of the method according to the invention. They consisted of the following compounds: methyltriethoxysilane, [0100] benzyl-triethoxysilane, [0101] (3-mercaptopropyl)trimethoxysilane, [0102] (3-aminopropyl)triethoxysilane, [0103] 3-(2,4 dinitrophenylamino)propyltriethoxysilane and [0104] N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0105] Table 3 gives, for each preparation, the weights (in grams) of the SiO.sub.2 monolith, trialkoxysilane (AMR) and chloroform used.

TABLE-US-00003 TABLE 3 Reagent Native Monolith R silica AMR Chloroform obtained 3-pyrrolylpropyl 1.2 3.1 150.40 g-pyrrole- SiO Methyl 0.57 1.52 70.3 g-methyl- SiO Benzyl 0.74 1.8 91.5 g-benzyl- SiO 3-mercaptopropyl 1.02 2.52 127.13 g-mercapto- SiO 3-aminopropyl 1.05 2.56 128 g-amino-SiO 3-(2,4 dinitrophenyl- 1.2 3 150 g-DNP- amino)propyl amino-SiO N-(2-aminoethyl)-3 1.35 3.3 168 g-Ae-amino- aminopropyl SiO

Example A4

Characterization of the Monoliths Obtained

[0106] The monoliths obtained according to examples A1, A2 and A3 (namely according to the three variants of the method according to the invention) were characterized by various analytical methods so as to reveal their macroporous, mesoporous and microporous character. The monoliths obtained according to the first variant of the method exhibited the same properties as those obtained according to the second variant. Consequently, the data presented below for monoliths synthesized according to example A1 were acceptable for monoliths synthesized according to example A2 carrying the same R groups.

[0107] The monoliths subjected to characterization were as follows: pyrrole-SiO-1a, methyl-SiO-1a, DNP-amino-SiO-1a, mercapto-1a, benzyl-SiO-2a, mercapto-SiO-1a, g-amino-SiO and g-mercapto-SiO.

[0108] The general appearance of a monolith according to the invention is presented in the photograph of FIG. 1a. It consists of an SiO.sub.2 monolith containing the N-(3-propyl)pyrrole groups of example A1, denoted by pyrrole-SiO-1a.

Macroporous Structure

[0109] The photographic plates of figures 1b to 1f were obtained by transmission electron microscopy (TEM). These plates were produced on pyrrole-SiO-1a, methyl-SiO-1a, DNP-amino-SiO-1a, benzyl-SiO-2a, mercapto-SiO-1a monoliths, containing respectively 3-pyrrolylpropyl groups (plate 1b), methyl groups (plate 1c), 3-(2,4-dinitrophenylamino)propyl groups (plate 1d), benzyl groups (plate 1e) and 3-mercaptopropyl groups (plate 1f).

[0110] The plate of FIG. 1g was obtained by scanning electron microscopy (SEM) from the monolith or g-mercapto-SiO.

[0111] These plates show that the macroscopic cells were polydispersed with a size varying between 5 μm and 30 μm. The macroscopic structure of the monoliths resembled an aggregation of hollow spheres (similar to that of the native silica monolith of example A3), with the exception of the monolith having (dinitrophenylamino)propyl groups (plate 1d), of which the intercellular walls were completely mineralized.

[0112] Mercury intrusion macroporosimetry measurements were performed at ambient temperature for various samples.

[0113] The sample was weighed and degassed under a vacuum of 6×10.sup.−6 MPa, before being placed in a measuring cell. The measuring cell was then filled with mercury at a pressure of 3.4×10.sup.−3 MPa and then successive pressures were generated between 3.4×10.sup.−3 MPa and 120 MPa (which corresponded to the theoretical pore diameters). At each pressure, the electrical capacity was measured by the rod of a penetrometer and a deduction was made of the volume of mercury that had penetrated into the sample. The results are given in the table 4 below.

TABLE-US-00004 TABLE 4 Density of Intrusion the volume Porosity Density skeleton (cm.sup.3 .Math. g.sup.−1) (%) (g .Math. cm.sup.−3) (g .Math. cm.sup.−3) Curve Pyrrole-SiO- 13.7 96.2 0.07 1.86 a 1a Methyl-SiO-1a 3.6 80 0.22 1.13 b DNP-amino- 3.38 92 0.27 1.64 c SiO-1a Benzyl-SiO-2a 5.12 89.4 0.17 1.65 d Mercapto-SiO- 9.92 93 0.09 1.36 e 1a g-amino-SiO 3.74 88 0.24 1.93 g-mercapto- 10.65 92 0.09 1.07 SiO

[0114] The results of mercury intrusion porosimetry measurements have been given in FIG. 2 which represents, for each sample, the differential intrusion (in ordinates, expressed in ml/g/nm) as a function of diameter of the intermacropore windows (in abscissas, expressed in nm). As the case may be, the curve corresponding to each monolith is referred to in the last column of the above table.

[0115] It follows from these measurements that the windows connecting two adjacent macropores have a bimodal character. These windows and the associated macropores correspond to the characteristic sizes that permit impregnation with and rapid flow of solvent within the material (Darcy's law). These interconnected macropores (by inter-pore windows) will make it possible to irrigate all the mesopores and in this way to optimize all the surface area of the materials, which constitutes an important property for impregnation by BXT compounds.

Mesoporous and Microporous Character

[0116] The mesoporous character was studied by transmission electron microscopy associated with small angle X-ray diffraction measurements (SAXS).

[0117] FIGS. 3a to 3e are transmission electron microscopy plates (TEM) produced on SiO.sub.2 monoliths. FIGS. 3f to 3e are SAXS diffusion profiles performed on the same samples. Intensity is given as ordinates (arbitrary units), as a function of the wave vector q (in Å.sup.−1).

[0118] FIGS. 3ka to 3 kb are SAXS diffusion profiles performed on other samples.

[0119] The correspondence between the monoliths and curves of FIG. 3 given in the following table.

TABLE-US-00005 Monolith MET plate SAXS curve Pyrrole-SiO-1a a f Methyl-SiO-1a b g DNP-amino-SiO-1a c h Benzyl-SiO-2a d i Mercapto-SiO-1a e j g-amino-SiO ka g-mercapto-SiO kb

[0120] It follows that all the materials exhibited a mesoporous character. The figures also show that [0121] mesopores were dispersed statistically for the methyl-SiO-1a monoliths (plate 3b and FIG. 3g) and the mercapto-SiO-1a monoliths (plate 3e and FIG. 3j); [0122] the mesopores were organized in a hexagonal manner in the pyrrole-SiO-1a, DNP-amino-SiO-1a and benzyl-SiO-2a monoliths; [0123] in the g-amino-SiO and g-mercapto-SiO monoliths, the mesopores had a polydisperse distribution extending from 10 to 6000 nm, with two main contributions centred on 150 nm and 700 nm for g-amino-SiO, and centred on 60 nm and 4000 nm for g-mercapto-SiO.

[0124] Specific surface area measurements were also performed by nitrogen adsorption-desorption techniques (B.E.T. and B.J.H. methods). The results are given in table 5 below.

TABLE-US-00006 TABLE 5 Specific Specific surface area surface area (m.sup.2 .Math. g.sup.−1) by (m.sup.2 .Math. g.sup.−1) by Total pore B.E.T B.J.H volume Pyrrole-SiO-1a 392 83 Methyl-SiO-1a 450 98 DNP-amino-SiO- 217 87 1a Benzyl-SiO-2a 107 14 Mercapto-SiO-1a 53 15 Native SiO.sub.2 725 220 0.34 g-amino-SiO 73 28 0.07 g-mercapto-SiO 381 63 0.19

[0125] From the results of table 5, it may be concluded that the monoliths had a super-microporous character (pore size between 10 and 20 Å) as well as a mesoporous character (pore size greater than 35 Å). These results confirm that the grafting of organic groups onto the surface of the pores reduces the specific surface area and the pore volume compared with native silica.

[0126] The BJH method essentially gave mesopores having a size greater than 35 Å. The microporosity was obtained by difference with the BET data. The pore size distribution, obtained by the theory of differential functions, gave a bimodality of the pore sizes centered on 15 Å (super-micropores) and 25 Å (mesopores).

[0127] The pore size distribution was also determined by the DFT (differential functional theory) method. The results are given in FIGS. 4a to 4g. These figures represent the pore width (in A) in abscissas, and the differential surface area (in m.sup.2/g) in ordinates for the above monoliths.

[0128] The correspondence between the monoliths and the figures is given in the table below.

TABLE-US-00007 Monolith FIG. 4 Pyrrole-SiO-1a a Methyl-SiO-1a b DNP-amino-SiO-1a c Benzyl-SiO-2a d Mercapto-SiO-1a e g-amino-SiO f g-mercapto-SiO g

[0129] The results that follow from these figures are in good agreement with the results obtained by the BET and BJH methods since, for all the samples, the curves exhibited a bimodal character with a peak around 10 Å (presence of micropores) and a peak around 22 Å (presence of mesopores).

[0130] The microporous character of the monoliths was also studied by NMR .sup.29Si measurements, of which the results are given in FIG. 5.

[0131] The spectra correspond, from top to bottom, to the methyl-SiO-1a, mercapto-SiO-1a, benzyl-SiO-1a, pyrrole-SiO-1a, and DNP-amino-1a monoliths.

[0132] The T and Q peaks of the spectra are attributed as indicated in table 6.

TABLE-US-00008 TABLE 6 T.sup.3: −63/− T2: −55/− Q.sup.4: −109 ppm Q.sup.3: −100 ppm Q.sup.2: −92 ppm 70 ppm 62 ppm Si(OSi).sub.4 HO-Si(OSi).sub.3 (HO).sub.2- R-Si (OSi)3 (HO)R- Si(OSi).sub.3 Si(OSi).sub.2

[0133] This method made it possible to identify and quantify the various siloxane groups present in the monoliths. Table 7 gives a comparison of the results obtained from NMR .sup.29Si measurements with the expected results from the molar ratios of the precursors of the reaction (TEOS and alkoxysilane groups).

TABLE-US-00009 TABLE 7 % R ↓ % TEOS trialkoxysilane % Q units % T units Methyl-SiO- 77.0 23.0 78.0 22.0 1a Mercapto- 78.8 21.2 79.0 21.0 SiO-1a Benzyl-SiO- 82.5 17.5 83.3 16.7 1a Pyrrole- 81.4 18.6 79.5 20.5 SiO-1a DNP-amino- 88.1 11.9 89.1 10.9 1a

[0134] The experimental results (two right hand columns) were in agreement with the theoretical calculations (two left hand columns) which show that the synthetic method used made it possible to control well the final composition of the material.

[0135] Moreover, infrared spectroscopy measurements were taken so as to verify that the final treatment of the monoliths at 180° C. for 6 hours had not damaged the R groups.

[0136] The spectra obtained are shown in FIGS. 6a to 6e. The correspondence between the monoliths and the figures is given in the table below.

TABLE-US-00010 Monolith FIG. 6 Pyrrole-SiO-1a a Methyl-SiO-1a b DNP-amino-SiO-1a c Benzyl-SiO-2a d Mercapto-SiO-1a e

[0137] These spectra show the signals corresponding respectively to the 3-pyrrolylpropyl group (1360 cm.sup.−1 and 1650 cm.sup.−1, FIG. 6a), the methyl group (2856 cm.sup.−1 and 2932 cm.sup.−1, FIG. 6b), the 3-(2,4-dinitrophenylamino)propyl group (1338 cm.sup.−1 and 1622 cm.sup.−1, FIG. 6c), the benzyl group (4 bands between 1450 cm.sup.−1 and 1650 cm.sup.−1, FIG. 6d) and the 3-mercaptopropyl group (690 cm.sup.−1, FIG. 6e).

[0138] The R groups present in the monoliths were thus not damaged by the effect of heat treatment.

Example B1

[0139] The supported catalysts were prepared from materials obtained according to the method of example A3, and carrying respectively N-(2-aminoethyl)-3-aminopropyl, 3-aminopropyl, 3-mercaptopropyl, 3-(2,4-dinitrophenylamino)propyl and N-(3-propyl)pyrrole groups and a material carrying 3-mercaptopropyl groups prepared according to the method of example 1.

Synthesis

[0140] A hybrid monolith obtained according to the method of example A3 was impregnated with a 5×10.sup.−2 M solution of Pd(CH.sub.3COO).sub.2 in THF for a period of two days, while employing three degassing cycles of 15 minutes each, and a 0.5 M NaBH.sub.4 solution was then added in a water/THF mixture (50/50). This mixture was allowed to stand for one day using the same degassing cycles as previously, and the materials were then recovered by filtration, washed with an ethanol/acetone mixture (80/20 by volume) for 24 hours with stirring, and dried in the open air.

[0141] The following table indicates the catalytic systems prepared and the modified monolith from which each one was derived.

TABLE-US-00011 Name of the catalytic system Initial monolith PD@g-AE-amino-SiO g-AE-amino-SiO (example 3) PD@g-Amino-SiO g-Amino-SiO (example 3) PD@g-Mercapto-SiO g-Mercapto-SiO (example 3) PD@Mercapto-SiO-1a Mercapto-SiO (example 1) PD@g-DNP-amino-SiO g-DNP-amino-SiO (example 3) Pd@pyrrole-SiO g-pyrrole-SiO (example 3)

Characterization by TEM

[0142] The catalytic systems obtained were characterized by transmission electron microscopy. FIG. 7 shows the TEM photographic plates obtained. The correspondence between various plates and the catalytic systems is given in the following table.

TABLE-US-00012 Catalytic system Plate PD@g-AE-amino-SiO 7a PD@g-Amino-SiO 7b PD@g-Mercapto-SiO 7c PD@Mercapto-SiO-1a 7d PD@g-DNP-amino-SiO 7e Pd@pyrrole-1a 7f

[0143] The monoliths used were obtained by the method of example 3, except for the PD@Mercapto-SiO.sub.2 monolith of FIG. 7d which was obtained by the method of example 1.

[0144] These plates gave important information on the degree of aggregation of the supported catalysts, knowing that an increase in the degree of aggregation corresponds to a reduction in the active surface area and consequently the catalytic efficiency.

Example B2

[0145] Supported catalysts were prepared from the same hybrid monoliths as those indicated in example B1, in the presence of triphenylphospine.

Synthesis

[0146] Pd(CH.sub.3COO).sub.2 (0.33 g, 1.5 mmol) was dissolved in 30 ml of THF in order to obtain a concentration of 5×10.sup.−2 mol.Math.1.sup.−1. Triphenylphosphine was then added (two equivalents, 3 mmol, 0.78 g). The mixture was stirred until completely dissolved. A change of color was then observed, the solution passing from a brown color to a bright red color. A 0.8 g quantity of hybrid material was added and three degassing cycles of 15 minutes each were carried out for three days so as completely to impregnate the hybrid material.

[0147] A freshly prepared solution of NaBH.sub.4 (10 equivalents, 0.56 g, 15 mmol) in 30 ml of a water/THF mixture (50/50 v/v), was added to the solution containing the hybrid material with gentle stirring. The solution became black.

[0148] The blocks of hybrid material were recovered by filtration, washed for two days with ethanol with stirring and then dried in the open air.

Characterization by TEM

[0149] The TEM plates obtained were similar to those for materials prepared according to example B1.

Characterization by XPS

[0150] FIGS. 8a and 8b represent the XPS diagrams of monoliths carrying N-(2-aminoethyl)3-amino-propyl groups and Pd particles generated by heterogeneous nucleation. FIG. 8a, which shows an extended energy range, shows the elements present within the aforementioned compound. FIG. 8b is an enlargement of the X-ray emission bands particular to palladium, and in particular peaks of electrons associated with the 3d.sub.5/2 and 3d.sub.7/2 orbitals. The 3d.sub.5/2 band was centered on 335 eV and the 3d.sub.7/2 band was centered on 340 eV. Such energies associated with the 3d.sub.5/2 and 3d.sub.7/2 electrons were characteristic of metallic palladium in the zero valence state (non oxidized) from the publication by Brun, M., Berthet, A., Bertolini, J. C.: XPS, ARS and Auger parameter of Pd and PdO, J. Electron Microsc. Relat. Phenom., 1999, vol. 104, p 55.

[0151] The palladium content was determined by elementary analysis for the sample of material carrying mercapto groups. It was 3.9% by weight.

Example B3

[0152] Supported catalysts were prepared from the hybrid monoliths prepared according to example 3.

Synthesis

[0153] 1 g of the monolith obtained according to example A3 was added to a solution containing Pd(CH.sub.3COO).sub.2 (0.33 g, 1.5 mmol) and triphenylphosphine PPh.sub.3 (4 equivalents, 6 mmol, 1.57 g) in 30 ml of THF to obtain a concentration of 5×10.sup.−2 mol.Math.l.sup.−1 of acetate, and was left in the dark for 2 days.

[0154] A freshly prepared solution of NaBH.sub.4 (10 equivalents, 0.56 g, 15 mmol) in 30 ml of a water/THF mixture 50/50 v/v), was added to the solution containing the hybrid material with gentle stirring. The color of the reaction medium changed from yellow to black in one hour.

[0155] The monolith of hybrid material was then recovered by filtration, washed for two days with ethanol until it became colorless and then dried in the open air.

[0156] A supported catalyst was prepared in this way, on the one hand with a g-amino-SiO monolith and on the other with a g-mercapto-SiO monolith.

Characterization with TEM

[0157] The TEM plates obtained were similar to those of materials prepared according to example B1.

Characterization by XPS

[0158] FIG. 9 represents the XPS diagram of the Pd@g-amino-SiO monolith carrying N-(2-aminoethyl)3-aminopropyl groups and Pd particles generated by heterogeneous nucleation. This diagram shows two peaks, at 335 eV and 340.8 eV, which correspond to electrons associated with the 3d.sub.5/2 and 3d.sub.7/2 orbitals of metallic palladium particles.

[0159] A Pd@g-mercapto-SiO monolith carrying mercaptopropyl groups and Pd particles generated by heterogeneous nucleation were obtained according to the same method, and its XPS diagram was similar to that of the Pd@g-amino-SiO monolith.

Elementary Analysis

[0160] The Pd content of the supported catalyst was determined by elementary analysis. It was 3.9% by weight for the sample carrying Pd@g-amino-SiO groups and 4.1% by weight for the sample carrying Pd@g-mercapto-SiO groups.

Example C1

[0161] The catalytic activity of the various catalytic systems obtained according to examples B1 and B2 was tested on the Suzuki-Myaura reaction, employing the following operating procedure.

[0162] A 50 ml three-necked flask was used provided with a condenser at −20° C.

[0163] 1 equivalent (0.097 g) of the catalytic system was introduced into the flask as well as 200 equivalents (0.576 g) of K.sub.2CO.sub.3, an internal standard and 5 mL of dioxane.

[0164] A mixture was prepared of 100 equivalents (0.3905 g) of iodobenzene, 150 equivalents (0.3584 g) of phenylboronic acid and 5 mL of dioxane, and this mixture was introduced into the three-necked flask with the aid of a syringe. The three-necked flask was then left in an oil bath at 115° C. under reflux with dioxane for 3 days and a follow-up was carried out by taking samples at regular intervals.

[0165] Assessments of the state of the reaction were established by liquid phase chromatography, bringing the temperature from 50° to 180° C. at a rate of 6° C. a minute on a Varian 3300, using an injector at 220° C., a detector at 200° C. at a pressure of 10 psi, a DB5 column that had a length of 30 m, an internal diameter of 0.25 mm and a film that had a thickness of 0.1 μm.

[0166] The degree of conversion obtained with each of the catalytic systems is shown as a function of time on FIGS. 10 and 12. As a comparison, the degree of conversion as a function of time for a conventional Pd catalyst on active carbon (considered as very efficient) is given in FIG. 11. On each of the figures, the degree of conversion, in percentage, is indicated as ordinates and the time (in hours) is indicated as abscissas.

[0167] The catalysts according to the invention that were tested are indicated in the following table with the corresponding figures:

TABLE-US-00013 Prepared Catalytic system according to Figure Pd@g-AE-amino-SiO Example B1 10a Pd@g-Mercapto-SiO Example B1 10b Pd@g-Mercapto-SiO Example B2 10c Pd@g-pyrrole-SiO Example B2 10d Pd@g-AE-amino-SiO Example B2 10e Pd@g-Amino-SiO Example B2 !0f

[0168] It appears that the catalytic systems according to the invention obtained by the method of, example B1 (without phosphine) possessed an activity close to that obtained by palladium nanoparticles on active carbon. They had however the advantage of being in a monolithic form and therefore not requiring a separation step with the catalyzed material by filtration or centrifugation for example. The materials tested thus possessed satisfactory performance and were more easily employed than a conventional catalyst such as the palladium/active carbon system.

[0169] It moreover appears that the material according to the invention obtained by the method of B2, that is to say in the presence of triphenylphosphine, possessed superior activity to that obtained by palladium nanoparticles on active carbon.

Example C2

[0170] The catalytic activity of the various materials obtained according to examples B2 and B3 were tested on the Mitzoroki-Heck reaction, that may be shown schematically in the following manner

##STR00004##

[0171] E and Z denoting isomers of stilbene.

[0172] A solution containing 10 mmol, (2.04 g) of iodobenzene 1, 15 mmol (1.56 g) of styrene 2, 11 mmol (1.11 g) of triethylamine, 5 mmol (0.85 g) of dodecane (as a reference standard for gas chromatography) and 10 mL of DMF and the supported catalyst were placed in a glass flask provided with a tap with sintered glass. The reaction medium was purged with argon for 10 min, and then the reactor was placed in an oil bath at 155° C., without stirring. Samples were extracted periodically and diluted with THF at 0° C., so as to follow the degree of conversion.

[0173] After the reaction had finished, the liquid phase was extracted from the reactor, under argon, through the sinter, a new mixture of reagents was introduced into the reactor and a new reaction was carried out. This operation was reproduced several times in order to test the stability of the catalyst with time.

[0174] The operations above were carried out on the one hand with a monolith bearing mercaptopropyl groups and on the other hand with a monolith carrying aminopropyl groups.

[0175] FIG. 13 shows the change in the degree of conversion with time, while the catalyst is used for successive reaction cycles, for the following catalysts: [0176] Pd@g-amino-SiO (0.11 g): curve indicated by a square □; [0177] Pd@g-mercapto-SiO (0.11 g): curve indicated by black circle •; [0178] Pd@mercapto-SiO (0.11 g): curve indicated by a triangle Δ; [0179] Pd@-amino-SiO (0.055 g): curved indicated by a circle ◯.

[0180] For the preparation of this catalyst, 0.055 g of support were used instead of 0.11 g. This was the same catalyst, but half the amount was used.

[0181] FIG. 13 shows that the catalysts gave a similar degree of conversion during their first use, which proceeded over 3 hours, and that the catalyst carrying mercapto groups and obtained from a monolith prepared according to either of samples A1 or A2 had a more stable activity during subsequent use than catalysts carrying amino groups or the catalyst carrying mercapto groups obtained by impregnation.

Example D1

[0182] An SiO.sub.2 monolith containing methyl groups, obtained by the method described in example A3 was used for the decontamination of a gas flow containing toluene.

[0183] 0.1021 g of said monolith was used for treating a gas flow containing 241.8 mg of toluene in 1 g hexane. These proportions corresponded to a toluene level close to that generally encountered in the atmosphere, namely 10 μg/m.sup.3. Hexane was used as a carrier for toluene by reason of its quite high saturated vapor pressure, preventing it from condensing on the walls and on account of the fact that it is transparent in UV-visible.

[0184] The percentage impregnation of the monolith by toluene was estimated by UV-visible spectroscopy. The absorption band for toluene in the UV-visible is situated at 268.2 nm.

[0185] FIG. 14 is a curve that represents in ordinates the percentage impregnation of the monolith by toluene, as a function of time, in minutes, (indicated as abscissas).

[0186] It appeared that 80% of toluene contained in the gas flow was absorbed by the monolith and that this phenomenon was stable with time, since it proceeded in the same way for more than an hour.

[0187] It should be noted that this result, although convincing, is not optimal on account of the fact that the measuring chamber was not totally filled with the monolith, but contained pieces of monolith separated by empty spaces.

[0188] Similar results were obtained with hybrid monoliths containing methyl or phenyl groups, synthesized according to the methods of examples A1 and A2.

Example D2

[0189] An SiO.sub.2 monolith containing phenyl groups, obtained by the method described in the example A3, was used for the decontamination of a liquid phase consisting of toluene.

[0190] The hybrid monolith became opalescent after one hour's immersion in the liquid phase containing toluene. The monolith was therefore not dissolved, but took the refractive index of the surrounding medium, which showed that it had been impregnated by toluene. This phenomenon came from the special porous character of the monolith (triple porosity), of its hydrophobic character induced by phenyl groups, and the inorganic Si—O—Si connectivity that insured cohesion of the porous edifice.

[0191] Similar results were obtained with hybrid monoliths containing methyl or phenyl groups, synthesized according to the methods of examples A1 and A2.