PROCESS FOR THE MANUFACTURE OF PULVERULENT, POROUS CRYSTALLINE METAL SILICATES EMPLOYING FLAME SPRAY PYROLYSIS

Abstract

The present invention relates to a process for the manufacture of a pulverulent, porous crystalline metal silicate, comprising the following steps: (a) hydrothermal synthesis employing an aqueous mixture comprising (A) a silicon source, (B) a metal source, and (C) an auxiliary component, yielding an aqueous suspension of reaction product 1, comprising a raw porous crystalline metal silicate; and (b) flame spray pyrolysis of reaction product 1, wherein the aqueous suspension obtained in step (a) is sprayed into a flame generated by combustion of a fuel in the presence of oxygen to form a pulverulent, porous crystalline metal silicate; wherein the aqueous suspension comprising reaction product 1 obtained in step (a) exhibits a solids content of ≤70% by weight; and wherein the effective peak temperature, T.sub.eff, experienced by at least 90% by weight of the porous crystalline metal silicate during flame pyrolysis, is in the range T.sub.min<T.sub.eff<T.sub.max, and wherein T.sub.min is 750° C., and wherein T.sub.max is 1250° C.

Claims

1-20. (canceled)

21. A process for preparing a pulverulent, porous crystalline metal silicate, comprising the following steps: (a) performing hydrothermal synthesis employing an aqueous mixture comprising (A) a silicon source; (B) a metal source; and (C) an auxiliary component; to yield an aqueous suspension of reaction product 1, comprising a raw porous crystalline metal silicate; and (b) performing flame spray pyrolysis of reaction product 1, wherein the aqueous suspension obtained in step (a) is sprayed into a flame generated by combustion of a fuel in the presence of oxygen to form a pulverulent, porous crystalline metal silicate; wherein: the aqueous suspension comprising reaction product 1 obtained in step (a) exhibits a solids content of ≤70% by weight; the effective peak temperature, T.sub.eff, experienced by at least 90% by weight of the porous crystalline metal silicate during flame pyrolysis, is in the range T.sub.min<T.sub.eff<T.sub.max, wherein T.sub.min is 750° C., and T.sub.max is 1250° C.; and wherein the metal source (B) is a source of titanium (Ti), iron (Fe) or aluminium (Al), and the auxiliary component (C) is selected from the group consisting of organic bases, quaternary ammonium hydroxides and mixtures thereof.

22. The process of claim 21, wherein component (A) is selected from the group consisting of: pyrogenic silicon dioxide; precipitated silicon dioxide; silicon dioxide produced by a sol-gel process; and mixtures thereof.

23. The process of claim 21, wherein in step (a), component (A) and component (B) are merged into a single component and this component is selected from the group consisting of: amorphous mixed metal-silicon oxide; amorphous silicon dioxide doped with metal oxide; amorphous silicon dioxide impregnated with metal; metal silicate; metal-doped tetraalkyl orthosilicate; and mixtures thereof.

24. The process of claim 21, wherein the metal source (B) is a source of titanium (Ti).

25. The process of claim 21, wherein the auxiliary component (C) is selected from the group consisting of: quaternary ammonium hydroxides; diamines; diols; and mixtures thereof.

26. The process of claim 21, wherein the auxiliary component (C) is selected from the group consisting of: tetraethylammonium hydroxide; tetrapropylammonium hydroxide; tetrabutylammonium hydroxide; tetrapentylammonium hydroxide; 1,6-diaminohexane, 1,2 pentanediol; and mixtures thereof.

27. The process of claim 21, wherein: component (A) is selected from the group consisting of: pyrogenic silicon dioxide; precipitated silicon dioxide; silicon dioxide produced by a sol-gel process; and mixtures thereof; the metal source (B) is a source of titanium (Ti); auxiliary component (C) is selected from the group consisting of: organic bases; quaternary ammonium hydroxides; and mixtures thereof; the porous crystalline metal silicate has a zeolite structure of MFI or MEL type; the fuel used for flame spray pyrolysis is hydrogen.

28. The process of claim 21, wherein: component (A) and component (B) are merged into a single component and this component is selected from the group consisting of: amorphous mixed metal-silicon oxide; amorphous silicon dioxide doped with metal oxide; amorphous silicon dioxide impregnated with metal; metal silicate; metal-doped tetraalkyl orthosilicate; and mixtures thereof; the metal source (B) is a source of titanium (Ti); auxiliary component (C) is selected from the group consisting of: organic bases; quaternary ammonium hydroxides; and mixtures thereof; the porous crystalline metal silicate has a zeolite structure of MFI or MEL type; the fuel used for flame spray pyrolysis is hydrogen.

29. The process of claim 21, wherein the auxiliary component is tetrapropylammonium hydroxide.

30. The process of claim 21, wherein T.sub.min is 800° C., and wherein T.sub.max is 1200° C.

31. The process of claim 21, wherein T.sub.min is 850° C., and wherein T.sub.max is 1100° C.

32. The process of claim 21, wherein the aqueous mixture in step (a) additionally comprises suitable seed crystals.

33. The process of claim 21, wherein the porous crystalline metal silicate has a zeolite structure of MFI or MEL type.

34. The process of claim 21, wherein the porous crystalline metal silicate has a zeolite structure of MFI type.

35. The process of claim 21, wherein the auxiliary component (C) is selected from the group consisting of: quaternary ammonium hydroxides; diamines; diols; and mixtures thereof; and wherein the metal source (B) is a source of titanium (Ti).

36. The process of claim 21, wherein the auxiliary component (C) is selected from the group consisting of: tetraethylammonium hydroxide; tetrapropylammonium hydroxide; tetrabutylammonium hydroxide; tetrapentylammonium hydroxide; 1,6-diaminohexane; 1,2 pentanediol; and mixtures thereof; and wherein the metal source (B) is a source of titanium (Ti).

37. The process of claim 21, wherein: the auxiliary component (C) is tetrapropylammonium hydroxide; the metal source (B) is a source of titanium (Ti); and the porous crystalline titanium silicate has a zeolite structure of MFI type.

38. The process of claim 21, wherein the fuel used for flame spray pyrolysis is hydrogen.

39. The process of claim 21, wherein the porous crystalline metal silicate obtained exhibits a loss on ignition according to DIN 18128:2002-12 of less than 5% by weight.

40. The process of claim 21, wherein step (b) is followed by a shaping step (c) comprising the following substeps: (i) adding water for obtaining an aqueous suspension of the pulverulent, porous crystalline metal silicate; (ii) mixing the suspension obtained in substep (1) with granulating aids; (iii) compacting, granulating, spray-drying, spray granulating and/or extruding the product obtained in substep (2) to obtain a porous crystalline metal silicate in the form of microgranules, spheres, tablets, solid cylinders, hollow cylinders or honeycombs.

Description

EXAMPLES

Example 1

Preparation of the Raw Suspension by Hydrothermal Synthesis

[0160] Synthesis of titanium silicalite-1 zeolite (TS-1; MFI structure type) was conducted in a 3 m.sup.3 pressure reactor in accordance with the corresponding method from Example 1 of EP 0814058 B1. The silicon source used was an amorphous, high-purity silicon dioxide (manufacturer: Evonik Resource Efficiency GmbH), and the titanium source used was an aqueous titanium-tetrapropylammonium hydroxide solution (Ti-TPA solution) having a content of 19.0% by weight of TiO.sub.2. The Ti-TPA solution was prepared as follows:

[0161] Mixing of 90.1 kg of deionized water, 167.3 kg of a 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem) and 141.6 kg of tetraethyl orthotitanate (manufacturer: Connect Chemicals GmbH) at 40° C. in a closed vessel for one hour. The exothermicity of the reaction resulted in a temperature rise of about 25° C. This was followed by the distillative removal of the ethanol formed at 80° C. at a distillation rate of 30 I/h. The target value for the resultant Ti-TPA solution was a TiO.sub.2 content of 19.0% by weight. After cooling, the Ti-TPA solution was used in the TS-1 synthesis.

[0162] The pressure reactor was initially charged with: 500 kg of high-purity silicon dioxide (Evonik Industries), 382 kg of a 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem), 193 kg of Ti-TPA solution, 10 kg of silicalite-1 seed crystals and 1800 kg deionized water. The mixture was stirred in the closed pressure reactor at a stirrer speed of 50 rpm at 170° C. for 3 h. The heating time to 170° C. was 180 min; after a cooling time of 150 min, the synthesis was ended. Stirring at a speed of 50 rpm was continued from start until end of the synthesis.

[0163] The silicalite-1 seed crystals were prepared by hydrothermal synthesis of 500 kg of high-purity silicon dioxide (Evonik Resource Efficiency GmbH), 400 kg of a 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem) and 1800 kg of deionized water in a pressure reactor. The mixture was stirred in the closed pressure reactor at a speed of 50 rpm at 160° C. for 3 h. The heating time to 160° C. was 180 min; after a cooling time of 150 min, the synthesis was ended. Stirring at a stirrer speed of 50 rpm was continued from start until end of the synthesis.

Example 2

Conventional Workup After the Hydrothermal Synthesis

[0164] Acetic acid (60% by weight) was added to the raw suspension described in Example 1 up to pH=7, and the precipitate formed was filtered on a filter press and washed with distilled water. The solids obtained were dried by means of spray drying with an inlet temperature of 420° C. and with an atomizer speed of 1700 min.sup.−1 (exit temperature of 110° C.). Subsequently, the partly dried powder was calcined at a Temperature not exceeding 650° C. in a rotary tube for 2 h. The product thus obtained had a BET surface area of 470 m.sup.2/g and an ignition loss (measured at 550° C.) of 0.65%. XRD analysis (FIG. 1) showed that the product obtained exhibits the crystal structure of titanium silicalite-1 (TS-1) (ICDD reference code: 01-089-8099). Pore analysis with nitrogen according to BJH gave a pore volume of 0.23 ml/g.

Example 3 (Negative Example)

Spray Calcination After Hydrothermal Synthesis (T.SUB.eff.=650° C.)

[0165] The raw suspension (15 kg/h) obtained in Example 1 was sprayed in a pilot plant with 18 m.sup.3/h of nitrogen for atomization through a two-phase nozzle with internal diameter 2 mm and gap 1 mm. The hydrogen/air flame was operated with 8 m.sup.3/h of hydrogen and 45 m.sup.3/h of primary air. The throughput of nitrogen was 18 m.sup.3/h and 25 m.sup.3/h of secondary air. The temperature measured 1.5 m below the ignition site was adjusted to 400° C. by slight variation of the hydrogen flow. The adiabatic combustion temperature in the reactor was about 544° C. The average residence time of a particle in the reactor was 1.35 s. The offgases, including calcined zeolite, were guided through a cooling zone (coolant temperature: 25° C.) having a diameter of 100 mm and a length of 6 m and then collected at filter candles at max. 250° C. By sequential cleaning of the filter candles, it was possible to collect the ready-calcined product (4.4 kg/h). The product thus obtained exhibited a loss on ignition (measured at 550° C.) of 8.6%, clearly indicating that it was unsuitable for further processing (shaping) in view of the fact that too much organic residue remained deposited on the surface of the product (loss on ignition clearly exceeded the limit value of 5%). XRD analysis (FIG. 2) showed that the product exhibits the crystal structure of TS-1 (ICDD reference code: 01-089-8099).

[0166] Simulation in Detail:

[0167] Input Parameters for the Gas Phase:

[0168] Atomization air: 18 Nm.sup.3/h

[0169] Primary air: 45 Nm.sup.3/h

[0170] Secondary air: 25 Nm.sup.3/h

[0171] H.sub.2: 8 Nm.sup.3/h

[0172] Turbulence model: Realizable k-□ Model.

[0173] Radiation model in the gas phase: Discrete Ordinate model with

[0174] Angular discretization: Theta divisions: 4; Phi divisions 4; Theta pixels: 1; Phi pixels: 1;

[0175] Boundary condition of walls: opaque, internal emissivity: 1;

[0176] Heat transfer coefficient to environment (only for outside wall): 5 W/m.sup.2/K; Environment temperature: 300 K.

[0177] Combustion model: finite-rate/eddy-dissipation

H.sub.2+0.5O.sub.2.fwdarw.H.sub.2O

[0178] Reaction Kinetics:

[0179] Arrhenius Rate: pre-factor=9.87e+8, Activation energy 3.1e+7 J/kmol, rate exponents for Hz and O.sub.2 are 1, for H.sub.2O is 0.

[0180] Mixing Rate: A=4, B=0.5

[0181] Properties/Property Model:

[0182] The Gas is treated as an ideal gas. Thermal conductivity, viscosity and heat capacity Cp of the gas mixture are calculated by using mass-weighted-mixing-law. Properties of pure components for H.sub.2, H.sub.2O (v), CO.sub.2, O.sub.2, N.sub.2 are obtained from material data base from Ansys Fluent. Mass diffusivity of each component in the gas phase is calculated using kinetic gas theory, the parameters required are all available from the Ansys Fluent data base.

[0183] Input Parameters for the Particle Phase:

[0184] Species/Properties: Density of particle ρ.sub.p and Cp of particle are calculated using mixing law of all components.

[0185] Species 1: H.sub.2O, initial mass fraction 60.3%

[00017]$\rho =998\frac{\mathrm{kg}}{m^3},\mathrm{Cp}=4182\frac{J}{\mathrm{kgK}},$

Latent heat of water=2263037 J/kg, Vaporization temperature T.sub.vap=284K, Boiling point: T.sub.bp=373 K, Saturation vapor pressure P.sub.sat(T.sub.p): piecewise-linear using 32 points from T=274-647 K.

[0186] Species 2: TPAOH, initial mass fraction 9.7%,

[00018]$\rho =1000\frac{\mathrm{kg}}{m^3},\mathrm{Cp}=3600\frac{J}{\mathrm{kgK}}$

[0187] Standard state enthalpy H.sup.0=−2.12e8 J/kmol (for calculation of reaction heat H.sub.reac)

[0188] Species 3: Silicate, initial mass fraction 30%,

[00019]$\rho =2660\frac{\mathrm{kg}}{m^3},\mathrm{Cp}=1052\frac{J}{\mathrm{kgK}},$

treated as inert.

[0189] Mass flow of suspension h.sub.p: initial 15 kg/h

[0190] Diameter (dp): initial particle diameter 22 μm

[0191] Group of particles: 100 (mass flow of each Group {dot over (m)}.sub.p,each group is {dot over (m)}.sub.p,total100, no significant difference between 100 and 1000 groups, thus 100 was used.)

[0192] Number of tries: 10 (stochastic tracking using discrete random walk model due to turbulence effect, 10 particle tracking in each group, totally 1000 particle trajectories with mass flow {dot over (m)}.sub.p,each group/10 were simulated).

[0193] Time scale constant: 0.15 (used for stochastic tracking).

[0194] Reaction Kinetics:

TPAOH+18.75O.sub.2.fwdarw.14.5H.sub.2O+CO.sub.2+N.sub.2

[0195] Arrhenius Rate: prefactor=0.2,

[0196] Activation energy 8e7 J/kmol

[0197] Rate exponent of O.sub.2: 1.

[0198] Particle motion was calculated using Equations 1-3. Particles experience inert heating, evaporation, boiling and combustion, their temperature was calculated using Equations 4-15.

[0199] FIG. 5 shows particle temperature vs. particle residence time of 3 exemplary out of 1000 (100 Groups×10 tries in each group) calculated particle trajectories obtained for example 3.

Example 4

Spray Calcination After Hydrothermal Synthesis (T.SUB.eff.=1000° C.)

[0200] The raw suspension (25 kg/h) obtained in Example 1 was sprayed in a pilot plant with 18 m.sup.3/h of air for atomization through a two-phase nozzle with internal diameter 2 mm and gap 1 mm. The hydrogen/air flame was operated with 8.5 m.sup.3/h of hydrogen and 27 m.sup.3/h of primary air. The throughput of nitrogen was 18 m.sup.3/h and 25 m.sup.3/h of secondary air. The temperature measured 1.5 m below the ignition site was adjusted to 700° C. by slight variation of the hydrogen flow. The adiabatic combustion temperature in the reactor was about 750° C. The average residence time of a particle in the reactor was about 1.1 s. The offgases, including calcined zeolite, were guided through a cooling zone (coolant temperature: 25° C.) having a diameter of 100 mm and a length of 6 m and then collected at filter candles at max. 250° C. By sequential cleaning of the filter candles, it was possible to collect the ready-calcined product (7.3 kg/h). The product thus obtained had a BET surface area of 489 m.sup.2/g and a loss on ignition (measured at 550° C.) of 0.3%. XRD analysis (FIG. 3) showed that the product exhibits the crystal structure of TS-1 (ICDD reference code: 01-089-8099).

[0201] Simulation of the effective particle temperature was performed analogously to example 3.

[0202] FIG. 6 shows particle temperature vs. particle residence time of 3 exemplary out of 1000 (100 Groups×10 tries in each group) calculated particle trajectories obtained for example 4.

Example 5: (Negative Example)

Spray Calcination After Hydrothermal Synthesis (T.SUB.eff.=1300° C.)

[0203] The raw suspension (15 kg/h) described in Example 1 was sprayed in a pilot plant with 18 m.sup.3/h of air for atomization through a two-phase nozzle with internal diameter 2 mm and gap 1 mm. The hydrogen/air flame was operated with 17.4 m.sup.3/h of hydrogen and 40 m.sup.3/h of primary air. The throughput of nitrogen was 18 m.sup.3/h and 25 m.sup.3/h of secondary air. The temperature measured 1.5 m below the ignition site was adjusted to 950° C. by slight variation of the hydrogen flow. The adiabatic combustion temperature in the reactor was about 980° C. The average residence time of a particle in the reactor was about 0.9 s. The offgases, including calcined zeolite, were guided through a cooling zone (coolant temperature: 25° C.) having a diameter of 100 mm and a length of 6 m and then collected at filter candles at max. 250° C. By sequential cleaning of the filter candles, it was possible to collect the ready-calcined product (4.4 kg/h). The product thus obtained had a BET surface area of 429 m.sup.2/g and a loss on ignition (measured at 550° C.) of 0.6%. XRD analysis (FIG. 4) showed some smaller signs of structural damage to the TS-1 (ICDD reference code: 01-089-8099). BET and XRD indicate that the structure is damaged with a resulting loss of surface area of about 15% (compared to example 4) and the product obtained is therefore unsuitable for further processing, i.e. shaping and use in an HPPO test reaction.

[0204] Simulation of the effective particle temperature was performed analogously to example 3.

[0205] FIG. 7 shows particle temperature vs. particle residence time of 3 exemplary out of 1000 (100 Groups×10 tries in each group) calculated particle trajectories obtained for example 5.

Example 6

Shaping of the Zeolite Powder from Example 2 (Conventional Workup)

[0206] The powder from Example 2 (1200 g) was mixed with 75 g of methyl hydroxyethyl cellulose (Tylose MH1000), 75 g of Licowax C, 1000 g of silica sol solution (Koestrosol 0830 AS) and 350 g of deionized water in an Eirich mixer. The mass obtained was extruded with an extruder (HB-Feinmechanik LTW 63) through a perforated plate with diameter 3.2 mm. The extrudates were then dried in a drying cabinet at 80° C. for one hour and calcined in a muffle furnace at 570° C. for 12 h.

Example 7

Shaping of the Zeolite Powder from Example 4 (Flame Spray Pyrolysis Workup)

[0207] The powder from Example 4 (1200 g) was mixed with 75 g of methyl hydroxyethyl cellulose (Tylose MH1000), 75 g of Licowax C, 1000 g of silica sol solution (Koestrosol 0830 AS) and 350 g of deionized water in an Eirich mixer. The mass obtained was extruded with an extruder (HB-Feinmechanik LTW 63) through a perforated plate with diameter 3.2 mm. The extrudates were then dried in a drying cabinet at 80° C. for one hour and calcined in a muffle furnace at 570° C. for 12 h.

Example 8

Catalytic Test with the Catalyst from Comparative Example 6 (Conventional Workup)

[0208] Epoxidation of propene was carried out with two fixed bed reactors, each containing 9 g of catalyst from Example 6 in the form of extrudates. The reactors were arranged in series (reactor 1.fwdarw.reactor 2) and were operated in up-flow mode. The first feed stream with a total flow rate of 20 g/h, consisting of methanol, hydrogen peroxide (60 wt %) and water, and a second feed stream consisting of 20 g/h of propylene were both fed to the first reactor. The reaction pressure was kept at 25 bar by means of a pressure retention valve downstream of the second reactor. The reaction mixture leaving the second fixed bed reactor was depressurized to ambient pressure. The resulting gas phase was analyzed for propylene, propylene oxide and oxygen, and the resulting liquid phase was analyzed for propylene oxide and hydrogen peroxide. The initial selectivity for propylene oxide after a reaction run time of 23 h was 91.1%. After 480 h, the selectivity for propylene oxide was 97.7%.

Example 9

Catalytic Test with the Catalyst from Example 7 (Flame Spray Pyrolysis Workup)

[0209] Epoxidation of propene was performed in the same way as in Example 8, but the catalyst prepared in Example 7 was used.

[0210] The initial selectivity for propylene oxide after a reaction run time of 25 h was 93.5%. After 480 h, the selectivity for propylene oxide was 98.6%.

TABLE-US-00001 TABLE 1 Comparison of the results of catalytic test reactions S(PO), % Space-time yield, after 480 h kg PO/kg cat-h Example 8: 97.7 0.21 Conventionally prepared catalyst (Example 6) Example 9: 98.6 0.21 Inventive catalyst (Example 7)

[0211] As shown by Examples 3-5 in comparison with Example 2, the process according to the invention contains much fewer process steps than the conventional process. Moreover, the process disclosed herein avoids problems of disposing wastewaters typically arising during filtration and cleaning of the product after hydrothermal synthesis. Surprisingly, the titanium silicalites obtained, after flame spray pyrolysis, have a porosity comparable to conventionally prepared titanium silicalite.

[0212] As apparent from Examples 8 and 9 (summarized in table 1), both, catalyst prepared conventionally (Example 6) as well as catalyst obtained in accordance with the present invention (Example 7), are highly active and selective in the epoxidation of propylene to propylene oxide (PO) after an operating time of 480 h. The catalyst obtained in accordance with the present invention, however, shows a selectivity for propylene oxide even higher by 0.9% than the conventional catalyst, while at the same time exhibiting comparable space-time yields. Using titanium silicalite-1 catalysts obtained in accordance with the invention, it is thus possible to distinctly increase the product yield of propylene oxide, based on unit time and reactor volume.

Example 10

[0213] Below described synthesis variations of example 1 were carried out in a 1 L lab autoclave and further processed in accordance with example 4 with T.sub.eff=1000° C. in order to prove that spray pyrolysis under suitable conditions can be applied to various synthesis products without destruction of the crystal structure.

[0214] General Description:

[0215] Zeolite was prepared according to the following procedure: In a typical experiment metal-source, silicon-source, auxiliary component water and optionally seed crystal-sol, were filled into a stainless-steel autoclave (Büchi, V=1.1 cm3, D=8.4 cm, H=20.3 cm, electrical heating) and gently mixed.

[0216] Alternatively, the silicon source was merged (impregnated) with the metal source prior to the synthesis by treating a silica xero- or hydrogel with a liquid titanium solution such as titanyl sulphate, titanium oxalate, titanium lactate (or other titanium containing solutions) resulting in a metal impregnated silicon dioxide, also called silica-titania xerogel or silica-titania hydrogel. In the here mentioned examples titanyl sulphate was used to be impregnated on a silica hydrogel (optionally followed by a drying step to reduce the water content). After the merge the hydrogel could optionally be dried into a xerogel in order to vary the water content of the material. The silica-titania xero- or hydrogel was added into the autoclave together with the other components.

[0217] For the synthesis of titanium silicalite-1 (MFI structure) optionally silicalite-1 or titanium-silicalite-1 seeds crystals (or a mixture thereof) could be used. For the synthesis of titanium silicalite-2 (MEL structure) optionally silicalite-2 or titanium-silicalite-2 seeds crystals (or a mixture thereof) could be used.

[0218] After the autoclave was sealed, the mixture was hydrothermally treated (heating rate of 1 Kmin-1) and stirred at 250-450 rpm. Then, the autoclave was cooled down to room temperature with a cooling rate of approximately 1 Kmin-1 to obtain the resulting zeolite containing aqueous suspension.

[0219] The raw suspension obtained after hydrothermal synthesis was processed and analyzed in accordance with example 4 with T.sub.eff=1000° C. [0220] a) Synthesis to obtain Titanium-Silicalite-1 (structure type MFI) by adding in the autoclave 120 g of fumed silica powder, 50 g of titanium oxalate, 20 g of silicalite-1 seed crystals in aqueous solution, 100 g of tetrapropylammoniumhydroxide (40% aqueous solution) and 200 g of water. Using the above described general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The water content of silicon source was <5 wt %. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0221] b) Synthesis to obtain Titanium-Silicalite-1 (structure type MFI) by adding in the autoclave 300 g of tetraethylorthosilicate >99%, 8 g of tetraethylorthotitanate (35%TiO.sub.2), 130 g of tetrapropylammoniumhydroxide (40% aqueous solution) and 250 g of water. Using the above described general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0222] c) Synthesis to obtain Titanium-Silicalite-1 (structure type MFI) by adding in the autoclave 250 g of silica-titania hydrogel (TiO.sub.2 2.5 wt. %, water content 60-80 wt %), 115 g of tetrapropylammoniumhydroxide (40% aqueous solution), 20 g of titanium-silicalite-1 seed crystals and 250 g of water. As described above, prior to the synthesis the silicon source (silica hydrogel) had been merged with the titanyl sulphate (50% in aqueous solution) to obtain a silica-titania hydrogel with a water content of 60-80%. Following the general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0223] d) As example c) but with a silica-titania hydrogel with a water content of 50-70 wt % and 300 g of water. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0224] e) As example c) but with a silica-titania hydrogel with a water content of 50-60 wt % and 300 g of water. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0225] f) As example c) but with a silica-titania hydrogel with a water content of 30-50 wt % and 300 g of water. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0226] g) As example c) but with a silica-titania xerogel with a water content of 10-30 wt % and 350 g of water. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0227] h) As example c) but with a silica-titania xerogel with a water content of <10 wt % and 450 g of water. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0228] i) As example d) but the autoclave was heated to 180° C. and kept stirring for 60 min. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0229] j) As example e) but the autoclave was heated to 180° C. and kept stirring for 60 min. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0230] k) As example e) but with 100 g of tetrapropylammoniumhydroxide (35% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0231] l) As example e) but with 150 g of tetrapropylammoniumhydroxide (20% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0232] m) As example e) but with 200 g of 1,6 Diaminohexane and no tetrapropylammoniumhydroxide (40% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0233] n) As example m) but with 100 g of 1,6 Diaminohexane and 50 g of tetrapropylammoniumhydroxide (40% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0234] o) As example m) but with 200 g of 1,2 Pentadiol instead of 1,6 Diaminohexane. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0235] p) As example n) but with 100 g of 1,2 Pentadiol instead of 1,6 Diaminohexane. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0236] q) As example n) but with 50 g of 1,2 Pentadiol and 50 g of 1,6 Diaminohexane and 50 of tetrapropylammoniumhydroxide (40% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0237] r) As example a) but with 200 g of 1,6 Diaminohexane and no tetrapropylammoniumhydroxide (40% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0238] s) As example a) but with 200 g of 1,2 Pentadiol and no tetrapropylammoniumhydroxide (40% aqueous solution). The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0239] t) As example e) but with a silica-titania hydrogel with 3.7 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0240] u) As example e) but with a silica-titania hydrogel with 3.5 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0241] v) As example e) but with a silica-titania hydrogel with 3.1 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0242] w) As example e) but with a silica-titania hydrogel with 2.8 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0243] x) As example e) but with a silica-titania hydrogel with 2.3 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0244] y) As example e) but with a silica-titania hydrogel with 1.8 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0245] z) As example e) but with a silica-titania hydrogel with 1.5 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0246] aa) As example e) but with a silica-titania hydrogel with 1.0 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0247] bb) As example e) but with a silica-titania hydrogel with 0.5 wt. % TiO.sub.2 content. The XRD-pattern showed the peak positions of Titanium-Silicalite-1. [0248] cc) Synthesis to obtain Titanium-Silicalite-2 (structure type MEL) by adding in the autoclave 250 g of silica-titania hydrogel (TiO.sub.2 2.5 wt. %), 115 g of tetrapropylammoniumhydroxide (40% aqueous solution), 20 g of silicalite-2 seed crystals and 300 g of water. Using the above described general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The water content of silica-titania precursor was 50-60 wt %. The XRD-pattern showed the peak positions of Titanium-Silicalite-2 (as in ICDD database). [0249] dd) Synthesis to obtain Iron-Silicalite-1 (structure type MFI) by adding in the autoclave 250 g of silica xerogel, 115 g of tetrapropylammoniumhydroxide (40% aqueous solution), 20 g of silicalite-1 seed crystals, 30 g of ammonia iron citrate and 350 g of water. Using the above described general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The water content of silica precursor was 20-30 wt %. The XRD-pattern showed the peak positions of Iron-Silicalite-1 (as in ICDD database). [0250] ee) Synthesis to obtain Aluminium-Iron-Silicalite-1, also called Iron-ZSM-5, (structure type MFI) by adding in the autoclave 250 g of silica xerogel, 115 g of tetrapropylammoniumhydroxide (40% aqueous solution), 20 g of silicalite-1 seed crystals, 30 g of ammonia iron citrate, 50 g of alumina nitrate and 350 g of water. Using the above described general description, the autoclave was heated to 160° C. and stirred for 180 min before cooling down. The water content of silica precursor was 20-30 wt %. The XRD-pattern showed the peak positions of Iron-ZSM-5 (as in ICDD database).

[0251] Crystallographic Data of Titanium Silicalite-1 (Source: ICDD Database)

[0252] Reference code: 01-089-8099

[0253] Name of the compound: silicon titanium oxide

[0254] ICSD code: 88413

[0255] Reference: Lamberti, C., Bordiga, S., Zecchina, A., Carati, A., Fitch, A. N., Artioli, G., Petrini, G., Salvalaggio, M., Marra, G. L., J. Catal., 183, 222, (1999)

TABLE-US-00002 List of reflections: Number h k I d [Å] 2θ [°] I [%] 1 0 1 1 11.17140 7.908 100.0 2 1 0 1 11.17140 7.908 100.0 3 2 0 0 10.07340 8.771 33.7 4 0 2 0 9.97825 8.855 36.2 5 1 1 1 9.74800 9.065 17.1 6 2 1 0 8.99270 9.828 1.3 7 2 0 1 8.05720 10.972 0.5 8 1 2 1 7.44190 11.882 1.1 9 2 1 1 7.44190 11.882 1.1 10 2 2 0 7.08909 12.476 0.3 11 0 0 2 6.71210 13.180 4.1 12 1 0 2 6.36799 13.896 8.3 13 1 1 2 6.06662 14.589 1.0 14 3 0 1 6.00599 14.738 9.2 15 0 3 1 5.96048 14.851 6.0 16 1 3 1 5.71559 15.491 5.5 17 0 2 2 5.58570 15.853 5.7 18 2 0 2 5.58570 15.853 5.7 19 2 1 2 5.36799 16.501 1.9 20 1 2 2 5.36799 16.501 1.9 21 2 3 1 5.14575 17.219 0.8 22 3 2 1 5.14575 17.219 0.8 23 4 0 0 5.03670 17.594 2.4 24 0 4 0 4.98912 17.764 3.4 25 4 1 0 4.88356 18.151 0.4 26 2 2 2 4.88356 18.151 0.4 27 4 0 1 4.71570 18.803 0.1 28 3 1 2 4.61852 19.202 2.4 29 1 4 1 4.55547 19.470 0.3 30 4 2 0 4.49635 19.729 0.2 31 2 4 0 4.45787 19.901 0.5 32 3 3 1 4.45787 19.901 0.5 33 0 1 3 4.36632 20.322 3.0 34 1 0 3 4.36632 20.322 3.0 35 4 2 1 4.26355 20.818 5.0 36 1 1 3 4.26355 20.818 5.0 37 2 0 3 4.08941 21.715 1.1 38 4 3 0 4.01553 22.119 1.9 39 2 1 3 4.01553 22.119 1.9 40 4 1 2 3.94894 22.497 0.3 41 4 3 1 3.85926 23.027 30.6 42 5 0 1 3.85926 23.027 30.6 43 3 4 1 3.82578 23.231 23.6 44 0 5 1 3.82578 23.231 23.6 45 1 5 1 3.75861 23.652 10.4 46 3 0 3 3.72380 23.877 15.6 47 0 3 3 3.72380 23.877 15.6 48 3 1 3 3.65139 24.357 12.3 49 1 3 3 3.65139 24.357 12.3 50 5 2 1 3.59942 24.714 1.2 51 4 4 0 3.54454 25.103 0.1 52 3 2 3 3.48877 25.511 1.8 53 2 3 3 3.48877 25.511 1.8 54 4 3 2 3.44594 25.834 4.1 55 3 4 2 3.44594 25.834 4.1 56 5 1 2 3.40404 26.157 1.0 57 1 5 2 3.38191 26.332 0.8 58 0 0 4 3.35780 26.524 2.2 59 6 0 0 3.35780 26.524 2.2 60 5 3 1 3.34523 26.626 1.1 61 4 0 3 3.34523 26.626 1.1 62 0 6 0 3.32608 26.782 2.1 63 3 5 1 3.32608 26.782 2.1 64 6 1 0 3.31043 26.911 3.6 65 1 0 4 3.31043 26.911 3.6 66 5 2 2 3.26581 27.286 0.6 67 1 1 4 3.26581 27.286 0.6 68 6 0 1 3.25744 27.357 0.7 69 3 3 3 3.24744 27.443 1.2 70 2 5 2 3.24744 27.443 1.2 71 6 1 1 3.21490 27.726 0.1 72 2 0 4 3.18399 28.001 0.7 73 6 2 0 3.18399 28.001 0.7 74 4 2 3 3.17173 28.111 0.4 75 1 2 4 3.14203 28.383 1.2