Title of Invention

"A METHOD FOR THE PREPARATION OF MICROPOROUS CRYSTALLINE TITANIUM CONTAINING MOLECULAR SIEVER (TITANIUM SILICALITE-1)"

Abstract

A method for the preparation of microporous crystalline titanium silicate molecular sieve (TS-1) having a silicalite-1 structure comprising forming a precursor mixture by combining/ hydrolyzing a hydrolysable silica source which is tetraalkyl orthosilicate and ethyl silicate, a hydrolysable titanium source as herein described, a growth medium of nitrogen-containing organic base, a surfactant, water, with/without organic solvent, wherein starting mixture (clear solution) of ingredients has a molar composition of 0.02-0.15 tetrapropylammonium hydroxide: 0.05-0.0008 TiO2: SiO2: 29-50 H2O, and the ratio of surfactant to SiO2 ratio is in the range 0.04-0.005 stirring the clear pale greening sol up to 1 hour and by heating it at autogenous pressure at a temperature in the range 120-170°C over a period of 16 to 96 hours.

Full Text

FIELD OF INVENTION The present invention describes a method for the preparation of microporous crystalline titanium silicate molecular sieve (TS-1) having a silicalite-1 structure comprised of silicon and titanium oxide. The methods described herein are particularly helpful for the synthesis of titanosilicate (of silicalite-1 structure) particularly designated and referred to herein after as TS-1 In particular, the present invention describes of titanosilicate (TS-1) by using tetraethylorthosilicate/ethylsilicate as source of silica, tetrabutylorthotitanate (TBOT) as a source of titanium, much reduced quantity of tetrapropylammonium hydroxide (TPAOH) as template, in conjuction with a novel use of some surfactants to facilitate the incorporation of titanium in the silica matrix with enhanced degree of titanium incorporation and consequently improved yield and catalystic performance. BACKGROUND ®F INVENTION: In the prior art of titanosilicate (TS-1) has been prepared by the isomorphous substitution of silica by titanium in the ZSM-5 - silicalite framework. Synthesis of TS-1 was first reported by Taramasso et al. (Taramasso, M; Perego, G; and Notari, B; U.S. Patent 4,410,501,1983). This patent has reported a procedure in which TS-1 is synthesized at a temperature of 175°C in 10 days under autogenous pressure. Though the product obtained was characterized by XRD to evaluate the crystallinity of the product, no UV-VIS spectra are reported to show the absence of anatase which is highly probable impurity that is formed along with TS-1 in its preparation. The raw materials used for silica, titanium and templates are tetraethylorthosilicate (TEOS), tetrabutylorthotitanate (TBOT), and tetrapropylammonium hydroxide (TPAOH), respectively. Robert J. Saxton et al. (Robert J. Saxton, John G Zajaceck, U.S. Patent 5,688,484,1997) has reported a non-hydrothermal method of making titanium-containing zeolite. Though the procedure uses TEOS and TBOT as sources of silica and titanium, respectively, they used hexamethyleneimine in combination with n-tripropylamine as template. In addition to this, they added a highly corrosive, fuming and difficult to handle, pyridine-hydrogen fluoride in the gel preparation. Moreover, the procedures reported in the examples cited show that the method had the disadvantages of cooling of the precursor gel mixture to 0°C and very long crystallization period (4 to 90 days)., and crystallization temperature as high as 150°C. Thangraj et al. (A. Thangraj; MJ. Eapen; S. Sivasanker and P.Ratnasamy, Zeolites, 1992, vol 12, p. 943) had reported a procedure for the synthesis of TS-1 which a fully crystalline product is obtained by hydrothermal crystallization of a precursor mixture at 170°C for 24 hours using TPAOH as template, TEOS as source of silica and TBOT as source of titanium. Two other reports, Perogo et al. [Perego, G; Belussi, G; Corno, C; Taramasso, M; Buonomo, F. and Esposito, A; in New Developments in Zeolite Science and Technology (Eds. Y. Murakami et al.) Studies in Surface Science and Catalysis 1986,28,129] and Kraushaar, B. et al. (Kraushaar, B: Ph.D. Thesis, The Technical University of Eindoven, 1989) have reported essentially the same procedure as above for the synthesis of TS-1. All the above reported procedures of TS-1 synthesis require stringent specifications on impurity levels of Na, K, Br-, NH4OH, etc. in the reactants used especially in TPAOH. The limits of impurities are, Na Most of the studies on the different methods by researchers from universities and industries have attempted to optimize the synthesis of titanosilicate (TS-1) in terms of both the activity of the resulting catalyst and the efficiency and economic aspects of the methods, particularly in the reduction in the time and temperature of hydrothermal crystallization, improve in yield, etc. The major characterization tools by these studies include: (1) transformation from doublet reflection to a singlet reflection as a change from monoclinic symmetry (pseudo orthorhombic) (silicalite-1) to an effective orthorhombic (TS-1), (2) unit cell volume, (3) Infrared examination of a characteristic absorption band at about 960 cm-1,which is absent in silicalite, TiOa (rutile, anatase) and alkaline titanates, (4) BET sorption isotherm with O2 indicating typical behavior of a molecular sieve with a pore volume saturation capacity of 0.16-0.18 ml per gm., (5) DRUV-VIS spectra. Among the above five characterization tools, the last one showing a single peak around 200 nm in the range of 200-600 nm has been accepted to be the authentic proof of titanium substitution in the lattice. As has been mentioned in the previous sections that the TS-1 is a versatile catalyst for variety of industrially important chemical reactions, some of the reactions may tolerate extra-framework titanium along with framework titanium towards the catalytic activity. This has been taken as a proof of showing al the titanium present in the solid to be in the framework / lattice. In accordance with some of the critical reports (B. Notari, Microporous Crystalline Titanium Silicates, Advances in Catalysis, vol. 41, 1996, p. 253), all the titanium can have lattice titanium can have lattice incorporation only upto Si/Ti = 25 mol. In view of this it is highly speculative to be all the titanium in the lattice of the product with Si/Ti =12 (U.S. Patent 5,885,546), and 20 (U.S. Patent 6,991,678B2). It is also reported that input titanium in the reaction gel after crystallization appears in the (a) tetrahedral lattice species (-200 nm in UV-VIS), (b) hexa-coordinated (octahedral coordination with water molecules in the coordination sphere) or small hydrated oligomeric TiOx species (270-280 nm) and (c) anatase (~330 nm). In the prior art, TS-1 has been reported to be a potential high-tech catalyst, capable of catalyzing selective oxidation reactions such as aromatic hydroxylation, epoxidation of alkenes, oxidation of alkanes, alcohols, ammoxidation of cyclohexane using hydrogen peroxide as oxidant. These catalytic properties attach a significant importance to the TS-1 catalyst. TS-1 is generally prepared from tetraethylorthosilicate (TEOS) as a source of silica, tetrabutylorthotitanate (TBOT) as the source of titanium,, and tetrapropylammonium hydroxide (TPAOH) as source of template and alkalinity. All these chemicals are expensive and their stringent specifications, especially of TPAOH, make the catalyst exorbitantly costly. Continuous efforts are in progress to lower the cost of TS-1 so that that the catalyst cost would be affordable to make the chemical reactions to be industrially attractive. These efforts include lowering of reaction temperature, crystallization period, substitution of raw materials by economically less-expensive ones, for silica, titanium, and template, reduction in raw material quantities, modification of synthesis procedure, improvement of quality and yield by effective incorporation of titanium in the framework/lattice tetrahedral titanium using different alkaline medium, etc. OBJECTS OF INVENTION: An object of this invention is to propose an improved process for the production of crystalline microporous titanium silicate, TS-1. Another object of this invention is to propose an improved process for the production of crystalline microporous titanium silicate, TS-1 which is cost effective. Further objection of this invention is to propose an improved process for producing a catalyst with improved catalytic performance. Still further object of this invention is propose an improved process with improved yield. BRIEF DESCRIPTION OF THE INVENTION: According to this invention there is provided a method for the preparation of microporous crystalline titanium silicate molecular sieve (TS-1) having a silicalite-1 structure comprising forming a precursor mixture by combining/hydrolyzing a hydrolysable silica source which is tetraalkyl orthosilicate and ethyl silicate, a hydrolysable titanium source as herein described, a growth medium of nitrogen-containing organic base, a surfactant, water, with/without organic solvent, wherein starting mixture (clear solution) of ingredients has a molar composition of 0.02-0.15 tetrapropylammonium hydroxide: 0.05-0.0008 TiO2: SiO2: 29-50 H2O, and the ratio of surfactant to SiO2 ratio is in the range 0.04-0.005 stirring the clear pale greening sol up to 1 hour and by heating it at autogenous pressure at a temperature in the range 120-170°C over a period of 16 to 96 hours. A process, in accordance with the present invention, provides a preparation of microporous crystalline titanosilicate (TS-1) with silicalite-1 structure having chemical composition expressed in the formula SiO2:xTiO2 wherein x ranges in SOxlO"3 to 8xlO~3, comprising of (i) adding dilute mieeller solution to the organic template, and stirred for half an hour to form a foamed clear solution. (ii) to above formulated solution silica a source is added slowly, drop wise within half an hour, further stirring for 1 hour to get a clear solution in which the silica to organic base ratio ranges between 0.02 to 0.015. (iii) adding a source of titanium diluted with organic solvent slowly within half an hour to obtain a transparent yellowish/light green solution by stirring for 1 hour. (iv) treating hydrothermally the above solution in closed autoclave / reactor at autogeneous pressure at a temperature in the range of 120 to 170 °C for a period of 16 to 72 hours. (v) separating the resultant solid material with / without ammonium nitrate solution treatment by suction filtration using Nutsch filter or centrifuge, drying, calcining the material in the range of 120 to 550°C in the presence of flowing air to obtain desired solid catalyst material. In one of the embodiment of the invention, the titanium source comprises of tetraalkylorthotitanate, preferably tetrabutylorthotitanate (TBOT). In another embodiment, the miceller / surfactant, of high molecular weight polymers including polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, and polycarboxylic ether, but were not limited to these were used. In an embodiment of present invention, the organic base comprises of aqueous quaternary ammonium hydroxide, preferably tetrapropylammonium hydroxide (TPAOH). In an embodiment, the silica source used include ethylsilicate (EtSi) and tetraethylorthosilicate (TEOS). In another embodiment the TEOS consists of mostly monomeric species. In yet another embodiment, the EtSi used, contained upto 40 wt% silica in the form of oligomeric / polymeric species of orthosilicates. i In another embodiment, the organic solvent used is the alcohol containing 2 to 4 carbon atoms. In another embodiment, the alcohol choice is from the groups consisting ethyl, propyl, butyl. In yet another embodiment, TPAOH to SiO2 ratio used is preferably 0.08. In yet another embodiment, the starting mixture (clear solution) of ingredients has a molar chemical composition of 0,02-0.15 TPAOH : 0.05-0.0008 TiO2 : SiO2 : 29-50 H2O. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig.l Summarizes the IR spectra for different framework vibrations (absorption bands) showing distinctly characteristic IR absorption band around 960-970 cm"1 assigned to tetrahedral titanium in the Silicalite-1 framework. Fig.2 It clearly shows well defined spherical crystalline habit with crystallites of uniform size ranging in 0.15-0.2 micron. Fig.3 Depicts the DRS-UV-Vis spectra for the typical TS-1 samples prepared in the present inventions. All the samples show a single peak around 200-220 nm as a conclusive evidence of titanium in the framework of Silicalite-1. DETAILED DESCRIPTION OF EMBODIMENTS: The present invention concerns mainly with the cost-effective process for the preparation of crystalline, microporous titanium silicate having Silicalite-1 structure. The process comprises of mixing slowly a clear solution of a hydrolysable source of silica with a surfactant diluted with water, stirred vigorously for some time, added slowly to this solution mixture is a clear solution of a hydrolysable titanium source diluted with an organic solvent, stirred vigorously over a sufficient length of time to get clear yellowish/light green solution, heated it in a closed autoclave at 120-170°C for less than 3 days., cooled it, separated white solid product by the conventional methods, washed it free of occluded species, dried and calcined the solid under programmed heating up to a temperature of 550°C., in the presence of flowing air. The chemical composition of the final titanium silicate (TS-1) in the anhydrous form is SiO2: xTiO2: where x According to the present invention, a hydrolysable source of silica is tetraethyl orthosilicate (>98% monomeric) and its replacement by much less expensive ethyl silicate (mixture of oligomers). In one of the embodiments of the present inventions, surfactants used are of the group of polyoxyethylene sorbitan monolaurate / monooleate, polycarboxylic ethers. The key function of these non-ionic species are (i) almost full incorporation of titanium in the framework by avoiding precipitation of extra-framework TiO2, (ii) facilitates the crystallization of TS-1 at much lower consumption of hazardous and highly expensive template, and thereby considerable reduction in the cost. In another embodiment of the inventions, the quaternary ammonium salt used as a template is a tetrapropyl ammonium hydroxide. The salient feature of the invention is the reduction up to 50% in the template quantity with N/Si (0.35 —> 0.18) for Si/Ti as low as 20, and from 0.18 -*• 0.05 for Si/Ti as high as 120 with the use of surfactants. The use of surfactants during preparation of final synthesis sol gives the freedom of not meticulously monitoring alcohol loss and its compensation. It tolerates alcohol to some extent during the hydrothermal crystallization. The resultant pH of the synthesis sol has to be > 9 and preferably >11, and is adjusted by the base aqueous solutions of tetrapropyl ammonium hydroxide. In one of the embodiments of the present invention, contrary to the prior art, the temperature at which the synthesis sol is prepared is essentially the ambient temperature. Thus it eliminates.the cooling of the solution of silica source and titanium source and heating of these two solutions before hydrolysis. The crystalline, microporous titanium silicate (TS-1) obtained in the final form in this invention is characterized by (i) X-ray powder diffraction (XRD) by Rigaku D-Max 2200 with CuKa (X = 1.5404 A) (ii) IR spectrum in the framework region (200-1200 cm"1) Using FTIR Specrometer Model Perkin Elmer Spectrum GX (iii) crystal habit and size by scanning electron micrograph Model JEOL JSM-6380LV and (iv) DRS-UV in the range of 200-600 nm using Model Labmda 19. Table 1 compares the XRD data for pure Silicalite and TS-1 (Table Remove) Table 1 8 The 26 values may vary by ± 0.05° b R.I.: Relative Intensity, vs: very strong, s: strong, m: medium, w: weak EXAMPLE 1 In this example, 809 g. of tetrapropyl ammonim hydroxide was mixed with 283 g. distilled, de-ionized water under stirring. 237 g. of ethylsilicate (ETSi, 40 wt% SiO2) was added to it and stirred for an hour. 27.8 g. titanium (IV) butoxide was mixed with 140 g. of isopropyl alcohol, which was added to the previous mixture and stirred for another hour to obtain a clear solution. The molar composition of the final sol was 20 SiO2: TiO2 : 10.1TPAOH : 28.9IPA : 654 H2O. The final sol was transferred into a stainless-steel autoclave and the hydrothermal crystallization was carried out at 160°C for 24 hours under stirring condition. After the crystallization was complete, the autoclave was cooled, and the contents were filtered / centrifuged, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.029 TiO2: 0.971 SiO2. EXAMPLE 2 In this example, 358 g. of tetrapropyl ammonim hydroxide (20 wt% solution in water) was mixed under stirring with 125 g. distilled, de-ionized water followed by the addition 150 g. tetraethyl orthosilicate (TEOS). The mixture was stirred for an hour and to it was added a mixture of 12.3 g. titanium (IV) butoxide and 62.2 g. of isopropyl alcohol. The clear solution was then further stirred for an hour before transferring into a stainless-steel autoclave under stirring. The hydrothermal crystallization was carried out at 160°C for 24 hours. The molar composition of the final sol was 20SiO2: TiO2: 10TPAOH : 29IPA : 653 H2O. After the crystallization was complete, the autoclave was cooled, and the contents were filtered / centrifuged, washed thoroughly with de-ionized water, and dried at 120°C for 16 hours and further calcined at 550°C in a flow of air for 12 hours. The molar composition of the organic free calcined material was 0.028 TiO2 : 0.972 SiO2. EXAMPLE 3 In this example, a solution of 40 g. of surfactant (polyoxyethylene sorbitan monolaurate) in 525 g. de-ionized water was prepared and mixed with 588 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring. Thereafter, 257 g. ethyl silicate was added with continuous stirring. The stirring was continued for an hour followed by the addition of a mixture of 30 g.titanium (IV) butoxide and 151 g. of isopropyl alcohol. The clear solution was then further stirred for an hour before transferring into a stainless-steel autoclave under stirring. The molar composition of the final sol was 20SiO2 : TiO2: 6.8TPAOH : 28.8IPA : 0.38 Surf: 647 H2O. The hydrothermal crystallization was carried out at 160°C for 24 hours. After the crystallization was complete, the autoclave was cooled, and the contents were filtered / centrifuged, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The XRD, IR, SEM and DRS-UV-Vis data are depicted in Table 1, and Fig. 1 to 3 respectively. The molar composition of the organic free calcined material was 0.028 TiO2 : 0.972 SiO2. EXAMPLE 4 In this example, 84 g. of surfactant (polyoxyethylene sorbitan monolaurate) was mixed with 647 g. de-ionized water and the solution was mixed with 1235 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring followed by the addition of 889 g. ethyl silicate. After stirring for an hour, a mixture of 63 g. titanium (IV) butoxide and 317 g. of isopropyl alcohol was added to previous mixture. The mixture was then further stirred for an hour to obtain a clear solution and transferred into a stainless-steel autoclave under stirring. The molar composition of the final sol was 33SiO2: TiO2: 6.7TPAOH : 28.8DPA : 0.38 Surf: 647 H2O. The crystallization of the sol was hydrothermally carried out at 160°C for 24 hours. The autoclave was cooled after the completion of the crystallization, and the contents were filtered, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and followed by calcination at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.020 TiO2: 0.980 SiO2. EXAMPLES In this example, a solution of 28.5 g. of surfactant (polyoxyethylene sorbitan monolaurate ) in 375 g. de-ionized water was prepared and mixed with 419 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring. 549 g of ethyl silicate was added to this mixture with continuous stirring. After stirring for an hour, a mixture of 21.4 g. titanium (IV) butoxide and 108 g. of isopropyl alcohol was added to the above solution. The clear solution was then further stirred for an hour and transferred into a stainless-steel autoclave. The molar composition of the final sol was 60 SiO2 : TiO2 : 6.8TPAOH : 29IPA : 0.4 Surf: 648 H2O. The hydrothermal crystallization was carried out at 160°C for 24 hours under stirring. After the crystallization was complete, the autoclave was cooled, and the contents were filtered, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.014 TiO2: 0.986 SiO2. EXAMPLE 6 In this example, 60 g. of surfactant (polyoxyethylene sorbitan monolaurate) was mixed with 801 g. de-ionized water and the solution was mixed with 896 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring followed by the addition of 1560 g. ethyl silicate After stirring for an hour, a mixture of 46 g. titanium (IV) butoxide and 230 g. of isopropyl alcohol was added to previous mixture. The mixture was then further stirred for an hour to obtain a clear solution and transferred into a stainless-steel autoclave under stirring. The molar composition of the final sol was 80 SiO2: TiO2: 6.7TPAOH : 28.8IPA : 0.38 Surf: 650 H2O. The crystallization of the sol was hydrothermally carried out at 160°C for 24 hours. The autoclave was cooled after the completion of the crystallization, and the contents were filtered, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and followed by calcination at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.0116 TiO2: 0.9884 SiO2. EXAMPLE 7 In this example, a solution of 9.7 g. of surfactant (polyoxyethylene sorbitan monolaurate) in 128 g. de-ionized water was prepared and mixed with 143 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring. 374 g ethyl silicate was added to it and after stirring for an hour, a mixture of 7.3 g. titanium (IV) butoxide and 37 g. of isopropyl alcohol was added and the clear solution was then further stirred for an hour and transferred into a stainless-steel autoclave. The molar composition of the final sol was 120SiO2 : TiO2 : 6.8TPAOH : 28.9IPA : 0.4 Surf: 647 H2O. The hydrothermal crystallization was carried out at 160°C for 24 hours under stirring. After the crystallization was complete, the autoclave was cooled, and the contents were filtered, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.0083 TiO2 :0.9917 SiO2. EXAMPLE 8 In this example, a solution of 98.4 g. of surfactant (polyoxyethylene sorbitan monolaurate ) in 201 g. de-ionized water was prepared and mixed with 226 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring followed by the addition of 98.4 g ethyl silicate. The stirring was continued for an hour followed by the addition of a mixture of 11.5 g.titanium (IV) butoxide and 71 g. of isobutyl alcohol. The clear solution was then further stirred for an hour before transferring into a stainless-steel autoclave under stirring. The molar composition of the final sol was 20SiO2: TiO2: 6.7TPAOH : 29IBA : 0.4 Surf: 647 H2O. The hydrothermal crystallization was carried out at 160°C for 24 hours. After the crystallization was complete, the autoclave was cooled, and the contents were filtered / centrifuged, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The molar composition of the organic free calcined material was 0.028 TiO2: 0.972 SiO2. EXAMPLE 9 In this example, a solution of 40 g. of surfactant (polyoxyethylene sorbitan monolaurate) in 525 g. de-ionized water was prepared and mixed with 588 g. tetrapropyl ammonim hydroxide (20 wt% solution in water) under stirring. Later, 257 g. ethyl silicate was added and stirring was continued for an hour followed by the addition of a mixture of 30 g. titanium (IV) butoxide and 151 g. of isopropyl alcohol. The clear solution was then further stirred for an hour before transferring into a stainless-steel autoclave under stirring. The molar composition of the final sol was 20SiO2 : TiO2: 6.8TPAOH : 28.8IPA : 0.38 Surf: 647 H2O. The hydrothermal crystallization was carried out at 140°C for 28 hours. After the crystallization was complete, the autoclave was cooled, and the contents were filtered / centrifuged, washed thoroughly with de-ionized water, and dried at 120°C for 12 hours and further calcined at 550°C in a flow of air for 16 hours. The XRD, IR, SEM and DRS-UV-Vis data are depicted in Table 1, and Fig. 1 to 3 respectively. The molar composition of the organic free calcined material was 0.029 TiOa : 0.971 SiC>2. EXAMPLE 10 In this example, catalytic activity of titanium silicate was determined by the oxidation of allyl alcohol to glycidol using hydrogen peroxide as the oxidizing agent. 0.07 g. of calcined TS-1 powder with silicon to titanium molar ratio 35 was taken in a round-bottom flask along with 0.6 g. allyl alcohol and 5 ml. methanol. The mixture was then stirred and temperature was raised to 60°C. 1.1 g hydrogen peroxide (30 wt % solution in water) was added to the mixture under agitation, and the reaction was carried out for an hour. Products were separated by filtration and analyzed by gas chromatography. Conversion of allyl alcohol to glycidol and selectivity of glycidol was determined from the product analysis. Conversion of % hydrogen peroxide was determined by direct titration of reaction samples with Cerium sulphate solution. The results of the catalytic activity are summarized in Table 2. EXAMPLE 11 In this example, 0.1 g. of calcined TS-1 powder with silicon to titanium molar ratio 35 was taken in a round-bottom glass flask along with 0.9 g. allyl alcohol and 8 ml. methanol. The mixture was then stirred and temperature was raised to 60°C. 1.7 g hydrogen peroxide (30 wt % solution in water) was added to the mixture under agitation, and the reaction was carried out for an hour. Products were separated by filtration and analyzed by gas chromatography. EXAMPLE 12 In this example, 0.07 g. of calcined TS-1 powder with silicon to titanium molar ratio was taken 45 in a round-bottom flask followed by the addition of 0.6 g. allyl alcohol and 5 ml. methanol. The mixture was then stirred and temperature was raised to 60°C. 1.1 g hydrogen peroxide (30 wt % solution in water) was added to the mixture under agitation, and the reaction was carried out for an hour. Products were separated by filtration and analyzed by gas chromatography. Table 2 (Table Remove) (*) Based on the absence/presence of a peak due to extra-framework titanium species in the DRUV-VIS spectra WE CLAIM: 1. A method for the preparation of microporous crystalline titanium silicate molecular sieve (TS-1) having a silicalite-1 structure comprising forming a precursor mixture by combining/hydrolyzing a hydrolysable silica source which is tetraalkyl orthosilicate and ethyl silicate, a hydrolysable titanium source as herein described, a growth medium of nitrogen-containing organic base, a surfactant, water, with/without organic solvent, wherein starting mixture (clear solution) of ingredients has a molar composition of 0.02-0.15 tetrapropylammonium hydroxide: 0.05-0.0008 TiO2: SiO2: 29-50 H2O, and the ratio of surfactant to SiO2 ratio is in the range 0.04-0.005 stirring the clear pale greening sol up to 1 hour and by heating it at autogenous pressure at a temperature in the range 120-170°C over a period of 16 to 96 hours. 2. The process as claimed in claim 1, where in the surfactant is selected from the family polyoxyethylene sorbitan monolaurate/monooleate, polycarboxylic ether. 3. The process as claimed in claim 1, wherein the titanium source comprises of titanium alkoxide (preferably) titanium IV butoxide). 4. The process as claimed in claim 1, wherein the growth medium is de-ionized water containing tetrapropyl ammonium hydroxide, butanol, isopropanel, ethanol and surfactant. 5. The method as claimed in claim 1, wherein the final solution mixture was essentially carried out at ambient temperature.

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2608-DEL-2006-Abstract-(09-03-2012).pdf

2608-DEL-2006-Abstract-(18-01-2012).pdf

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