The present invention relates to a photocatalytic process for oxidation of aromatic hydrocarbons. More particularly, the present invention relates to a process for oxidation of aromatic hydrocarbons using noble metal deposited vanadium-titania composite catalyst with high selectivity and yield of corresponding oxidized product at ambient conditions.

BACKGROUND AND PRIOR ART OF THE INVENTION

Photocatalysis plays an important role to solve some of the environmental issues. Among most of the semiconductor photocatalysts, Ti0 ₂ plays a major role due to its extraordinary chemical stability by minimizing photocorrosion and its high oxidizing ability through holes produced upon light absorption. Benzene oxidation to phenol by photocatalysis is one of the important reactions attempted by many researchers, but without significant breakthrough. Direct oxidation of benzene through cumene process is currently practiced harsh method for the production of phenol which involves three steps; wherein benzene and propylene are compressed to a pressure of 30 bar at 250°C, in the presence of a acid catalyst, such as phosphoric acid. The disadvantage of above synthesis process is formation of cumene-hydroperoxide, which is an explosive and acetone as a side product. Idc et al in J. Am. Chem. Soc, 2010, 132, 16762-16764 reports a process for the synthesis of phenol with improved yield and selectivity, but it suffers from the disadvantage in that the process necessarily requires a seed of the product and works well at very low reactant concentrations, but not at normal laboratory scale of 1 -10 ml or at industrial scale. 62% yield and with 96% phenol selectivity for photocatalytic benzene oxidation in visible light with layered titanate containing immobilized gold nanoparticles in the interlayer space is reported. However, the above result is possible only when the initial amount of benzene is few hundred ppm (x) but in the presence of large excess of seed amount of phenol (lOx or 30 x).When there is no seed amount of phenol added, no phenol production was observed. Ide et al in Chem. Commun., 2011, 47, 1 1531-11533 also reported benzene oxidation over Au/Ti0 ₂ with 13% yield and 89% phenol selectivity after 24 h under C0 ₂ atmosphere (230 kPa) under 1-sun irradiation conditions.

Zhang ct al in J. Am. Chem. Soc, 2009, 131, 11658-1 1659 produced good results for phenol synthesis with improved yield, but catalyst synthesis is difficult. Fe doped g- carbon nitride coated on SBA-15 was the catalyst used, which exhibited 1 1.9% benzene conversion with 20.7% phenol selectivity at 60°C in visible light.

Article titled "Facile in situ synthesis of visible-light plasmonic photocatalysts Μ@ΊΪ0 ₂ (M = Au, Pt, Ag) and evaluation of their photocatalytic oxidation of benzene to phenol" by Z Zheng et al. published in J. Mater. Chem., 201 1 ,21, pp 9079- 9087 reports a facile in situ method of preparing noble-metal plasmonic photocatalysts M@Ti0 ₂ (M = Au, Pt, Ag) and the synthesis leads to a homogeneous loading of noble-metal nanoparticles on the surface of Ti0 ₂ particles, which allows photocatalytic reactions to take place under visible-light on the whole Ti0 ₂ surface. The photocatalysts M@Ti0 ₂ (M = Au, Pt, Ag), Au@Ti0 ₂ exhibits a high yield (63%) and selectivity (91%) for the oxidation of benzene to phenol in aqueous phenol. Zheng ct al. follows the same procedure as that of Ide et al. (J. Am. Chem. Soc, 2010, 132, 16762-16764) to evaluate benzene oxidation with few hundred ppm of benzene.

Article titled "Multi transition metal catalysts supported on Ti0 ₂ for hydroxylation of benzene to phenol with hydrogen peroxide" by H Yamada et al. published in Journal of Industrial and Engineering Chemistry, 2007, 13 (5), pp 870-877 reports liquid phase hydroxylation of benzene to phenol with hydrogen peroxide catalyzed by multi transition metals (Fe (III), V (V), and Cu (II)) supported on Ti0 ₂ at room temperature. This reports focuses on the effects of second and third metal loading on the reaction performance. Bi- and tri-metal oxide catalysts showed obviously higher benzene conversion and phenol yield than single metal Fe supported on Ti0 ₂ , and the best phenol yield obtained is 9.7 %. Article titled "Nanosize gold catalysts promoted by vanadium oxide supported on titania and zirconia for complete benzene oxidation" by D Andrceva et al. published in Applied Catalysis A: General, 2001 , 209 (1-2), pp 291-300 reports complete benzene oxidation reaction using Au-V ₂ 0 ₅ / ^r ri0 ₂ and Au-V ₂ 0 ₅ /Zr0 ₂ catalytic systems. They reports the strong synergistic effect between gold and vanadia was established when molecular oxygen was used as an oxidizing agent.

Article titled "Gold supported catalysts on titania and ceria, promoted by vanadia or molybdena for complete benzene oxidation" by R Nedyalkova et al. published in Materials Chemistry and Physics, 2009; 1 16(1), pp 214-218 reports the catalytic activity in complete benzene oxidation (CBO) to C0 ₂ over gold catalysts supported on titania and ceria. They also reports addition of either vanadia or molybdena as promoter was applied and conclude that gold catalysts supported on ceria exhibit higher activity than those supported on titania.

Article titled "Complete benzene oxidation over gold-vanadia catalysts supported on nanostructured mesoporous titania and zirconia" by V Idakiev et al. published in Applied Catalysis A: General, 2003, 243 (1), pp 25-39 reports the new generation of gold-vanadia catalysts supported on mesoporous titania and zirconia for complete benzene oxidation to C0 ₂ . They also reports the presence of gold enhanced the V ⁵⁺ →V ³⁺ reduction step and depending on the preparation method, differences in the reduction behavior were established.

Article titled "The oxidative destruction of hydrocarbon volatile organic compounds using palladium-vanadia-titania catalysts" by T Garcia et al. published in catalysis Letters, August 2004, Volume 97, Issue 1-2, pp 99-103 reports a range of titania supported palladium catalysts modified by the addition of vanadium and tested for the total oxidation of short chain hydrocarbons to C0 ₂ . The addition of vanadium decreased the palladium dispersion, but temperature programmed reduction studies showed that the combination of palladium with vanadium dramatically increased the ease of catalyst reduction. The prior art processes shows poor yield and selectivity. Further, there are side products formation on prolonged light exposure under photocatalysis conditions. Therefore, to overcome prior art drawbacks there is a need in the art to provide a simple process for the oxidation of aromatic hydrocarbons with higher yield and selectivity preferably at ambient conditions.

OBJECTIVE OF INVENTION

The main objective of present invention is to provide a photocatalytic process for the oxidation of aromatic hydrocarbons with high yield and selectivity using noble metal deposited vanadium-titania composite catalyst.

Another objective of present invention is to provide a photocatalytic process for the oxidation of benzene to phenol with high yield and selectivity using gold deposited vanadium-titania composite catalyst. SUMMARY OF THE INVENTION

Accordingly, present invention provides a photocatalytic process for oxidizing aromatic hydrocarbons comprising the steps of:

i. treating 1 to 30% aromatic hydrocarbon with an aqueous 10 to 30% hydrogen peroxide solution and 10 to 50% C¾CN in presence of 0 to 2 % noble metal deposited vanadium-titania composite catalyst to obtain a reaction mixture;

ii. irradiating the reaction mixture as obtained in step (i) for period in the range of 6-18 hours at room temperature in the range of 25 to 30°C under UV-visible light source of 400 watts at > 200 nm in presence of solvent followed by filtering to obtain to obtain oxidized product;

In an embodiment of the present invention, aromatic hydrocarbon used arc selected from the group consisting of benzene, toluene, naphthalene, xylene and the like.

In another embodiment of the present invention, solvent used is selected from acetonitrile.

In yet another embodiment of the present invention, the noble metal is selected from the group consisting of Au, Ag, Cu,Co, Pd, Ir, Pt and such like and combinations thereof. In yet another embodiment of the present invention, noble metal deposited vanadium- titania composite catalyst is preferably selected from lAu/TV2, Cuo. ₅ Pdo. ₅ /TV2, Au+Ag/TV2, Au+Ag+Pt/TV2, lAg/TV2, Pt-Cu/TV2, Cu+Pd/TV2. ABBREVIATIONS USED

1 Au/TV2: Gold deposited vanadium-titania composite catalyst

'fV2: Vanadium-titania composite

1 Ag/TV2: Silver deposited vanadium-titania composite catalyst

Cu ₀ .5/Pdo.5 TV2: Cu and Pd deposited vanadium-titania composite catalyst

Au+Ag/TV2: Au and Ag deposited vanadium-titania composite catalyst

Au+Ag ⁽ -PI/TV2: Au, Ag and Pt deposited vanadium-titania composite catalyst Pt-Cu/TV2: Pt and Cu deposited vanadium-titania composite catalyst

Cu+Pd/TV2: Cu and Pd deposited vanadium-titania composite catalyst BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1: XRD pattern of different materials, namely, Ti0 ₂ , TV2, lAu/TV2, and 3Au/TV2. Inset shows the low angle XRD pattern, indicating the disordered mesoporous nature. lAu and 3Au indicates the weight percent of gold deposited on titania.

Fig. 2: (a) N ₂ adsorption-desorption isotherm, and (b) pore size distribution pattern of Ti0 ₂ TV2 and Au/TV2materials.

Fig. 3: TEM images of a) TV2, b-c) Au/TV2, HRTEM images of d) lAu/TV2, e) 3Au/TV2, and f) SEM image of lAu/TV2. Abundantly available direct p-n heteroj unctions between (111) facets of nano Au cluster and (101) facets of titania particles are shown in d and e. SAED pattern given in panel d shows (101) is the major facet of Ti0 ₂ exposed on the surfaces.

Fig. 4: UV irradiation time dependence of photocatalytic benzene oxidation results for, (a) benzene conversion and phenol selectivity with TV2, and (b) phenol yield with TV2. (c) Phenol yield observed with TV2, lAu/TV2 and 3Au/TV2 after 18h UV irradiation. DETAILED DESCRIPTION OF THE INVENTION

Present invention provides a photocatalytic process for the oxidation of aromatic hydrocarbons with high yield and selectivity using noble metal deposited vanadium- . titania composite catalyst.

the present invention provides a photocatalytic process for the oxidation of benzene to phenol with high yield and selectivity using gold deposited vanadium-titania composite catalyst.

The present invention provides a photocatalytic process for the oxidation of aromatic hydrocarbons with high yield and selectivity using noble metal deposited vanadium- titania composite catalyst.

The photocatalytic process for oxidizing aromatic hydrocarbons with high yield and selectivity comprises treating said aromatic compound with an aqueous hydrogen peroxide solution in presence of noble metal deposited vanadium-titania composite catalyst followed by irradiating the reaction mixture for 6-18 hours under UV-visible light source of 400 watts at > 200 nm, wherein irradiation is done in presence of solvent.

The aromatic hydrocarbons are various substituted and/or branched hydrocarbons and their isomers.

The aromatic hydrocarbons are selected from benzene, toluene, naphthalene, xylene and the like.

The present invention provide an electronically integrated nanocomposite composition ABC, wherein A is selected from oxides of transition metals, preferably Ti, Fe, Zn, B is an metal cation, selected from V, Mn, Co, Fe, Cr , and C is selected from metals, preferably Au, Ag, Pt, Pd, Cu. In an embodiment of ABC, C may have more than one component and up to three components, such as Au+Ag, Au+Cu, Au-i-Ag-t-Pt. Similarly, B may have more than one component up to three components, such as V + Co, V + Mn + Co.

The noble metal is selected from Au, Ag, Cu, Co, Pd, Ir, Pt and such like and combinations thereof. The metal-ion in the metal-titania composite comprises a transition metal, alone or in combinations thereof. The transition metal are selected from Mn, Co, Fe, Cr, V, and such like and combinations thereof. The noble metal selected from Au, Ag, Cu, Co, Pd, Ir, Pt and such like and combinations thereof.

The noble metal deposited vanadium-titania composite catalyst is preferably selected from 1AU TV2, Cu ₀ . ₅ /Pd ₀ .5/TV2, Au+Ag/TV2, Au+Ag+Pt/TV2, lAg/TV2, Pt- Cu/TV2, Cu+Pd/TV2.

The present invention provides a photocatalytic process for the oxidation of benzene to phenol with high yield and selectivity using gold deposited vanadium-titania composite catalyst.

The photocatalytic process for oxidation of benzene to phenol comprises treating benzene with an aqueous hydrogen peroxide solution in presence of gold deposited vanadium-titania composite catalyst followed by irradiating for 18 hours under UV- visiblc light source of 400 watts at > 200 nm wherein irradiation is done in presence of acetonitrilc.

The catalyst is characterized to confirm the mesoporousnanocrystalline material, as seen in XRD. The UV absorption isotherm confirms mesoporosity, pore size distribution and pore volume specified. With reference to fig 1, PXRD pattern of all materials is found to match with that of anatase phase (JCPDS 21-1272). No peaks that corresponds to oxides of vanadium are observed which indicates that Ti0 ₂ and TV2 retain the anatase phase with no V ₂ 0 ₅ phase. No V2O5 formation in TV2 indicates the potential of SCM method to introduce V into the Ti0 ₂ lattice. Broad nature of the peaks confirms the presence of nanocrystalline particles. No peaks were observed for metallic Au in lAu/TV2 and 3Au/TV2, which indicates high dispersion of Au onTV2.The respective average crystallite size, calculated from peak width with Scherrer equation, is observed to be between 8-12 nm. Inset in Fig. 1 shows the low angle XRD pattern. A single diffraction peak is observed around 0.8 demonstrates the mesoporous nature of the Tii _-x V _x 0 ₂ materials. Unlike ordered mesoporous materials, such as SBA-15 and MCM-48, all TV2 and titania materials exhibit only one peak around 0.8° without any extra peaks. This highlights the presence of disordered mesoporosity for all TV2 materials.

The N ₂ adsorption-desorption studies has been carried out to investigate the textural properties of mcsoporousTi0 ₂ , TV2,lAu/TV2 and 3Au TV2 materials. Fig 2a shows N ₂ adsorption-desorption isotherm studies measured at 77 and analysed by BET method for surface area, and (b) Barret- Joyner-Halenda (BJH) pore size distribution of Ti0 ₂ and all TV2 materials. Surface area and porosity have been calculated for all of the materials and the results are given in Table 1. All TV2 materials show a type IV adsorption-desorption isotherm with H2 hysteresis loop which clearly indicates presence of mesopores. The average pore size distribution in the range of 4.5±2 nm and overall pore volume 0.26±0.02 cc g ^'1 is observed.TV2exhibits high surface area (166 m ² g ^" ') than Ti0 ₂ (1 17 m ² g ^~ '). However, when gold is introduced on the surface of TV2, surface area decreased marginally than that of TV2. Due to high dispersion of gold nanoparticlcs on TV2 the surface area of Au _3x /TV2 (151 m ² g-') is similar to that of Au _x /TV2 ( 156 m ² g ^' ').The pore size distribution profile indicates the presence of mesopores in all of the catalysts. A significant shift in pore size towards lower value is evident for 3Au/TV2 (Fig. 2b) highlighting the introduction of gold nanoclusters in pores too. HRTEM and SE : Morphology and textural properties of TV2 and Au/TV2 materials were analyzed by HRTEM and SEM and representative images are shown in Fig 3. Generally TV2 and lAu/TV2 (and Ti0 ₂ , not shown) exhibits spherical particles and a disordered mesoporous structure (Fig. 3a-c).TV2 and Au/TV2materials shows similar textural characteristics as that of Ti0 ₂ . Disordered mesoporosity arises due to the intergrowth of fundamental particles and the same leads to aggregates with significant extra framework void space. Nanocrystalline nature and anatase phase of the materials were confirmed by selected-area electron diffraction (SAED) pattern. HRTEM shows the particle size of around 14 nm with d-spacingof 0.35 nm which corresponds to (101) plane of the Ti0 ₂ . These results are well supported with XRD as well as with N ₂ adsorption isotherm results. The disordered mesoporous structure has additional advantages like low diffusional barriers, since the depth of mesopores are minimum to a few nanometers, unlike several hundred nanometers in conventional ordered mesoporous materials, like SB A- 15. These types of mesopores are known as pseudo 3D(p3D) mesopores. This disordered ρ3Ό mesoporous framework provides an easy route for the diffusion of reactants due to less diffusion barriers as well as small diffusion length due to low meso channel depth. Fig 3b demonstrates the particles are electrically interconnected together which helps for fast mobility of charge carriers to the surface of catalyst where the reaction could occur. The presence of gold is clearly visible by HRTEM (Figs. 3b and c). The d-spacing measured is 0.24 nm which correspons to (1 11) plane of metallic Au. Gold particle size is about 7-8 nm. Very importantly, Au-Ti0 ₂ heteroj unction is observed easily with Au TV2; (11 1) facets of nano gold is in direct contact with (101) facets of titania is shown in Pigs. 3d-e. Indeed this is a criticial and necessary feature of Au/TV2 catalysts that is essential to separate the charge carriers and hence enhances the diffusion of charge carriers towards the surface of the catalysts from the bulk. Both V and Au acts as electron trapping centers, and hence the extent of hole utilisation increases significantly. This also leads to a decrease in charge recombination. In fact, this observation is in good agreement with PL results, which show an increase in energy transfer and hence increase in emission features than TV2.

Tabic 1: Physicochemical properties of Ti0 ₂ , TV2 and Au/TV2 catalysts

Figure 4a-b shows the photocatalytic activity measured with TV2 catalyst at different time intervals for benzene to phenol oxidation under UV irradiation. Fig 4c shows the phenol yield observed with TV2 and Au/TV2 catalysts after 18 h irradiation. TV2 shows 3% benzene conversion with 100% selectivity after 6h irradiation. Benzene conversion increased linearly from 3 to 13% with increasing irradiation time from 6 to 24 h, respectively; however, a decrease in phenol selectivity (100 to 85%, Table 2) is also observed. Table 2 displays a set of benzene oxidation results with different catalysts using UV + visible light irradiation. lAu/TV2 (TV2) gives 18% (9%) benzene conversion and 16% (8.2%) phenol yield after UV irradiation for 18 h. A simple doubling of catalytic activity after gold deposition highlights the importance of Au in selectively separating and storing electrons from electron-hole pairs. Tabic 2: Photocatalytic benzene oxidation

Catalyst with high concentration of Au (3Au/TV2) gives low benzene conversion (5 %) and phenol yield (4.5 %); these results are reproduced with catalysts prepared in same and different batches. Low activity observed with 3Au/TV2 is attributed to two reasons, namely, the formation of large gold clusters on TV2due to large gold deposition (lug. 3e). Further, large amount of gold also hinders the light absorption and hence the extent of light utilization becomes relatively low. This reiterates the necessity of optimum amount of gold.

EXAMPLES

Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention. Example 1 : Synthesis of V doped Ti0 ₂ catalyst

The synthesis of V-doped Ti0 ₂ catalyst was carried with 1 : 1 molar ratio of urea to total metal ions (Ti + V).In a typical synthesis procedure, 0.04 molar concentration of titanium tetra isopropoxide was hydrolyzed with distilled water then the precipitate obtained was added to 7.5 ml HN0 ₃ and 10 ml distilled water. To the above solution, 2Wt% of ammonium metavanadate and lg of urea were added. All reactants were taken in a 250 ml beaker and the aqueous solution was stirred for lh, followed by introduction of the above solution in the beaker into a muffle furnace maintained at 400°C. Evaporation of water starts in the beginning followed by flameless combustion results in a solid powder material. Similarly synthesis of Ti0 ₂ was carried out by following the above procedure but without adding any vanadium precursor.

Example 2: synthesis of Cr doped Ti0 ₂ catalyst

The synthesis of Cr-doped Ti0 ₂ catalyst was carried with 1 : 1 molar ratio of urea to metal ions (Ti + Cr).In a typical synthesis procedure, 0.04 molar concentration of titanium tetra isopropoxide was hydrolyzed with distilled water then the precipitate obtained was added to 7.5 ml HN0 ₃ and 10 ml distilled water. To the above solution, 0.5 Wt % of chromium nitrate nonahydrate and lg of urea were added. All reactants were taken in a 250 ml beaker and the aqueous solution was stirred for lh, followed by introduction of the above solution in the beaker into a muffle furnace maintained at 400 ^° C. Hvaporation of water starts in the beginning followed by flameless combustion results in a solid powder material. The above resulting catalyst materials is named has TCrO.5.

Example 3: synthesis of Mn doped Ti0 ₂ catalyst

The synthesis of Mn-doped Ti0 ₂ catalyst was prepared with 1 : 1 molar ratio of urea to metal ions (Ti + Mn). In a typical synthesis procedure, 0.04 molar concentration of titanium tetra isopropoxide was hydrolyzed with distilled water then the precipitate obtained was added to 7.5 ml HNO3 and 10 ml distilled water. To the above solution, 1 Wt% of manganese nitrate and 1 g of urea were added. All reactants were taken in a 250 ml beaker and the aqueous solution was stirred for lh, followed by introduction of the above solution in the beaker into a muffle furnace maintained at 400°C. Evaporation of water starts in the beginning followed by flameless combustion resulting in a solid powder material. The final obtained catalyst was named has TMnl .

Example 4: Synthesis of Co doped Ti0 ₂ catalyst

The synthesis of Co-doped Ti0 ₂ catalyst was carried with 1 : 1 molar ratio of urea to metal ions (Ti + Co).In a typical synthesis procedure, 0.04 molar concentration of titanium tetra isopropoxide was hydrolyzed with distilled water then the precipitate obtained was added to 7.5 ml HNO3 and 10 ml distilled water. To the above solution, 2Wt% of cobalt nitrate and lg of urea were added. All reactants were taken in a 250 ml beaker and the aqueous solution was stirred for lh, followed by introduction of the above solution in the beaker into a muffle furnace maintained at 400°C. Evaporation of water starts in the beginning followed by flameless combustion results a solid powder material. The final obtained catalyst was named has TCo ₂ . Example 5: V + Mn doped Ti0 ₂ catalyst

The synthesis of V + Mn doped Ti0 ₂ catalyst was carried with 1 : 1 molar ratio of urea to metal ions (Ti + V + Mn).In a typical synthesis procedure, 0.04 molar concentration of titanium tetra isopropoxide was hydrolyzed with distilled water then the precipitate obtain was added to 7.5 ml HN0 ₃ and 10 ml distilled water. To the above solution, lWl% of manganese nitrate, 1 Wt % of ammonium metavanadate and lg of urea were added. All rcactants were taken in a 250 ml beaker and the aqueous solution was stirred for lh, followed by introduction of the above solution in the beaker into a muffle furnace pre-heated at 400 °C. Evaporation of water starts in the beginning followed by flameless combustion results a solid powder material. The final obtained catalyst was named has TVMn.

Example 6: Deposition of gold

Gold deposition was carried by photodeposition method using HAuCl as the gold precursor. In a 250 ml quartz round bottom flask, 30 ml of 0.0005M HAuC was taken in 120 ml of MeOH with 500mg of catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ = 200-400 nm). After photo deposition powder sample was separated by centrifugation and finally the Au deposited powder sample was dried at 40 ^° C for 12 h. This was named as named as 1 Au/TV2. ICP analysis showed the Au-content to be 0.95 wt%.

Example 7: Deposition of copper

Copper deposition was carried by photodeposition method using copper nitrate as the copper precursor. In a 250 ml quartz round bottom flask, 30 ml of 0.5wt% of Copper nitrate was taken in 120 ml of MeOH with 500mg of catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ ~ 200-400nm). After photo deposition powder sample was separated by centrifugation and finally the Cu deposited powder sample was dried at 40 ^° C for 12 h. This was named as named as 3Cu/TV2. ICP analysis showed the Cu-content to be 2.96wt%.

Example 8: Deposition of Ag

Silver deposition was carried by photodeposition method using AgN0 ₃ as the silver precursor. In a 250 ml quartz round bottom flask, 30 ml of lwt% of AgN0 ₃ was taken in 120 ml of MeOH with 500 mg of catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ = 200- 400nm). After photo deposition powder sample was separated by centrifugation and finally the Ag deposited powder sample was dried at 40°C for 12 h. This was named as named as 1 Ag/TV2. ICP analysis showed the Ag-content to be 0.95 wt%.

Example 9: Deposition of Pt on Cu/TV2

Platinum deposition was carried by photodeposition method using platinum ammonium chloride as the Pt precursor. In a 250 ml quartz round bottom flask, 30 ml of 0.5 wt% of NH ₄ PtCl ₄ was taken in 120 ml of MeOH with 500 mg of Cu/TV2 catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ = 200-400nm). After photo deposition powder sample was separated by centrifugation and finally the Pt deposited Cu/TV2 (namely Pt-Cu/TV2) powder sample was dried at 40°C for 12 h. ICP analysis showed the Pt-content to be 0.45wt%. Example 10: Deposition of Cu and Pd

Copper and palladium deposition was carried by photodeposition method using Copper nitrate as the copper precursor and palladium chloride as the Pd precursor. In a 250 ml quartz round bottom flask, 30 ml of 0.5wt% of Copper nitrate and 0.5wt% of PdCl ₂ were taken in 120 ml of MeOH with 500 mg of catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ = 200-400nm). After photo deposition powder sample was separated by centrifugation and finally the Cu and Pd deposited powder sample was dried at 40°C for 12 h. This was named as named as Cu+Pd/TV2. ICP analysis showed the Cu and Pd-content to be 0.46 and 0.48 wt% respectively.

Example 11: Deposition of Au, Ag and Pt

Au, Ag and Pt deposition was carried by photodeposition method using HAuCU as the gold precursor, AgN0 ₃ as the Ag precursor and platinum ammonium chloride as the Pt precursor. In a 250 ml quartz round bottom flask, 30 ml of 0.5wt% of HAuCLj and 0.5wt% of AgN0 ₃ and 0.5wt% of Pt precursor were taken in 120 ml of MeOH with 500 mg of catalyst. Above solution was bubbled with Ar at a rate of 50 ml/min. for lh to remove any dissolved oxygen and generate inert atmosphere. Irradiation with 400 W UV lamp was carried out for 1 h (λ = 200-400nm). After photo deposition powder sample was separated by centrifugation and finally the Au, Ag and Pt deposited powder sample were dried at 40°C for 12 h. This was named as named as Au+Ag+Pl/TV2. ICP analysis showed the Au and Ag and Pt-content to be 0.44, 0.45 and 0.48 wt% respectively.

Example 12: Oxidation of aromatic compounds

30 mg of the composite designated as Au TV2 is suspended in 5ml of reactant solution comprising 1ml of benzene, 2ml of CH ₃ CN and 2ml 25% H ₂ 0 ₂ . The suspended solution taken in air tight 50 ml volume quartz glass round bottomed flask is irradiated for 6, 12 and 18 hours under UV-visiblc light source of 400 watts at > 200 nm. To maintain constant room temperature during light irradiation, air cooling was maintained with fans in an air-conditioned laboratory. After the reaction, the solution is filtered, and the filtrate is subjected to separation of organic layer and subjected to product analysis by GC. Similarly the other compositions are also evaluated for photocatalyticoxidation of benzene.

Example 13: Oxidation of Toluene to ortho-hydroxy toluene or o-cresol

30 mg of the composite designated as Au/TV2 is suspended in 5 ml of reactant solution comprising 1ml of toluene, 2 ml of CH ₃ CN and 2 ml 25% H ₂ 0 ₂ . The suspended solution taken in air tight 50 ml volume quartz glass round bottom flask is irradiated for 18 hours under UV-visible light source of 400 watts at > 200 nm. To maintain constant room temperature during light irradiation, air cooling was maintained with fans in an air-conditioned laboratory. After the reaction, the solution is filtered, and the filtrate is subjected to separation of organic layer and subjected to product analysis by GC. 18 h irradiation experiments shows 12 % toluene conversion, and 90 % (8.1 %) o-hydroxy toluene selectivity (yield), o-hydroxy toluene and o- cresol arc the same. H

Example 14: Hydroxylation of Naphthalene

25 mg of the composite designated as Cuo.5/Pdo.5/TV2 is suspended in 5 ml of reactant solution comprising 0.8 g of naphthalene, 2 ml of CH ₃ CN and 2 ml 25% H ₂ 0 ₂ . The suspended solution taken in air tight 50 ml volume quartz glass round bottom flask was irradiated for 18 hours under UV-visible light source of 400 watts at > 200 run. To maintain constant room temperature during light irradiation, air cooling was maintained with fans in an air-conditioned laboratory. After the reaction, the solution is filtered, and the filtrate is subjected to separation of organic layer and subjected to product analysis by GC. 18 h irradiation experiments shows 14 % naphthalene conversion, and 92 % (13 %) hydroxy naphthalene selectivity (yield).

Example 15: Hydroxylation of o-Xylcnc

30 mg of the composite designated as Au/Ag/TV2 is suspended in 5 ml of reactant so ution comprising 1 ml of o-xylene, 2 ml of CH ₃ CN and 2 ml 25% I I2O2. The suspended solution taken in air tight 50 ml volume quartz glass round bottom flask was irradiated for 18 hours under UV-visible light source of 400 watts at > 200 nm. To maintain constant room temperature during light irradiation, air cooling was maintained with fans in an air-conditioned laboratory. After the reaction, the solution is filtered, and the filtrate is subjected to separation of organic layer and subjected to product analysis by GC. Product analysis shows 16 % o-xylene conversion, and 89 % (14.3 %) p-hydroxy xylene (or 3,4-xylenol) selectivity (yield). ADVANTAGES OF THE INVENTION

• The photocatalytic partial oxidation of aromatic hydrocarbons is possible at ambient conditions and don't need any high temperature/pressure.

• No seed amount of product need to be added to initiate the reaction

• Catalyst can be recycled many times to perform the oxidation reactions.