HETEROGENEOUS MESOPOROUS SILVER CONTAINING MANGANESE CATALYST FIELD OF INVENTION

This invention related to a method for producing 2,5-diformylfuran (DFF) by oxidation of 5-hydroxymethylfurfural by utilizing heterogeneous ICaT-4 catalyst. This process is very economical as it involved high yield and excellent selectivity for DFF without using an expensive catalyst and with reduced energy consumption. The use of heterogeneous catalyst and simple separation process for the product makes this process clean and sustainable. The catalyst found to be very active without any substantial deactivation and have good reusability. The product isolation and purification is also discussed.

BACKGROUND OF THE INVENTION

Chemicals derived from biomass feedstock are bringing the world on a sustainable platform. Carbohydrate feedstock has a remarkable opportunity to act as a future renewable biomass resource for substituting petroleum feedstock. 5- hydroxymethylfurfural (HMF) obtained from carbohydrate serve as a prospective building block.

Oxidation of HMF gives products such as 2,5-diformylfuran (DFF), hydroxymethyl furan carboxylic acid (HMFCA), formylfuran carboxylic acid (FFCA) and furandicarboxylic acid (FDCA). 2,5-diformylfuran (DFF) is a versatile compound, and there are several reports describing its useful application as monomer, as pharmaceutical intermediates, nematocides, antifungal agents, ligands, in photography as cross-linking agent for poly (vinyl alcohol), for battery separators, as a foundry sand binders, for metal electroplating, in electro optical devices, as organic phosphors and luminophores and for preparing new polymeric materials for specific application. Several methods have been utilized for preparation of DFF from 5-hydroxymethylfurfural but most of the method end with mixture of oxidative products and results in low product selectivity and low yield. Hence it is desirable to develop alternative method for production of 2,5-diformylfuran from 5-hydroxymethylfurfural.

US 2008103318 disclose a method of oxidizing 5-hydroxymethylfurfural (HMF) in water by contacting with the catalyst comprising of Zr0 ₂ is mixed with platinum (II) acetyl acetone in presence of air or oxygen.

US 4977283 disclose the process for the oxidation of 5-hydroxymethylfurfural, which comprises of oxygen as oxidizing agent in the presence _^ of a catalyst which contains platinum or palladium or mixture of both supported on activated carbon.

US 2003055271 discloses the method for oxidation of 5-hydroxymethylfurfural to 2,5- diformylfuran in presence of a metal (Mn and Co) bromide catalyst and oxidant such as air or oxygen. This invention also relates to polymerization of the dialdehyde and to the decarbonylation of the dialdehyde to unsubstituted furan. However, the yields were not very high, including the corrosive nature of the system as a major disadvantage.

US 2003130528 discloses the process for preparation of 2,5-diformylfuran from source of fructose in a one-pot, two-step reaction by using vanadium catalyst. In this process initially 5-hydroxymethylfurfural is formed by reacting fructose source with cation exchange resin then without isolating it is oxidized by using vanadium catalyst in presence of oxidant such as air or oxygen.

US 2006128843 discloses the method of reduction of 2,5-(hydroxymethyl)furaldehyde to 2,5-(hydroxymethyl) tetrahydrofuran and 2,5-bis(hydroxymethyl)tetrahydrofuran by reacting with the catalyst comprising of nickel and zirconium with particular pressure and temperature.

According to the process in Studies in Surface Science and Catalysis 108 (1997) 399- 406; selective air oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxaldehyde is performed in a batch reactor at 363 K in the presence of supported V ₂ 0 ₅ /Ti0 ₂ catalyst with different vanadium loadings, and in toluene and methyl isobutyl ketone as the solvents. The catalyst is not recyclable and yield is low.

According to the process in Catalysis Communication 9 (2008) 268-288; 5- hydroxymethylfurfural is oxidized to 2,5-diformylfuran by using Mn(III)-salen catalysts and sodium hypochlorite, in pH 1 1.3 phosphate buffer-CH ₂ Cl ₂ biphasic system. It gave 63-89% yield, but the reaction was sluggish taking 24 h

According to the process in Applied Catalysis A: General 289 (2005) 197-204; the selective oxidation of 5-hydroxymethyl-2-furaldehyde to furan-2,5-dicarboxaldehyde by catalytic systems based on vanadyl phosphate and oxidizing agent are air or oxygen and dimethylformamide is used as solvent. The use of the solvent such as DMF caused many problems in term of environmental impact, recovery and DFF purification. There are many reports available for preparation of DFF by oxidation of HMF using various classical oxidants but it was required in stoichiometric quantity such as Cr0 ₃ - pyridine, barium manganate, pyridinium chlorochromate (PCC), Pb(OAc)4-pyridine, K ₂ Cr ₂ 0 ₇ -DMSO, 2,2,6,6-teramethylpiperidine-l -oxide (TEMPO), trimethylammonium chlorochromate.

This invention deals with the process for oxidation of HMF to DFF by using ICaT-4 as oxidizing catalysts in presence of air as oxidant. The product selectivity was 100 %, catalyst is highly reusable. As no process available at industrial scale thus, this process is suitable for a further industrial exploration.

OBJECTIVE OF THE INVENTION

The objective of the present invention is to develop a process for production of 2,5- diformylfuran (DFF) from 5-hydroxymethylfurfural (HMF) with simplest reaction workup and with minimum production cost. One of the objectives of the present invention to provide a single solvent, simple catalytic process that converts the HMF to DFF in excellent selectivity and yield with minimum energy input. Another objective of the present invention is to develop process for production of 2,5- diformylfuran which utilizes batch mode reactor or batch reactor system in series.

Yet another objective of the present invention is to develop an improved method for 2,5- diformylfuran from 5-hydroxymethyfurfural whereby drawbacks of prior art approaches are avoided and to get the easiest reaction procedure with maximum selectivity to 2,5- diformylfuran.

Another objective of the present invention is to utilize oxygen or oxygen containing gases or air as oxidant.

Another objective of the present invention is to provide an environmentally safe and easy process for production of 2,5-diformylfuran from 5-hydroxymethylfurfural at low cost to validate the possibility of its extrapolation to the chemical industry. Another objective of the present invention is to develop process for production of 2,5- diformylfuran in which product is isolated in pure form by filtration, extraction, distillation and sublimation.

Another objective of the present invention is to utilize jninimum quantity_ _. of heterogeneous reusable ICaT-4 catalyst to produce 2,5-diformylfuran from 5- hydroxymethylfurfural .

Another objective of the present invention is to develop method for preparation of 2,5- diformylfuran from 5-hydroxymethylfurfural, which utilizes minimum energy and gives minimum waste. SUMMARY OF INVENTION

The group of invention directed to a convenient method for producing 2,5-diformylfuran (DFF) by oxidation of 5-hydro ymethylfurfural by utilizing heterogeneous ICaT-4 (Institute of Chemical Technology) catalyst. The use of heterogeneous catalyst and simple separation process for the product makes this process clean and sustainable. The catalyst found to be very active without any substantial deactivation and have good reusability.

Calcined manganese mesoporous molecular sieve substituted with silver was synthesized by precipitation method under acidic condition. Silver loading was varied from 0.1 to 50% (weight basis). The material is calcined from 300 °C to 600 °C to gives active catalyst ICaT-4. The present invention based on oxidation of 5-hydroxymethyl furfural to 2,5-diformylfuran by using ICaT-4 catalyst and air or oxygen or oxygen containing gases as oxidant in batch mode operation. 2,5-Diformylfuran is isolated from reaction mass by filtration, extraction, vacuum distillation and sublimation.

BRIEF DISCRIPTION OF DRAWINGS

Drawing 1 : Effect of catalyst loading

Drawing 2: Effect of temperature

Drawing 3: Effect of air pressure

Drawing 4: Effect of HMF concentration

STATEMENT OF INVENTION

A present process of invention for production of 2,5-diformylfuran at substantial yield and purity from oxidation of 5-hydroxymethylfurfural by using heterogeneous calcined mesoporous (ICaT-4) catalyst in the presence of oxygen or oxygen containing gases or air has comprising steps of

A) preparing homogeneous solution of 5-hydroxymethylfurfural with the organic or aqueous solvent or mixture thereof.

B) providing at least one of the oxidant such as oxygen, air or oxygen containing gases. C) reacting homogeneous solution with heterogeneous mesoporous ICaT-4 catalyst for reaction time to produce 2,5-diformylfuran.

D) isolating 2,5-diformylfuran from reaction mixture of step C) by a process selected from the group comprising of filtration, evaporation, extraction and vacuum distillation alone or in combination.

E) purifying 2,5-diformylfuran by sublimation under reduced pressure.

In the present process for production of 2,5-diformylfuran from oxidation of 5- hydroxymethylfurfural, wherein heterogeneous mesoporous catalyst (ICaT-4) comprises of calcined manganese mesoporous material substituted with silver comprises of silver loading from 0.1 to 50% wt/wt.

In the present process, wherein reactions of homogeneous solution with heterogeneous mesoporous (ICaT-4) catalyst in presence of oxidant is carried out in batch reactor or a batch reactor system in series for production of 2,5-diformylfuran from oxidation of 5- hydroxymethy lfurfural .

In the present process at least one of the oxidant is provided under pressure in the range of 1.0 bar to 100 bar more preferably 2 to 50 bar.

In the present process, heterogeneous calcined mesoporous catalyst (ICaT-4) are in range of 1.0%) to 80%) wt/wt based on 5-hydroxymethylfurfural. The homogeneous solution of 5-hydroxymethylfurfural has concentration in the range of 0.1 % to 70%> wt/wt, more preferably in the range of 1.0% to 40 % wt/wt of homogeneous solution.

In the present process according to claim 1 wherein reaction of homogeneous solution with heterogeneous mesoporous (ICaT-4) is carried out at temperature in the range 30 °C to 350 °C, more preferably in the range of 50 °C to 250 °C. After reaction, 2,5-diformylfuran is isolated from reaction mixture preferably by any known means such as filtration, liquid-liquid extraction, vacuum distillation and sublimation. DETAIL DESCRIPTION OF INVENTION

In accordance with the principle of the group of present invention directed to a convenient oxidation process for preparation of a platform chemical, 2,5-diformylfuran from 5 -hydroxymerthyl furfural has been developed, wherein 5 -hydroxymethylfurfural is reacted with ICaT-4 (Institute of Chemical Technology) catalyst in presence of oxygen or oxygen containing gases or air to prepare 2,5-diformylfuran (DFF) with high selectivity, is described. ICaT-4 catalyst is comprises of calcined manganese mesoporous material substituted with silver, was synthesized by precipitation method under acidic condition.

The process according to the invention utilizes heterogeneous ICaT-4 which is easily re- generable and shows excellent recyclability for production of 2,5-diformylfuran from oxidation of 5-hyroxymethylfurfural. 2,5-diformylfuran produced from 5- hydroxymethylfurfural act as platform chemical because of the wide range of the chemical intermediates and end products is produced from these compounds which used in the polymer industry, fuel and pharmaceutical industries. The reaction is shown as below:

Oxidation of 5 -hydroxymethylfurfural (HMF) to 2,5-Diformyl furan (DFF)

The invention related to the process for the oxidation of 5 -hydroxymethylfurfural to 2,5- diformylfuran is carried out in batch mode operation by using an autoclave reactor. Reaction is agitated with four bladed pitch turbine impeller. Temperature is maintained at +1°C of the desired value by PID controller and pressure is regulated with mass flow controller. One of the embodiments of the present invention, 2,5-diformylfuran preparation from oxidation of 5-hydroxymethylfurfural, wherein reaction is carried out using heterogeneous ICaT-4 catalyst. It gives high efficiency and excellent selectivity for 2,5- diformylfuran.

One of the embodiments of the present invention for 2,5-diformylfuran production utilized heterogeneous ICaT-4 catalyst. It is easily separable, regenerable, recyclable and cost effective catalyst. Reusable or recyclable heterogeneous catalysts are preferred for use in industry, as they provide increased efficiency, economical and industrial feasibility.

One of the embodiments of the present invention for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural, wherein oxidant is preferably an oxygen, oxygen containing gas or air and/or mixture thereof.

In accord with the present invention for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural is carried out for 1.0 to 100 bar oxidant pressure more preferably 2 to 50 bar. The reaction velocity is increased with increasing oxidant pressure.

One of the embodiments of the present invention wherein production of 2,5- diformylfuran from oxidation of 5-hydroxymethylfurfural is carried out by using the solvent selected from the group of solvent such as water, methanol, ethanol, isopropyl alcohol, butanol, acetone, acetonitrile, dimethyl formamide, dimethyl sulfoxide and/or mixture thereof.

In accord with the present invention for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural, wherein typically about 0.1 to 50% amount of the catalyst based on weight of 5-hydroxymethylfurfural are used in the reaction mixture. The used catalyst is recycled several times to check process feasibility for industrial utilization. One of the embodiments of the present invention conducted exhaustive research on method of producing 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural under mild conditions and with reduced energy consumption to get cost-effective process for industrial prospects.

One of the embodiments of the present invention for production of 2,5-diformylfuran from oxidation. of 5-hydroxymethylfurfural, wherein reaction temperature is in the range of 30 °C to 350 °C, more preferably in the range of 50 °C to 250 °C are selected. In accord with the present invention for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural is carried out for the time 1.0 min to 10 hours, more preferably for 1.0 min to 4 hours depending upon the type of solvent, amount of catalyst and pressure of oxidant used. One of the embodiments of the present invention for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural is monitored online on HPLC by using ultraviolet (UV) detector.

Another embodiments of the present invention is to develop process for production of 2,5-diformylfuran in which product is isolated in pure from the reaction mixture by any known means such as filtration, liquid-liquid extraction, vacuum distillation and sublimation.

A few of the numerous examples for production of 2,5-diformylfuran from oxidation of 5-hydroxymethylfurfural are considered as illustrative in terms of principles of the invention are listed below.

EXAMPLE 1: Preparation of ICaT-4 catalyst

ICaT-4 catalyst is comprises of calcined manganese mesoporous material substituted with silver, was synthesized by precipitation method under acidic condition. Silver loading is varied from 0.01% to 30% w/w. Manganese acetate (10.5 g) and appropriate amount of silver nitrate is dissolved in water (70 ml) followed by addition of nitric acid (2 ml) to make acidic solution. Weight of the silver is taken as per the silver loading in the final catalyst. Potassium permanganate (26.6 gm) is added to the mixture of solution. The resulting mixture is filter and dried at 120 °C for 12 hrs and calcined at 450 °C for 4 hrs to get the active catalyst ICaT-4.

EXAMPLE 2-5:

All experiments are carried out in batch mode operation by using 100 cm ³ autoclave reactor. A four bladed pitch turbine impeller is used for agitation. The temperature is maintained at + 1 °C of the desired value by PID controller. The rector is equipped with gas inlet and outlet ports, sample port, rupture disc and a magnetic drive to vary the speed of agitation. Air cylinder is used along with constant pressure regulator for supply of air. The reaction is performed _^ by loading autoclave reactor with 5-hydroxymethylfurfural (HMF) (0.0025 mol), 40 ml of isopropyl alcohol. Specific amount of the ICaT-4 catalyst is added to the reaction mixture (mentioned in Table 1). Air is charged up to 15 atm pressure and temperature is raised to 145 °C. Through out the reaction, air pressure was maintained constant by a mass flow controller. The effect of catalyst loading is studied with respect to conversion of HMF (Drawing 1). The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield -quantitatively. Increase in catalyst loading results in higher conversion of HMF and DFF yield, due to a proportional increase in the number of active sites of the catalyst. The selectivity of DFF is 100% in all the cases.

EXAMPLE 6-10:

All the reactions are carried out in batch mode operation by using 100 cm autoclave reactor. The reaction is performed by loading autoclave reactor with 5- hydroxymethylfurfural (HMF) (0.0025 mol), 40 ml of isopropyl alcohol. Specific amount of the ICaT-4 catalyst (0.0075 g/cm ³ ) is added to the reaction mixture. Air is charged up to 15 atm pressure and temperature is raised to 145 °C. Reaction mixture is agitated with a four bladed pitch turbine impeller. The reaction temperature is maintained at 145 °C with an accuracy of + 1 °C by PID controller. Through out the reaction, air pressure was maintained constant by a mass flow controller. The effect of silver loading on catalyst is studied with respect to conversion of HMF (mentioned in Table 2). The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield quantitatively. Increase in silver loading results in higher conversion of HMF and DFF yield. The selectivity of DFF is 100% in all the cases.

EXAMPLE 11-14:

All the reactions are carried out in batch mode operation by using 100 cm ³ autoclave reactor. The reaction is performed by loading autoclave reactor with 5- hydroxymethylfurfural (HMF) (0.0025 mol), 40 ml of isopropyl alcohol. Specific amount of the ICaT-4 catalyst (0.0075 g/cm of 15%w/w silver loaded catalyst), is added to the reaction mixture. Air is charged up to 15 atm pressure. Reaction mixture is agitated with a four bladed pitch turbine impeller. The reaction temperature is maintained at desire value with an accuracy of + 1 °C by PID controller. The temperature of the reaction is varied in these examples (mentioned in Table 3). Through out the reaction, air pressure was maintained constant by a mass flow controller. The effect of temperature is studied with respect to HMF conversion (Drawing 2). The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield quantitatively. Increase in temperature results in higher conversion of HMF and DFF yield. The selectivity of DFF is 100% in all the cases.

EXAMPLE 15-19:

All the reactions are carried out in batch mode operation by using 100 cm ³ autoclave reactor. The reaction is performed by loading autoclave reactor with 5- hydroxymethylfurfural (HMF) (0.0025 mol), 40 ml of isopropyl alcohol. Specific amount of the ICaT-4 catalyst (0.0075 g/cm ³ of 15%w/w silver loaded catalyst), is added to the reaction mixture. Reaction mixture is agitated with a four bladed pitch turbine impeller. The reaction temperature is maintained at 145 °C with an accuracy of + 1 °C by PID controller. The air pressure of the reaction is varied in these examples (mentioned in Table 4). Through out the reaction, specific air pressure was maintained constant by a mass flow controller. The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield quantitatively. Increase in pressure results in higher conversion of HMF and DFF yield. The effect of air pressure is studied with respect to HMF conversion (Drawing 3). The selectivity of DFF is 100% in all the cases. Table-4

Temperature Time %Conversion

Example Air pressure (atm) (OC) (min) of HMF

15 5 145 240 38

16 10 145 240 59

17 15 145 240 80

18 20 145 240 83

19 25 . 145 240 89

EXAMPLE 20-23:

All the reactions are carried out in batch mode operation by using 100 cm ³ autoclave reactor. The reaction is performed by loading autoclave reactor with specific amount of 5-hydroxymethylfurfural (HMF), 40 ml of isopropyl alcohol. The ICaT-4 catalyst (0.0075 g/cm ³ ) is added to the reaction mixture. Air is charged up to 15 atm pressure. Reaction mixture is agitated with a four bladed pitch turbine impeller. The reaction temperature is maintained at 145 °C with an accuracy of + 1 °C by PID controller. Concentration of HMF is varied in these examples (mentioned in Table 5). Through out the reaction, air pressure was maintained constant by a mass flow controller. The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield quantitatively. The selectivity of DFF is 100% in all the cases. The different amount of HMF is used in these examples to evaluate its effect on conversion and yield (Drawing 4).

EXAMPLE 24-28:

All the reactions are carried out in batch mode operation by using 100 cm ³ autoclave reactor. The reaction is performed by loading autoclave reactor with 5- hydroxymethylfurfural (HMF) (0.0025 mol), 40 ml of isopropyl alcohol. Specific amount of the ICaT-4 catalyst (0.0075 g/cm ³ ), is added to the reaction mixture. Air is charged up to 15 atm pressure. Reaction mixture is agitated with a four bladed pitch turbine impeller. The reaction temperature is maintained at 145 °C with an accuracy of ± 1 °C by PID controller. Through out the reaction, air pressure was maintained constant by a mass flow controller. The progress of the reaction is monitor on HPLC by using UV detector. Calibration curve method is adopted for calculating percentage conversion and percentage yield quantitatively. The selectivity of DFF is 100% in all the cases. The reusability of the catalyst is tested by conducting five runs. After completion of the reaction, the catalyst is filtered and washed with IPA. Then it is calcined at 400 °C for 2 hrs. The reusability of the catalyst is mentioned in these examples (Table 6).

EXAMPLE 29:

The isolation and purification of 2,5-diformylfuran (DFF) is carried out by a process selected from the group consisting of filtration, evaporation, extraction, distillation and sublimation. Reaction mass is filtered through filter paper to remove solid heterogeneous ICaT-4 catalyst. Catalyst was washed with 50 cm of IPA. Reaction mass is distilled under reduced pressure to remove IPA and then DFF is extracted with organic solvent such as ethyl acetate, diethylether, methyl isobutyl ketone, dichloromethane, methyl- tertiary-butyl ether, butyl acetate. Organic layer is dried by using sodium sulfate and distilled under reduced pressure to get pure DFF. Further purification is done by vacuum sublimation.