Description: 0074NF2023
FORM 2

THE PATENTS ACT, 1970
(39 of 1970)

&

THE PATENTS [AMENDMENTS] RULES, 2021

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

CO-PRODUCTION OF PROPYLENE AND METHANOL VIA OXIDATIVE DEHYDROGENATION OF PROPANE USING CO2 AS A SOFT OXIDANT

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH, Anusandhan Bhawan,
2, Rafi Marg, New Delhi-110 001, India, an Indian Registered Body
incorporated under the Registration of Societies Act (XXI of 1860).

The following specification particularly describes the invention and the manner in which it is to be performed:
FIELD OF THE INVENTION
The present invention relates to a catalytic process for the co-production of propylene and methanol by the oxidative dehydrogenation of propane using CO2 as a soft oxidant over a solid oxide catalyst. Particularly, the present invention relates to a noble metal-free catalyst and the catalyst contain one metal from group IV-B (i.e., Zr). in a fixed bed continuous reactor system under atmospheric/ near atmospheric pressure. More particularly, the present invention relates to a process for preparing solid oxide catalyst i.e. Zr-supported alumina-silicate ZK-5 (KFI) zeolite.

BACKGROUND OF THE INVENTION
Today, most olefins, such as propylene, are produced by steam cracking. Various factors, such as constantly depleting crude oil reserves, energy-intensive conversion processes, lower selectivity for a particular olefin, and skyrocketing oil prices, are forcing the petrochemical industry to look for cheaper feedstocks and better-converting technologies. With the advent of technology, shale gas production has recently increased. The growth of shale gas has sparked extensive research into methane upgrading processes. However, shale gas-derived methane is relatively more expensive due to strict ethane limits. This has caused ethane prices to drop significantly. Therefore, dedicated propylene production has shifted from naphtha feed to lighter shale condensates. The development of dedicated technologies such as propane dehydrogenation (PDH), the methanol-to-olefins (MTO) process and the Fischer-Tropsch-to-olefins process are being explored as viable alternatives to replace traditional propylene production technologies. Industrially, two PDH processes, namely Catofin® and Oleflex,® are the most widespread. However, both technologies require a high temperature of >600°C and a low pressure of ~ 1 bar. However, high temperature favours the high yield but leads to heavy coke deposition on the catalyst surface, causing rapid catalyst deactivation. The traditional catalysts used supported or pure zeolite (KFI). Increasing concerns about environmental sustainability have made it necessary to find alternative ways to produce chemicals with biodegradability, renewability and reduced dependence on petroleum products. The oxidative dehydrogenation of propane (ODP) with a suitable oxidant in the presence of a heterogeneous catalyst is of interest as it addresses the disadvantages of direct dehydrogenation. Generally, O2, CO2, H2O2, and N2O has been intensively studied for several decades. Despite the availability of numerous oxidants, due to factors such as availability, cost, non-toxicity, etc., the study mainly focuses on only two oxidants, i.e., O2 and CO2. On the other hand, CO2 has been extensively explored as a mild oxidising agent in oxidative dehydrogenation reactions. This is due to the over-oxidation of propane and propylene to COx observed even at low O2 levels, resulting in lower propylene selectivity and yield. When using CO2 as an oxidising agent, deep oxidation of the reaction products is prevented in comparison to O2. Another benefit of using CO2 as an oxidising agent is its utilisation. Global CO2 emissions from energy combustion and industrial processes recovered in 2021, reaching their highest annual level to date. CO2 oxidative PDH (propane dehydrogenation) takes this abundant carbon dioxide and uses it to produce high-value propylene.

For alternative available technology/ process, reference can be made to the patent application WO1995023123A1 by ABB Lummus Crest Inc. wherein R. J. Gartside et al. explored an endothermic dehydrogenation process of hydrocarbon feed over CrOx/Al2O3 catalyst with alkaline promoter for the production of propylene. An Adiabatic fixed bed was used at 565-649°C to achieve 48-65% C3 conversion. Propylene was obtained with 80-88% selectivity at 0.3-0.5 bar pressure but the catalyst cycle time is very low. Additionally, the poisonous in nature of Cr is also a matter of concern.

Reference can be made to the patent application WO2007018982A1 filled by Sud-Chemie Inc. on an adiabatic, non-oxidative dehydrogenation of hydrocarbons. In the patent V. Fridman and his co-worker describe a catalyst bed that includes a first layer of a catalyst and a second layer of a catalyst. The hydrocarbon feed first contacts the catalysts of the first layer, wherein the catalysts of each layer exhibit different, predetermined capacities for the production of coke. Moreover, the catalyst deactivates fast as only 20h time-on-steam was detailed. The catalyst consists of 70 to 90% by weight alumina and from 10 to 30% by weight one or more chromium compounds. Such a high concentration of poisonous Cr was used to achieve the production of propylene.

Reference can also be made to the patent application WO2013089859A1 by UOP Llc. detailing a hydrocarbon dehydrogenation process using an inert diluent over Pt-Sn on Al2O3 with an alkaline promoter. A propane conversion of ~25% with propylene selectivity of 91% was achieved at 2-3 bar pressure. The high cost of Pt makes the CAPEX high for the process and the temperature (550-620°C) of the process is relatively high.

Reference can also be made to the US patents US5151401A and US5073662A by Phillips Petroleum Company, detailing the preparation of supported platinum catalyst for the dehydrogenation of propane to propylene. The catalyst comprises with Pt and Sn over a mixture of ZnAl2O3 and CaAl2O3; where the amount of Pt may vary 0.3-0.6 wt% over a porous support contains about 89.6 wt % zinc aluminate, about 9.1 wt % calcium aluminate and about 1.3 wt % stannic oxide. Over 40% propane conversion was noted with 89% propylene selectivity at 550-590°C. However, the reaction pressure is high (5-6 bar) compared to others with the use of noble metal.

Reference can also be made to the patent application WO2014016811A1 by Sabic Innovative Plastics Ip. for an alkane dehydrogenation catalyst comprising a precious metal e.g. Pt, Pd, Rh, Ir with Sn or Zn over porous SAPO-34. A propane conversion of 48-65% with propylene selectivity of 88-93% was achieved at 0.1-6 bar pressure. The reaction temperature is very high (560-600°C), and the catalyst is costly as it contains Pt. Moreover, the catalyst cycle time is very short (15-30 minutes) and hence requires rapid regeneration protocol.

Reference can be made to the Journal “Journal of Catalysis 352, 2017, 361-370”, wherein Li et al. reported a PtSn/TS-1 catalyst for propane dehydrogenation. At optimal conditions, 48% propane conversion was observed with 95% propylene selectivity, but a relatively high temperature was used (590°C), and the catalyst also showed deactivation via coke formation within 8th h of reaction.

Reference may also be made to Journal “Catalysis Letters 141, 2011, 120-127”, in which effect of the effect of sodium has been assessed on PtSn/AlSBA-15 catalysts for the production of propylene. A propane conversion of =12% was achieved with 94% propylene selectivity at 590°C. However, the main drawback is low propane conversion and rapid deactivation caused by prompt agglomeration and coking during the reforming process.
OBJECTS FOR THE INVENTION
The main object of the present invention is to provide a catalytic process for the co-production of propylene and methanol by the oxidative dehydrogenation of propane using CO2 as a soft oxidant over a solid oxide catalyst.
Another object of the present invention is to provide a catalytic process to combine (1) dehydrogenation of propane (PDH) and (2) CO2 hydrogenation with the in-situ prepared hydrogen during the PDH to produce propylene and methanol in a single rector in a once.
Yet another object of the present invention is to provide a noble metal-free catalyst, and the catalyst contain one metal from group IV-B (i.e., Zr).
Yet another object of the present invention is to provide a process which works continuously in fixed bed reactor more than 4 h without any major deactivation of the catalyst to produce propylene and methanol from propane dehydrogenation using CO2 as a soft oxidant.
Yet another object of the present invention is to provide a process that can convert impure propane streams to impure propylene, such as mixtures of C3 and C4 hydrocarbons in varying proportions as may be found in commercial Liquefied Petroleum Gas (LPG) or mixtures of C2-C4 hydrocarbons that might be commercially co-produced with natural gas (NG) or natural gas liquids (NGL) streams.

SUMMARY OF THE INVENTION
Accordingly, present invention provides a process for producing propylene and methanol by oxidative dehydrogenation and CO2 hydrogenation of propane using CO2 as a soft oxidant over an solid oxide catalyst comprising the steps of:
(a) loading of the catalyst in fixed bed down flow reactor;
(b) passing a mixture of propane and CO2 in absence or presence of 10-20% nitrogen as a carrier gas in the reactor;
(c) keeping the reactor at atmospheric pressure, at a temperature in the range of 400-500?C with a gas hourly space velocity (GHSV) in the range of 3000-6000 h-1 over Zr supported ZK-5 catalysts for a period ranging between 1 to 4 hrs to obtain propylene and methanol.
In an embodiment of the present invention, CO2 and propane mole ratio is ranging between 0.5-3.
In another embodiment of the present invention, propylene selectivity is ranging between 80-95%.
In yet another embodiment of the present invention, methanol selectivity is ranging between 90-99%
In yet another embodiment of the present invention, the conversion percentage of propane and CO2 is ranging between ~3-8% and 0.5-3%.
In yet another embodiment of the present invention, C2 and C4 hydrocarbons selectivity ranging between ~3-10% and 1-3% respectively.
In yet another embodiment of the present invention, solid oxide catalyst comprising a transition metal from group IV-B impregnated on small pore alumina-silicate ZK-5 (KFI) zeolite support;
In yet another embodiment of the present invention, the amount of transition metal is ranging between 1 to 10 wt% of the support.
In yet another embodiment of the present invention, transition metal used is Zr.
In yet another embodiment, present invention provides a process for the preparation of solid oxide catalyst comprising the steps of:
(a) dissolving transition metal source in water containing 1-5wt% of PVP-40/CTAB/glucose based on ZK-5 support followed by heating at 30-50°C to obtain a solution A;
(b) dissolving Zeolite (ZK-5) powder in water to obtain a solution B;
(c) adding solution A as obtained in step (a) in to the solution B as obtained in step (b) and kept at starring for a period in the range of 4 to 6h at temperature in the range of 20 to 35?C to obtain a mixture;
(d) placing the mixture as obtained in step (c) inside the oven at temperature in the range of 60 to 80°C for a period in the range of 10 to 15h to obtain catalyst powder;
(e) calcinating the catalyst powder as obtained in step (d) at temperature in the range of 450 to 550 °C for a period in the range of 4 to 6 h in an environment comprising air or nitrogen to obtain the catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 represents X-ray Diffraction (XRD) pattern of the prepared ZK-5, 1% Zr supported ZK-5 and 10% Zr supported ZK-5 catalyst.
Figure 2 represents SEM images with particle size distribution of (a) ZK-5, (b)Zr(1%)/ZK-5 and (c) Zr(10%)/ZK-5 catalyst.
Figure 3 represents TGA Profile of fresh ZK-5 and Zr(1%)/ZK-5 catalyst.

DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a catalytic process for co-production of propylene and methanol by the oxidative dehydrogenation of propane using CO2 as a soft oxidant over solid oxide catalyst.
In the process, the in-situ produced hydrogen is consumed for CO2 hydrogenation over a single catalytic material to give propylene along with methanol. The working catalyst consists of a monometallic (Zr) on small pore zeolite (ZK-5). The amount of transition metal is maintained between 1 and 10% by weight based on the ZK-5 (KFI) zeolite support. The catalyst was prepared by a wet impregnation process and calcined at temperatures of 450 to 550°C. The process pressure was atmospheric pressure in a temperature range of 400–500°C with a gas hourly space velocity (GHSV) in the range of 3000–6000 h-1. The catalyst proved to be stable for a period of 4 to 6 h on dehydrogenation conditions with CO2 as the soft oxidant at atmospheric pressure.

Synthesis of ZK-5 (KFI) Zeolite
i. A solution of potassium hydroxide and alumina in distilled water was prepared with constant stirring up to 80?C until a clear solution is visible.
ii. The Alumina solution was cooled down at room temperature [20 to 35oC].
iii. Another two separate solutions of strontium nitrate and silicic acid in distilled water were prepared with constant stirring for 1h and then mixed in one beaker.
iv. The final mix solution of strontium nitrate and silicic acid was added in the alumina solution, and whole solution was poured in an autoclave and kept in the oven at 150 to 180?C for 48 to 100 hr.
v. After hydrothermal treatment, autoclave was cold down at room temperature. Resulted white material was filtered and washed with excess distilled water and followed by drying the materials in oven at a 90 to 100?C temperature for 10- 12 h;
vi. Calcination of the materials at 450 to 550?C for 4-6 h in air to get solid ZK-5(KFI) type zeolite.

Synthesis of Zr impregnated ZK-5 catalysts
I. Zirconyl chloride octa hydrate (Sigma-Aldrich) as a source of Zr dissolved in water consisting of 1-5wt% of PVP-40, CTAB or glucose and heated at 50°C. The solution is continuously stirred for 2 to 3h to ensure the complete dissolution of salt and obtain a solution A;
II. In a separate beaker, Zeolite (ZK-5) powder is taken into distilled water and obtained a solution B;
III. Solution A is added to solution B and kept at stirring for 4 to 6h at room temperature [20 to 35oC].
IV. After that, the mixture was kept inside the oven at 60 to 80°C for overnight [10 to 15 hr].
V. Calcination of the catalyst powder at 450 to 550°C for 4 to 6 h in air to get Zr impregnated ZK-5 catalyst.
The amount of transition metal is maintained between 1 and 10% by weight based on the ZK-5 (KFI) zeolite support.

Propane Dehydrogenation [PDH]
I. PDH of propane was carried out in a fixed bed down-flow reactor loaded with solid oxide catalyst using CO2 as a soft oxidant to get Propylene and Methanol.
II. The reaction temperature is preferably in the range of 400 to 500 °C;
III. The gas hourly space velocity (GHSV) is preferably in the range (3000 h-1 to 6000 h-1)
IV. The process pressure was kept at 1 atmosphere.

EXAMPLES
The following examples are given as a way of illustration only and should not be construed to limit the scope of the present invention.

EXAMPLE 1: Synthesis of ZK-5 (KFI) Zeolite
ZK-5 (KFI) small pore zeolite was synthesised using the hydrothermal method. A solution of 25g of potassium hydroxide and 15 g of alumina in 60 ml of distilled water is prepared with constant stirring up to 80°C until a clear alumina solution is visible. Alumina solution was cooled down at 30°C. Two separate solutions of strontium nitrate (2g in 60 ml of distilled water) and silicic acid (65 g in 120 ml of distilled water) were prepared with constant stirring for 1h and then mixed in one beaker. Final mixed solution of strontium nitrate and silicic acid was added in the alumina solution and whole solution pour in an autoclave and kept in oven at 150?C for 100 h. After the 100 h hydrothermal treatment, autoclave was cold down at 30°C; resulting white material was filtered and washing with excess distilled water and followed by drying the materials in oven at a temperature at 100 ?C for 12 h. Calcination of the materials at 550?C for 6 h in air to get solid ZK-5(KFI) type zeolite.

Example 2: Synthesis of Zr(1%) impregnated ZK-5 catalysts
Zr impregnated ZK-5 catalyst was synthesised using wet-impregnation method.
0.25g of PVP-40 was taken in 10ml water and zirconyl chloride octa hydrate (0.09g, Sigma-Aldrich) as source of Zr is added to it and heated at 50°C. The solution is stirring continuously for 2 hr to ensure the complete dissolution of salt and name as A. In a separate beaker, 5g as synthesised ZK-5 (from example 1) is taken in to 50 ml of distilled water and named as B. Further, solution A is added (dropwise) to the solution B and kept at stirring for 5h at 28?C. After that, the mixture was kept inside the oven at 80°C for 14h. Calcination of the dried materials at 550°C for 6 h in air to get Zr-ZK-5 catalyst.

Example 3: Synthesis of Zr(10%) impregnated ZK-5 catalysts
Zr impregnated ZK-5 catalyst was synthesised using wet-impregnation method.
0.25g of PVP-40 was taken in 10ml water and zirconyl chloride octa hydrate (0.97g, Sigma-Aldrich) as source of Zr is added to it heated at 50°C. The solution is stirring continuously for 2 hr to ensure the complete dissolution of salt and name as A. In a separate beaker, 5g as synthesised ZK-5 (from example 1) is taken in to 50 ml of distilled water and named as B. Further, solution A is added (dropwise) to the solution B and kept at stirring for 6h at 30?C. After that, the mixture was kept inside the oven at 80°C for 15h. Calcination of the dried materials at 550 °C for 6 h in air to get Zr-ZK-5 catalyst of 40-60 nm size.

Example 4: Synthesis of Zr(1%) impregnated ZK-5 catalysts
Zr impregnated ZK-5 catalyst was synthesised using wet-impregnation method.
0.25g of glucose was taken in 10ml water and zirconyl chloride octa hydrate (0.09g, Sigma-Aldrich) as source of Zr is added to it heated at 50°C. The solution is stirring continuously for 2 hr to ensure the complete dissolution of salt and name as A. In a separate beaker, 5g as synthesised ZK-5 (from example 1) is taken in to 50 ml of distilled water and named as B. Further, solution A is added (dropwise) to the solution B and kept at stirring for 4h at 27?C. After that, the mixture was kept inside the oven at 80°C for 13h. Calcination of the dried materials at 550°C for 6 h in air to get Zr-ZK-5 catalyst of 40-60 nm size.

Example 5: Synthesis of Zr(10%) impregnated ZK-5 catalysts
Zr impregnated ZK-5 catalyst was synthesised using wet-impregnation method.
0.25g of CTAB was taken in 10ml water and zirconyl chloride octa hydrate (0.97g, Sigma-Aldrich) as source of Zr is added to it heated at 50°C. The solution is stirring continuously for 2 hr to ensure the complete dissolution of salt and name as A. In a separate beaker, 5g as synthesised ZK-5 (from example 1) is taken in to 50 ml of distilled water and named as B. Further, solution A is added (dropwise) to the solution B and kept at starring for 4h at 30?C. After that, the mixture was kept inside the oven at 80°C for 15h. Calcination of the dried materials at 550°C for 6 h in air to get Zr-ZK-5 catalyst of 40-60nm size.

EXAMPLE 6: Propane Dehydrogenation
This example describes the propane dehydrogenation [PDH] in presence of CO2 in a fixed bed down-flow reactor with C3H8-CO2 mole ratio 2 using all the synthesised nanocrystalline (40-55 nm) zeolites as the catalysts. The dehydrogenation of propane was carried out in a fixed bed stainless steel tube down flow reactor at atmospheric pressure. Typically, 1 g of as-prepared catalyst (palletised, 80 mesh) was loaded into a packed stainless-steel tube reactor between Silicon carbide and reaction was carried out in a temperature range of 400-500°C. The mixture of propane and CO2 is introduced through the mass flow controller.
The reaction is carried out in absence or presence of 10-20% nitrogen as a carrier gas; at atmospheric pressure, at a temperature in the range of 400-500?C with a gas hourly space velocity (GHSV) in the range of 3000-6000 h-1 over Zr supported ZK-5 catalysts for a period ranging between 1 to 4 hrs to obtain propylene and methanol.

The product analysis presented in Table 1.
Process conditions
Zr(1%)/KFI catalyst : 1 g (Example 1)
Pressure: 1 atmosphere
Total flow = 50 ml/min (GHSV = 3000)
Reaction time: 3 h
The Molar ratio of CO2/Propane: 2
Table -1
Catalyst
(Zr/KFI) Temperature
(°C) C3H8 Conv. (%) CO2 Conv. (%) C3H6 selectivity (%) CH3OH selectivity (%)
Zr(1%)/KFI 400 3.5 0.5-1 95 92%

Example 7: Effect of Temperature
The example describes the effect of temperature on propane conversion in a fixed bed down-flow reactor. The product analysis presented in Table -2.
Process Conditions
Zr(1%)/KFI catalyst : 1 g of Example-2
Pressure: 1 atmosphere
Total flow = 50 ml/min (GHSV = 3000)
Reaction time: 3 h
The Molar ratio of CO2/Propane: 2
Catalyst
(Zr/KFI) Temperature
(°C) C3H8 Conv. (%) CO2 Conv. (%) C3H6 selectivity (%) CH3OH selectivity (%)
Zr(1%)/KFI 450 5.1 1.5 85 96%

Example 8: Effect of Temperature
The example describes the effect of temperature on propane conversion in a fixed bed down-flow reactor. The product analysis presented in Table -3.
Process Conditions:
Zr(1%)/KFI catalyst : 1 g (Example 4)

Pressure: 1 atmosphere
Total flow = 50 ml/min (GHSV = 3000)
Reaction time: 3 h
The Molar ratio of CO2/Propane: 2
Catalyst
(Zr/KFI) Temperature
(°C) C3H8 Conv. (%) CO2 Conv. (%) C3H6 selectivity (%) CH3OH selectivity (%)
500 7.3 2.1 91 99

Example 9: Effect of Zr (wt%) and GHSV
The example describes the effect of Zr (wt%) and GHSV on propane conversion in a fixed bed down-flow reactor. The product analysis presented in Table -6.
Process Conditions:
Zr(10%)/KFI catalyst : 0.5 g (Example 5)
Pressure: 1 atmosphere
Total flow = 50 ml/min (GHSV = 6000)
Reaction time: 3 h
The Molar ratio of CO2/Propane: 2
Catalyst
(Zr/KFI) Temperature
(°C) C3H8 Conv. (%) CO2 Conv. (%) C3H6 selectivity (%) CH3OH selectivity (%)
500 5.2 1.6 87 99

Example 10
Co-production of propylene and methanol via oxidative dehydrogenation of propane using CO2 was compared with the equilibrium conversion calculated using the equation below
C3H8 ? C3H6 + H2 (?H?298 = 124.3 kJ mol-1)
(Reference can be taken from Chang et al. Chem. Soc. Rev., 2021, 50, 3315-3354)

Conversion of Propane against the thermotical limits
Temperature
(°C) Conversion (mol %) Equilibrium Conversion (mol %)
Selectivity (mol %)
Dehydrogenation of Propane in presence of CO2 400 3.5 3.7 95
450 5.1 7.2 85
500 7.3 13.7 91

ADVANTAGES OF THE INVENTION
The main advantages of the present invention are:
• The process of the present invention co-production of propylene and methanol at atmospheric pressure in a single step with a single catalyst.
• The process runs at atmospherics pressure to achieve 80-95% propylene selectivity at a temperature of 450°C.
• The employed catalyst does not contain any noble metal and monometallic and contain only one metal from group IV-B.
• The catalyst can be prepared easily and used in very low amounts (GHSV range of 3000-6000 h-1) and therefore, very economical to produce Propylene and Methanol. , C , Claims:We claim
1. A process for producing propylene and methanol by oxidative dehydrogenation and CO2 hydrogenation of propane using CO2 as a soft oxidant over an solid oxide catalyst comprising the steps of:
a) loading of the catalyst in fixed bed down flow reactor;
b) passing a mixture of propane and CO2 in absence or presence of 10-20% nitrogen as a carrier gas in the reactor;
c) keeping the reactor at atmospheric pressure, at a temperature in the range of 400-500?C with a gas hourly space velocity (GHSV) in the range of 3000-6000 h-1 over Zr supported ZK-5 catalysts for a period ranging between 1 to 4 hrs to obtain propylene and methanol.
2. The process as claimed in claim 1, wherein CO2 and propane mole ratio is ranging between 0.5-3.
3. The process as claimed in claim 1, wherein propylene selectivity is ranging between 80-95%.
4. The process as claimed in claim 1, wherein methanol selectivity is ranging between 90-99%
5. The process as claimed in claim 5, wherein the conversion percentage of propane and CO2 is ranging between ~3-8% and 0.5-3%.
6. The process as claimed in claim 1, wherein C2 and C4 hydrocarbons selectivity ranging between ~3-10% and 1-3% respectively.
7. The process as claimed in claim 1, wherein solid oxide catalyst comprising a transition metal from group IV-B impregnated on small pore alumina-silicate ZK-5 (KFI) zeolite support;
8. The process as claimed in claim 7, wherein the amount of transition metal is ranging between 1 to 10 wt% of the support.
9. The process as claimed in claim 7, wherein transition metal used is Zr.
10. A process for the preparation of solid oxide catalyst comprising the steps of:
a) dissolving transition metal source in water containing 1-5wt% of PVP-40/CTAB/glucose based on ZK-5 support followed by heating at 30-50°C to obtain a solution A;
b) dissolving Zeolite (ZK-5) powder in water to obtain a solution B;
c) adding solution A as obtained in step (a) in to the solution B as obtained in step (b) and kept at starring for a period in the range of 4 to 6h at temperature in the range of 20 to 35?C to obtain a mixture;
d) placing the mixture as obtained in step (c) inside the oven at temperature in the range of 60 to 80°C for a period in the range of 10 to 15h to obtain catalyst powder;
e) calcinating the catalyst powder as obtained in step (d) at temperature in the range of 450 to 550 °C for a period in the range of 4 to 6 h in an environment comprising air or nitrogen to obtain the catalyst.

Dated this ……3rd ………… day of …………November ……………2023.

Digitally signed by
Er. Ajayta Agarwal
Sr. Scientist
Innovation Protection Unit
Council of Scientific & Industrial Research