WO2020225597A1

WO2020225597A1 - An adsorbent composition for removal of high boilers from contaminated heat transfer fluid

Info

Publication number: WO2020225597A1
Application number: PCT/IB2019/061272
Authority: WO
Inventors: Satish Kumar; Sunil PETER; Sunil AGRAHARI; Prakash Kumar; Kalpana Gopalakrishnan; Raksh Vir Jasra; Rajesh Mohan; Madhur KHAJURIA; Lokesh Gupta
Original assignee: Reliance Industries Limited
Priority date: 2019-05-04
Filing date: 2019-12-23
Publication date: 2020-11-12

Abstract

The present disclosure relates to an adsorbent composition for removal of high boilers from a contaminated heat transfer fluid and a process for preparation thereof. The adsorbent composition comprises activated bauxite in an amount in the range of 5 to 40 wt% of the total mass of the composition; a layered double hydroxide in an amount in the range of 50 to 80 wt% of the total mass of the composition; and a binder in an amount in the range of 5 to 15 wt% of the total mass of the composition. The present disclosure further relates to a process for removal of high boilers from a heat transfer fluid by contacting the contaminated heat transfer fluid with the adsorbent composition comprising bauxite, a layered double hydroxide, and a binder.

Description

AN ADSORBENT COMPOSITION FOR REMOVAL OF HIGH BOILERS FROM CONTAMINATED HEAT TRANSFER FLUID

This is an application for a patent of addition to the Indian Patent Application No. 201721017607 filed on 19.05.2017.

FIELD

The present disclosure relates to an adsorbent composition for removal of high boilers from a heat transfer fluid and a process for preparing the same. The present disclosure further provides a process for removal of high boilers from the contaminated heat transfer fluid.

DEFINITIONS As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used to indicate otherwise.

Contaminated heat transfer fluid refers to the heat transfer fluid used over a long period of time and having more than 4 wt% high boiler content. High Boilers refers to the oxidative degradation products (large molecules) formed in the heat transfer fluids due to excessive heating and which typically have higher boiling points than the original heat transfer fluids.

Low Boilers refers to the thermal cracking products (small molecules and / or fragments) formed in the heat transfer fluids due to excessive heating and which typically have lower boiling points than the original heat transfer fluids.

Chemisorption refers to adsorption method wherein the adsorbed material(s) is/are held by chemical bonds.

Extruding Aide refers to an additive which reduces or eliminates surface defects that appear during extrusion process. Dry basis refers to an expression of the calculation in which the presence of water is ignored for the purposes of the calculation. Water is neglected because addition and removal of water are common processing steps, and also happen naturally through evaporation and condensation; it is frequently useful to express compositions on a dry basis to remove these effects.

Feed processing capacity refers to the maximum output that can be produced in a process. With reference to the present disclosure, the feed processing capacity of the adsorbent compositions refers to the amount of the contaminated heat transfer fluid in grams that is effectively treated per gram of the adsorbent composition till the high boiler content in the treated heat transfer fluid is <1.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

Heat transfer fluids are used for a wide range of indirect heat transfer applications. It is thermally stable, does not decompose readily at high temperatures, and can be used effectively in either liquid or vapor phase systems. Its normal application range is 12 °C to 400 °C, and its pressure range is from atmospheric to 152.5 psig (10.6 bar).

However, when heat transfer fluids are used over a long period of time oxidative degradation may occur due to excessive heating, which leads to the formation of larger molecules such as polymers or solids. Similarly, excessive heating of the heat transfer fluids also results in thermal cracking, thereby forming smaller molecules or the fragments or coke. Typically, two types of degradation products or contaminants are known“low boilers” and“high boilers”. Low Boilers decrease the flash point and the viscosity of the heat transfer fluids and increases the vapor pressure. High Boilers increase the viscosity of the heat transfer fluids.

Presence of these contaminants, mostly high boilers in the contaminated heat transfer fluids cause fouling of heat transfer surfaces and corrosion of the system components, which further leads to reduction in the heat transfer efficiency.

Indian Patent Application No. 201721017607 discloses an adsorbent composition used for reducing impurities in the contaminated heat transfer fluid. The adsorbent composition comprises a layered double hydroxide in an amount in the range of 15 to 70 wt% of the total mass of the composition; alumina in an amount in the range of 30 to 85 wt% of the total mass of the composition; and optionally activated bauxite in an amount in the range of 15 to 50 wt% of the total mass of the composition. The adsorbent composition as disclosed in Indian Patent Application No. 201721017607 effectively reduces TAN of the contaminated heat transfer fluid. However, it was observed that the adsorbent composition as disclosed in the Indian Patent Application No. 201721017607, can remove high boilers in the contaminated heat transfer fluid to a very low extent. Moreover, the feed processing capacity of the the adsorbent composition of 201721017607 was very low.

There is, therefore, felt a need for an adsorbent composition that can effectively remove high boilers from the contaminated heat transfer fluids.

OBJECTS Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.

It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present disclosure is to provide an adsorbent composition for removal of high boilers from a contaminated heat transfer fluid.

Another object of the present disclosure is to provide a process for preparation of the adsorbent composition.

Still another object of the present disclosure is to provide a process for removal of high boilers from the contaminated heat transfer fluid using the adsorbent composition. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure relates to an adsorbent composition for removal of high boilers from a contaminated heat transfer fluid. In a first aspect, the present disclosure provides an adsorbent composition comprising activated bauxite in an amount in the range of 5 to 40 wt% of the total mass of the composition on dry basis; a layered double hydroxide in an amount in the range of 50 to 80 wt% of the total mass of the composition on dry basis; and a binder in an amount in the range of 5 to 15 wt% of the total mass of the composition on dry basis.

The adsorbent composition has bulk density in the range of 500 to 600 kg/m ; BET Surface area in the range of 330 to 370 m / g; pore volume in the range of 0.50 to 0.65 cc/g; pore diameter in the range of 90 to 110 A; and size 1 to 3 mm.

Typically, activated bauxite comprises aluminium oxide (AI2O3) in an amount in the range of 45 to 65 wt% of the total mass of bauxite; iron oxide (Ee2(¾) in an amount in the range of 5 to 15 wt% of the total mass of bauxite; silica (Si(¾) in an amount in the range of 15 to 25 wt% of the total mass of bauxite; titanium oxide (Ti(¾) in an amount in the range of 1 to 5 wt% of the total mass of bauxite and calcium oxide (CaO) in an amount in the range of 1 to 5 wt% of the total mass of bauxite.

In a second aspect, the present disclosure provides a process for preparing the adsorbent composition for removal of high boilers from a contaminated heat transfer fluid.

The process comprises the step of activating bauxite to obtain activated bauxite. The activated bauxite has particle size in the range of 0.25 to 1 mm, bulk density in the range of 1020 to 1050 m /g; BET surface area in the range of 110 to 130 m /g, pore volume in the range of 0.15 to 0.25 cc/g, and pore diameter in the range of 60 to 70 A. The activated bauxite is mixed with a layered double hydroxide and a binder to obtain a mixture. The so obtained mixture is kneaded in a fluid medium comprising a pre-determined amount of water, at least one surfactant and at least one extruding aide, followed by extrusion of the kneaded mixture to form shaped articles. The shaped articles are dried and calcined to obtain the adsorbent composition.

In a third aspect, the present disclosure provides a process for removal of high boilers from a contaminated heat transfer fluid by contacting with the adsorbent composition, said process comprising activated bauxite, a layered double hydroxide, and a binder to obtain a treated heat transfer fluid having reduced content of the high boilers.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

The present disclosure will now be described with the help of the accompanying drawing, in which: Figure 1 illustrates a schematic representation of a process for removal of the high boilers from a contaminated heat transfer fluid.

Figure 2 illustrates a comparative graphical representation of the adsorption capacity of the activated bauxite and the adsorption capacity of the adsorbent composition of the present disclosure.

Figure 3 illustrates a comparative graphical representation of the adsorption capacity of the prior art adsorbent composition and the adsorption capacity of the adsorbent composition of the present disclosure at 250 °C and at 300 °C.

DETAILED DESCRIPTION Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising,"“including,” and“having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed. Heat transfer fluids are used for multifarious heat transfer applications. However, during working of the process, excessive heating of the fluids leads to the formation of contaminants such as high boilers and low boilers. The presence of these contaminants, mostly high boilers in the heat transfer fluid causes fouling of heat transfer surfaces and corrosion of the system components, which further leads to reduction in the heat transfer efficiency.

The present disclosure, therefore, provides an adsorbent composition for removal of high boilers from a contaminated heat transfer fluid.

In a first aspect, the present disclosure provides an adsorbent composition comprising Layered double hydroxide in an amount in the range of 50 to 80 wt% of the total mass of the composition on dry basis; an activated bauxite in an amount in the range of 5 to 40 wt% of the total mass of the composition on dry basis; and a binder in an amount in the range of 5 to 15 wt% of the total mass of the composition on dry basis.

The adsorbent composition of the present disclosure is characterized by bulk density in the range of 500 to 600 kg/m 3 ; BET Surface area in the range of 330 to 370 m 2 /g; pore volume in the range of 0.50 to 0.65 cc/g; pore diameter in the range of 90 to 110 A; and size 1 to 3 mm.

In accordance with an exemplary embodiment of the present disclosure, the adsorbent composition is characterized by bulk density of 560 kg/m 3 ; BET Surface area of 350 m 2 /g; pore volume of 0.58 cc/g; pore diameter of 101 A.

In accordance with the embodiments of the present disclosure, activated bauxite comprises aluminium oxide (AI2O3) in an amount in the range of 45 to 65 wt% of the total mass of bauxite; iron oxide (Fe2C>3) in an amount in the range of 5 to 15 wt% of the total mass of bauxite; silica (S1O2) in an amount in the range of 15 to 25 wt% of the total mass of bauxite; titanium oxide (Ti(¾) in an amount in the range of 1 to 5 wt% of the total mass of bauxite; calcium oxide (CaO) in an amount in the range of 1 to 5 wt% of the total mass of bauxite; and water.

In accordance with the embodiments of the present disclosure, the layered double hydroxide is hydrotalcite. Typically, hydrotalcite is characterized by magnesium oxide (MgO) to aluminium oxide (AI2O3) ratio in the range of 4 to 5, particle size in the range of 0.30 to 0.60m and BET surface area in the range of 10 m /g to 40 m /g. In accordance with the embodiments of the present disclosure, the binder is at least one selected from bentonite clay and kaolinite clay. In accordance with the exemplary embodiment of the present disclosure, the binder is bentonite clay.

The feed processing capacity of said adsorbent composition is in the range of 70 to 160 gm/gm.

The process comprises the following sub-steps:

Initially, bauxite is activated to obtain activated bauxite characterized by particle size in the range of 0.25 to 1 mm, bulk density in the range of 1020 to 1050 m / g; BET surface area in the range of 110 to 130 m /g, pore volume in the range of 0.15 to 0.25 cc/g, and pore diameter in the range of 60 to 70 A.

In accordance with the embodiments of the present disclosure, the step activating bauxite involves heating bauxite at a temperature in the range of 100 C to 200 C for a time period in the range of 5 hrs to 7 hrs to obtain activated bauxite.

The heating increases the porosity and surface area of bauxite. The activated bauxite thus prepared is effective in removing high boilers from the contaminated heat transfer fluid.

The activated bauxite is then mixed with a layered double hydroxide and a binder to obtain a mixture. The so obtained mixture is kneaded in a fluid medium comprising a pre-determined amount of water, at least one surfactant and at least one extruding aide.

In accordance with the present disclosure, the binder helps in enhancing the surface area and the surfactant is responsible for generating the meso pores and macro pores in the adsorbent composition, thereby creating more space for high boilers such as heavier impurities to get adsorbed on the adsorbent. The kneaded mixture is further extruded to form shaped articles. The shaped articles are dried under inert atmosphere at a temperature in the range of 80 °C to 150 °C for a time period in the range of 1 hour to 5 hours, followed by calcining at a temperature in the range of 300 °C to 600 °C for a time period in the range of 3 hours to 6 hours to obtain the adsorbent composition. In accordance with the embodiments of the present disclosure, the amount of water in the fluid medium is in the range of 70 to 80 wt%.

In accordance with the embodiments of the present disclosure, amount of extruding aide in the fluid medium is in the range of 5 to 20 wt%. In accordance with the embodiments of the present disclosure, the extruding aide is at least one selected from the group consisting of acetic acid, nitric acid, ortho-phosphoric acid, lubolic acid and ethanol.

In accordance with the embodiments of the present disclosure, the amount of the surfactant in the fluid medium is in the range of 2 to 10 wt%. In accordance with the embodiments of the present disclosure, the surfactant is fatty acid, preferably behenic acid, lauric acid, and lignoceric acid.

In a third aspect, the present disclosure provides a process for removal of high boilers from a contaminated heat transfer fluid by contacting with the adsorbent composition comprising activated bauxite, a layered double hydroxide, and a binder to obtain a treated heat transfer fluid having substantially reduced high boilers.

In accordance with the embodiments of the present disclosure, the step of contacting is carried out at a temperature in the range of 200 °C to 350 °C. In accordance with an exemplary embodiment of the present disclosure, the step of contacting is carried out at 250 °C. In accordance with another exemplary embodiment of the present disclosure, the step of contacting is carried out at 300 °C.

In accordance with the embodiments of the present disclosure, the step of contacting is carried out at a pressure in the range of 1 bar to 10 bar. In accordance with the exemplary embodiment of the present disclosure, the step of contacting is carried out at the pressure of 1 bar. In accordance with the embodiments of the present disclosure, the step of contacting is carried out at a liquid hourly space velocity (LHSV) in the range of 0.5 per hour to 5 per hour. In accordance with the exemplary embodiment of the present disclosure, the step of contacting is carried out at a liquid hourly space velocity (LHSV) of 1 per hour

The present disclosure is further illustrated with help of the figures. Figure-1 discloses a schematic representation of the process apparatus for removal of high boilers from the contaminated heat transfer fluid. Typically, the assembly used in the process for the removal of high boilers comprises a feed tank (1) adapted to store the contaminated heat transfer fluid, a pump (2), a fixed bed column (3) loaded with adsorbent composition, an electric heater furnace (4) and a condenser (5). Contaminated heat transfer fluid is passed through the fixed bed column at a liquid hourly space velocity (LHSV) in the range of 0.5 per hour to 5 per hour with the help of the pump. The temperature of the fixed bed column is maintained in the range of 200 to 350 °C with the help of an electric furnace and further passed through condenser to obtain the treated heat transfer fluid.

In accordance with the process of the present disclosure, the adsorbent composition is introduced in the contaminated heat transfer fluid without interrupting or discontinuing the continuous process.

The present disclosure provides an economical adsorbent composition that is capable of reducing high boiler content to less than 1 % in the contaminated heat transfer fluid. Further, the inventors of the present application surprisingly found that the adsorbent composition of the present application has enhanced feed processing capacity as compared to the prior art adsorbent compositions. The higher feed processing capacity of the present adsorbent is because of higher pore volume, bigger size of pores and higher surface area as compared to the prior art adsorbent composition and activated alumina. The adsorbent composition of the present disclosure can be recycled, thereby making the process economical in the long run. Further, the process is very efficient and no loss of heat transfer fluid occurs during decontamination process, with a recovery of >99%.

The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.

EXPERIMENTAL DETAILS Experiment 1: Activation of the bauxite Bauxite containing 45-65% alumina (AI2O₃), (5-15%) iron oxide (Fe2(¾), 15-25% silica (S1O2), 1-5% titanium oxide (Ti(¾), 1-5% calcium oxide (CaO) and rest water in various proportions was thermally treated to fine tune the physicochemical properties such as particle size, surface area, pore volume and pore size.

The bauxite was heated at 180 C for a time period of 6 hrs to obtain activated bauxite

2

characterized by particle size was 0.5 to 1mm, BET surface area 119 m / g, pore volume 0.19 cc/g, and pore size of 64A, respectively, as provided in table 1.

Experiment 2: Preparing the adsorbent composition in accordance with the present disclosure

20 g (on dry weight basis) activated bauxite was mixed with 70 g (on dry weight basis) hydrotalcite and 10 g (on dry weight basis) bentonite clay to produce a mixture. The mixture was agglomerated with a solution comprising water (80 wt%), extruding aide (15 wt%), and surfactant (5 wt%) to produce dough. The dough was then introduced into an extruder to form extrudates, wherein the size of each extrudate was 3 mm. The extrudates were air dried at 100 °C followed by calcining the dried extrudates at 550°C for 5 hours to obtain the adsorbent composition.

Physiochemical properties of the adsorbent composition are given below in table 1.

Table 1:

From Table 1, it is evident that the adsorbent composition of the present disclosure has increased surface area, pore volume and pore diameter as compared to the activated bauxite and the prior art adsorbent composition. The binder used in the composition helps to improve the surface area, while the surfactant used is responsible for creating the meso and macro pores in the final composition, thereby creating more space for high boilers such as heavier impurities to get adsorbed on the adsorbent.

Experiment 3: Treatment of the contaminated heat transfer fluid using adsorbent composition of experiment 2 of the present disclosure. A contaminated heat transfer fluid (1.0 kg) (Therminol VP1) having high boiler content of 4% and viscosity of 2.62 cSt was passed through a fixed bed of 20g of adsorbent composition obtained in Experiment 2 at 250 °C, liquid hourly space velocity (LHSV) of 1 h ¹, and a pressure of 2 bar. After the treatment, the treated heat transfer fluid with 3% of high boilers content and viscosity of 2.60 cSt was obtained. Different physicochemical properties of the treated heat transfer fluid are tabulated in Table- 2 given below.

Experiment 4: Treatment of the contaminated heat transfer fluid using activated bauxite of experiment 1 (comparative example)

Same experimental procedure was followed as described in experiment 4, except that the activated bauxite prepared in experiment 1 was used as adsorbent.

Different physicochemical properties of the treated heat transfer fluid are tabulated in Table- 2 given below.

Experiment 5: Treatment of the contaminated heat transfer fluid using adsorbent composition of experiment 3 (prior art, comparative example) Same experimental procedure was followed as described in experiment 4, except that the prior art adsorbent composition prepared in experiment 3 was used as adsorbent.

5 Experiment 6: Effect of the temperature on the treatment of the contaminated heat transfer fluid using adsorbent composition of experiment 2 of the present disclosure.

Same experimental procedure was followed as described in experiment 4, except that the treatment was carried out at 300 °C.

Different physicochemical properties of the treated heat transfer fluid are tabulated in Table- 10 2 given below.

Experiment 7: Effect of the temperature on the treatment of the contaminated heat transfer fluid using adsorbent composition of experiment 3 (Prior art, comparative example)

Same experimental procedure was followed as described in experiment 4, except that the 15 prior art adsorbent composition prepared in experiment 3 was used as adsorbent and treatment was carried out at 300 °C.

TABLE-2: Physicochemical properties of the treated heat transfer fluid

From Table-2, it is observed that the adsorbent composition of the present disclosure (Refer to Exp. 3 and 6) effectively removes high boilers from the contaminated heat transfer fluids as compared to activated bauxite (Refer to Exp. 4) and the prior art adsorbent (Refer to Exp. 5 and 7).

5 Further, it is evident from Table-2 that the feed processing capacity of the adsorbent composition of the present disclosure is higher as compared to activated bauxite. The enhanced feed processing capacity of the adsorbent composition of the present disclosure is further observed in Figure 2 [graph 2(B)], as compared to the activated bauxite [graph 2(A)] Furthermore, from Figure 3, it is evident that the adsorbent composition of the present disclosure [graph 3(C) and 3 (D)] has enhanced feed processing capacity as compared to the prior art adsorbent composition [graph 3(A) and 3 (B)].

The higher feed processing capacity is because of higher pore volume, bigger size of pore and higher surface area as compared to the prior art adsorbent composition.

The feed processing capacity of the adsorbent composition of the present disclosure decreases with increasing temperature; however, the efficiency increases with temperature.

TECHNICAL ADVANCEMENTS

The present disclosure described herein above has several technical advantages including, but not limited to, an adsorbent composition and a process for preparing the same that: is economical and environment friendly; and has enhanced feed processing capacity.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

The use of the expression“at least” or“at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary. While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. An adsorbent composition for removal of high boilers from a contaminated heat transfer fluid, said adsorbent composition comprising: a. activated bauxite in an amount in the range of 5 to 40 wt% of the total mass of the composition on dry basis; b. a layered double hydroxide in an amount in the range of 50 to 80 wt% of the total mass of the composition on dry basis; and c. a binder in an amount in the range of 5 to 15 wt% of the total mass of the composition on dry basis.

2. The composition as claimed in claim 1, wherein said activated bauxite comprises: i. aluminium oxide (AI2O3) in an amount in the range of 45 to 65 wt% of the total mass of bauxite; ii. iron oxide (Fe2C>3) in an amount in the range of 5 to 15 wt% of the total mass of bauxite; iii. silica (Si(¾) in an amount in the range of 15 to 25 wt% of the total mass of bauxite; iv. titanium oxide (Ti(¾) in an amount in the range of 1 to 5 wt% of the total mass of bauxite; and v. calcium oxide (CaO) in an amount in the range of 1 to 5 wt% of the total mass of bauxite.

3. The composition as claimed in claim 1, wherein said activated bauxite has particle size in the range of 0.25 to 1 mm, bulk density in the range of 1020 to 1050 m /g; BET surface area in the range of 110 to 130 m /g, pore volume in the range of 0.15 to 0.25 cc/g, and pore diameter in the range of 60 to 70 A.

4. The composition as claimed in claim 1, wherein said layered double hydroxide is hydrotalcite having magnesium oxide (MgO) to aluminium oxide (AI2O3) ratio in the range of 4 to 5, BET surface area in the range of 10 to 40 m / g and particle size in the range of 0.30 to 0.60 pm.

5. The composition as claimed in claim 1, wherein said binder is at least one selected from bentonite clay and kaolinite clay.

6. The composition as claimed in claim 1, wherein said binder is bentonite clay.

7. The composition as claimed in claim 1, wherein said adsorbent composition has bulk density in the range of 500 to 600 kg/m³; BET Surface area in the range of 330 to 370 m / g; pore volume in the range of 0.50 to 0.65 cc/g; pore diameter in the range of 90 to 110 A; and size 1 to 3 mm.

8. The composition as claimed in claim 1, wherein the feed processing capacity of said adsorbent composition is in the range of 70 to 160 gm/gm.

9. A process for preparing an adsorbent composition for removal of high boilers from a contaminated heat transfer fluid, the process comprising: i. activating bauxite to obtain activated bauxite; ii. mixing said activated bauxite with a layered double hydroxide and a binder to obtain a mixture; iii. kneading said mixture in a fluid medium comprising a pre-determined amount of water, at least one surfactant and at least one extruding aide; and iv. extruding said kneaded mixture to form shaped articles; and v. drying and calcining the shaped articles to obtain the adsorbent composition.

10. The process as claimed in claim 9, wherein said step of activating bauxite comprises heating bauxite at a temperature in the range of 100 to 200 °C for a time period in the range of 5 to 7 hrs to obtain activated bauxite.

11. The process as claimed in claim 9, wherein said step of drying the shaped articles is carried out under inert atmosphere at a temperature in the range of 80 °C to 150 °C for a time period in the range of 1 hour to 5 hours.

12. The process as claimed in claim 9, wherein said step of calcining the dried shaped articles is carried out under inert atmosphere at a temperature in the range of 300 °C to 600 °C for a time period in the range of 3 hours to 6 hours to obtain the adsorbent composition.

13. The process as claimed in claim 9, wherein the amount of water in the fluid medium is in the range of 70 to 80 wt%.

14. The process as claimed in claim 9, wherein the amount of extruding aide in the fluid medium is in the range of 5 to 20 wt% and said extracting aid is at least one selected from the group consisting of acetic acid, nitric acid, ortho-phosphoric acid, lubolic acid and ethanol.

15. The process as claimed in claim 9, wherein the amount of the surfactant in the fluid medium is in the range of 2 to 10 wt% and wherein said surfactant is at least one fatty acid selected from the group consisting of behenic acid, lauric acid, and lignoceric acid.

16. A process for removal of high boilers from a contaminated heat transfer fluid, said process comprising: contacting said contaminated heat transfer fluid with an adsorbent composition as claimed in claim 1, comprising activated bauxite, a layered double hydroxide, and a binder to obtain a treated heat transfer fluid having substantially reduced high boilers.

17. The process as claimed in claim 16, wherein said step of contacting is carried out at a temperature in the range of 150 °C to 350 °C.

18. The process as claimed in claim 16, wherein said step of contacting is carried out at a pressure in the range of 1 bar to 10 bar.

19. The process as claimed in claim 16, wherein said step of contacting is carried out at a liquid hourly space velocity (LHSV) in the range of 0.5 per hour to 10 per hour.

20. The process as claimed in claim 16, wherein said treated heat transfer fluid medium has high boiler content of less than 3%.