Description:FIELD OF THE INVENTION:
The present invention relates to the field of aviation fuels. Particularly, the present invention provides a single step continuous flow process for the preparation of JP-10 (Jet Propellent) fuel from dicyclopendiene (DCPD) by subjecting DCPD to combination of catalytic hydrogenation and catalytic isomerization in a fixed bed reactor. Further, the product obtained is a JP-10 fuel comprising mixture of exo-THDCPD (major), endo-THDCPD (minor), and adamantane (byproduct).

BACKGROUND OF THE INVENTION:
High-calorific-value liquid fuels play a critical role in various aerospace applications, spanning from spacecraft, rockets, ramjets, to turbofans. The performance of engines in these missions’ hinges significantly upon two fundamental attributes: the density and volumetric energy of aviation fuels. Notably, fuel tank design for military and space missions is compelled to achieve maximum compactness, driven by the necessity to accommodate intricate electronics and essential components. Consequently, the development and utilization of high-density fuels have emerged as a paramount solution to address crucial properties, foremost among them being the augmentation of density and volumetric net heat of combustion (NHOC) when juxtaposed with conventional aviation fuels.

Beyond these intrinsic advantages, high-density fuels prefer elevated propulsion energy, contributing extensively to the extension of flight ranges and the augmentation of payload capacities for missiles and aircraft alike. Amid the myriad high-density liquid fuels (referred to as HED fuels) that have been synthesized and studied, JP-10 conspicuously stands out as one of the most widely utilized. In direct comparison with aviation kerosene, JP-10 boasts a suite of superlative attributes, featuring a substantial density rating of 0.94 g/cm³, a high volumetric heat value of 39.6 MJ/L, a notably low freezing point registered at -79°C, and a commendable flash point of 54°C. What distinguishes it further is its capacity to deliver higher energy density in contrast to distilled kerosene, exemplified by Jet-A.

JP-10, often denoted as exo-tetrahydrodicyclopentadiene (exo-THDCPD) from a chemical perspective, is composed of 96.5 wt% exo THDCPD, 2.5 wt% endo THDCPD, and 1 wt% adamantane. The conventional synthesis route for JP-10 unfolds in two sequential stages. It commences with the hydrogenation of dicyclopentadiene (DCPD), a hydrocarbon by product derived from the steam cracking of naphtha and widely accessible. This hydrogenation process predominantly yields the endo-isomer, characterized as a solid form - endo-THDCPD. An essential next step entails isomerization, converting the endo-THDCPD into its exo-isomer, which assumes a liquid state. Despite their similarities in physicochemical properties and high volumetric energy content, the differentiation between these two isomers lies predominantly in their respective freezing points, notably -79°C for the exo-isomer and 77°C for the endo-isomer. Therefore, the process of isomerization, particularly the transformation of endo into exo THDCPD, is deemed indispensable.

Heterogeneous solid acid zeolites have garnered considerable attention for their role in catalyzing the isomerization of endo-THDCPD to exo-THDCPD due to their numerous advantages, including cost-effectiveness, ease of recovery, and reusability. In the isomerization process, two pivotal factors come into play: the catalyst's activity and its shape-selective pore dimensions. Given that the dimensions of endo-THDCPD are approximately 0.67 nm * 0.65 nm, HY-type zeolites (0.74 nm * 0.74 nm) emerge as the prime candidates for facilitating the diffusion of reactants into their pores. However, it's worth noting that a moderate level of acidity is crucial for the isomerization of endo to exo-THDCPD; excessively strong acidity can inadvertently trigger side reactions, degradation, and undesirable coke formation. Furthermore, intense acidity tends to increase the yield of adamantane (ADM) while diminishing the selectivity of exo isomers. Interestingly, the strength of acidity plays a more pivotal role in the isomerization reaction than the sheer number of acidic sites available.

A study conducted by Zhang et al. Green Chemistry 9, no. 6 (2007): 589-593 reported a synthesis route for JP-10 utilizing fluorine-modified HY zeolites in an autoclave (batch) at 195°C and atmospheric pressure (1 atm.) over a duration of 4 hours. This process achieved a commendable 96% conversion of endo-THDCPD, coupled with an impressive 94% selectivity for exo-THDCPD. However, the elevated reaction temperature of 195°C resulted in the formation of 2.32 wt% adamantane and coke, further complicating the task of separating adamantane from the reaction mixture. Also, usually auto clave (batch) and pressure 1 atm. deactivate catalyst.

Khan et al. Journal of Nanoscience and Nanotechnology 19, no. 12 (2019): 7982-7992 explored the synthesis of JP-10 with a Ni-MCM-41 catalyst in an autoclave at 150°C and 30 bar of H2 pressure, extending over 11 hours to yield an 85% exo-THDCPD. It's important to note that MCM-41, while effective, is a relatively expensive mesoporous material compared to zeolites. and the introduction of metal content (Ni) brings its own set of challenges. Further, the reaction is carried out in a batch reactor, not continuous.

In a separate avenue of research, acidic ionic liquids (ILs) have emerged as catalysts for the isomerization of endo to exo-THDCPD. Wang et al. investigated ILs composed of various 1-alkyl-3-methylimidazolium chlorides ([RMIM]Cl) and different metal chlorides, with a particular focus on ([BMIM]Cl)/AlCl3, which demonstrated exceptional performance when compared to zeolite catalysts. This catalyst system showcased excellent conversion and selectivity, reaching an impressive 98%. Similarly, Wang et al. Fuel 91, no. 1 (2012): 164-conducted isomerization experiments using supported ILs, harnessing the advantages of high activity and ease of separation. However, the challenge lies in scaling up ionic liquid processes to an industrial level and addressing the inherent handling complexities. It's important to reiterate that the strength of acidity significantly outweighs the number of acidic sites in terms of influence. Ionic liquids are homogeneous in nature and can be used for batch reaction. Further, use of ionic liquids cannot make the process continuous. The ionic liquid chosen in corrosive due to chloride presence. It demands special material of construction for the reactor vessel to avoid corrosion.

Furthermore, operational parameters such as temperature, pressure, and reaction time exert a substantial influence on the overall performance of the isomerization reaction. Notably, reaction pressure wields a significant impact on conversion and selectivity, while higher temperatures exceeding 150°C may precipitate oligomerization, leading to the formation of double bond polymers.

The ongoing research endeavours in this field are directed towards developing a catalytic system for the production of JP-10 (exo-THDCPD) through a batch mode process characterized by milder operating conditions. To this end, various catalyst formulations have been devised and evaluated, with the overarching goal of maximizing JP-10 yield under mild conditions, ideally achieving an adamantane (ADM) yield not exceeding 1 wt%.

Various methodologies have been documented for the synthesis of JP-10 fuel, with catalysts such as AlCl3, ionic liquids, and sulfuric acid playing instrumental roles. Among these, AlCl3 demonstrates remarkable isomerization activity, a characteristic attributed to its role as a Lewis acid catalyst in its liquid phase. This unique characteristic extends the contact time between the AlCl3 and the endo THDCPD molecules, ultimately enhancing the yield and selectivity of the endo isomer in the synthesis process.

Nevertheless, these techniques are not without their challenges and limitations. Most notably, they lack the regenerability of the catalyst, exhibit concerns of widespread corrosion, and necessitate post-treatment procedures such as incineration to manage and remove the residual waste AlCl3, which poses negative environmental and biological implications. Additionally, the handling of substantial quantities of acids and AlCl3 raises valid safety concerns and can adversely affect production efficiency, making the exploration of alternative methods imperative.

To address the challenges of the prior art and advancement in the field, there is a need to develop methods for synthesis of JP 10 fuel with advanced catalyst and minimising the yield of the byproduct. When homogeneous catalysts like ionic liquids are used, always the process to be carried out in two steps and in batch mode not in continuous mode. Continuous production of JP-10 has several technological advantages, when compared to two stage and batch processes.

SUMMARY OF THE INVENTION
Accordingly, the present invention provides a single step continuous flow process for the preparation of a JP-10 fuel from dicyclopentadiene (DCPD) in a fixed bed reactor comprising subjecting dicyclopentadiene to a hydrogenation in presence of a hydrogenation catalyst and an isomerization in presence of an isomerization catalyst in combination in the fixed bed reactor to obtain the JP-10 fuel comprising exo-tetrahydrodicyclopentadiene, endo-tetrahydrodicyclopentadiene, and adamantane. Wherein both the hydrogenation catalyst and isomerization catalyst are in an extrudate form.

The combination of these two catalysts (hydrogenation catalyst and isomerization catalyst) is to make the process continuous.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The following figures form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the figures in combination with the detailed description of the specific embodiments presented herein.

Figure 1 depicts a single step continuous flow process for the preparation of a JP-10 fuel in the fixed bed reactor.

DETAILED DESCRIPTION OF THE INVENTION:
For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in light of the remainder of the disclosure and understood as by a person of skill in the art.

The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below. The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”. The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations. Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps. The term “including” is used to mean “including but not limited to”. “including” and “including but not limited to” are used interchangeably.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods and materials are now described.

The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.

The term “JP 10” as defined herein refers to jet propellent10 fuel.

In an aspect, the present invention provides a single step continuous flow process for the preparation of a JP-10 fuel from dicyclopentadiene (DCPD) in a fixed bed reactor comprising:
subjecting dicyclopentadiene to a hydrogenation in presence of a hydrogenation catalyst and an isomerization in the presence of an isomerization catalyst in combination in the fixed bed reactor to obtain the JP-10 fuel comprising exo-tetrahydrodicyclopentadiene, endo-tetrahydrodicyclopentadiene, and adamantane.
Wherein both the hydrogenation catalyst and isomerization catalyst are in an extrudate form.

In an embodiment of the present invention, the hydrogenation catalyst comprises 0.1 - 5 wt% of a metal on 85 – 94 wt% of a support.

In another embodiment of the present invention, the metal is selected from the group consisting of Pt, Pd, Ni, Ru, Rh, Cu, Mo, and W.

In another embodiment of the present invention, the support is selected from the group consisting of Silica (SiO2), Alumina-Silica (Al2O3-SiO2), Alumina, ?-Al2O3, Magnesium silicate (Talc), Zirconia (ZrO2), and ZSM-5.

In another embodiment of the present invention, the hydrogenation catalyst comprises 0.3-1 wt% of Pd and 93.0 - 93.7 wt% of ?-Al2O3.

In another embodiment of the present invention, the hydrogenation catalyst is prepared by incipient impregnation method, or wet impregnation method.

In another embodiment of the present invention, the hydrogenation catalyst is prepared in extrudate form using a binder in a range of 5 to 10 wt%.

In another embodiment of the present invention, the binder is selected from the group consisting of pseudo boehmite, ludox silica, precipitated silica and hydroxy propyl methyl cellulose.

In another embodiment of the present invention, the isomerisation catalyst comprises metal or its oxide in a range of 0.1 - 5 wt.%, a solid acid zeolite in a range of 40 to 60 wt.% and a binder in a range of 40 to 60 wt.%, wherein the metal is selected from the group consisting of Pt, Pd, Ni, Ru, Rh, Cu, Mo, and W.

In another embodiment of the present invention, the zeolite is selected from the group consisting of HY zeolite, beta zeolite, ZSM-5, MCM-41, ZSM-22, and Mesoporous Y zeolite.

In another embodiment of the present invention, the binder is selected from the group consisting of Pseudo boehmite, ludox silica, precipitated silica and Hydroxy propyl methyl cellulose.

In another embodiment of the present invention, zeolite is desilicated with a base to obtain mesoporous zeolite with improved acidity, wherein the base is selected from the group consisting of NaOH and Tetrabutyl ammonium hydroxide. In one of the preferred embodiments, the obtained mesoporous zeolite is mesoporous Y zeolite.

In another embodiment of the present invention, Platinum metal in a range of 0.1 to 0.5 wt% is incorporated on base modified zeolite to improve stability.

In another embodiment of the present invention, the hydrogenation catalyst and the isomerization catalyst are in the same reactor and wherein, the hydrogenation catalyst is loaded in a top bed of the fixed bed reactor and the isomerization catalyst is loaded in a bottom bed of the fixed bed reactor, both separated by inert material preferably, Silicon carbide.

In another embodiment of the present invention, the solvent used in feed with dicyclopentadiene, and the solvent is selected from the group consisting of hexane and exo-THDCPD.

In another embodiment of the present invention, the yield of exo-THDCPD is 74 % when hexane is used as solvent in 50 wt % ratio along with DCPD in the feed.

In another embodiment of the present invention, the hydrogenation catalyst and the isomerization catalyst are regenerated through simple coke burning and regenerated by adding 0.3 wt% Cl in the catalyst.

In another embodiment of the present invention, the yield of adamantane obtained is less than 1 %.

Mesoporous nature of the isomerization catalyst used in the proposed invention is imparting stability for at least 200 hours of continuous operation, enabling regeneration/reuse of the isomerization catalyst, and avoiding deactivation of the isomerization catalyst due to coking, enabling continuous production of exo-THDCPD from DCPD.

In an embodiment of the present invention, hydrogenation catalyst is a noble and non-noble metal catalyst synthesized through incipient impregnation and wet impregnation methods.

In an embodiment of the present invention, isomerization catalyst is a solid acid catalyst based on zeolites.

In an embodiment of the present invention, isomerization catalyst is based on Mesoporous Y zeolites.

In a preferred embodiment of the present invention, mesoporous zeolite is a mesoporous Y zeolite.

In an embodiment of the present invention, the hydrogenation and isomerisation reaction in the fixed bed reactor is carried out at temperature in the range of 150 - 200 °C; H2 pressure in the range of 20-40 bar and H2/HC mole ratio of 3. Here, HC denotes hydrocarbon.

In an embodiment of the present invention, pre-treatment of the catalyst is carried out at temperature in the range of 350 - 600 °C and H2 pressure in the range of 5 - 10 bar.

The chemicals required for precipitation and making extrudates include peptizing agents (nitric acid, citric acid), plasticizer (Hydroxy propyl methyl cellulose), sodium carbonate Na2CO3, Cetyl Trimethyl Ammonium Bromide (CTAB), Ethylene diamine.
Pretreatment is for activating the metal oxide on the catalyst. When catalyst is loaded into the reactor, active metal is present in oxide form, but it is not active. The metal in reduced form is usually active. Hence, the pretreatment involves reduction or conversion of the metal oxide into metallic form. It needs temperature treatment along with hydrogen, and usually conducted at temperatures of 500 °C and H2 pressure of 7 bars.

In an embodiment of the present invention, catalyst pretreatment is done at temperature of
500 °C and under H2 pressure of 7 bars.

In a preferred embodiment of the present invention, the process and solvent conditions are as below:
Step 1: The single step production of JP-10 fuel production is carried out by loading the two catalysts in a single reactor.
Step 2: The top bed catalyst is hydrogenation catalyst and bottom bed is the isomerization catalyst, both separated by inert Silicon carbide.
Step 3: Both the catalysts are prepared in extrudate form using alumina as binder.
Step 4: Solvent in fixed bed reactor: -
• One of the key parameters to achieve best yields in single step is the selection of right solvent. The solvent acts as both heat sink for the exothermic reaction as well as solvent for solid DCPD produced during the hydrogenation step.
• Hexane and Exo-THDCPD (JP-10) both are used as solvents. Best results (74% of JP-10 yield in single step) are achieved when hexane is used as solvent in 50wt.% ratio along with DCPD in the feed.
Catalyst stability is also tested for 180 hrs. and is found to have stable activity.

EXAMPLES:
The disclosure will now be illustrated with working examples, which are intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure.

Example 1: Hydrogenation catalyst formulations.
a. Extrudate form.
Hydrogenation catalyst formulation is synthesized by mixing metals and their oxides in amount in a range of 0.1 – 5 wt% and support/structural promoters in a range of 85 – 94 wt% and finally the catalysts are prepared in extrudate form using binder in a range of 5 – 10 wt%. List of materials and their amounts for hydrogenation catalyst formulation in extrudate form is tabulated in table 1.

Table 1. List of materials and their amounts for hydrogenation catalyst formulation in extrudate form
S.No. List of Materials wt% ranges
1 Metals and/or their oxides:
Pt, Pd, Ni, Ru, Rh, Cu, Mo, W 0.1 - 5
2 Support/Structural Promoters:
Silica (SiO2), Alumina-Silica (Al2O3-SiO2), Alumina (Al2O3), ?-Al2O3, Magnesium silicate (Talc), Zirconia (ZrO2), ZSM-5 85 – 94%
3 Binders:
Pseudo boehmite, ludox silica, precipitated silica, Hydroxy propyl methyl cellulose 5 – 10%

a. Powder form.
Hydrogenation catalyst formulation in powder form is synthesized by mixing metals and their oxides in amount in a range of 0.1 – 5 wt% and support/structural promoters in a range of 95 – 99.9 wt%. List of materials and their amounts of hydrogenation catalyst formulation in powder form is tabulated in table 2.

Table 2. List of materials and their amounts of hydrogenation catalyst formulation in powder form
S. No. List of Materials wt% ranges
1 Metals and/or their oxides:
Pt, Pd, Ni, Ru, Rh, Cu, Mo, W 0.1 - 5
2 Support/Structural Promoters:
Silica (SiO2), Alumina-Silica (Al2O3-SiO2), Alumina (Al2O3), ?-Al2O3, Magnesium silicate (Talc), Zirconia (ZrO2), ZSM-5 95 – 99.9%

The difference between extrudate and powder form is that binder is not generally used in powder form. Also, the binder used is generally boehmite (alumina oxy hydroxide) which after heat treatment becomes part of alumina. Results for extrudate form and powder form of the hydrogenation catalyst are shown in the table 3.

Table 3. Results for extrudate form and powder form of the hydrogenation catalyst
Catalyst Conversion Endo % Selectivity Exo % Exo yield % ADM yield %
Extrudate form 75 92.17 68 0.48
Powder form 89 97.5 87 0.70

Although powder form shows better activity over extrudate, due to high exposed surface area associated with smaller particles. However, the catalyst cannot be loaded in powder form for continuous evaluation, it has to be in extrudate form.

Example 2: Best hydrogenation catalyst formulation in extrudate form.
Several catalysts were synthesized and evaluated in a lab scale reactor and finalized best catalyst formulation with 0.3 – 1.0 wt% Pd/?-Al2O3 as final formulation. Table 4 indicates the textural and physical characteristics of the hydrogenation catalyst final formulation in extrudate form.

Table 4. Textural and physical characteristics of the hydrogenation catalyst in extrudate form
Component Unit of Measurement Amount/concentration
Pd wt% 0.3-1.0
?-Al2O3 Support wt% 93.0-93.7
Pseudo boehmite Binder wt% 5 - 10
Physical characteristics of the final hydrogenation catalyst formulation
Average Crushing Strength Min/Max/Average (kg) 14.31/18.32/16.32
Surface Area m2/gm 190
Pore Volume N2 PV cc/g 0.40
Average pore radius nm 4.0
Pd dispersion % 70
Catalyst (tap) density g/cc 0.72

Example 3: Isomerisation catalyst formulation.
a. Extrudate form.
Isomerisation catalyst formulation is synthesized by mixing metals and/or their oxides in amount in a range of 0.1 – 5 wt% and solid acid zeolite in a range of 40 – 60 wt% and finally the catalysts are prepared in extrudate form using binder in a range of 40 – 60 wt%. List of materials and their amounts of hydrogenation catalyst formulation in extrudate form is tabulated in table 5.

Table 5. List of materials and their amounts of hydrogenation catalyst formulation in extrudate form
S.No. List of Materials wt% ranges
1 Metals and/or their oxides:
Pt, Pd, Ni, Ru, Rh, Cu, Mo, W 0.1 - 5
2 Solid Acid zeolite:
HY zeolite, Beta zeolite, ZSM-5, MCM-41, ZSM-22, Mesoporous Y zeolite 40 – 60%
3 Binders:
Pseudo boehmite, ludox silica, precipitated silica, Hydroxy propyl methyl cellulose 40 – 60%

b. Powder form.
Isomerization catalyst in powder form is synthesized by mixing metals and/or their oxides in amount in a range of 0.1 – 5 wt% and solid acid zeolite in a range of 95 – 99.9 wt%. List of materials and their amounts of hydrogenation catalyst formulation in powder form is tabulated in table 6.

Table 6. List of materials and their amounts of hydrogenation catalyst formulation in powder form
S. No. List of Materials wt% ranges
1 Metals and/or their oxides:
Pt, Pd, Ni, Ru, Rh, Cu, Mo, W 0.1 - 5
2 Solid Acid zeolite:
HY zeolite, Beta zeolite, ZSM-5, MCM-41, ZSM-22, Mesoporous Y zeolite 95 – 99.9%

Example 4: Best Isomerisation catalyst formulation in extrudate form.
Several catalysts were synthesized and evaluated in a lab scale reactor and finalized best catalyst formulation with 0.1 – 5 wt% Pt/ Mesoporous Y zeolite as final formulation. Table 7 indicates the textural characteristics of the isomerisation catalyst final formulation in extrudate form.

Table 7. Textural characteristics of the isomerisation catalyst in extrudate form
Component Unit of Measurement Amount/concentration
Pt wt% 0.1 - 5
Mesoporous Y zeolite wt% 40 – 60%
Pseudo boehmite Binder wt% 40 – 60%

Example 5: One step flow process in the fixed bed reactor.
The single step process involves transformation of powder form of both the hydrogenation and isomerization catalysts into extrudate form using suitable binders. The extrudate form of the catalysts are loaded as two separate beds in a single tubular reactor, with hydrogenation and isomerization as top and bottom beds respectively and separated by silicon carbide inert. The feed DCPD is continuously pumped into the reactor in down-flow passion, and the product JP-10 comprises exo-tetrahydrodicyclopentadiene, endo-tetrahydrodicyclopentadiene, and adamantane. is continuously collected from bottom of the reactor. Reaction temperature is 175 °C, pressure 25 bar and H2/feed mole ratio at 3 and weight hour space velocity (WHSV) is maintained at 1 h-1. To ease the process of selecting right catalyst, catalysts are usually screened in powder form in batch process, prior to use it in a continuous process (Fig. 1).

Example 6: Evaluation of Various Zeolites for Isomerization.
In the process of isomerization, the pivotal factors under consideration include the catalyst's activity and the dimensions of its shape-selective pores. Given the dimensions of endo-THDCPD at approximately 0.67 nm * 0.65 nm, Y-type zeolites (measuring 0.74 nm * 0.74 nm) emerge as the prime candidates for facilitating the diffusion of reactants within these pores. Various zeolites have undergone extensive assessment for their efficacy in converting endo-THDCPD to exo-THDCPD. Several zeolite catalysts have been thoroughly evaluated for their effectiveness in converting endo-THDCPD to exo-THDCPD, including HY, Beta, ZSM-5, and Mordenite Zeolites( MOR). The exo-product yield is as follows: 74.24% for HY, 69.77% for Beta, 11.62% for ZSM-5, and 8.59% for MOR.

Notably, HY zeolites have exhibited remarkable selectivity, yielding a substantial quantity of exo-THDCPD, along with a 2.34% production of adamantane. It's crucial to highlight that elevating the temperature to 200°C to boost exo yield can also lead to an increase in adamantane yield beyond 1 wt%. Consequently, a paramount objective is to devise a method that yields a high exo-THDCPD output while maintaining adamantane levels below 1 wt%. As adamantane isn't produced at lower temperatures. When tested, HY zeolite at 150°C yielded 59.17%, while adamantane showed zero wt% yield., it is imperative to establish a reaction protocol where the temperature remains relatively low, while ensuring a high exo-THDCPD yield.

Example 7: Desilication of HY zeolites.
Among all the zeolites, HY zeolites showed superior results with approx. 60 % yield of exo THDCPD at 150 oC temperature and atmospheric pressure where no adamantane yield is obtained. In order to increase the yield further, the total acidity needs to be increased. The simplest and economical method to increase acidity is the desilication of HY zeolites with base. Desilication of HY zeolites has been done using different templates with concentration of 0.05 M including NaOH, TBAOH (Tetrabutylammonium hydroxide), CTAB (Cetyltrimethyl ammonium bromide). The exo-product yield is as follows: 55.87% for HY (NaOH), 87.11% for HY (TBAOH), 84.39% for HY (CTAB). The result shows that among all three templates TBAOH, offers the best results. However, the TBAOH and CTAB are very expensive templates so for large scale synthesis, an alternative economical viable template needs to be identified. Since NaOH is relatively inexpensive raw material for introducing the mesoporosity in HY zeolite. The effectiveness of type of templates on the activity has been studied. Different concentration of NaOH template have been thoroughly evaluated to synthesize desilicated HY zeolites. The exo-product yield is as follows: 55.87% for NaOH (0.05 M), 79.47% for NaOH (0.025 M), 83.63% for NaOH (0.01 M) and 86.34% for NaOH (0.005 M). Therefore, lower concentration of NaOH, provided higher activity for isomerization of endo to exo THDCPD reaction.

The desilication process to obtain mesoporous zeolite begins by taking 10g of HY zeolite and dispersing it in a 200 ml solution of 0.05M TBAOH. Stir this mixture for 30 minutes. Once the 30-minute mark is reached, recover the solid product contained in the beaker. This resultant mixture can be directly employed in the subsequent step of the process. Following the base treatment, the next phase involves an ammonia exchange procedure, which utilizes a 0.5M NH4SO4 solution. 20ml of the NH4SO4 solution is taken and put into a 250 mL round-bottom flask, where 10g of zeolite combines with it in a 2:1 ratio. This mixture was stirred for 4 hours at a temperature of 60°C. Subsequently, centrifugation of the reaction mixture (operating at 5000 rpm for 5 minutes) was carried out and then collected the solid product. This procedure should be repeated a minimum of 2 times to ensure thorough completion.

The final step in this process involves meticulous washing of the solid product using deionized (DI) water. Once washed, the product was allowed to dry overnight at a temperature of 90°C. Following this, initiate calcination, heating at 550°C for a duration of 10 hours while ramping up the temperature at a rate of 2°C per minute. These same steps should be meticulously repeated for the synthesis involving NaOH and CTAB.
Establishing advantageous effects shown by desilicated HY zeolites.
(a). XRD data.
X-ray Diffraction (XRD) serves as an exceptionally valuable technique for evaluating the crystal structure of a wide range of materials, encompassing zeolites such as the highly stable Y-type (HY) zeolites. In the context of HY zeolites, the desilication process entails the extraction of silicon atoms from the zeolite framework, leading to a reduction in the crystallinity of the zeolite structure and its related properties. Rigorous XRD experiments have corroborated that desilication indeed leads to a minor decline in the crystallinity of HY zeolites.

Interestingly, despite this decrease in crystallinity, the fundamental structural attributes of HY zeolites endure with minimal modification. The XRD analysis underscores the persistence of all characteristic peaks affiliated with HY zeolites, signifying that the structural integrity of HY zeolites remains predominantly unchanged following the desilication process.

(b). Acidity data.
The increase in acidity resulting from the desilication of HY zeolites, from 3587.7 to 4265.6 µmol/g, plays a pivotal role in enhancing the zeolite's activity at lower temperatures. This increased acidity represents a substantial advantage gained through the desilication process of HY zeolites.

Evaluation of the isomerization catalysts for fixed bed reactor.
1. Base treatment of HY zeolite (isomerization catalyst) to modify acidity and improve catalyst activity:
HY zeolite is treated with different bases of varying concentration to decrease silica content (desilication) and widen up the pores as well increase overall acidity. The improvement in acidity with expected pore widening has improved the isomerization activity is shown in table 8.
Table 8. Effect of base treatment of HY zeolite on isomerization activity
Base treatment Endo Conv. (%) Exo Selectivity Exo Yield Adamantane Yield
No treatment 59.6 99.2 59.17 0
NaOH (0.005 M) 91.13 94.74 86.34 0.8
Tetrabutyl ammonium hydroxide (TBAOH) 89.39 97.46 87.11 0.73

Initial screening of the isomerization catalysts is carried out in a reactor to select the best catalyst for a fixed bed operation. Under the similar reaction conditions of temp 150 °C and reaction of 6 hours under N2 environment, the exo-yields are improved to 86.34% from 59.17% through NaOH treatment. Though other bases such as TBAOH are found to slightly increase the overall exo-yields, considering the lower cost of NaOH over TBAOH, the former is selected for treatment of the isomerization catalyst for further studies in fixed bed reactor. TBAOH treated HY zeolites is selected for the treatment of Isomerization catalyst for further studies in fixed bed reactor.

2. Catalysts for Single Step JP-10 Production in Fixed Bed Reactor.
The isomerization catalyst has been made into extrudates for industrial scale applicability, using alumina as binder < 40 %. The isomerization catalyst has been tested along with hydrogenation catalyst (Pd/?-Al2O3) maintaining the hydrogenation catalyst as top bed, followed by isomerization catalyst at the bottom.

Although negligible/no amount of adamantane is found during the fixed bed reaction as shown in the table 9, the isomerization catalyst is found to deactivate rapidly, and the exo-yields are very low compared to the batch process. Even though catalyst in powder form (used for batch process) is more active than extrudate form due to small particle sizes. But still continuous process has several advantages over batch process, as in batch process, the reaction has to be stopped several times viz. every 6 hrs and catalyst to be changed, this affects continuity in the production. The powder form of catalyst is not suitable for continuous process as the catalyst in powder form moves of in the reactor tube and is not retained for long time in the reactor.

Table 9. Results for single Step JP-10 Production in Fixed Bed Reactor
Reaction Time DCPD conversion Exo Selectivity Exo yield Adamantane Yield
12 hrs 97.51 20.94 20.42 0
18 hrs 94.57 30.86 29.18 0
24 hrs 96.25 18.05 17.37 0
30 hrs 96.18 12.72 12.49 0
Reaction conditions: Temp: 170 °C, H2 pressure = 25 bar, H2/HC mole ratio = 3, WHSV = 1h-1 and 50% of hexane is used as solvent.

3. Addition of Platinum to increase catalyst stability.
As the deactivation is found to occur due to coke deposition at the reaction temperature, 0.3 wt% of Pt metal is impregnated into the base modified HY zeolite and extruded with 40% of alumina to make the industrial relevant formulation. The isomerization catalyst is evaluated along with the hydrogenation catalyst. The Pt metal incorporation has significantly improved the stability of the catalyst as shown in table 10. Also, the formulation is active only for isomerization reaction and the side product adamantane is always maintained < 1%.

Table 10. Effect of Platinum incorporation on isomerization catalyst stability
Reaction Time DCPD conversion Exo Selectivity Exo yield Adamantane Yield
24 hrs 99.32 63.3 62.86 0.59
48 hrs 99.47 66.1 65.74 0.72
72 hrs 99.36 74.33 73.85 0.63
96 hrs 99.56 72.41 72.09 0.58
120 hrs 99.56 72.22 71.90 0.58
144 hrs 99.53 72.51 72.17 0.57
168 hrs 99.60 73.35 73.06 0.57
192 hrs 99.65 74.10 73.84 0.63

4. Catalyst regeneration studies.
The catalyst could be regenerated for both hydrogenation and isomerization through simple coke burning and rejuvenated by adding 0.3 wt% Cl in the catalyst. After carrying out the stability studies for ˜ 190 hrs, both the catalysts are unloaded and checked for regenerability. The results of table 11 show that the catalysts can be regenerated successfully as the exo-yields could be reproduced by using the regenerated catalyst.

Table 11. Catalyst regeneration studies
Reaction Time DCPD conversion Exo Selectivity Exo yield Adamantane Yield
12 hrs 100 67.11 67.11 0.00
24 hrs 99.37 74.22 73.75 1.54
48 hrs 97.93 76.01 74.44 1.20
72 hrs 97.38 61.87 60.25 0.67

5. Solvent evaluation data.
One of the key parameters to achieve best yields in single step is the selection of right solvent. The solvent acts as both heat sink for the exothermic reaction as well as solvent for solid DCPD produced during the hydrogenation step. Hexane and Exo-THDCPD (JP-10) both are used as solvents. Best results (74% of JP-10 yield in single step) are achieved when hexane is used as solvent in 50% wt ratio along with DCPD in the feed. The solvent evaluation data is shown in table 12.

Table 12. Solvent evaluation data
Time / Hrs DCPD Conv. Product Selectivity wt%
ENDO EXO Adamantane Others
Hexane as solvent
8 97.95 12.88 57.2 0.45 29.4
72 99.65 8.50 74.10 0.63 16.75
170 100 18.67 70.08 0.24 11.01
Exo-THDCPD as solvent
24 100 28.63 61.84 0 9.53
36 96.1 26.82 63.67 0 9.5
102 100 37.28 54.62 0 8.10

, Claims:1. A single step continuous flow process for the preparation of a JP-10 fuel from dicyclopentadiene (DCPD) in a fixed bed reactor comprising:
subjecting dicyclopentadiene to a hydrogenation in presence of a hydrogenation catalyst and an isomerization in presence of an isomerization catalyst in combination in the fixed bed reactor to obtain the JP-10 fuel comprising exo-tetrahydrodicyclopentadiene, endo-tetrahydrodicyclopentadiene, and adamantane.
wherein both the hydrogenation catalyst and isomerization catalyst are in an extrudate form.
2. The process as claimed in claim 1, wherein the hydrogenation catalyst comprises 0.1 - 5 wt% of a metal on 85 – 94 wt% of a support.
3. The process as claimed in claim 2, wherein the metal is selected from the group consisting of Pt, Pd, Ni, Ru, Rh, Cu, Mo, and W.
4. The process as claimed in claim 2, wherein the support is selected from the group consisting of Silica (SiO2), Alumina-Silica (Al2O3-SiO2), Alumina, ?-Al2O3, Magnesium silicate (Talc), Zirconia (ZrO2), and ZSM-5.
5. The process as claimed in claim 2, wherein the hydrogenation catalyst comprises 0.3-1 wt.% of Palladium (Pd) and 93.0-93.7 wt.% of ?-Al2O3.
6. The process as claimed in claim 2, wherein the hydrogenation catalyst is prepared by incipient impregnation method, or wet impregnation method.
7. The process as claimed in claim 2, wherein the hydrogenation catalyst is prepared in extrudate form using a binder in a range of 5 to 10 wt%.
8. The process as claimed in claim 7, wherein the binder is selected from the group consisting of pseudo boehmite, ludox silica, precipitated silica and hydroxy propyl methyl cellulose.
9. The process as claimed in claim 1, wherein the isomerisation catalyst comprises metal or its oxide in a range of 0.1 - 5 wt.%, a solid acid zeolite in a range of 40 to 60 wt.% and a binder in a range of 40 to 60 wt.%, wherein the metal is selected from the group consisting of Pt, Pd, Ni, Ru, Rh, Cu, Mo, and W.
10. The process as claimed in claim 9, wherein the zeolite is selected from the group consisting of HY zeolite, beta zeolite, ZSM-5, MCM-41, ZSM-22, and Mesoporous Y zeolite.
11. The process as claimed in claim 9, wherein the binder is selected from the group consisting of Pseudo boehmite, ludox silica, precipitated silica and Hydroxy propyl methyl cellulose.
12. The process as claimed in claims 9 - 11, wherein the zeolite is desilicated with a base to obtain mesoporous zeolite with improved acidity, wherein the base is selected from the group consisting of NaOH and Tetrabutyl ammonium hydroxide.
13. The process as claimed in claim 12, wherein Platinum (Pt) metal in a range of 0.1 to 0.5 wt% is incorporated on base modified zeolite to improve stability.
14. The process as claimed in claim 1, wherein the hydrogenation catalyst and the isomerization catalyst are in the same reactor and wherein, the hydrogenation catalyst is loaded in a top bed of the fixed bed reactor and the isomerization catalyst is loaded in a bottom bed of the fixed bed reactor, both separated by inert material preferably, Silicon carbide.
15. The process as claimed in claim 1, wherein solvent used in feed with dicyclopentadiene and the solvent is selected from the group consisting of hexane and exo-THDCPD.
16. The process as claimed in claim 15, wherein yield of exo-THDCPD is 74 % when hexane is used as solvent in 50 wt % ratio along with DCPD in the feed.
17. The process as claimed in claim 1, wherein the hydrogenation catalyst and the isomerization catalyst are regenerated through simple coke burning and regenerated by adding 0.3 wt% Cl in the catalyst.
18. The process as claimed in claim 1, wherein the yield of adamantane obtained is less than 1 %.