Claims:WE CLAIM:

1. A process for preparing a catalyst composite for producing para-substituted dialkyl benzene from mono-alkyl benzene, said process comprising:
I. mixing
a. zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1,
b. a compositing agent,
c. phosphoric acid or its salt, and
d. water
to obtain an extrudable mass;
II. extruding said extrudable mass to obtain extruded bodies; and
III. drying said extruded bodies at a temperature in the range of 80 °C to 120 °C to obtain dried extruded bodies; and
IV. calcining said dried extruded bodies at a temperature in the range of 500 °C to 600 °C to obtain said catalyst composite.
2. The process as claimed in claim 1, wherein said compositing agent is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, pseudoboehmite, silica and gallium oxide.
3. The process as claimed in claim 1, wherein said alkali salt of phosphoric acid is potassium dihydrogen phosphate.
4. The process as claimed in claim 1, wherein said zeolite is selected from the group consisting of zeolites of the pentasil family.
5. The process as claimed in claim 1, wherein said zeolite is unmodified zeolite.
6. The process as claimed in claim 1, wherein said zeolite is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite.
7. The process as claimed in claim 6, wherein said hetero-atom incorporated zeolite is at least one selected from the group consisting of Al-ZSM-5, Ga-ZSM-5, Fe-ZSM-5, B-ZSM-5, Ga-Al-ZSM-5, Fe-Al-ZSM-5, B-Al-ZSM-5, Cr-ZSM-5 and Cr-Al-ZSM-5.
8. The process as claimed in claim 1, wherein the weight ratio of said compositing agent to phosphoric acid or its salt is in the range of 1:0.5 to 1:1.5.
9. The process as claimed in claim 1, wherein said extrudable mass obtained in step (I) comprises an extrusion aid, wherein said extrusion aid is hydroxy propyl methyl cellulose.
10. The process as claimed in claim 1, wherein said extruded bodies have at least one shape selected from the group consisting of spherical, cylindrical, tri-lobe, tetra-lobe, star, ring, tablets, pellets, and honeycomb structure.
11. A catalyst composite comprising:
- zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1;
- a compositing agent; and
- a phosphorus component.
12. The catalyst composite as claimed in claim 11, wherein said zeolite is selected from the group consisting of zeolites of the pentasil family.
13. The catalyst composite as claimed in claim 11, wherein said zeolite is unmodified zeolite.
14. The catalyst composite as claimed in claim 11, wherein said zeolite is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite.
15. The catalyst composite as claimed in claim 14, wherein said hetero-atom incorporated zeolite is at least one selected from the group consisting of Al-ZSM-5, Ga-ZSM-5, Fe-ZSM-5, B-ZSM-5, Ga-Al-ZSM-5, Fe-Al-ZSM-5, B-Al-ZSM-5, Cr-ZSM-5 and Cr-Al-ZSM-5.
16. The catalyst composite as claimed in claim 11, wherein said compositing agent is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, pseudoboehmite, silica, and gallium oxide.
17. A process for selectively producing para-substituted-dialkyl benzene from mono-alkyl benzene using a catalyst composite as claimed in claim 1 or claim 11, said process comprising:
contacting a hydrocarbon comprising mono-alkyl benzenes, an alkylating agent, optionally a carrier gas, with said catalyst composite in a reactor to obtain a product mixture comprising dialkyl benzene, wherein the mass of para-substituted dialkyl benzene is in the range of 60 wt% to 95 wt% of the total mass of dialkyl benzene.
18. The process as claimed in claim 17, wherein said para-substituted dialkyl benzene is at least one selected from the group consisting of para-xylene, para-ethyl toluene, para-diethyl benzene, and para-di-iso-propyl benzene.
19. The process as claimed in claim 17, wherein said mono-alkyl benzene is at least one selected from the group consisting of toluene, ethyl benzene, iso-propyl benzene, and mixture comprising xylene and ethyl benzene.
20. The process as claimed in claim 17, wherein said alkylating agent is at least one selected from the group consisting of methanol, ethanol, propanol, iso-propanol, ethylene and propylene.
21. The process as claimed in claim 17, wherein the mole ratio of said mono-alkyl benzene to said alkylating agent is in the range of 20:1 to 1:20.
22. The process as claimed in claim 17, wherein said carrier gas is at least one selected from the group consisting of hydrogen and steam.
23. The process as claimed in claim 17, wherein said process is carried out at a temperature in the range of 20 °C to 700 °C, preferably 50 °C to 600 °C, at a pressure in the range of 0.01 bar to 100 bar, preferably 0.1 bar to 80 bar for a time period in the range of 0.001 hour to 50 hours, preferably 0.01 hour to 40 hours.
, Description:FIELD
The present disclosure relates to a catalyst composite and a process for preparing the same.
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 indicate otherwise.
Coking: The term “coking” refers to a method of thermal cracking that used to deposite carbonaceoous mater on zeolite surface and pore mouth.
Silanation: The term “silanation” refers to a process of covering of a metallosilicate catalyst with alkoxysilane molecules, followed by calcination thereby resulting in deposition of inert silica on surface of metallosilicate catalyst.
Compositing agent: Compositing agent is the material used for combining with a different material of separate source to form a single composite material.
Selectivity: The term “selectivity” as used herein refers to the ratio of the desired product formed to the total product (desired and undesired) formed.
Para-isomer selectivity: The term “p-isomer selectivity” refers to the selectivity/content of p-isomer in the mixed isomers.

Unmodified zeolite: The term “unmodified zeolite” refers to the as synthesized zeolite in its proton form that is not pre-treated and/or post-treated to change its properties. Modificatioin of zeolite can be done by various processes such as coking of zeolite, and treating zeolite with steam, impregnation with oxides of metal or non-metal.
Pentasil zeolite: The term “pentasil zeolite” refers to a family of silicate / aluminosilicate structures composed of five membered ring structure as building unit.
BACKGROUND
Para-xylene is produced from naphtha through a number of catalytic processes. Para-xylene produced in the mixture, having xylene isomers, viz meta-xylene, and ortho-xylene, is separated by either crystallization or adsorptive technology.
Para-xylene can also be produced through selective alkylation or disproportionation of toluene by employing modified zeolites of pentasil family. Such modification includes in-situ coking of zeolite, or impregnation of oxides of metal/non-metal on the zeolite. Silanated zeolite are well known catalysts for selective production of para-xylene though alkylation or disproportionation of toluene. However, the process of silanation of zeolite is multistep and cumbersome that requires handling of large amounts of organic solvents, involves special and high-priced organo-silicon compound, long procedures and the like. Overall, the process of silanation of zeolite results in very low productivity during catalyst production, which results in up shooting of the catalyst production cost. Also, the catalyst produced using conventional processes had moderate selectivity for para-substituted dialkyl benzene.
Therefore, there is felt a need to provide a catalyst composite that mitigates the aforestated drawbacks.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide a catalyst composite having enhanced selectivity for para-isomer in dialkyl benzene.
Still another object of the present disclosure is to provide a simple and economic process for preparing the catalyst composite.
Yet another object of the present disclosure is to provide an economic and energy efficient process for selectively producing para- substituted dialkyl benzene from mono-alkyl benzene.
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
In an aspect, the present disclosure relates to a process for preparing a catalyst composite for producing para-substituted dialkyl benzene from mono-alkyl benzene. The process comprises mixing of zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, a compositing agent, phosphoric acid or its salt, and water to obtain an extrudable mass. The extrudable mass further comprises an extrusion aid, wherein the extrusion aid is hydroxy propyl methyl cellulose. The extrudable mass is extruded to obtain extruded bodies. The extruded bodies are dried at a temperature in the range of 80 °C to 120 °C to obtain dried extruded bodies. The dried extruded bodies are calcined at a temperature in the range of 500 °C to 600 °C to obtain the catalyst composite.
The extruded bodies have at least one shape selected from the group consisting of spherical, cylindrical, tri-lobe, tetra-lobe, star, ring, tablets, pellets, and honeycomb structure.
The present disclosure further relates to a catalyst composite comprising zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, and a compositing agent, and a phosphorus component.
The zeolite is selected from the group consisting of zeolites of the pentasil family and is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite.
The compositing agent is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, pseudoboehmite, silica, and gallium oxide.
In another aspect, the present disclosure relates to a process for selectively producing para- substituted dialkyl benzene from mono-alkyl benzene. The process comprises contacting a hydrocarbon comprising mono-alkyl benzenes, an alkylating agent, and optionally a carrier gas, with the catalyst composite in a reactor to obtain para-substituted dialkyl benzene in the range of 60 wt% to 95 wt% of the total mass of dialkyl benzene.
The mole ratio of the mono-alkyl benzene to the alkylating agent is in the range of 20:1 to 1:20.
The process is carried out at a temperature in the range of 20 °C to 700 °C, preferably 50 °C to 600 °C, at a pressure in the range of 0.01 bar to 100 bar, preferably 0.1 bar to 80 bar for a time period in the range of 0.001 hour to 50 hours, preferably 0.01 hour to 40 hours.

DETAILED DESCRIPTION
Para-xylene is produced from naphtha through a number of catalytic processes and separated by either crystallization or adsorptive technology. Para-xylene can also be produced through conventional processes. The catalyst produced using conventional processes had moderate selectivity for para-substituted dialkyl benzene.
Therefore, the present disclosure envisages an effective catalyst composite, prepared in a simple, and economic way, having enhanced selectivity for producing para- substituted dialkyl benzene from mono-alkyl benzene.
In an aspect of the present disclosure, there is provided a process for preparing a catalyst composite for producing para-substituted dialkyl benzene from mono-alkyl benzene.
In one embodiment of the present disclosure, the process for preparing catalyst composite comprises the following steps:
In the first step, zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, a compositing agent, phosphoric acid or its salt, and water are mixed to obtain an extrudable mass.
In accordance with the embodiment of the present disclosure, the extrudable mass of the first step further comprises an extrustion aid, wherein the extrusion aid is hydroxy propyl methyl cellulose.
The zeolite is selected from the group consisting of zeolites of the pentasil family and is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite. The hetero-atom incorporated zeolite is at least one selected from the group consisting of Al-ZSM-5, Ga-ZSM-5, Fe-ZSM-5, B-ZSM-5, Ga-Al-ZSM-5, Fe-Al-ZSM-5, B-Al-ZSM-5, Cr-ZSM-5 and Cr-Al-ZSM-5. In accordance with an embodiment of the present disclosure, the zeolite is unmodified zeolite.
The compositing agent is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, pseudoboehmite, silica and gallium oxide. The compositing agent has low acid strength (almost neutral) of terminal hydroxyl groups that affects the performance of the catalyst composite of the present disclosure.
The salt of phosphoric acid is potassium dihydrogen phosphate.
The weight ratio of the compositing agent to phosphoric acid or its salt is in the range of 1:0.5 to 1:1.5.
In the second step, the so obtained extrudable mass is extruded to obtain extruded bodies.
The extruded bodies have at least one shape selected from the group consisting of spherical, cylindrical, tri-lobe, tetra-lobe, star, ring, tablets, pellets, and honeycomb structure.
In the third step, the extruded bodies are dried at a temperature in the range 80 °C to 120 °C to obtain dried extruded bodies.
In the fourth step, the dried extruded bodies are calcined at a temperature in the range of 500 °C to 600 °C to obtain the catalyst composite.
The process for preparing catalyst composite involves simple steps and avoids the long procedural steps such as the step of pretreatment of the zeolite and hence it is simple, energy efficient and economic.
In another aspect of the present disclosure, there is provided a catalyst composite comprising zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, a compositing agent, and a phosphorus component.
The zeolite is selected from the group consisting of zeolites of the pentasil family and is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite. The hetero-atom incorporated zeolite is at least one selected from the group consisting of Al-ZSM-5, Ga-ZSM-5, Fe-ZSM-5, B-ZSM-5, Ga-Al-ZSM-5, Fe-Al-ZSM-5, B-Al-ZSM-5, Cr-ZSM-5 and Cr-Al-ZSM-5.
The compositing agent is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, pseudoboehmite, silica, and gallium oxide.
The catalyst composite prepared in accordance with the present disclosure is converted to its active proton form by repeated ion exchange with ammonium salt solution, followed by drying at 120 °C for 12 hours in an air oven and calcined at 540 °C in flowing air for 6 hours.
In still another aspect of the present disclosure, there is provided a process for selectively producing para-substituted dialkyl benzene from mono-alkyl benzene. The process comprises contacting a hydrocarbon comprising mono-alkyl benzenes, an alkylating agent, and optionally a carrier gas with catalyst composite in a reactor to obtain a product mixture comprising dialkyl benzene, wherein the mass of para-substituted dialkyl benzene is in the range of 60 wt% to 95 wt% of the total mass of dialkyl benzene.
The mono-alkyl benzene is at least one selected from the group consisting of toluene, ethyl benzene, iso-propyl benzene, and a mixture of xylene and ethyl benzene.
The alkylating agent is at least one selected from the group consisting of methanol, ethanol, propanol, iso-propanol, ethylene and propylene. The mole ratio of the mono-substituted aromatics to the alkylating agent is in the range of 20:1 to 1:20.
The carrier gas is at least one selected from the group consisting of hydrogen and steam.
The process is carried out at a temperature in the range of 20 °C to 700 °C, preferably 50 °C to 600 °C, at a pressure in the range of 0.01 bar to 100 bar, preferably 0.1 bar to 80 bar for a time period in the range of 0.001 hour to 50 hours, preferably 0.01 hour to 40 hours.
The para-substituted dialkyl benzene is at least one selected from the group consisting of para-xylene, para-ethyl toluene, para-diethyl benzene, and para-di-iso-propyl benzene.
The catalyst composite of the present disclosure has para-selectivity greater than 85 % than that with alumina based composite.
The catalyst composite prepared in accordance with the present disclosure can be regenerated and reused repeatedly after removal of carbonaceous materials deposited on the catalyst composition during the alkylation process. Further, since the catalyst composite of the present disclosure is highly selective for para-isomer, the catalyst composite prevents production of benzene co-products and thus reduces the load on the separation unit. Therefore, the process for preparing para-susbstituted dialkyl benzene from mono-alkyl benzene using catalyst composite of the present disclosure is economic and energy efficient.
Overall, the process of the present disclosure for preparing the catalyst composite is simple, energy efficient and economic.
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 DETAIL:
Experiment 1 (Comparative experiment): Preparation of shaped ZSM-5 zeolite composite with alumina:
4.11 g of Pseudoboehmite alumina (obtained from Condia, having LOI 27 wt%) and 7.58 g of ZSM-5 zeolite having silica to alumina ratio (SAR) of 180, were mixed thoroughly in a mortar-pastel to obtain a mixture. 4.72 g of aqueous solution of 3.7 % acetic acid was added to a mixture and pugged thoroughly to obtain an extrudable mass. The so obtained extrudable mass was extruded using a 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature for 1 hour followed by further drying at 120 °C for 6 hours in an air oven to obtain dried extrudates. The so obtained dried extrudates were calcined at 540 °C for 6 hours under flowing air to obtain the catalyst composite. The zeolite content in the final composite (on loss free basis) was 70 wt%.
Experiment 2: Preparation of shaped catalyst composite with alumina and potassium di hydrogen phosphate (KH2PO4)
7.58 g of ZSM-5 (SAR 180) zeolite, 1.72 g of Pseudoboehmite alumina, 1.58 g of KH2PO4, 0.13 g of HPMC, and 4.21 g of DM water were taken in a mortar-pastel and mixed thoroughly to obtain an extrudable mass. The so obtained extrudable mass was pugged for 10 minutes and extruded using 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature for 1 hour followed by further drying at 120 °C for 6 hours to obtain dried extrudates. The so obtained dried extrudates were calcined at 540 °C for 6 hours under flowing air to obtain the catalyst composite. The zeolite content of the catalyst composite was 70 wt%.
It is evident from experiments 1-2 of the present disclosure that the process for preparing catalyst composite involves simple steps and avoids the long procedural steps such as the step of pretreatment of the zeolite and hence it is energy efficient and economic.
Experiments 3-4
Catalyst composites prepared in experiments 1-3 were converted to active proton form by repeated ion exchange with 5 wt% ammonium salt solution, followed by drying at 120 °C for 12 hours in an air oven and calcination at 540 °C in flowing air for 6 hours.
Catalytic performance of these activated catalyst composites were evaluated for methylation of toluene in a fixed bed down flow reactor. Feed containing toluene and methanol at a mole ratio of 6:1, was pre-heated to 200 °C in a preheater and fed to the reactor and contacted with the catalyst composites prepared in experiments 1-2 at 430 °C and at weight hourly space velocity of 3 h-1. Hydrogen was employed as a carrier gas at hydrogen to hydrocarbon mole ratio of 2:1. (Weight Hourly Space Velocity, i.e.WHSV, is defined as weight of hydrocarbon feed passing over unit weight of catalyst per unit time).
The products were cooled in a condenser and were collected from the separator. The hydrocarbons in the products were analyzed by standard Gas Chromatographic method. For the purpose of comparison among the different catalysts prepared as exemplified in experiments 1-2, the reaction conditions were kept fixed as above. Results of catalytic performances of the composites prepared in experiment 1 to experiment 2 are given in table 1.
Table 1: Catalytic performances of the composites prepared in experiments 1-2
Experiment No Catalyst from Toluene Conv., wt% Xylene Yield, wt% p-Xylene Selectivity, %
Experiment 3 Experiment 1
(Comparative experiment) 12.6 12.2 43.3
Experiment 4 Experiment 2 11.6 11.9 81.6

From table 1, it is found that para-xylene selectivity for the catalyst composites of present disclosure is 88.45 % higher than that with alumina based composite (comparative experiment 1).
It is evident from table 1 that the catalyst composites prepared in accordance with the present disclosure provides higher selectivity for para-xylene than that with the catalyst composites prepared in comparative experiment 1.
Experiment 5
The experiment shows the performance of the catalyst composite as prepared in experiment 2 of the present disclosure in presence of water as co-feed and in the absence of hydrogen as a carrier gas.
Feed containing toluene and methanol at a mole ratio of 6:1 along with 20 wt% of steam pre-heated at 200 °C was fed to the reactor and contacted with the catalyst composite at 430 °C and at weight hourly space velocity (WHSV) of 3 h-1. No hydrogen gas was used in this case. The products were cooled in a condenser and were collected from a separator. The hydrocarbons in the products were analyzed by standard Gas Chromatographic method and results are shown in Table 2.
Table 2: Catalytic performances of the composite prepared in experiment 2 with water as co-feed.
Experiment No Catalyst from Tol. Conv.,
wt% Xylene Yield,
wt% P-Xylene Selectivity,
%
Experiment 5 Experiment 2 8.0 8.7 84.5

From table 2, it is found that the catalyst composite of the present disclosure as prepared in experiment 5, when used in methylation of toluene in presence of water as co-feed and in the absence of hydrogen as carrier gas, provides higher selectivity for para-xylene. Since, the hydrogen is not used as carrier gas, the process for converting mono-alkyl benzene to para-sustituted dialkyl benzene is energy efficient.
Experiments 6-7
Catalyst composites prepared in experiment 1-2 were converted to active proton form by repeated ion exchange with 5 wt% ammonium salt solution, followed by drying at 120 °C for 12 hours in an air oven and calcination at 540 °C in flowing air for 6 hours.
Catalytic performance of these activated catalyst composites were evaluated for ethylation of a hydrocarbon stream rich in ethyl benzene (EB) [mixed xylene solvent (MXS)]. Composition of MXS hydrocarbon stream comprised of EB 73.78 wt%, xylenes 24.32 wt% and C9 and higher 0.59 wt%.
Feed containing MXS and ethanol at a mole ratio of 8:1, was pre-heated to 200 °C in a preheater and fed to the reactor and contacted with the catalyst composites prepared in experiments 1-3 at 330 °C and at WHSV of 3 h-1. Hydrogen was employed as a carrier gas at hydrogen to hydrocarbon mole ratio of 2:1.
Total Diethyl Benzene (DEB) yield and para-diethyl benzene (PDEB) isomer selectivity was taken as performance criteria. Results of catalytic performances of the composites prepared in experiment 1 to experiment 2 are given in table 3.
Table 3: Catalytic performances of the composites prepared in experiments 1-2
Experiment No Catalyst from DEB. Yield, wt% PDEB Selectivity, %.,
Experiment 6 Experiment 1
(Comparative experiment) 11.5 43.1
Experiment 7 Experiment 2 6.8 92.6

From table 3, it is found that PDEB selectivity for the catalyst composites of the present disclosure is 114 % higher than that with alumina based composite (comparative experiment 1).
It is evident from table 3 that the catalyst composites prepared in accordance with the present disclosure provides higher selectivity for para-diethyl benzene (PDEB) than that with the catalyst composites prepared in comparative experiment 1.
Overall, the process of the present disclosure for preparing the catalyst composite is simple, energy efficient and economic. Further, the catalyst composite of the present disclosure has enhanced selectivity for producing para-substituted dialkyl benzene from mono-alkyl benzene. Still further, the process for alkylating mono-alkyl benzene into para-substituted dialkyl benzene is economic and energy efficient.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
- a simple, energy efficient and economic process for preparing a catalyst composite;
- a catalyst composite having enhanced selectivity for producing para-substituted dialkyl benzene from mono-alkyl benzene; and
- an economic and energy efficient process for preparing para-substituted dialkyl benzene from mono-alkyl benzene.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
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 invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of experiment only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions, and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment 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.