Claims:WE CLAIM:

1. A process for preparing a catalyst composite for producing para-substituted dialkyl benzene from mono-alkyl benzene, said process comprising:
a. reacting alumina with phosphoric acid or its salt in water to obtain a hydrogel comprising aluminium phosphate;
b. mixing zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, and optionally alumina to obtain a mixture;
c. mixing said hydrogel, said mixture, and water to obtain a mass;
d. pugging said mass to obtain a pugged mass;
e. extruding said pugged mass to obtain extruded bodies;
f. drying said extruded bodies at a temperature in the range of 80 °C to 120 °C to obtain dried extruded bodies; and
g. 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 reaction of said alumina with said phosphoric acid or its salt is carried out under stirring for a time period in the range of 5 minutes to 30 minutes.
3. The process as claimed in claim 1, wherein said alumina is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, and pseudoboehmite.
4. The process as claimed in claim 1, wherein said alkali salt of phosphoric acid is potassium dihydrogen phosphate.
5. The process as claimed in claim 1, wherein said zeolite is selected from the group consisting of zeolites of the pentasil family.
6. The process as claimed in claim 1, wherein said zeolite is unmodified zeolite.
7. 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.
8. The process as claimed in claim 7, 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.
9. The process as claimed in claim 1, wherein the weight ratio of said alumina to said phosphoric acid or its salt is in the range of 0.5:1 to 1.5:1, preferably 0.5:1 to 0.6:1.
10. The process as claimed in claim 1, wherein said mixture obtained in step (b) comprises an extrusion aid, wherein said extrusion aid is hydroxy propyl methyl cellulose.
11. 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 honey comb.
12. A catalyst composite comprising:
- zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1;
- aluminium phosphate; and
- optionally alumina.
13. The catalyst composite as claimed in claim 12, wherein said zeolite is selected from the group consisting of zeolites of the pentasil family.
14. The catalyst composite as claimed in claim 12, wherein said zeolite is unmodified zeolite.
15. The catalyst composite as claimed in claim 12, wherein said zeolite is at least one selected from the group consisting of ZSM-5, ZSM-11, and hetero-atom incorporated zeolite.
16. The catalyst composite as claimed in claim 15, 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.
17. The catalyst composite as claimed in claim 12, wherein said alumina is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, and pseudoboehmite.
18. A process for selectively producing para-substituted-dialkyl benzene from mono-alkyl benzene using a catalyst composite as claimed in claim 1 or claim 12, said process comprising:
contacting a hydrocarbon comprising mono-alkyl benzenes, an alkylating agent, 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 55 wt% to 98 wt% of the total mass of dialkyl benzene.
19. The process as claimed in claim 18, 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.
20. The process as claimed in claim 18, 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.
21. The process as claimed in claim 18, wherein said alkylating agent is at least one selected from the group consisting of methanol, ethanol, propanol, iso-propanol, ethylene and propylene.
22. The process as claimed in claim 18, wherein the mole ratio of said mono-alkyl benzene to said alkylating agent is in the range of 20:1 to 1:20.
23. The process as claimed in claim 18, wherein said carrier gas is at least one selected from the group consisting of hydrogen and steam.
24. The process as claimed in claim 18, 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 matter 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 the 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. Modification of zeolite can be done by various processes such as coking of zeolite, and treating zeolite with the help of steam, impregnation with oxides of metal or non-metal.
Pentasil zeolite: The term “pentasil zeolite” refers to any of a family of silicate /aluminosillicate 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 reacting alumina with phosphoric acid or its salt in water to obtain a hydrogel comprising aluminium phosphate. Zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, and optionally alumina are mixed to obtain a mixture. The mixture further comprises an extrusion aid, wherein the extrusion aid is hydroxy propyl methyl cellulose. The hydrogel, the mixture, and water are mixed to obtain a mass. The mass is pugged to obtain a pugged mass. The pugged 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, aluminium phosphate, and optionally alumina.
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 alumina is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, and pseudoboehmite.
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 a carrier gas, with the catalyst composite in a reactor to obtain para-substituted dialkyl benzene in the range of 55 wt% to 98 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, and 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.
The process for preparing catalyst composite comprises the following steps:
In the first step, alumina is reacted with phosphoric acid or its salt in water to obtain a hydrogel comprising aluminium phosphate.
The alumina is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, and pseudoboehmite.
In accordance with an embodiment of the present disclosure, the salt of phosphoric acid is potassium dihydrogen phosphate.
The weight ratio of the alumina to the phosphoric acid is in the range of 0.5:1 to 1.5:1, preferably 0.5:1 to 0.6:1.
The reaction of the alumina with the phosphoric acid or its salt is carried out under stirring for a time period in the range of 5 minutes to 30 minutes.
In the second step, zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, and optionally alumina are mixed to obtain a mixture.
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 the embodiments of the present disclosure, the zeolite is unmodified zeolite.
In accordance with an embodiment of the present disclosure, the mixture of the second step comprises an extrusion aid, wherein the extrusion aid is hydroxy propyl methyl cellulose.
In the third step, the hydrogel, the mixture, and water are mixed to obtain a mass.
In the fourth step, the mass is pugged to obtain a pugged mass.
In the fifth step, the pugged 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 sixth step, the extruded bodies are dried at a temperature in the range 80 °C to 120 °C to obtain dried extruded bodies.
In the seventh 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 step of pre-treatment or post-treatment of the zeolite is not used in the process of the present disclosure and hence it is simple, energy efficient and economic.
In another aspect of the present disclosure, there is provided a catalyst composite comprising (i) zeolite having a mole ratio of silica to alumina in the range of 50:1 to 250:1, (ii) aluminium phosphate, and (iii) optionally alumina.
In accordance with an embodiment of the present disclosure, 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 alumina is at least one selected from the group consisting of hydrated alumina, non-hydrated alumina, and pseudoboehmite.
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.
Conventionally, clays, alumina and silica are used as catalyst compositing materials. The catalyst composites prepared using conventionally used compositing agent have low para-isomer selectivity and hence a separation unit is required to separate para-isomers from other dialkyl benzenes. Whereas, the present disclosure discloses the use of aluminium phosphate hydrogel for preparing catalyst composite of the present disclosure. The catalyst composite prepared using aluminium phosphate hydrogel is found to be highly selective for para-substituted dialkyl benzene during alkylation of mono-alkyl benzene.
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 a carrier gas with the 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 55 wt% to 98 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 comprising 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 of 27 to 98 % higher than that with alumina based composite and silica 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 composite 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 (Comparative experiment): Preparation of shaped ZSM-5 zeolite composite with silica:
22.6 g of ZSM-5 (SAR 180) zeolite powder, 0.37 g of hydroxypropyl methyl cellulose (HPMC) and 1.82 g of precipitated silica (having LOI 6.46 wt%) were mixed thoroughly in a mortar-pastel to obtain a mixture. To this mixture, 11.3 g of colloidal silica (40 wt% suspension in water) was added and mixed thoroughly to obtain a resultant mixture. 5.4 g of demineralized (DM) water was added to the resultant 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 extrudate 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 3: Preparation of shaped catalyst composite in accordance with the present disclosure with aluminium phosphate hydrogel
0.573 g of Pseudoboehmite alumina was taken in a Teflon beaker and 1.0 g DM water was added to it and stirred with a magnetic bar for 10 minutes to obtain a slurry. 2.84 g of phosphoric acid (H3PO4) was added drop wise to the slurry with continuous stirring to obtain a homogeneous aluminium phosphate hydrogel. Separately, 7.58 g of ZSM-5 (SAR 180), 1.145 of Pseudoboehmite alumina and 0.13 g of hydroxyl propyl methyl cellulose (HPMC) were mixed thoroughly in mortar-pestle to obtain a mixture. Aluminium phosphate hydrogel was then mixed with the mixture and pugged thoroughly with extra 1.03 g of DM water for 10 minutes to obtain a pugged mass. The so obtained pugged mass was 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 in the catalyst composite was 70 wt%.
Experiment 4: Preparation of shaped catalyst composite with aluminium phosphate hydrogel
3.39 g of Pseudoboehmite alumina was taken in a teflon beaker and 2.0 g of DM water was added to it and stirred with a magnetic bar for 10 minutes to obtain a slurry. 5.67 g of phosphoric acid (H3PO4) was added drop wise to the slurry to obtain a homogeneous aluminium phosphate hydrogel. 1.0 g of DM water was added to the hydrogel and stirred for another 10 min. The so obtained hydrogel was mixed with a separately prepared mixture of 0.13 g of HPMC and 15.18 g of ZSM-5 zeolite (SAR 180) powder and pugged thoroughly with extra 0.76 g of DM water for 10 minutes to obtain a pugged mass. The so obtained pugged mass was 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%.
Experiment 5: Preparation of shaped catalyst composite with aluminium phosphate hydrogel
1.69 g of Pseudoboehmite alumina was taken in a teflon beaker and 1.0 g of DM water was added to it and stirred with a magnetic bar for 10 minutes to obtain a slurry. 2.27 g of phosphoric acid (H3PO4) was added drop wise to the slurry to obtain a aluminium phosphate hydrogel. 1.0 g of DM water was added to the so obtained hydrogel and stirred for another 10 minutes. The so obtained hydrogel was mixed with a separately prepared mixture of 0.13 g of HPMC and 7.58 g of ZSM-5 zeolite (SAR 180) powder and pugged thoroughly with extra 0.81 g of DM water for 10 minutes to obtain a pugged mass. The so obtained pugged mass was 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%.
Experiment 6: Preparation of shaped catalyst composite with aluminium phosphate hydrogel
1.69 g of Pseudoboehmite alumina was taken in a teflon beaker and 1.2 g of DM water was added to it and stirred with a magnetic bar for 10 minutes to obtain a slurry. 3.4 g of phosphoric acid (H3PO4) was added drop wise to the slurry to obtain a aluminium phosphate hydrogel. This hydrogel was stirred for another 10 minutes. The so obtained hydrogel was mixed with a separately prepared mixture of 0.13 g of HPMC and 7.58 g of ZSM-5 zeolite (SAR 180) powder and pugged thoroughly with extra 1.07 g of DM water for 10 minutes to obtain a pugged mass. The so obtained pugged mass was 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 3-6 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 7-12
Catalyst composites prepared in experiments 1-6 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 1-6 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 1-6, the reaction conditions were kept fixed as above. Results of catalytic performances of the composites prepared in experiment 1 to experiment 6 are given in table 1.
Table 1: Catalytic performances of the composites prepared in experiments 1-6
Experiment No Catalyst from Toluene Conv., wt% Xylene Yield, wt% p-Xylene Selectivity, %
Experiment 7 Experiment 1
(Comparative experiment) 12.6 12.2 43.3
Experiment 8 Experiment 2
(Comparative experiment) 11.3 11.2 49.7
Experiment 9 Experiment 3 11.1 11.6 73.0
Experiment 10 Experiment 4 11.4 11.6 74.0
Experiment 11 Experiment 5 13.2 13.1 55.3
Experiment 12 Experiment 6 10.4 11.2 74.0

From table 1, it is found that para-xylene selectivity for the catalyst composites of present disclosure is 27 to 70 % higher than that with alumina based composite (comparative experiment 1). Similarly, the para-xylene selectivity for the catalyst composite of the present disclosure is 11 to 48.8 % higher than that with silica based catalyst composite (comparative experiment 2).
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 and 2.
Experiments 13--18
Catalyst composites prepared in experiment 1-6 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 1-6 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 6 are given in table 2.
Table 2: Catalytic performances of the composites prepared in experiments 1-6
Experiment No Catalyst from DEB. Yield, wt% PDEB Selectivity, %.,
Experiment 13 Experiment 1
(Comparative experiment) 11.5 43.1
Experiment 14 Experiment 2
(Comparative experiment) 11.7 48.5
Experiment 15 Experiment 3 7.5 79.9
Experiment 16 Experiment 4 6.5 80.7
Experiment 17 Experiment 5 10.8 69.7
Experiment 18 Experiment 6 6.3 84.8

From table 2, it is found that PDEB selectivity for the catalyst composites of the present disclosure is 61 to 96.7 % higher than that with alumina based composite (comparative experiment 1). Similarly, the PDEB selectivity for the catalyst composite of the present disclosure is 43 to 74.8 % higher than that with silica based catalyst composite (comparative experiment 2).
It is evident from table 2 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 and 2.
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.