Description:FIELD
The present disclosure relates to a catalyst for the selective production of para-di-substituted aromatics and a process for its preparation.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Development of new composition as a catalyst and hydrocarbon conversion process in the area of refining and petrochemicals has a commercial interest. Substitution of existing catalyst and process with newer, cheaper, and simpler catalyst material with higher efficacy and selectivity to desired product, with longer service life, and enhanced energy efficiency, process reliability and smoother operation is always sought for. It is also preferred that the new catalyst and process are capable of improving the productivity employing existing raw material to produce value added products with reduced raw material consumption.
Conventionally, para-di-substituted aromatics such as para-xylenes are produced from naphtha through a number of catalytic process and in the form of a near thermodynamic equilibrium mixture of all the three xylene isomers, viz. meta-xylene, para-xylene and ortho-xylene, from which para-xylene is separated by either crystallization or adsorptive technology. However, the conventional process of preparing para-di-substituted aromatics are associated with various drawbacks such as huge plant setup cost, separation unit which further adds to the cost and the like.
Further, para-di-substituted aromatics can also be produced by a method wherein selective alkylation or disproportionation of toluene can be done by employing modified zeolites. However, it requires multistep and cumbersome process of modifying the zeolite for fine control of the pore openings of zeolite.
Therefore, there is, felt a need to provide a catalyst for the selective production of para-di-substituted aromatics and a process for its preparation that mitigates the drawbacks mentioned herein above or at least provides a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems given in the background or to at least provide a useful alternative.
An object of the present disclosure is to provide a catalyst for the selective production of para-di-substituted aromatics.
Another object of the present disclosure is to provide a catalyst that is highly selective to para-isomer, thereby reducing the load on the separation unit.
Yet another object of the present disclosure is to provide a catalyst that is highly energy efficient.
Still another object of the present disclosure is to provide a simple, efficient and economic process for the preparation of a catalyst for the selective production of para-di-substituted aromatics.
Yet another object of the present disclosure is to provide a simple, efficient and economic process for the selective production of para-di-substituted aromatics.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a catalyst for the selective production of para-di-substituted aromatics. The catalyst comprises a silanated composite, wherein the composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
The present disclosure further relates to a process for the preparation of a catalyst for the selective production of para-di-substituted aromatics. The process comprises the step of mixing a pentasil zeolite with at least one compositing material in a predetermined mass ratio to obtain a mixture. The mixture is pugged by using water for a first predetermined time period to obtain a dough followed by extruding the dough to obtain extrudates. The extrudates are dried at a temperature in the range of 30 °C to 150 °C for a time period in the range of 5 hours to 10 hours followed by calcination at a first predetermined temperature for a second predetermined time period to obtain a composite. The composite is soaked in a solution of a silicate compound for a third predetermined time period to obtain a silanated composite. The silanated composite is dried at a temperature in the range of 100 °C to 160 °C for a time period in the range of 20 hours to 30 hours followed by calcining at a second predetermined temperature for a fourth predetermined time period to obtain the catalyst.
The present disclosure furthermore relates to a process for the selective production of para-di-substituted aromatics. The process comprises contacting an aromatic hydrocarbon stream and an alkylating agent with a catalyst at predetermined conditions by using a carrier gas to obtain the para-di-substituted aromatics; wherein the catalyst comprises a silanated composite and the composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
DETAILED DESCRIPTION
The present disclosure relates to a catalyst for the selective production of para-di-substituted aromatics and a process for its preparation.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Conventionally, para-di-substituted aromatics such as para-xylene is produced from naphtha though a number of catalytic process and in the form a near thermodynamic equilibrium mixture of all the three xylene isomers, viz. meta-xylene, para-xylene and ortho-xylene, from which para-xylene is separated by either crystallization or adsorptive technology. However, the conventional process of preparing para-di-substituted aromatics are associated with various drawbacks such as huge plant setup cost, separation unit which further adds to the cost and the like.
Further, para-di-substituted aromatics can also be produced by a reported method wherein selective alkylation or disproportionation of toluene can be done by employing modified zeolites. However, it requires multistep and cumbersome process of modifying the zeolite for fine control of the pore openings of zeolite.
The present disclosure provides a catalyst for the selective production of para-di-substituted aromatics and a process for its preparation.
In an aspect, the present disclosure provides a catalyst for the selective production of para-di-substituted aromatics.
The catalyst comprises a silanated composite, wherein the composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
The composite is silanated by a silicate compound selected from tetraethyl orthosilicate (TEOS), tetramethoxy silane (TMOS) and tetrapropyl orthosilicate (TPOS). In an exemplary embodiment of the present disclosure, the silicate compound is tetraethyl orthosilicate (TEOS).
The pentasil zeolite can be selected from ZSM-5, 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, Zn-ZSM-5 and Cr-Al-ZSM-5. In an exemplary embodiment of the present disclosure, the pentasil zeolite is selected from ZSM-5.
The compositing material can be at least one selected from the group consisting of zinc phosphate, zinc phosphate hydrogel, aluminium oxide, zinc oxide, gallium oxide, aluminium phosphate, aluminium phosphate hydrogel, oxides of combination of aluminium and phosphorous, oxides of combination of zinc and phosphorous and oxides of mixture thereof. In an exemplary embodiment of the present disclosure, the compositing material is zinc phosphate hydrogel.
In an embodiment of the present disclosure, a mass ratio of the pentasil zeolite to the compositing material is in the range of 95:5 to 5:95. In an exemplary embodiment of the present disclosure, the mass ratio of the pentasil zeolite to the compositing material is 70:30.
In an embodiment of the present disclosure, the silanated composite is in a shape selected from spherical, cylindrical, trilobe, tetralobe, ring, tablets, pellets and honey comb. In an exemplary embodiment of the present disclosure, the shape of silanated composite is cylindrical.
In another aspect, the present disclosure provides a process for the preparation of a catalyst for the selective production of para-di-substituted aromatics. The process comprises the following steps:
a. mixing a pentasil zeolite with at least one compositing material in a predetermined mass ratio to obtain a mixture;
b. pugging the mixture by using water for a first predetermined time period to obtain a dough followed by extruding the dough to obtain extrudates;
c. drying the extrudates at a temperature in the range of 30 °C to 150 °C for a time period in the range of 5 hours to 10 hours followed by calcining at a first predetermined temperature for a second predetermined time period to obtain a composite;
d. soaking the composite in a solution of a silicate compound for a third predetermined time period to obtain a silanated composite; and
e. drying the silanated composite at a temperature in the range of 100 °C to 160 °C for a time period in the range of 20 hours to 30 hours followed by calcining at a second predetermined temperature for a fourth predetermined time period to obtain the catalyst.
The process is described in detail herein below.
In a first step, a pentasil zeolite is mixed with at least one compositing material in a predetermined mass ratio to obtain a mixture.
The pentasil zeolite can be selected from ZSM-5, 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, Zn-ZSM-5 and Cr-Al-ZSM-5. In an exemplary embodiment of the present disclosure, the pentasil zeolite is selected from ZSM-5.
The compositing material can be at least one selected from the group consisting of zinc phosphate, zinc phosphate hydrogel, aluminium oxide, zinc oxide, gallium oxide, aluminium phosphate, aluminium phosphate hydrogel and oxides of combination of aluminium and phosphorous, oxides of combination of zinc and phosphorous and oxides of mixture thereof. In an exemplary embodiment of the present disclosure, the compositing material is zinc phosphate hydrogel.
In an embodiment of the present disclosure, the predetermined mass ratio of the pentasil zeolite to the compositing material is in the range of 95:5 to 5:95. In an exemplary embodiment of the present disclosure, the predetermined mass ratio of the pentasil zeolite to the compositing material is 70:30.
In a second step, the mixture is pugged by using water for a first predetermined time period to obtain a dough followed by extruding the dough to obtain extrudates.
In accordance with the present disclosure, the first predetermined time period is in the range of 5 minutes to 20 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 10 minutes.
In a third step, the extrudates are dried at a temperature in the range of 30 °C to 150 °C for a time period in the range of 5 hours to 10 hours followed by calcination at a first predetermined temperature for a second predetermined time period to obtain a composite.
In accordance with the present disclosure, the first predetermined temperature is in the range of 450 °C to 600 °C. In an exemplary embodiment of the present disclosure, the first predetermined temperature is 540 °C.
In accordance with the present disclosure, the second predetermined time period is in the range of 2 hours to 10 hours. In an exemplary embodiment of the present disclosure, the first predetermined time period is 6 hours.
In a fourth step, the composite is soaked in a solution of a silicate compound for a third predetermined time period to obtain a silanated composite.
In accordance with the present disclosure, the third predetermined time period is in the range of 2 hours to 10 hours. In an exemplary embodiment, the third predetermined time period is 6 hours.
The silicate compound is selected from tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS) and tetra propyl orthosilicate (TPOS). In an exemplary embodiment of the present disclosure, the silicate compound is tetraethyl orthosilicate (TEOS).
The solution of the silicate compound is prepared in at least one fluid medium selected from toluene, methanol, benzene, xylene, paraffinic hydrocarbons having carbon number C4 to C8, alcohols having carbon number C1 to C6 and combinations thereof. In an exemplary embodiment of the present disclosure, the fluid medium is a mixture of toluene and methanol.
In accordance with the present disclosure, a concentration of the solution of the silicate compound is in the range of 2% to 30%.
Single step silanation of the composite in accordance with the present disclosure, significantly improves the selectivity of the catalyst towards the production of para isomer.
In a fifth step, the silanated composite is dried at a temperature in the range of 100 °C to 160 °C for a time period in the range of 20 hours to 30 hours followed by calcining at a second predetermined temperature for a fourth predetermined time period to obtain the catalyst.
In accordance with the present disclosure, the second predetermined temperature is in the range of 450 °C to 600 °C. In an exemplary embodiment of the present disclosure, the second predetermined temperature is 540 °C.
In accordance with the present disclosure, the fourth predetermined time period is in the range of 2 hours to 10 hours. In an exemplary embodiment of the present disclosure, the first predetermined time period is 6 hours.
The inventors of the present disclosure has unexpectedly observed that the catalyst made up of pentasil zeolite and the compositing material in accordance with the present disclosure, is highly selective for para-di-substituted aromatics during alkylation of mono-substituted aromatics with alkanol or alkene.
The inventors have surprisingly found that the catalyst of the present disclosure provides much higher selectivity for the para-di-substituted isomers in the alkylation of mono-substituted aromatics, as compared to those when other conventional catalysts are used.
The most probable reasons for having some unique properties in the catalyst of the present disclosure, may be (i) extremely low acid strength (almost neutral) of terminal hydroxyl groups, (ii) mechanism of forming the catalyst, thereby altering the chemical, textural, mechanical aspects of the formed bodies, and the like.
In still another aspect, the present disclosure provides a process for the selective production of para-di-substituted aromatics.
The process comprises the step of contacting an aromatic hydrocarbon stream and an alkylating agent with a catalyst at predetermined conditions by using a carrier gas to obtain the para-di-substituted aromatics.
The catalyst used in the process for the selective production of para-di-substituted aromatics comprises a silanated composite; wherein the composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
The aromatic hydrocarbon is mono-substituted aromatic hydrocarbon. The mono-substituted aromatic hydrocarbon can be selected from the group consisting of toluene, ethyl benzene, phenol and iso-propyl benzene. In an exemplary embodiment of the present disclosure, the mono-substituted aromatic hydrocarbon is toluene. In another exemplary embodiment of the present disclosure, the mono-substituted aromatic hydrocarbon is ethyl benzene.
The para-di-substituted aromatic hydrocarbon can be selected from the group consisting of para-xylene, para-ethyl toluene, para-diethyl benzene, para-ethyl phenol, para-cresol, para-cymene and para-di-iso-propyl benzene. In an exemplary embodiment of the present disclosure, the para-di-substituted aromatic hydrocarbon is para-xylene. In another exemplary embodiment of the present disclosure, the para-di-substituted aromatic hydrocarbon is para-diethyl benzene.
In one embodiment of the present disclosure, the alkylating agent is an alkanol selected from the group consisting of methanol, ethanol, propanol and iso-propanol. In an exemplary embodiment of the present disclosure, the alkanol is methanol. In another exemplary embodiment of the present disclosure, the alkanol is ethanol.
In another embodiment of the present disclosure, the alkylating agent is an alkene selected from the group consisting of ethylene and propylene.
In accordance with an embodiment of the present disclosure, a mole ratio of the mono-substituted aromatic hydrocarbon to the alkylating agent is in the range of 20:1 to 1:20. In an exemplary embodiment of the present disclosure, the mole ratio of the mono-substituted aromatic hydrocarbon to the alkylating agent is 6:1.
The carrier gas is selected from steam and hydrogen gas. In an exemplary embodiment of the present disclosure, the carrier gas is hydrogen gas.
The steam is used in an amount in the range of 5 wt% to 50 wt% with respect to the total amount of the aromatic hydrocarbon. The hydrogen gas is used in an amount in the range of 0 mole to 10 moles per mole of the aromatic hydrocarbon.
In accordance with the present disclosure, the process for the selective production of para-di-substituted aromatics is carried out at a temperature in the range of 200 °C to 500 °C. In an exemplary embodiment of the present disclosure, the process is carried out at a temperature of 330 °C.
In accordance with the present disclosure, the process for the selective production of para-di-substituted aromatics is carried out at a pressure in the range of 0.1 bar to 10 bar. In an exemplary embodiment of the present disclosure, the process is carried out at a pressure of 1 bar.
In accordance with the present disclosure, the process for the selective production of para-di-substituted aromatics is carried out at a contact time period in the range of 1 hour to 20 hours. In an exemplary embodiment of the present disclosure, the process is carried out at a contact time of 5 hours.
The catalyst of the present disclosure is highly selective in producing para-di-substituted aromatics through alkylation of mono-substituted aromatics. The present disclosure provides a catalyst which is modified by only a single step silanation method.
Para-di-substituted aromatics such as para-xylene can be conventionally produced through selective alkylation or disproportionation of toluene employing modified zeolites of pentasil family. However, such modifications include multistep and cumbersome process of in-situ coking of zeolite or impregnation of oxides of metal/non-metal on the zeolite. In contrast, the silanated catalyst of the present disclosure which is modified by only a single step silanation is proved to be excellent to achieve the desired selectivity level of the para-isomer aromatics.
The catalyst and the process as disclosed in the present disclosure can be easily adopted in the existing commercial aromatics complexes for augmentation of para-xylene production and thus, the naphtha consumption per ton of para-xylene product can be significantly reduced.
The process for production of para-substituted aromatics using the catalyst of present disclosure:
(i) is quite simple and selective since it essentially do not produce benzene co-product;
(ii) is highly selective to para-isomer, and thus reduces load on the separation unit; and
(iii) highly energy efficient because of (i) and (ii).
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
Experimental details:
Experiment 1: Process for the preparation of the catalyst for the selective production of para-di-substituted aromatics in accordance with the present disclosure
Example 1:
a. Preparation of ZnPO-ZSM-5 composite by using zinc phosphate gel:
Gel of ZnO and H3PO4 was prepared by mixing 3.83 g ZnO with 5.37g of H3PO4 and 1.07g of DM water in a Teflon beaker. The gel so obtained was added to 15.05 g of ZSM-5 zeolite powder (of SAR 180) and mixed vigorously in a mortar pastel to obtain a mixture. The mixture was pugged thoroughly by adding 3.3 g DM water for 10 minutes to obtain a dough and extruded using 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature (28 °C) for 1 hour followed by drying at 120 °C for 6 hours to obtain dried extrudates. The dried extrudates were calcined at 540 °C for 6 hours under flowing air to obtain a ZnPO-ZSM-5 composite. Zeolite content in final composite was 70% by weight.
b. Silylation of ZnPO-ZSM-5 composite with 0.25 ml tetraethyl orthosilicate (TEOS):
14 g of the ZnPO-ZSM-5 composite obtained from the above step were soaked in a solution of tetraethyl orthosilicate (TEOS) (dissolving 3.3 g of TEOS in to a mixture of 14 ml toluene and 9 ml methanol) for 6 hours to obtain a slurry. Thereafter, the solvent mixture (toluene and methanol) was slowly distilled out to obtain a silanated composite that were treated in an air oven at 120 °C in the presence of moisture for 24 hours followed by calcination at 540 °C for 6 hours to obtain the catalyst. This catalyst was labeled as ZnPO-ZSM-5 (0.25).
Example 2:
a. Preparation of ZnPO-ZSM-5 composite by using zinc phosphate gel:
Same procedure as in Example 1 (a) was followed to prepare ZnPO-ZSM-5 composite.
b. Silylation of ZnPO-ZSM-5 composite with 0.35 ml TEOS:
10 g of the ZnPO-ZSM-5 composite obtained from the above step were soaked in a solution of tetraethyl orthosilicate (TEOS) (dissolving 3.35 g of TEOS in to a mixture of 10 ml toluene and 6 ml methanol) for 6 hours to obtain a slurry. Thereafter, the solvent mixture (toluene and methanol) was slowly distilled out to obtain a silanated composite that were treated in an air oven at 120 °C in the presence of moisture for 24 hours followed by calcination at 540 °C for 6 hours to obtain the catalyst. This catalyst was labeled as ZnPO-ZSM-5 (0.35).
Example 3:
a. Preparation of ZnPO-ZSM-5 composite by using zinc phosphate gel:
Same procedure as in Example 1 (a) was followed to prepare ZnPO-ZSM-5 composite.
b. Silylation of ZnPO-ZSM-5 composite with 0.15 ml TEOS
14 g of the ZnPO-ZSM-5 composite obtained from the above step were soaked in a solution of tetraethyl orthosilicate (TEOS) (dissolving 1.95 g of TEOS in to a mixture of 14 ml toluene and 8.4 ml methanol) for 6 hours to obtain a slurry. Thereafter, the solvent mixture (toluene and methanol) was slowly distilled out to obtain a silanated composite that were treated in an air oven at 120 °C in the presence of moisture for 24 hours followed by calcination at 540 °C for 6 hours to obtain the catalyst. This catalyst was labeled as ZnPO-ZSM-5 (0.15).
Comparative Examples: Preparation of catalysts without silanation
Comparative Example 1: Preparation of SiO2-ZSM-5 composite
37.9 g ZSM-5 (of SAR 180) zeolite powder, 0.63 g hydroxypropyl methyl cellulose (HPMC) (extrusion aid) and 8.02 g precipitated silica and 18.75 g colloidal silica (Ludox AS 40 from E. Merck / Aldrich) (compositing material) were mixed thoroughly in a mortar-pastel to obtain a mixture. 22.78 g demineralized (DM) water was added to the mixture and pugged thoroughly for 10 minutes to obtain a dough. The dough was extruded using 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature for 1 hour followed by drying in an air oven at 120 °C for 6 hours to obtain dried extrudates. The dried extrudates were calcined at 540 °C for 6h under flowing air to obtain SiO2-ZSM-5 composite. Zeolite content in final composite was 70% by weight.
Comparative Example 2: Preparation of Al2O3-ZSM-5 composite
10 g Condia alumina and 7.58 g ZSM-5 zeolite having (of SAR 180) were mixed thoroughly in a mortar-pastel to obtain a mixture. 4.72 g aqueous solution of 3.7% acetic acid was added to the mixture and pugged thoroughly for 10 minutes to obtain a dough. The dough was extruded using a 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature for 1 hour followed by drying in an air oven at 120 °C for 6 hours to obtain dried extrudates. The dried extrudates were calcined at 540 °C for 6h under flowing air to obtain Al2O3-ZSM-5 composite. Zeolite content in final composite was 70% by weight.
Comparative Example 3: Preparation of AlPO-ZSM-5 composite with aluminium phosphate gel
3.39 g of Condia alumina was taken in a teflon beaker and 2.0 g DM water was added to it and stirred with magnetic bar for 10 minutes to obtain a slurry. 5.67 g H3PO4 was added drop wise to the slurry to obtain a thick and smooth gel. 1 g DM water was added in to the gel and stirred for another 10 minutes. This gel was added to a mixture of 0.13 g hydroxypropyl methyl cellulose (HPMC) (extrusion aid) and 15.18 g of ZSM-5 zeolite (SAR 180) powder and pugged thoroughly by adding 0.76 g DM water for 10 minutes to obtain a dough. The dough was extruded using 1.5 mm die to obtain extrudates. The extrudates were dried at room temperature for 1 hour followed by drying in an air oven at 120 °C for 6 hours to obtain dried extrudates. The dried extrudates were calcined at 540 °C for 6h under flowing air to obtain AlPO-ZSM-5 composite. Zeolite content in final composite was 70% by weight.
Experiment 2: Performance of the catalysts prepared in accordance with the present disclosure and the catalysts of comparative example on the production of para-di-substituted aromatics
The performance of the zeolite extrudates in terms of di-ethylbenzene (DEB) yield and para-diethylbenzene selectivity was evaluated in an all-glass integrated down-flow atmospheric pressure reactor. An ethyl benzene rich mixed xylene solvent (MXS) stream and ethanol were used as feed, and hydrogen was employed as carrier gas. The performance test reactions were carried out at a temperature of 330 °C, pressure of 1 bar, contact time of 5 hours, whsv of 3 h-1, MXS to ethanol mole ratio of 8 and hydrogen to hydrocarbon mole ratio of 2. Products of the reaction were analyzed by gas-chromatography following standard analytical method referred as UOP 744 method. Yield of di-ethyl benzene (DEB yield) and the para-isomer selectivity among the diethyl benzene isomers (PDEB isomer selectivity), were defined as performance criteria. The results are shown in Table 1.
Table 1: Performance of the catalysts of Examples 1-3 and the catalysts of comparative example on the production of para- diethyl benzene
Examples Catalyst DEB Yield (wt %) Selectivity (%)
Example 1 ZnPO-ZSM-5 (0.25) 7.7 99.1
Example 2 ZnPO-ZSM-5 (0.35) 7.5 97.2
Example 3 ZnPO-ZSM-5 (0.15) 7.9 97.9
Comparative Example 1 SiO2-ZSM-5 11.5 43.1
Comparative Example 2 Al2O3-ZSM-5 11.7 48.5
Comparative Example 3 AlPO-ZSM-5 7.5 79.9
Example 1 (without silanation) ZnPO-ZSM-5 8.5 57.5
Table 2: Performance of the catalysts of Examples 1-3 and the catalysts of comparative example on the production of para- xylene
Examples Catalyst Toluene conversion (wt %) Total xylene production (wt %) Selectivity (%)
Example 1 ZnPO-ZSM-5 (0.25) 23.72 25.9 94.1
Example 2 ZnPO-ZSM-5 (0.35) 20.5 21.2 87.2
Example 3 ZnPO-ZSM-5 (0.15) 24.72 26 92.1
Comparative Example 1 SiO2-ZSM-5 24.5 25.8 43.6
Comparative Example 2 Al2O3-ZSM-5 24.9 26.1 48.8
Comparative Example 3 AlPO-ZSM-5 25.2 26.6 71.3
Example 1 (without silanation) ZnPO-ZSM-5 24.8 25.5 47.7
Reaction condition: Catalyst amount 1.73 g; press. Atmospheric; down flow fixed bed glass reactor; reaction temperature 330 °C; carrier gas H2. Toluene: MeOH :: 6:3 mol; Feed flow 10 ml/h.
From Tables 1 and 2, it is proved that the catalyst of the present disclosure is very effective in converting a mixture of toluene and methanol with high selectivity for para-xylene and converting a mixture of ethyl benzene with ethanol with very high selectivity for para-diethyl benzene.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? a catalyst for the selective production of para-di-substituted aromatics that;
• is highly selective to para-isomer, thereby reducing the load on the separation unit; and
• is highly energy efficient; and
? a process for the preparation of a catalyst for the selective production of para-di-substituted aromatics that:
• is a simple, efficient and economic.
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 example 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.
, Claims:WE CLAIM:
1. A catalyst for the selective production of para-di-substituted aromatics, said catalyst comprising a silanated composite;
wherein said composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
2. The catalyst composition as claimed in claim 1, wherein said composite is silanated by a silicate compound selected from tetraethyl orthosilicate (TEOS), tetramethoxy silane (TMOS) and tetrapropyl orthosilicate (TPOS) to obtain said silanated composite.
3. The catalyst as claimed in claim 1, wherein said pentasil zeolite is selected from ZSM-5, 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, Zn-ZSM-5 and Cr-Al-ZSM-5.
4. The catalyst as claimed in claim 1, wherein said compositing material is at least one selected from the group consisting of zinc phosphate, zinc phosphate hydrogel, aluminium oxide, zinc oxide, gallium oxide, aluminium phosphate, aluminium phosphate hydrogel, oxides of combination of aluminium and phosphorous, oxides of combination of zinc and phosphorous and oxides of mixture thereof.
5. The catalyst as claimed in claim 1, wherein a mass ratio of said pentasil zeolite to said compositing material is in the range of 95:5 to 5:95.
6. The catalyst as claimed in claim 1, wherein said silanated composite is in a shape selected from spherical, cylindrical, trilobe, tetralobe, ring, tablets, pellets and honey comb.
7. A process for the preparation of a catalyst for the selective production of para-di-substituted aromatics, said process comprising the following steps:
a. mixing a pentasil zeolite with at least one compositing material in a predetermined mass ratio to obtain a mixture;
b. pugging said mixture by using water for a first predetermined time period to obtain a dough followed by extruding said dough to obtain extrudates;
c. drying said extrudates at a temperature in the range of 30 °C to 150 °C for a time period in the range of 5 hours to 10 hours followed by calcining at a first predetermined temperature for a second predetermined time period to obtain a composite;
d. soaking said composite in a solution of a silicate compound for a third predetermined time period to obtain a silanated composite; and
e. drying said silanated composite at a temperature in the range of 100 °C to 160 °C for a time period in the range of 20 hours to 30 hours followed by calcining at a second predetermined temperature for a fourth predetermined time period to obtain said catalyst.
8. The process as claimed in claim 7, wherein said pentasil zeolite is selected from ZSM-5, 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, Zn-ZSM-5 and Cr-Al-ZSM-5.
9. The process as claimed in claim 7, wherein said compositing material is at least one selected from the group consisting of zinc phosphate, zinc phosphate hydrogel, aluminium oxide, zinc oxide, gallium oxide, aluminium phosphate, aluminium phosphate hydrogel, oxides of combination of aluminium and phosphorous, oxides of combination of zinc and phosphorous and oxides of mixture thereof.
10. The process as claimed in claim 7, wherein said predetermined mass ratio of said pentasil zeolite to said compositing material is in the range of 95:5 to 5:95.
11. The process as claimed in claim 7, wherein said first and said second predetermined temperatures are independently in the range of 450 °C to 600 °C.
12. The process as claimed in claim 7, wherein said first predetermined time period is in the range of 5 minutes to 20 minutes.
13. The process as claimed in claim 7, wherein said second, said third and said fourth predetermined time periods are independently in the range of 2 hours to 10 hours.
14. The process as claimed in claim 7, wherein said silicate compound is selected from tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS) and tetra propyl orthosilicate (TPOS).
15. The process as claimed in claim 7, wherein said solution of said silicate compound is prepared in at least one fluid medium selected from toluene, methanol, benzene and xylene.
16. The process as claimed in claim 7, wherein a concentration of said solution of said silicate compound is in the range of 2 % to 30 %.
17. A process for the selective production of para-di-substituted aromatics, said process comprising contacting an aromatic hydrocarbon stream and an alkylating agent with a catalyst at predetermined conditions by using a carrier gas to obtain said para-di-substituted aromatics;
wherein said catalyst comprises a silanated composite and said composite is a complex of a pentasil zeolite and at least one compositing material selected from the group consisting of oxides of group IIB elements and group VA elements, and a combination thereof.
18. The process as claimed in claim 17, wherein said aromatic hydrocarbon is mono-substituted aromatic hydrocarbon, wherein said mono-substituted aromatic hydrocarbon is selected from the group consisting of toluene, ethyl benzene, phenol and iso-propyl benzene.
19. The process as claimed in claim 17, wherein said para-di-substituted aromatic hydrocarbon is selected from the group consisting of para-xylene, para-ethyl toluene, para-diethyl benzene, para-ethyl phenol, para-cresol, para-cymene and para-di-iso-propyl benzene.
20. The process as claimed in claim 17, wherein said alkylating agent is an alkanol selected from the group consisting of methanol, ethanol, propanol and iso-propanol.
21. The process as claimed in claim 17, wherein said alkylating agent is an alkene selected from the group consisting of ethylene and propylene.
22. The process as claimed in claim 17, wherein a mole ratio of said mono-substituted aromatic hydrocarbon to said alkylating agent is in the range of 20:1 to 1:20.
23. The process as claimed in claim 17, wherein said carrier gas is selected from steam and hydrogen gas.
24. The process as claimed in claim 23, wherein said steam is used in an amount in the range of 5 wt% to 50 wt% with respect to the total amount of said aromatic hydrocarbon; and wherein said hydrogen gas is used in an amount in the range of 0 mole to 10 moles per mole of said aromatic hydrocarbon.
25. The process as claimed in claim 17, wherein said process is carried out at a temperature in the range of 200 °C to 500 °C.
26. The process as claimed in claim 17, wherein said process is carried out at a pressure in the range of 0.1 bar to 10 bar.

27. The process as claimed in claim 17, wherein said process is carried out at a contact time period in the range of 1 hour to 20 hours.

Dated this 23rd day of December, 2022

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant
TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI