Claims:WE CLAIM:
1. A process for preparing a MWW zeolite, wherein the MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1;
the process comprising the following steps,
i. mixing at least one source of group IVA element (M), at least one source of group-IIIA element (Y), at least one alkali, at least one organic templating agent, and water to obtain a first mixture, followed by stirring the first mixture to obtain a hydrogel; and
ii. subjecting the hydrogel to hydrothermal treatment by stirring the hydrogel at a temperature in the range of 100 °C to 300 °C to obtain crystals of the MWW zeolite.
2. The process as claimed in claim 1, wherein the first mixture is stirred for a time period in the range of 2 hour to 12 hours, and the hydrothermal treatment is carried out for a time period in the range of 200 hours to 400 hours.
3. The process as claimed in claim 1, wherein the step of hydrothermal treatment is carried out at a pressure in the range of 20 bar to 50 bar and the stirring is carried out at a speed of 100 rpm to 600 rpm.
4. The process as claimed in claim 1, wherein in the step (i) the source of group IVA element (M) is at least one compound selected from the group consisting of oxides, and salts of group IVA elements, and organic compounds of group IVA elements.
5. The process as claimed in claim 1, wherein in the step (i) the source of group IVA element (M) is at least one compound selected from the group consisting of alkali silicates, silica, precipitated silica, colloidal silica, and organo-silicon compounds.
6. The process as claimed in claim 1, wherein in the step (i) the source of group IIIA element (Y) is at least one compound selected from the group consisting of oxides, alkoxides, halides, oxyhalides, nitrate salts, sulphate salts, double salts, complex compounds, sodium salts, and potassium salts of group IIIA elements.
7. The process as claimed in claim 1, wherein in the step (i) the source of group IIIA element (Y) is at least one compound selected from the group consisting of alumina, aluminum alkoxides, sodium aluminate, aluminum sulphate, aluminum nitrate, gallium alkoxides, sodium gallate, gallium sulphate, gallium nitrate, organic compounds of aluminum, and organic compounds of gallium.
8. The process as claimed in claim 1, wherein in the step (i) the alkali added is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.
9. The process as claimed in claim 1, wherein in the step (i) the organic templating agent added is selected from the group consisting of N,N,N-trimethyl-1-adamantammonium hydroxide (TMAda+OH-), N,N,N,N',N',N'-hexamethylpentanediammonium (Me6-diquat-5), adamantyl trimethyl ammonium cation, adamantyl trimethyl ammonium cation in the presence of isobutyl amine, and N(16)-methyl-sparteinium hydroxidet.
10. The process as claimed in claim 1, wherein the organic templating agent is C5-Diquarternary ammonium salt represented as Formula –II,

Formula II
wherein, X is selected from the group consisting of phosphate, halogens, sulfate, bisulfate, bisulfite, carbonate, bicarbonate, hexafluorophosphate, nitrate, oxyhalogen, perchlorate, carboxylate, amide, alkoxide, and etherate and R is an aliphatic straight chain hydrocarbon group.
11. The process as claimed in claim 1, wherein in the step (i) the mole ratio of the alkali to MO2 is in the range of 0.005:1 to 10:1, preferably 0.1: 1 to 1: 1.
12. The process as claimed in claim 1, wherein in the step (i) the mole ratio of the organic templating agent to MO2 is in the range of 0.01:1 to 5:1, preferably 0.1: 1 to 0.5: 1.
13. The MWW zeolite prepared by the process as claimed in claim 1, wherein the MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1; and
characterized by surface area in the range of 420 to 450 m2g-1, micropore area in the range of 280 to 300 m2g-1, external surface area in the range of 125 to 150 m2g-1, total pore volume in the range of 0.60 to 0.70 cc, micropore volume in the range of 0.10 to 0.15 cc, and average pore diameter in the range of 55 to 75 Å.
14. The MWW zeolite as claimed in claim 13, wherein the mole ratio of MO2 to Y2O3 is in the range of 10:1 to 80:1, preferably 20: 1 to 40: 1.
15. The MWW zeolite as claimed in claim 13, wherein the MWW zeolite is
SiO2: 0.3Al2O3.
16. A shaped MWW zeolitic composite comprising:
• a MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1;
• at least one binder.
17. A process for preparing shaped MWW zeolitic composite as claimed in claim 16, the process comprising:
a. mixing at least one source of group IVA element (M), at least one source of group-IIIA element (Y), at least one alkali, at least one organic templating agent, and water to obtain a first mixture, followed by stirring the first mixture to obtain a hydrogel;
b. subjecting the hydrogel to hydrothermal treatment by stirring the hydrogel at a temperature in the range of 100 °C to 300 °C to obtain crystals of the MWW zeolite;
c. adding at least one binder to crystals of the MWW zeolite to obtain an admixture; and
d. activating the admixture by heating at a temperature in the range of 400 °C to 600 °C to obtain shaped MWW zeolitic composite.
18. The process as claimed in claim 17, wherein the weight ratio of MWW zeolite to the binder is in the range of 95: 5 to 5: 95, preferably in the range of 90: 10 to 60: 40 on the basis of loss on ignition (LOI).
19. The process as claimed in claim 17, wherein the weight ratio of MWW zeolite to the binder is 70: 30 on the basis of loss on ignition (LOI).
20. The process as claimed in claim 17, wherein the binder is at least one selected from the group consisting of alumina, silica and clay.
21. A process for reducing olefin content of a hydrocarbon stream, the process comprising:
contacting olefin contaminated hydrocarbon stream with a shaped MWW zeolitic composite comprising MWW zeolite at a temperature in the range of 100 °C to 500 °C, at a pressure in the range of 100 bar to 300 bar and for a time period in the range of 1 hours to 20 hours to obtain a treated hydrocarbon stream having more than 50% reduced olefin content;
wherein said MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
22. The process as claimed in claim 21 includes the step of regenerating said shaped MWW zeolitic composite by repeatedly heating to a temperature in the range of 400 to 600 °C.
, Description:FIELD
The present disclosure relates to a process for preparing a MWW zeolite for reducing the olefin content in hydrocarbons, MWW zeolitic composite prepared thereof and a process for reducing the olefin content of a hydrocarbon stream using MWW zeolitic composite.
DEFINITIONS
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
Organic templating agent relates to cationic organic species added to synthesis media to aid/guide in the polymerization of the anionic building blocks that form the framework.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Development of new compositions for application in hydrocarbon conversion processes in the area of refining and petrochemicals is of commercial interest. In the process of para-xylene production from aromatic complexes, the post-reforming streams are subjected to benzene and toluene recovery. The C8+ aromatics stream, containing a mixture of xylenes (para-, meta- and ortho-) and the heavy aromatics (C9 and highers) remains contaminated with high boiling point olefins, which are needed to be removed before the stream is sent for para-xylene recovery by adsorption process. This removal of olefin contaminants is essential in aromatic complexes for para-xylene production to safe guard the adsorbent molecular sieves, since olefins are poisonous to adsorbents.
Conventionally, adsorption units containing clay are used for reducing the olefin content of hydrocarbon streams. However, the use of clays for this application is associated with drawbacks such as the clays have short life, need frequent change-overs, and generate of a huge amount of spent clay as solid waste. Further, these clay materials cannot be regenerated. Therefore, substitution of clay with newer environment friendly material with higher efficacy and service life, and enhanced process reliability and smoother operation is always sought for.
Recently it was observed that zeolitic compositions having MWW-type frame work are better materials for substitution of clay. However, their ability to adsorb olefin is comparatively low. Further, the preparation of MWW zeolite and its composite is associated with drawbacks such as laborious and costly process, and requires special conditions and reagents.
Therefore, there is felt a need to provide a simple and economical process for the preparation of the MWW zeolite and its composite. Further, it is desired that the MWW zeolitic composite is capable of effectively reducing the olefin content of hydrocarbon stream and that the MWW zeolitic composite is capable of being regenerated by a simple process.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a MWW zeolite.
Another object of the present disclosure is to provide a process for the preparation of a MWW zeolite.
Still another object of the present disclosure is to provide a MWW zeolitic composite that is capable of effectively reducing the olefin content of a hydrocarbon stream.
Yet another object of the present disclosure is to provide a process for the preparation of a MWW zeolite, which is less laborious and less costly process, and does not require special conditions and reagents.
Further object of the present disclosure is to provide a MWW zeolitic composite that is capable of being regenerated by a simple process.
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 one aspect, the present disclosure provides a process for preparing a MWW zeolite, wherein the MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
The process comprises the following steps.
At least one source of group IVA element (M), at least one source of group IIIA element (Y), at least one alkali, at least one organic templating agent, and water are mixed to obtain a first mixture, followed by stirring the first mixture for a time period in the range of 2 hour to 12 hours to obtain a hydrogel. The hydrogel is subjected to hydrothermal treatment by stirring at a temperature in the range of 100 °C to 300 °C, at a pressure in the range of 20 bar to 50 bar for a time period in the range of 200 hour to 400 hours to obtain crystals of the MWW zeolite.
In another aspect, the present disclosure provides shaped MWW zeolitic composite comprising
• MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1; and
• at least one binder.
The present disclosure further provides a process for preparing shaped MWW zeolitic composite comprising MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1. The MWW zeolite of the present disclosure has surface area in the range of 420 to 450 m2g-1, micropore area in the range of 280 to 300 m2g-1, external surface area in the range of 125 to 150 m2g-1, total pore volume in the range of 0.60 to 0.70 cc, micropore volume in the range of 0.10 to 0.15 cc, and average pore diameter in the range of 55 to 75 Å.
The process comprises the following steps.
At least one source of group IVA element (M), at least one source of group IIIA element (Y), at least one alkali, at least one organic templating agent, and water are mixed to obtain a first mixture, followed by stirring the first mixture for a time period in the range of 2 hour to 12 hours to obtain a hydrogel. The hydrogel is subjected to hydrothermal treatment by stirring at a temperature in the range of 100 °C to 300 °C, at a pressure in the range of 20 bar to 50 bar for a time period in the range of 200 hour to 400 hours to obtain crystals of the MWW zeolite. At least one binder is added to crystals of the MWW zeolite to obtain an admixture. The admixture is then activated by heating at a temperature in the range of 400 °C to 600 °C to obtain shaped MWW zeolitic composite.
In still another aspect, the present disclosure provides a process for reducing the olefin content of a hydrocarbon stream using shaped zeolitic composite. The process comprising contacting olefin contaminated hydrocarbon stream with a shaped zeolitic composite at a temperature in the range of 100 °C to 500 °C, at a pressure in the range of 100 bar to 300 bar and for a time period in the range of 1 hours to 20 hours to obtain a treated hydrocarbon stream having reduced olefin content; wherein MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
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.
The present disclosure envisages a process for preparing a MWW zeolite for reducing the olefin content in hydrocarbons.
In a first aspect, the present disclosure provides a process for preparing a MWW zeolite, wherein the MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
The process involves the following steps.
At least one source of group IVA element (M), at least one source of group IIIA element (Y), at least one alkali, at least one organic templating agent, and water are mixed to obtain a first mixture. The first mixture is stirred for a time period in the range of 1 hour to 12 hours to obtain a hydrogel.
The hydrogel is subjected to hydrothermal treatment involving stirring the hydrogel at a speed in the range of 100 rpm to 600 rpm, at a temperature in the range of 100 °C to 300 °C and at a pressure in the range of 20 bar to 50 bars for a time period in the range of 200 hour to 400 hours to obtain crystals of the MWW zeolite.
The source of group IVA element (M) is at least one compound selected from the group consisting of oxides, and salts of group IVA elements, and organic compounds of group IVA elements. Preferably, the source of group IVA element (M) is at least one compound selected from the group consisting of alkali silicates, silica, precipitated silica, colloidal silica, and organo-silicon compounds.
In accordance with one embodiment of the present disclosure, the source of group IVA element (M) is colloidal silica (SiO2).
The source of group IIIA element (Y) is at least one compound selected from the group consisting of oxides, alkoxides, halides, oxyhalides, nitrate salts, sulphate salts, double salts, complex compounds, sodium salts, and potassium salts of group IIIA elements. Preferably, the source of group IIIA element (Y) is at least one compound selected from the group consisting of alumina, aluminum alkoxides, sodium aluminate, aluminum sulphate, aluminum nitrate, gallium alkoxides, sodium gallate, gallium sulphate, gallium nitrate, organic compounds of aluminum, and organic compounds of gallium.
In accordance with one embodiment of the present disclosure, the source of group IIIA element (Y) is sodium aluminate.
In accordance with the embodiments of the present disclosure, the alkali is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide. In accordance with one embodiment of the present disclosure, the alkali is sodium hydroxide.
The organic templating agent is at least one selected from the group consisting of N,N,N-trimethyl-1-adamantammonium hydroxide (TMAda+OH-), N,N,N,N',N',N'-hexamethylpentanediammonium (Me6-diquat-5), adamantyl trimethyl ammonium cation, adamantyl trimethyl ammonium cation in the presence of isobutyl amine, and N(16)-methyl-sparteinium hydroxide.
In accordance with the embodiments of the present disclosure, the organic templating agent is C5-Diquarternary ammonium salt represented as Formula-II,

Formula II
wherein, X is selected from the group consisting of phosphate, halogens, sulfate, bisulfate, bisulfite, carbonate, bicarbonate, hexafluorophosphate, nitrate, oxyhalogen, perchlorate, carboxylate, amide, alkoxide, and etherate and R is an aliphatic straight chain hydrocarbon group.
In accordance with the one embodiment of the present disclosure, the organic templating agent is Diquat-5 dibromide salt.
In accordance with the embodiments of the present disclosure, the mole ratio of MO2 to Y2O3 is in the range of 10:1 to 80:1, preferably 20: 1 to 40: 1. In accordance with the exemplary embodiment of the present disclosure, the mole ratio of MO2 to Y2O3 is 30:1.
In accordance with the embodiments of the present disclosure, the mole ratio of the alkali to MO2 is in the range of 0.005:1 to 10:1, preferably 0.1: 1 to 1: 1.
In accordance with the embodiments of the present disclosure, the mole ratio of the organic templating agent to MO2 is in the range of 0.01:1 to 5:1, preferably 0.1: 1 to 0.5: 1.
In accordance with the present disclosure provides a MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
In accordance with the present disclosure, the MWW zeolite prepared is of at least one type selected from the group consisting of MCM-49, MCM-22, and MCM-56. Preferably, the MWW zeolite is MCM-22 type.
In accordance with the preferred embodiment of the present disclosure, the group IVA element is silicon, and the group IIIA element is aluminum. The MWW zeolite is represented by,
aSiO2:bAl2O3.
The MWW zeolite of the present disclosure has surface area in the range of 420 to 450 m2g-1, micropore area in the range of 280 to 300 m2g-1, external surface area in the range of 125 to 150 m2g-1, total pore volume in the range of 0.60 to 0.70 cc, micropore volume in the range of 0.10 to 0.15 cc, and average pore diameter in the range of 55 to 75 Å.
In accordance with the preferred embodiments of the present disclosure, MWW zeolite synthesized with diquarternary ammonium salt is obtained with improved pore properties that decrease the diffusion limitations of the organic moieties in any application, which further leads to increase in life time of the process.
In second aspect, the present disclosure provides a process for preparing shaped MWW zeolitic composite comprising MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
The process comprises the following steps.
At least one source of group IVA element (M), at least one source of group IIIA element (Y), at least one alkali, at least one organic templating agent, and water are mixed to obtain a first mixture, followed by stirring the first mixture for a time period in the range of 2 hour to 12 hours to obtain a hydrogel. The hydrogel is subjected to hydrothermal treatment by stirring at a temperature in the range of 100 °C to 300 °C, at a pressure in the range of 20 bar to 50 bar for a time period in the range of 200 hour to 400 hours to obtain crystals of the MWW zeolite. At least one binder is added to crystals of the MWW zeolite to obtain an admixture; The admixture is then activated by heating at a temperature in the range of 400 °C to 600 °C to obtain shaped MWW zeolitic composite.
In accordance with the present disclosure, shaped MWW zeolitic composite comprises:
• MWW zeolite represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1; and
• at least one binder.
In accordance with the embodiments of the present disclosure, the binder is at least one selected from the group consisting of silica, alumina, and clay.
The weight ratio of MWW zeolite to the binder is in the range of 95: 5 to 5: 95 on the basis of loss on ignition (LOI), preferably is in the range of 90: 10 to 60: 40 on the basis of loss on ignition (LOI). In accordance with the exemplary embodiments of the present disclosure, the weight ratio of MWW zeolite to the binder is 70: 30.
In accordance with the embodiments of the present disclosure, the shaped form is selected from the group consisting cylindrical extrudates, sphere, trilobe-shaped extrudates, tetralobe-shaped extrudates, tablets, particles, micro-spheres, rings, and honey-comb structure.
In accordance with preferred embodiments of the present disclosure, the shaped form is selected from cylindrical extrudates, and trilobe.
In third aspect, the present disclosure provides a process for reducing the olefin content of a hydrocarbon stream using the shaped zeolitic composite comprising MWW zeolite of the present disclosure. The process comprises the step of contacting olefin contaminated hydrocarbon stream with shaped zeolitic composite comprising the MWW zeolite at a temperature in the range of 100 °C to 500 °C, at a pressure in the range of 100 bar to 300 bar and for a time period in the range of 1 hours to 20 hours to obtain a treated hydrocarbon stream having reduced olefin content, wherein the MWW zeolite is represented by Formula-I,
aMO2:bY2O3 …….. Formula-I
wherein, M is at least one element selected from the group IVA elements, Y is at least one element selected from the group IIIA elements, and ‘a’ and ‘b’ are molar fractions, wherein ‘a’ is in the range of 1 to 100 and ‘b’ is in the range of 0.1 to 0.2 and the mole ratio of a: b is in the range of 10:1 to 500: 1.
In accordance with the present disclosure, the reduction of the olefin content of the treated hydrocarbon stream is in the range from 50% to 90%. Further, the benzene content and toluene content of the treated hydrocarbon stream is less than 200 ppm.
It is observed that the reduction of the olefin content of the hydrocarbon stream obtained by the process of the present disclosure is greater, when the process is carried out at a higher temperature.
The process for olefin reduction using the shaped zeolitic composite of the present disclosure is carried out either in liquid phase or in vapour phase. The process is carried out in a reactor selected from the group consisting of fixed bed reactor, fluidized bed reactor, trickle bed reactor, moving bed reactor, reactor having continuous circulation, and static bomb reactor.
For effective reduction in olefin content of a hydrocarbon stream, the shaped zeolitic composite of the present disclosure is used in suitable weight proportion. The weight ratio of the hydrocarbon stream to the zeolitic composite is in the range of 100:1 to 1:100, preferably is in the range of 80:1 to 1:80, and more preferably is in the range of 60:1 to 1:60.
The amount of hydrocarbon stream (expressed in terms of weight) which is in contact with unit mass of the catalyst composite of the present disclosure for a unit time is expressed as contact time and it is stated in the units of time. For the process of the present disclosure, the contact time of the hydrocarbon stream and the zeolitic catalyst composite is in the range of 0.1 hour to 12 hours, preferably 0.2 hour to 8 hours.
The spent catalyst composite comprising MWW zeolite is recovered and the recovered catalyst composite can be reused for the next cycle after regeneration.
In accordance with the embodiments of the present disclosure, the recovered catalyst composite comprising MWW zeolite is regenerated and reused for at least 10 cycles.
Due to regeneration and reuse of the spent catalyst, the process of the present disclosure generates low volume of solid waste. Thus, the process of the present disclosure for reducing the olefin content of a hydrocarbon stream is cost effective, and environmentally friendly. Further, it is observed, the production of unwarranted aromatic compounds from undesired side reactions, during the process of reduction of olefin content of a hydrocarbon stream using the MWW zeolitic composite of the present disclosure is low.
The present disclosure further provides a process for preparation of C5-diquarternary ammonium salts.

In accordance with the present disclosure, the synthesis of the salt of Diquat-5 can be carried out by reacting the secondary amine with any organic or inorganic precursor salt represented as
X-R-X
wherein, R is the organic cation and X is an organic or inorganic anion.
In accordance with the exemplary embodiment of the present disclosure, R is C5 chain.
In accordance with the exemplary embodiment of the present disclosure, X is at least one selected from the group consisting of phosphate, halogens, e. g., flouride, chloride, bromide, or iodide, sulfate, bisulfate, bisulfite, carbonate, bicarbonate, hexafluorophosphate, nitrate, oxyhalogen, such as chlorate, C1O3-, or perchlorate, ClO4. Representative suitable organic anions are carboxylate, R-COO-, amide, RCONHZR, alkoxide, R3CO-, or etherate, RO.
In accordance with the present disclosure, the process for preparing diquarternary ammonium salt comprises following steps:
• dissolving a secondary amine in at least one solvent under continuous stirring to obtain a first mixture;
• adding to first mixture any organic or inorganic precursor salt slowly under continuous stirring to obtain a reaction mixture;
• refluxing the reaction mixture for a time period in the range of 10 hour to 50 hour to obtain a product mixture comprising crystals of diquarternary ammonium salt; and
• cooling the product mixture followed by filtration and drying to obtain crystals of diquarternary ammonium salt.
In accordance with the present disclosure, the organic templates have good flexibility and feasibility. It’s end groups and chain length can be selectively altered to facilitate the formation of diverse microporous topology, and to tailor the crystal morphology or mesoporosity. The conformational rigidity and hydrophobicity of these structure directing agents are the two most important factors determining the pore architecture of the crystallized product.
In accordance with the present disclosure, MWW zeolite synthesized with diquarternary ammonium salt is obtained with improved pore properties that decrease the diffusion limitations of the organic moieties in any application, which further leads to increase in life time of the process.
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.
EXAMPLES
Example 1: Preparation of Diquat-5 dibromide (iso-Pr4-diquat-5) salt
Diisopropylamine (61.94 grams, 0.6 mole) (98% pure, Aldrich Chemical Company) was added to round bottomed flask containing mixture of acetonitrile and toluene (600 ml, 1:1 ratio), while the contents of the flask were stirred continuously. Then, 1, 5 dibromopentane (22.94 grams 0.1 moles) (98% pure, Aldrich Chemical Company) was added drop wise while stirring. The flask was fitted with reflux condenser to minimize the loss of organic components during reflux. The reaction mixture was refluxed for about 40 hours. White crystals of Diquat-5 dibromide salt were formed and separated. The reaction flask was cooled by immersion in water-ice bath. The product was then filtered on a Buchner funnel. Product crystals were washed on the funnel several times with anhydrous diethyl ether.
Yield of the product was 98% and purity was confirmed by H1-NMR.
Examples 2-4: Preparation of MWW zeolite in accordance with the process of the present disclosure
Zeolite having an MWW-type framework was prepared in accordance with the process of the present disclosure. The group IVA element was silicon, and its source was colloidal silica. The group IIIA element was aluminum, and its source was sodium aluminate.
Example 2: Preparation of MWW zeolite in accordance with the process of the present disclosure
NaOH (17.6 g) was added to water (720 g) followed by the addition of sodium aluminate (6.1 g) (55 % Al2O3, 45 % Na2O, Aldrich) while stirring. In the next step Diquat-5 produced in example 1 (87 g) was added followed by slow addition of precipitated silica (63 g) while stirring to obtain a first mixture. The so obtained first mixture was continuously stirred until a homogeneous solution was formed with a molar gel composition of 1SiO2:0.03Al2O3:0.27Na2O:40H2O:0.2SDA
The above gel was transferred into a Teflon lined autoclave and hydrothermally crystallized at 170°C for 7 days. Formed crystallized product was separated by centrifugation and washed with distilled water followed by drying in an oven.
X-ray diffraction study of MWW zeolite is provided in Figure 1, which shows the peaks corresponding to MCM-22 along with small impurity of Ferririte phases.
The molar composition of the crystallized product obtained is given in Table 1 below.
Example 3: Preparation of MWW zeolite in accordance with the process of the present disclosure
NaOH (17.6 g) was added to water (358 g) followed by the addition of sodium aluminate (6.1 g) (55 % Al2O3, 45 % Na2O, Aldrich) while stirring. In the next step Diquat-5 produced in example 1 (56 g) was added followed by slow addition of precipitated silica (63 g) while stirring to obtain a first mixture. The so obtained first mixture was continuously stirred until a homogeneous solution was formed with a molar gel composition of 1SiO2:0.033Al2O3:0.27Na2O:20H2O:0.13SDA
The above gel was transferred into a Teflon lined autoclave and hydrothermally crystallized at 165 °C for 10 days. Formed crystallized product was separated by centrifugation and washed with distilled water followed by drying in an oven.
X-ray diffraction study of MWW zeolite is provided in Figure 2, which shows the peaks corresponding to MCM-22 along with small impurity of Ferririte phases.
The molar composition of the crystallized product obtained is given in Table 1 below.
Example 4: Preparation of MWW zeolite in accordance with the process of the present disclosure
NaOH (12 g) is added to water (592 g) followed by the addition of sodium aluminate (6.1 g) (55 % Al2O3, 45 % Na2O, Aldrich) while stirring. In the next step Diquat-5 produced in example 1 (87 g) was added followed by slow addition of precipitated silica (63 g) while stirring to obtain a first mixture. The so obtained first mixture was continuously stirred until a homogeneous solution was formed with a molar gel composition of 1SiO2:0.033Al2O3:0.2Na2O:33H2O:0.2SDA
The above gel was transferred into a Teflon lined autoclave and hydrothermally crystallized at 165 °C for 15 days. Formed crystallized product was separated by centrifugation and washed with distilled water followed by drying in an oven.
X-ray diffraction study of MWW zeolite is provided in Figure 3, which shows the peaks corresponding to MCM-22 without any additional peaks.
The molar composition of the crystallized product obtained is given in Table 1 below.
For comparative analysis, a similar zeolite was prepared using conventional templating agents. The zeolite was prepared by the following procedure.
Example 5: Composition for control experiment prepared using conventional templating agent) (Comparative example)
NaOH (2 g) was added to water (268 g) followed by the addition of sodium aluminate (6.1 g) (55 % Al2O3, 45 % Na2O, Aldrich) while stirring. In the next step hexamethyleneimine (18.2 g) (Aldrich, 99% purity) was added followed by slow addition of precipitated silica (63 g) while stirring. Mixture was continuously stirred until a homogeneous solution was formed with a molar gel composition of 1SiO2:0.033Al2O3:0.075 Na2O:15H2O:0.2SDA.
The above gel was transferred into a Teflon lined autoclave and hydrothermally crystallized at 170 °C for 2 days. Formed crystallized product was separated by centrifugation and washed with distilled water followed by drying in an oven.
X-ray diffraction study of MWW zeolite is provided in Figure 4, which shows pure phase of MCM-22.
The molar composition of the crystallized product obtained is given in Table 1 below.
Table 1: Molar gel composition and crystallization conditions of example 2 to 5
Example 2 3 4 5
SiO2/Al2O3 30 30 30 30
Na2O/SiO2 0.27 0.26 0.2 0.075
R/SiO2 0.2 0.13 0.2 0.2
H2O/SiO2 40 20 33 15
SDA or R Diquat-5 Diquat-5 Diquat-5 HMI
Crystallization Time/days 7 10 15 2
Temperature/°C 170 165 165 170
Phase MCM-22/F* MCM-22/F MCM-22 MCM-22
*F indicates presence of small impurity of Ferrierite phase.
The physico-chemical properties of the MWW type zeolite obtained in examples 4 and 5 are given below in Table 2.
Table 2: Physico-chemical properties of the MWW type zeolite obtained in examples 4 and 5
Sr. No. Properties MCM-22* Diquat-MCM-22
1. SA (m2g-1) 422 424
2. Micropore area (m2g-1) 322 287
3. External Surface area
(m2g-1) 100 137
4. Total pore volume
(cc) 0.56 0.62
5. Micropore Vol (cc) 0.19 0.14
6. Mesopore Vol (cc) 0.37 0.48
7. Average pore diameter
(Å) 54 66
* prepared using HMI as template
From table 2, it is evident that the improvement in the pore properties and external surface area of the MWW type zeolite obtained by the process of the present disclosure is observed as compared to the pore properties and external surface area of the MWW type zeolite obtained by the conventional process.
Example 6: Forming shaped zeolitic composite comprising MWW zeolite obtained in example 4
The MWW zeolite obtained from examples 4 was mixed with psuedobohemite alumina to obtain an admixture. The admixture was shaped in the form of cylindrical extrudates. The shaped cylindrical extrudates of the zeolitic composite were activated by heating at 550 °C for 6 hours.
The weight ratio of the MWW zeolite obtained from example 4 to psuedobohemite alumina, on loss on ignition (LOI) basis, was 70:30.
Example 7: Forming shaped zeolitic composite comprising MWW zeolite obtained in comparative example 5
The MWW zeolite obtained from examples 5 was mixed with psuedobohemite alumina to obtain an admixture. The admixture was shaped in the form of cylindrical extrudates. The shaped cylindrical extrudates of the zeolitic composite were activated by heating at 550 °C for 6 hours.
The weight ratio of the zeolitic composite obtained from example 5 to psuedobohemite alumina, on loss on ignition (LOI) basis, was 70:30.
The composition and average crush strength of the cylindrical extrudates of the zeolitic composite are presented in Table 3.
Table 3: Compositions of shaped zeolitic composite and average crush strength thereof
Examples 6 7
MWW Zeolitic composite from example 4 5
MWW Zeolitic composite Alumina w/w (on LOI basis) 70:30 70:30
Average Crush Strength (Kgf) 5.7 5.7

Cylindrical extrudates prepared from the MWW zeolitic composite obtained from examples 6-7 showed average crushing strength in the range of 5.6 to 5.7 Kgf.
Thus, the crushing strength of the extrudates of the MWW zeolitic composite of the present disclosure is similar to that of the zeolitic composite prepared using conventional templating agents. It is clear that the crushing strength of the MWW zeolitic composite of the present disclosure do not alter.
Examples 8-9:
Catalytic performance of the shaped zeolitic composites obtained from examples 6-7 were evaluated by measuring the amount of reduction of the olefin content from a commercial C8+ aromatic stream.
The commercial C8+ aromatic stream used for this evaluation was a deheptanizer bottom hydrocarbon stream. Composition of the commercial C8+ aromatic stream is shown herein below in Table 4.
Table 4: Composition of deheptanizer column bottom
Component wt%
Non-aromatics 1.3
Toluene 1.56
Ethyl benzene 8.31
Xylenes 44.51
C9Aromatics 36.16
C10Aromatics + Heavy Aromatics 8.09

The shaped MWW zeolitic composite (5 g) obtained from example 6 was charged to a stainless steel bomb reactor containing a feed of commercial deheptanizer column bottom hydrocarbon stream (35 g). The reactor was purged with nitrogen to remove air and was closed. The bomb reactor was heated at the temperature and for the time period mentioned in Table 5. After this, the reactor was cooled; the treated hydrocarbon stream was separated, and analyzed for the amount of olefin.
Olefin concentrations of the feed and treated hydrocarbon stream were determined as Bromine Index (BI) of the sample following standard test method ASTM D-1491.
Performance of other sample was evaluated using cylindrical extrudates of the zeolitic composites obtained from examples 7. The results are presented in Table 5.
Table 5: Olefin reduction of the commercial C8+ aromatics stream (feed)
Ex. No. Catalyst Details from Reaction Conditions Results % BI Reduction (Olefin Conv.)
Temperature
°C Time h Feed
BI Product BI
8 Example 6
(Present Disclosure) 180 3 600 234 61
9 Example 7
(Comparative) 180 3 600 365 39
BI = bromine index
It is observed that, the cylinder shaped extrudates of the MWW zeolitic composite of the present disclosure provides higher reduction of the olefin content of the deheptanizer column bottom stream (C8+ aromatics stream) as compared to the cylindrical extrudates of the MWW zeolitic composite obtained using conventional templating agent.
Examples 10-12: Regeneration of spent MWW zeolitic composite
The MWW zeolitic composite is said to be spent zeolitic composite when the olefin removal efficiency of the zeolitic composite reaches to 50% or lower as compared to that at the beginning of the experiment.
Example 10: Regeneration of spent MWW zeolitic composite
Fresh MWW zeolitic composite (20 g) was subjected to accelerated aging conditions. After 8 days of continuous operation, the extent of the olefin content reduction of the hydrocarbon stream achieved by the MWW zeolitic composite decreased to 44% as compared to that of the fresh MWW zeolitic composite, indicating that the zeolitic composite was spent.
The spent MWW zeolitic composite was separated and was dried in an oven at 120 °C for two hours. The dried spent MWW zeolitic composite was then calcined in air at 540 °C for 6 hours. The calcined MWW zeolitic composite was cooled to ambient temperature to obtain regenerated zeolitic composite.
The extrudates were clean white after regeneration process. Weight of the regenerated zeolitic composite was 17.3 g. The regenerated MWW zeolitic composite, thus obtained, was first regenerated zeolitic composite.
The first regenerated MWW zeolitic composite (5 g) was employed for reduction of olefins from a fresh feed of commercial deheptanizer bottom stream under conditions similar to those described in Example 8. Reaction conditions and results are provided in Table 6.
Example 11:
The first regenerated MWW zeolitic composite (14.0 g) was subjected to accelerated aging conditions. After 8 days of continuous operation, extent of the olefin content reduction of the hydrocarbon stream achieved by the zeolitic composite decreased to 43% olefin reduction as compared to that of the first regenerated zeolitic composite at the beginning, indicating that the first regenerated MWW zeolitic composite was spent.
The spent first MWW zeolitic composite was separated and was regenerated using the process mentioned hereinabove. Weight of regenerated clean white extrudates was found to be 11.2 g. This sample was second regenerated MWW zeolitic composite.
The second regenerated MWW zeolitic composite (5 g) were employed for reduction of olefins from a fresh feed of commercial deheptanizer bottom stream under conditions similar to those described in Example 8. Reaction conditions and results of the test are given in Table 6.
Example 12:
The second regenerated MWW zeolitic composite (8 g) was subjected to accelerated aging conditions. After 8 days of continuous operation, the extent of the olefin content reduction of the hydrocarbon stream achieved by of the MWW zeolitic composite decreased to 43% olefin reduction as compared to that of the second regenerated MWW zeolitic composite at the beginning, indicating that the second regenerated MWW zeolitic composite was spent. The third time spent MWW zeolitic composite was regenerated following the procedure as described earlier.
5 g of the third regenerated cylindrical extrudates of the MWW zeolitic composite were employed for reduction of olefins from a fresh feed of commercial deheptanizer bottom stream as described earlier in Example 8. Reaction conditions and results of the test are given in Table 6.
Table 6: Regenerability of the MWW zeolitic composite
Example No No of Regeneration Reaction Conditions Results % BI Reduction (Olefin Conv.)
Temperature
°C Time
h Feed
BI Product
BI
9 Fresh 180 3 600 234 61
10 1 180 3 600 227 62
11 2 180 3 600 240 60
12 3 180 3 600 234 61

From Table 6, it is clear that the MWW zeolitic composite of the present disclosure can be recycled and reused. The MWW zeolitic composite of the present disclosure can be regenerated by calcination in oxidizing atmosphere.
Example 13:
The extent of benzene and toluene formation during the process of reducing olefins from commercial C8 aromatics stream using the MWW zeolitic composite of the present disclosure was evaluated.
Cylindrical extrudates of the MWW zeolitic composite (10 g) of the present disclosure were mixed with a feed of commercial deheptanizer column bottom hydrocarbon stream (35 g) in a stainless steel bomb. The reactor was purged with nitrogen to remove air and was closed. The bomb reactor was heated at 180 °C for 3 hours. After this, the reactor was cooled to ambient conditions.
The treated hydrocarbon stream was analyzed by gas chromatography (GC). During this run, the olefin reduction of the feed of commercial deheptanizer column bottom hydrocarbon stream was found to be 61%.
The amounts of lighters and aromatics of the feed and treated hydrocarbon stream are shown Table 7.
Table 7: GC Analysis of feed hydrocarbon stream and treated hydrocarbon stream
Feed Product
Lighters 0.32 0.31
Benzene 0.00 0.00
Toluene 0.27 0.29
C8 Aromatics 54.59 54.37
C9 Aromatics 38.81 38.87
C10 and heavies 6.02 6.17

It is observed from Table 7 that there was no benzene formation during this run. Furthermore, it is observed that toluene formation was 200 ppm.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? a process for preparing a MWW zeolite;
? a process for reducing the olefin content of a hydrocarbon stream using zeolitic composite comprising MWW zeolite; and
? a MWW zeolitic composite that can be regenerated by a simple process.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation