Claims:1. A process for preparing a zeolitic composition having an MWW-type framework and being represented by Formula-I,
aMO2:bY2O3:cXO2…….. 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, X is at least one element selected from the group IIIB elements; and a, b, and c are molar fractions,
the process comprising the following steps,
- mixing at least one source of group IVA element (M), at least one source of group-IIIA element (Y), at least one source of group IIIB element (X), at least one alkali, at least one organic templating agent, and water under stirring to obtain a first mixture having a pH in the range of 10 to 13 followed by further stirring the first mixture to obtain a hydrogel; and
- subjecting the hydrogel to hydrothermal treatment by stirring the hydrogel at a temperature in the range of 10 °C to 300 °C to obtain the zeolitic composition.
2. The process as claimed in claim 1, wherein the first mixture is stirred for a time period in the range of 0.1 hour to 120 hours, and the hydrothermal treatment is carried out for a time period in the range of 0.1 hour to 300 hours.
3. The process as claimed in claim 1, wherein 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.
4. The process as claimed in claim 1, wherein 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.
5. The process as claimed in claim 1, wherein 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.
6. The process as claimed in claim 1, wherein 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.
7. The process as claimed in claim 1, wherein the source of group IIIB element (X) is at least one compound selected from the group consisting of nitrate salts, acetate salts, carbonate salts, sulphate salts, and halide salts of group IIIB elements, and organic compounds of group IIIB elements.
8. The process as claimed in claim 1, wherein the source of group IIIB element (X) is at least one compound selected from the group consisting of cerium nitrate, cerium acetate, ammonium ceric nitrate, cerium halides, cerium carbonate, and cerium sulphate.
9. The process as claimed in claim 1, wherein the alkali is at least one selected from the group consisting of sodium hydroxide, and potassium hydroxide.
10. The process as claimed in claim 1, wherein the organic templating agent is selected from the group consisting of N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAda+OH-), N,N,N,N',N',N'-hexamethylpentanediammonium (Me6-diquat-5), hexamethyleneimine, aniline, cyclohexyl amine, piperidine, adamantyl trimethyl ammonium cation, adamantyl trimethyl ammonium cation in presence of isobutyl amine, N(16)-methyl-sparteinium hydroxide, triethylamine, and methyltriethylammonium bromide.
11. The process as claimed in claim 1, wherein the mole ratio of the alkali to MO2 is in the range of 0.005:1 to 10:1.
12. The process as claimed in claim 1, wherein the mole ratio of the organic templating agent to MO2 is in the range of 0.05:1 to 5:1.
13. The process as claimed in claim 1, wherein the step of hydrothermal treatment is carried out at a pressure in the range of 1 bar to 100 bar and involves stirring the hydrogel at a speed in the range of 10 rpm to 600 rpm.
14. The process as claimed in claim 1, further comprising a step of preparing shaped form of the zeolitic composition, the step of preparation of shaped form comprising the following sub-steps,
(i) mixing the zeolitic composition with at least one binder to obtain an admixture; and
(ii) preparing shaped form from the admixture followed by activation to obtain the shaped form of the zeolitic composition.
15. The process as claimed in claim 14, wherein the weight ratio of the zeolitic composition to the binder is in the range of 95:5 to 5:95 on the basis of loss on ignition (LOI).
16. The process as claimed in claim 14, wherein the step of activation involves heating the shaped form at a temperature in the range of 400 °C to 700 °C for a period in the range of 4 hours to 48 hours.
17. A zeolitic composition prepared by the process as claimed in any one of claims 1 to 16, the zeolitic composition being represented by Formula-I,
aMO2:bY2O3:cXO2…….. Formula-I
wherein, X is at least one element selected from the group-IIIB elements, 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, b, and c are molar fractions.
18. The zeolitic composition as claimed in claim 17, wherein ‘a’ ranges from 10 to 80, ‘b’ ranges from 0.005 to 3, and ‘c’ ranges from 0.001 to 5.
19. The zeolitic composition as claimed in claim 17, wherein the mole ratio of MO2 to XO2 is in the range of 20:1 to 500:1, and the mole ratio of MO2 to Y2O3 is in the range from 10:1 to 80:1.
20. The zeolitic composition as claimed in claim 17, wherein the group IIIB element (X) is cerium (Ce), and the amount of CeO2 in the zeolitic composition is in the range of 0.1 weight% to 5.0 weight%.
21. A process for reducing the olefin content of a hydrocarbon stream, the process comprising contacting the zeolitic composition as claimed in any one of claims 17 to 20 with the hydrocarbon stream at a temperature in the range of 0 °C to 500 °C at a pressure in the range of 0.01 bar to 300 bar to obtain a treated hydrocarbon stream having reduced olefin content.
22. The zeolitic composition of any one of the claims 17 to 20 for reducing olefin content of a hydrocarbon stream, wherein such use is stopped when the extent of the olefin content reduction of the hydrocarbon stream reaches to 50% w/w or lower as compared to the extent of the olefin content reduction of the hydrocarbon stream at the beginning of the process, after which a spent zeolitic composition is obtained.
23. A process for regenerating the spent zeolitic composition as claimed in claim 22, the process comprising the following steps,
(a) drying the spent solid zeolitic composition at a temperature in the range of 100 °C to 200 °C for a period in the range of 1 hour to 12 hours to obtain a dried spent zeolitic composition; and
(b) calcining the dried spent zeolitic composition at a temperature in the range of 400 °C to 700 °C in the presence of an oxidant for a period in the range of 4 hours to 48 hours to obtain a regenerated zeolitic composition.
, Description:FIELD
The present disclosure relates to a process for preparing a zeolitic composition having MWW-type framework.
BACKGROUND
In the petrochemical industry, zeolitic compositions having MWW-type framework (also referred to as MWW zeolite compositions) are used for a range of applications, such as a catalysis, adsorption, and as a filler. MWW zeolitic compositions can be used as adsorbents for reducing the olefin content of a hydrocarbon stream; however, their ability to adsorb olefin is low.
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.
Certain activities of a MWW zeolitic composition can be altered by incorporation of a heteroatom in the zeolitic framework. However, the preparation of MWW zeolitic composition containing a heteroatom is associated with drawbacks. Synthesis of zeolite with a heteroatom in its framework is difficult and requires special conditions. Typically, fluoride containing media is used for the synthesis of zeolite with a heteroatom. However, this approach increases the crystallization time. Further, the fluoride containing media is toxic, and very low amount of the heteroatom can be incorporated into the zeolite frame work using this approach. Furthermore, this method is very sensitive to the reagents and reaction conditions such as silica source, fluid mediums, templates, temperature, time, pH, and the like, and therefore, reproducibility of synthetic method is a serious issue. Another approach for the synthesis of zeolite with a heteroatom is using an organic silicon compound, such as tetraethyl orthosilicate (TEOS), as a silica source. However, this approach is laborious and costly.
Therefore, there is felt a need to provide a simple process for the preparation of the MWW zeolitic composition containing a heteroatom. Further, it is desired that the MWW zeolitic composition is capable of reducing the olefin content of hydrocarbon stream and that the MWW zeolitic composition 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 process for the preparation of a MWW zeolitic composition containing a heteroatom.
Another object of the present disclosure is to provide a MWW zeolitic composition containing a heteroatom that is capable of reducing the olefin content of a hydrocarbon stream.
Yet another object of the present disclosure is to provide a MWW zeolitic composition containing a heteroatom 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 zeolitic composition having an MWW-type framework and being represented by Formula-I,
aMO2:bY2O3:cXO2…….. 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, X is at least one element selected from the group IIIB elements; and a, b, and c are molar fractions.
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 source of group IIIB element (X), at least one alkali, at least one organic templating agent, and water are mixed under stirring to obtain a first mixture having a pH in the range of 10 to 13, followed by further stirring the first mixture to obtain a hydrogel.
The hydrogel is subjected to hydrothermal treatment by stirring the hydrogel at a temperature in the range of 10 °C to 300 °C to obtain the zeolitic composition.
The first mixture is stirred for a time period in the range of 0.1 hour to 120 hours, and the hydrothermal treatment is carried out for a time period in the range of 0.1 hour to 300 hours.
The source of group IVA elements (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.
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, magnesium 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 the embodiments of the present disclosure, the source of group IIIB element (X) is at least one compound selected from the group consisting of nitrate salts, acetate salts, carbonate salts, sulphate salts, and halide salts of group IIIB elements, and organic compounds of group IIIB elements.
The source of group IIIB element (X) is at least one compound selected from the group consisting of cerium nitrate, cerium acetate, ammonium ceric nitrate, cerium halides, cerium carbonate, and cerium sulphate.
The alkali is selected from the group consisting of sodium hydroxide, and potassium hydroxide.
The organic templating agent is at least one selected from the group consisting of N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAda+OH-), N,N,N,N',N',N'-hexamethylpentanediammonium (Me6-diquat-5), hexamethyleneimine, aniline, cyclohexyl amine, piperidine, adamantyl trimethyl ammonium cation, adamantyl trimethyl ammonium cation in presence of isobutyl amine, N(16)-methyl-sparteinium hydroxide, triethylamine, and methyltriethylammonium bromide.
The mole ratio of the alkali to MO2 is in the range of 0.005:1 to 10:1. The mole ratio of the organic templating agent to MO2 is in the range of 0.05:1 to 5:1.
The step of hydrothermal treatment is carried out at a pressure in the range of 1 bar to 100 bar and involves stirring the hydrogel at a speed in the range of 10 rpm to 600 rpm.
The process of the present disclosure further comprises a step of preparing shaped form of the zeolitic composition. The step of preparation of shaped form comprises the following sub-steps.
The zeolitic composition is mixed with at least one binder to obtain an admixture. Shaped form is prepared from the admixture followed by activation to obtain the shaped form of the zeolitic composition.
The weight ratio of the zeolitic composition to the binder is in the range of 95:5 to 5:95 on the basis of loss on ignition (LOI). The step of activating involves heating the shaped form at a temperature in the range of 400 °C to 700 °C for a period in the range of 4 hours to 48 hours.
The weight ratio of the zeolitic composition to the binder ranges from 95:5 to 5:95. The step of activating involves heating the shaped form at a temperature in the range of 400 °C to 700 °C for a period of 4 hours to 48 hours.
In second aspect, the present disclosure provides a zeolitic composition prepared by the process of the present disclosure, the zeolitic composition being represented by Formula-I,
aMO2:bY2O3:cXO2…….. Formula-I
wherein, X is at least one element selected from the group-IIIB elements, 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, b, and c are molar fractions.
The mole fraction ‘a’ ranges from 10 to 80, ‘b’ ranges from 0.005 to 3, and ‘c’ ranges from 0.001 to 5. The mole ratio of MO2 to XO2 is in the range of 20:1 to 500:1, and the mole ratio of MO2 to Y2O3 is in the range from 10:1 to 80:1.
The group IIIB element (X) is cerium (Ce), and the amount of CeO2 in the zeolitic composition is in the range of 0.1 weight% to 5.0 weight%.
In third aspect, the present disclosure provides a process for reducing the olefin content of a hydrocarbon stream using the zeolitic composition. The process comprising contacting the zeolitic composition of the present disclosure with a hydrocarbon stream at a temperature in the range of 0 °C to 500 °C at a pressure in the range of 0.01 bar to 300 bar to obtain a treated hydrocarbon stream having reduced olefin content.
The use of zeolitic composition of the present disclosure for reducing olefin content of a hydrocarbon stream is stopped when the extent of the olefin content reduction of the hydrocarbon stream reaches to 50% w/w or lower as compared to the extent of the olefin content reduction of the hydrocarbon stream at the beginning of the process, after which a spent zeolitic composition is obtained.
In fourth aspect, the present disclosure provides a process for regenerating the spent zeolitic composition. The process comprises the following steps.
The spent solid zeolitic composition is dried at a temperature in the range of 100 °C to 200 °C for a period in the range of 1 hour to 12 hours to obtain a dried spent zeolitic composition.
The dried spent zeolitic composition is calcined at a temperature in the range of 400 °C to 700 °C in the presence of an oxidant for a period in the range of 4 hours to 48 hours to obtain regenerated zeolitic composition.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates an XRD diffractogram of zeolitic composition prepared in accordance with Example 1, (A) as synthesized, and (B) calcined;
Figure 2 illustrates an XRD diffractogram of zeolitic composition containing cerium prepared in accordance with Example 2, (A) as synthesized, and (B) calcined; and
Figure 3 illustrates an XRD diffractogram of zeolitic composition containing cerium prepared in accordance with Example 3, (A) as synthesized, and (B) calcined.

DETAILED DESCRIPTION
MWW zeolitic compositions can be used as adsorbents for reducing the olefin content of a hydrocarbon stream; however, their ability to adsorb olefin is low. The activity of a MWW zeolite composition can be altered by incorporation of heteroatom in the zeolite framework. However, processes for the preparation of the MWW zeolitic composition containing a heteroatom are associated with drawbacks such as being tedious, multi-step and cumbersome. Further, such processes result in incorporation of a low amount of the heteroatom in the zeolitic composition. Furthermore, it is desirable that the MWW zeolitic composition is capable of regeneration by a simple process.
The present disclosure envisages a process for preparing a zeolitic composition having an MWW-type framework which can be used for olefin reduction of a hydrocarbon stream.
In first aspect, the present disclosure provides a process for preparing a zeolitic composition having an MWW-type framework and being represented by Formula-I,
aMO2:bY2O3:cXO2…….. 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, X is at least one element selected from the group IIIB elements; and a, b, and c are molar fractions.
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 source of group IIIB element (X), at least one alkali, at least one organic templating agent, and water are mixed under stirring to obtain a first mixture having a pH in the range of 10 to 13. The first mixture is further stirred to obtain a hydrogel.
The hydrogel is subjected to hydrothermal treatment involving stirring the hydrogel at a temperature in the range of 10 °C to 300 °C to obtain the zeolitic composition.
The first mixture is stirred for a time period in the range of 0.1 hour to 120 hours. The hydrothermal treatment is carried out for a time period in the range of 0.1 hour to 300 hours.
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 exemplary 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 source of group IIIB element (X) is at least one compound selected from the group consisting of nitrate salts, acetate salts, carbonate salts, sulphate salts, and halide salts of group IIIB elements, and organic compounds of group IIIB elements.
In accordance with one embodiment of the present disclosure, the source of group IIIB element (X) is at least one compound selected from the group consisting of cerium nitrate, cerium acetate, ammonium ceric nitrate, cerium halides, cerium carbonate, and cerium sulphate.
In accordance with first exemplary embodiment of the present disclosure, the source of the group IIIB element (X) is cerric nitrate.
In accordance with second exemplary embodiment of the present disclosure, the source of the group IIIB element (X) is cerric acetate.
The process of the present disclosure provides zeolitic compositions, wherein the amount of heteroatom such as cerium is high.
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.
The organic templating agent is selected from the group consisting of N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAda+OH-), N,N,N,N',N',N'-hexamethylpentanediammonium (Me6-diquat-5), hexamethyleneimine, aniline, cyclohexyl amine, piperidine, adamantyl trimethyl ammonium cation, adamantyl trimethyl ammonium cation in presence of isobutyl amine, N(16)-methyl-sparteinium hydroxide, triethylamine, and methyltriethylammonium bromide.
In accordance with one embodiment of the present disclosure, the organic templating agent is hexamethyleneimine.
The mole ratio of the alkali to MO2 is in the range of 0.005:1 to 10:1.
In accordance with one embodiment of the present disclosure, the mole ratio of the alkali to MO2 is 1.5:1.
In accordance with the embodiments of the present disclosure, the mole ratio of the organic templating agent to MO2 is in the range of 0.05:1 to 5:1.
In accordance with one embodiment of the present disclosure, the mole ratio of the organic templating agent to MO2 is 0.26:1.
In accordance with one embodiment of the present disclosure, the mole ratio of the organic templating agent to MO2 is 0.3:1.
In accordance with the embodiments of the present disclosure, the mole ratio of water to MO2 is in the range of 5:1 to 50:1.
In accordance with the one embodiment of the present disclosure, the mole ratio of water to the MO2 is 15:1.
In accordance with the embodiments of the present disclosure, the hydrothermal treatment is carried out at a pressure in the range of 1 bar to 100 bar.
The hydrothermal treatment is carried out at the autogenous pressure generated in the reactor during the step of stirring the hydrogel at a temperature in the range of 10 °C to 300 °C.
In accordance with the embodiments of the present disclosure, the step of hydrothermal treatment involves stirring the hydrogel at a speed in the range of 10 rpm to 600 rpm.
In accordance with one exemplary embodiment of the present disclosure, the step of hydrothermal treatment involves stirring the hydrogel at a speed of 250 rpm.
The process of the present disclosure further involves a step of preparing shaped forms of the zeolitic composition. The step of preparation of shaped form involves the following sub-steps.
The zeolitic composition is mixed with at least one binder to obtain an admixture. Shaped form is prepared from the admixture followed by activation to obtain shaped form of the zeolitic composition.
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.
In accordance with the embodiments of the present disclosure, the weight ratio of the zeolitic composition and the binder is in the range of 95:5 to 5:95 on the basis of loss on ignition (LOI).
In accordance with one exemplary embodiment of the present disclosure, the weight ratio of the zeolitic composition and the binder is 70:30, on the basis of loss on ignition (LOI).
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.
The process step of activating the shaped forms involves heating at a temperature in the range of 400 °C to 700 °C for a period in the range of 4 hours to 48 hours.
Thus, the present disclosure provides a zeolitic composition having an MWW-type framework by a simple process.
In second aspect, the present disclosure provides a zeolitic composition prepared by the process of the present disclosure. The zeolitic composition is represented by Formula-I,
aMO2:bY2O3:cXO2…….. Formula-I
wherein, X is at least one element selected from the group-IIIB elements, 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, b, and c are molar fractions.
The molar fraction ‘a’ ranges from 10 to 80, ‘b’ ranges from 0.005 to 3, and ‘c’ ranges from 0.001 to 5. The mole ratio of MO2 to XO2 is in the range of 20:1 to 500:1. The mole ratio of MO2 to Y2O3 is in the range from 10:1 to 80:1.
In accordance with one exemplary embodiment of the present disclosure, the mole ratio of MO2 to Y2O3 is 38:1. In accordance with another exemplary embodiment of the present disclosure, the mole ratio of MO2 to Y2O3 is 43:1.
In accordance with an exemplary embodiment of the present disclosure, the group IIIB element (X) is cerium (Ce), and the amount of CeO2 in the zeolitic composition is in the range of 0.1 weight% to 5.0 weight%. Preferably, the amount of CeO2 in the zeolitic composition is in the range of 1.1 weight% to 3.5 weight%.
In accordance with the preferred embodiment of the present disclosure, the group IVA element is silicon, and the group IIIA element is aluminum. The zeolitic composition is represented by,
aSiO2:bAl2O3:cXO2,
wherein, X is at least one element selected from the group IIIB elements; and a, b, and c are molar fractions.
In third aspect, the present disclosure provides a process for reducing the olefin content of a hydrocarbon stream using the MWW zeolitic composition of the present disclosure. The process comprises contacting the zeolitic composition with a hydrocarbon stream at a temperature in the range of 0 °C to 500 °C at a pressure in the range of 0.01 bar to 300 bar to obtain a treated hydrocarbon stream having reduced olefin content.
The reduction of the olefin content of the hydrocarbon stream using the zeolitic composition of the present disclosure is in the range from 50% to 90%.
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 zeolitic composition 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 zeolitic composition of the present disclosure is used in suitable weight proportion. The weight ratio of the hydrocarbon stream to the zeolitic composition 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 zeolitic composition 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 composition is in the range of 0.1 hour to 12 hours, preferably 0.2 hour to 8 hours.
It is observed that the reduction of the olefin content of the hydrocarbon stream obtained by the process of the present disclosure is higher as compared to that obtained by similar zeolitic composition not having a group IIIB element (X) oxide. Thus, the zeolitic composition of the present disclosure is efficient. Higher efficiency for olefin reduction of the zeolitic composition of the present disclosure results in a lower frequency of change-over.
The use of the zeolitic composition of the present disclosure for reducing olefin content of a hydrocarbon stream is stopped when the extent of the olefin content reduction of the hydrocarbon stream reaches to 50% w/w or lower as compared to the extent of the olefin content reduction of the hydrocarbon stream at the beginning of the process, after which a spent zeolitic composition is obtained.
The spent zeolitic composition is recovered and the recovered zeolite composition can be reused for the next cycle after regeneration.
In accordance with the embodiments of the present disclosure, the recovered zeolitic composition is regenerated and reused for at least 10 cycles.
In fourth aspect, the present disclosure provides a process for regenerating the spent zeolitic composition obtained in the process of the olefin reduction of a hydrocarbon stream. The process comprises the following steps.
The spent zeolitic composition is dried at a temperature in the range of 100 °C to 200 °C for a period in the range of 1 hour to 12 hours to obtain dried spent zeolitic composition. The dried spent zeolitic composition is calcined at a temperature in the range of 400 °C to 700 °C, in the presence of an oxidant, for a period in the range of 4 hours to 48 hours to obtain regenerated zeolitic composition.
The oxidant is at least one selected from the group consisting of oxygen, ozone, and air.
In accordance with the preferred embodiment of the present disclosure, the oxidant is a combination of oxygen and air. In accordance with one embodiment of the present disclosure, the step of calcining is carried out in the presence of air containing oxygen in the range of 0.05 to 20 % v/v.
Optionally, the oxidant is diluted with at least one inert gas selected from the group consisting of nitrogen, argon, and helium. In accordance with one embodiment of the present disclosure, the step of calcination is carried out in the presence of a mixture of oxidant, and inert gas, wherein the amount of oxidant ranges from 0.1% to 50% v/v.
Thus, the spent zeolitic composition obtained in the process of the olefin reduction of the hydrocarbon stream is regenerated by a simple process. 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 zeolitic composition of the present disclosure is low.
The disclosure will now be described with reference to the examples, which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The laboratory scale experiments provided herein can be scaled up to industrial or commercial scale.

EXAMPLES
Examples 1-4: Preparation of zeolitic composition having MWW-type framework in accordance with the process of the present disclosure
Zeolitic composition having an MWW-type framework was prepared using cerium as group IIIB element. The source of cerium was cerium nitrate or cerium acetate. The group IVA element was silicon, and its source was colloidal silica. The group IIIA element was aluminum, and its source was sodium aluminate. The amount of various components used for the preparation of the zeolitic composition of the present disclosure is provided herein below in Table1.
For comparative analysis, a similar zeolitic composition was prepared without using any group IIIB element. The zeolitic compositions were prepared by the following procedure.
Example: 1 (Composition for control experiment, without a group IIIB element) (Comparative example)
To a vigorously stirred mixture containing 185 g water (H2O), 2.46 g sodium hydroxide (NaOH), 6.3 g sodium aluminate (NaAlO2), and 20.23 g of hexamethylene imine (HMI), was slowly added 154 g colloidal silica (Ludox AS-40) to obtain a first mixture having a pH of 11.8. The first mixture was further stirred continuously at room temperature for 2 hours to achieve a homogeneous hydrogel having the molar composition presented in Table 1.
The hydrogel was transferred into an autoclave, wherein the hydrogel was subjected to hydrothermal treatment at 170 ?C under stirring for 24 hours at 50 rpm to obtain the zeolitic composition having the molar composition presented in Table 2.

Example: 2 (Composition of the present disclosure with cerium as X and Cerium Nitrate as source)
To a mixture containing 100 g H2O, 2.08 g NaOH, and 3.71 g NaAlO2, was slowly added cerium nitrate solution (35.35 g H2O and 2.17 g cerium nitrate), and the resultant mixture was stirred vigorously. To the vigorously stirred mixture, was gently added 19.83 g HMI, followed by the addition of 113 g Ludox AS-40 to obtain a first mixture having a pH of 11.7. The first mixture was stirred continuously at room temperature for 2 hours to obtain a hydrogel composition presented in Table 1.
The resulting hydrogel was transferred into an autoclave, wherein the hydrogel was subjected to hydrothermal treatment at 170 °C under stirring at a speed of 250 rpm for 48 hours to obtain the zeolitic composition having the molar composition presented in Table 2.

Example: 3 (Composition of the present disclosure with cerium as X and Cerium Nitrate as source)
To a mixture containing 100 g H2O, 2.41 g NaOH, and 3.34 g NaAlO2, was slowly added cerium nitrate solution (40 g H2O and 3.35 g cerium nitrate) and the resultant mixture was stirred vigorously. To the vigorously stirred mixture, was gently added 24 g HMI, followed by the addition of 116 g Ludox AS-40 to obtain a first mixture having a pH of 11.7. The first mixture was stirred continuously for 2 hours to obtain a homogeneous hydrogel with a molar composition presented in Table 1.
The resulting hydrogel was transferred into an autoclave, wherein the hydrogel was subjected to a hydrothermal treatment at 170 °C under stirring at 250 rpm for 48 hours to obtain the zeolitic composition having the molar composition presented in Table 2.
Example: 4 (Composition of the present disclosure with cerium as X and Cerium Acetate as source)
To a mixture containing 50 g H2O, 2.08 g NaOH, 3.71 g NaAlO2 was slowly added cerium (III) acetate solution (85 g H2O and 1.59 g cerium (III) acetate) and the resultant mixture was stirred vigorously. To the vigorously stirred mixture, was gently added 19.83 g HMI, followed by the addition of 113 g Ludox AS-40 to obtain a first mixture having a pH of 11.7. The mixture was stirred continuously for 2 hours to obtain a homogeneous hydrogel with a molar composition presented in Table 1.
The resulting hydrogel was transferred into an autoclave, wherein the hydrogen was subjected to a hydrothermal treatment at 170 °C under stirring at 250 rpm for 48 hours to obtain the zeolitic composition having the molar composition presented in Table 2.

Table 1: Compositions and conditions for the preparation of the MWW zeolitic composition and characterization thereof
Example 1 2 3 4
Molar ratio of components
SiO2/(Al2O3+CeO2) - 30 30 30
SiO2/Al2O3 30 38 43 38
SiO2/CeO2 - 150 100 150
H2O/SiO2 15 15 15 15
Na/SiO2 0.15 0.15 0.15 0.15
HMI/SiO2 0.2 0.26 0.3 0.26
Crystallisation Conditions
Temperature (°C) 170 170 170 170
Stirring speed (rpm) 250 250 250 250
Time (h) 24 48 48 48
Characteristic Properties
Surface Area, /m2g-1 422 475 400 450
* HMI – hexamethyleneimine

Characterization of the zeolitic composition
The zeolitic compositions obtained in examples 1, 2, 3 and 4 were analyzed by X-ray powder diffraction (XRD) technique for phase determination of the crystalline composition. Figure 1 illustrates an XRD diffractogram of the zeolitic composition prepared in accordance with Example 1, (A) as synthesized and (B) calcined. Figure 2 illustrates an XRD diffractogram of the zeolitic composition containing cerium prepared in accordance with Example 2, (A) as synthesized and (B) calcined. Figure 3 illustrates an XRD diffractogram of the zeolitic composition containing cerium prepared in accordance with Example 3, (A) as synthesized and (B) calcined.
The BET surface area of the zeolitic composition obtained in examples 1-4 was found to be in the range of 400 to 475 m2g-1.
Table 2: Molar fractions of MWW zeolitic composition of examples 1-4
Example SiO2/Al2O3 SiO2/CeO2
1 26 --
2 37 140
3 49 95
4 35 142

Example 5-8: Forming shaped bodies of the zeolitic composition
The zeolitic composition obtained from example 1 was mixed with psuedobohemite alumina to obtain an admixture. The admixture was shaped in the form of cylindrical extrudates. The shaped cylindrical extrudates were activated by heating at 550 °C for 6 hours.
The weight ratio of the zeolitic composition obtained from example 1 to psuedobohemite alumina, on loss on ignition (LOI) basis, was 70:30.
Similarly, the zeolitic compositions obtained from examples 2, 3 and 4 were also converted into cylindrical extrudates in a similar manner as described in Example 1, and then activated at the same temperature for same time.
The composition and average crush strength of the cylindrical extrudates of the zeolitic composition are presented in Table 3.
Table 3: Compositions of shaped bodies of zeolitic composition and average crush strength thereof
Examples 5 6 7 8
Zeolitic composition from example 1 2 3 4
Zeolitic composition: Alumina w/w (on LOI basis) 70:30 70:30 70:30 70:30
Average Crush Strength (Kgf) 5.7 5.7 5.6 5.6
Cylindrical extrudates prepared from the zeolitic compositions obtained from examples 5-8 showed average crushing strength in the range of 5.6 to 5.7 Kgf.
Thus, the crushing strength of the extrudates of the zeolitic composition of the present disclosure is similar to that of the zeolitic composition prepared without use of a heteroatom. It is clear that the crushing strength of the zeolitic composition of the present disclosure do not alter due to the incorporation of cerium as heteroatom.

Examples 9-12:
Catalytic performance of the shaped zeolitic composites obtained from examples 5-8 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 zeolitic composition (5 g) obtained from example 5 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.
Performances of other samples were evaluated using cylindrical extrudates of the zeolitic compositions obtained from examples 6, 7 and 8. The results are presented in Table 5.
Example 9 is a comparative example, while examples 10, 11, and 12 are related to the cylindrical extrudates of the zeolitic compositions of the present disclosure.
Table 5: Olefin reduction of the commercial C8+ aromatics stream (feed)
Example No Catalyst from Reaction Conditions Results % BI Reduction (Olefin Conv.)
Temp. (°C) Time (h) Feed BI Prod. BI
9 Example 5 165 2 604 485 20
10 Example 6 165 2 604 399 34
11 Example 7 165 2 604 387 36
12 Example 8 165 2 604 393 35
BI = bromine index
It is observed that, the cylinder shaped extrudates of the zeolitic compositions 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 zeolitic compositions without a group-IIIB element.

Examples 13-16:
A second set of runs was carried out using similar procedure as mentioned in examples 9-12; expect that runs were carried out at 175 °C for 3 h. The results are shown in Table 6.
Example 13 is a comparative example of reduction of olefin content of a hydrocarbon stream using zeolitic composition prepared without a group-IIIB element, while examples 14, 15, and 16 are examples of reduction of olefin content of a hydrocarbon stream using of zeolitic compositions of the present disclosure.
Table 6: Reduction in olefin content of commercial C8+ aromatics stream
Example No Catalyst Details from Reaction Conditions Results % BI Reduction (Olefin Conv.)
Temp., °C Time, h Feed BI Prod. BI
13 Example 5 175 3 604 426 29
14 Example 6 175 3 603 295 51
15 Example 7 175 3 603 283 53
16 Example 8 175 3 604 290 52
BI = bromine index
It is observed that, the cylindrical extrudates of the zeolitic compositions of the present disclosure provides higher reduction of olefin from the deheptanizer column bottom stream (C8+ aromatics stream) as compared to the cylindrical extrudates of the zeolitic compositions without the group-IIIB element.
Further, it is observed that the reduction of the olefin content from the deheptanizer column bottom stream is greater when the hydrocarbon stream and zeolitic composition are contacted at higher temperature.
Examples 17-19: Regeneration of spent zeolitic composition
The zeolitic composition is said to be spent zeolite composition when the olefin removal efficiency of the catalyst composition reaches to 50% or lower as compared to that at the beginning of the experiment.
Example 17: Regeneration of spent catalyst
Fresh catalyst (18.0 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 zeolitic composition decreased to 44% as compared to that of the fresh zeolitic composition, indicating that the zeolitic composition was spent.
The spent zeolitic composition was separated and was dried in an oven at 120 °C for two hours. The dried spent zeolitic composition was then calcined in air at 540 °C for 6 hours. The calcined zeolitic composition was cooled to ambient temperature to obtain regenerated zeolitic composition.
The extrudates were clean white after regeneration process. Weight of the regenerated zeolitic composition was 17.3 g. The regenerated zeolitic composition, thus obtained, was first regenerated zeolitic composition.
The first regenerated zeolitic composition (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 13. Reaction conditions and results are provided in Table 7.
Example 18:
The first regenerated zeolitic composition (12.0 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 composition decreased to 43% olefin reduction as compared to that of the first regenerated zeolitic composition at the beginning, indicating that the first regenerated zeolitic composition was spent.
The spent first zeolitic composition 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 zeolitic composition.
The second regenerated zeolitic composition (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 13. Reaction conditions and results of the test are given in Table 7.
Example 19:
The second regenerated zeolitic composition (6.2 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 zeolitic composition decreased to 43% olefin reduction as compared to that of the second regenerated zeolitic composition at the beginning, indicating that the second regenerated zeolitic composition was spent. The third time spent zeolitic composition was regenerated following the procedure as described earlier.
5 g of the third regenerated cylindrical extrudates of the zeolitic compositions were employed for reduction of olefins from a fresh feed of commercial deheptanizer bottom stream as described earlier in Example 13. Reaction conditions and results of the test are given in Table 7.
Table 7: Regenerability of the zeolitic composition
Example No No of Regeneration Reaction Conditions Results % BI Reduction (Olefin Conv.)
Temp., °C Time, h Feed BI Prod BI
Example 13 Fresh 175 3 603 295 51
Runs with regenerated zeolitic composition
Example 17 1 175 3 603 303 50
Example 18 2 175 3 606 299 51
Example 19 3 175 3 592 296 50

From Table 7, it is clear that the zeolitic compositions of the present disclosure can be recycled and reused. The zeolitic composition of the present disclosure can be regenerated by calcination in oxidizing atmosphere.

Example 20:
The extent of benzene and toluene formation during the process of reducing olefins from commercial C8 aromatics stream using the zeolitic composition of the present disclosure was evaluated.
Cylindrical extrudates of the zeolitic composition (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 4 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 79%.
The amounts of lighters and aromatics of the feed and treated hydrocarbon stream are shown Table 8.

Table 8: 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 54.58 54.37
C9 Aromatics 38.81 38.87
C10 aromatics and heavies 6.02 6.16

It is observed from Table 8 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 zeolitic composition having MWW framework that efficiently reduces the olefin content of a hydrocarbon stream; and
? a zeolitic composition composition having MWW framework that can be regenerated by a simple process.

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 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.