CLIAMS:1. A process for removing color causing compounds from heavy alkylated benzene, said process comprising the following steps:
a. passing said heavy alkylated benzene through a packed bed of adsorbent;
b. displacing the color causing compounds from said adsorbent using at least one solvent; and
c. regenerating the adsorbent using an inert gas.

2. The process of claim 1, wherein said adsorbent is activated carbon.

3. The process of claim 1, wherein said solvent is selected from the group comprising heavy normal paraffin and n-nonane.

4. The process of claim 1, wherein said inert gas is nitrogen.

5. The process of claim 1, wherein the regeneration of the adsorbent is carried out at a temperature ranging from 180 to 220°C for 4 to 6 hours. ,TagSPECI:FIELD

The present disclosure relates to a process for removing color causing compounds from heavy alkylated benzene (HAB).

BACKGROUND

Heavy alkylated benzene (HAB) is produced during alkylation of benzene with olefin(s) and primarily contains dialkyl benzenes and di-phenyl alkanes with small quantities of condensed ring aromatics like methyl anthracenes, tetralins and indanes. The formation of dialkyl benzenes can be suppressed up to some extent by taking a high ratio of benzene to olefin. Di/tri-phenyl alkanes are generated due to the presence of di, tri-olefins -during alkylation reaction. The other compounds may either come from linear alkyl benzene (LAB) feed stock, formed during alkylation reaction or separation process.

HAB, which is a by-product in LAB plants, has a yellowish color. The C=C bonds on conjugation with aromatic rings are chromophoric in nature. In HAB, poly aromatic rings with C=C double bond in alkyl side chain may also conjugate with the p-electron cloud of the aromatic ring and could be one of the reasons for the coloring in HAB.

Usually, sulfuric acid treatment and adsorption techniques are used to remove color causing compounds from HAB. Sulfuric acid treatment method is hazardous and the post treatment process involves the use of excess acid followed by washing with water to remove the acid and finally drying using nitrogen. This results in acid sludge formation which needs to be disposed.

Accordingly, there is a need for simple, cost efficient and environment friendly process for removing the color causing compounds from heavy alkylated benzene.

OBJECTS

Some of the objects of the present disclosure which at least one embodiment is adapted to provide, are described herein below:
It is an object of the present disclosure to provide a simple and efficient process for removing color from heavy alkylated benzene.
It is yet another object of the present disclosure to provide an adsorption process for removing color from heavy alkylated benzene.
It is still another object of the present disclosure to provide a process for regenerating the saturated adsorbent using eco-friendly, non-carcinogenic solvents.
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 accordance with the present disclosure there is provided a process for removal of color causing compounds from heavy alkylated benzene, said process comprising the following steps: passing said heavy alkylated benzene through a packed bed of adsorbent; displacing the color causing compounds from said adsorbent using at least one solvent; and regenerating the adsorbent with the help of an inert gas.

DETAILED DESCRIPTION

Linear alkyl benzene (LAB) plant produces linear alkyl benzene via alkylation of benzene with olefins of 10 to 14 carbon atoms using hydrofluoric acid. In this process, around 10 to 12 % HAB is also produced along with detergent grade linear alkyl benzene. Heavy alkylate is separated from the detergent-quality linear alkyl aromatics by conventional separation methods such as distillation. The HAB, obtained as a by-product of LAB plant has a yellowish color. Conventionally, sulfuric acid treatment and adsorption techniques are used to remove color causing substances from the HAB feed.

Conventionally, the adsorptive process employs clays and carbons as adsorbents. Normally, these are used only once through the process and used in landfills after they get saturated with impurities. This results in environmental pollution. In some cases regeneration of the saturated adsorbents is also carried out using steam or solvent such as benzene.

LAB plants carry out re-processing of off-spec material (colored HAB) by mixing it with the feed to an alkylation reactor. This material then moves through all distillation columns of the alkylation unit along with the normal feed to alkylation, resulting in additional operating cost. In order to ensure that the off-spec material does not disturb the normal operating conditions, the feed rate is kept extremely low as compared to normal processing rate. The lowering of the feed to alkylation reduces the production of the LAB plant.

Accordingly, the present disclosure provides a process for removing color causing compounds from heavy alkylated benzene (HAB), the process comprises three steps.

In the first step, an adsorbent is used to remove the color causing compounds from the HAB. The process is carried out at ambient temperature in a continuous operation.
In an embodiment of the present disclosure activated carbon is used as the adsorbent to remove the color causing compounds from the HAB.

In the second step, the color causing compounds are displaced from the adsorbent saturated with the color causing compounds. Non-limiting examples of solvents that can be used to displace the color causing compounds from adsorbent include heavy normal paraffin (HNP) and n-nonane. The displacement of adsorbed species is carried out at ambient temperature. The color causing compounds are present in the solvent used to displace the color causing compounds from the adsorbent.
The solvent used for displacing the color causing compounds from the adsorbent is continuously passed through the adsorbent bed till the Saybolt No. /ASTM No. of the inlet and outlet of the solvent remains the same. Initially, there is a decrease in the Saybolt No. /ASTM No. as the color causing compounds are washed off in the solvent. Eventually, all the color causing compounds are washed off and the Saybolt No. /ASTM No. of the solvent increases; and the Saybolt No. /ASTM No. of the inlet and outlet of the solvent remains same.

In an embodiment of the present disclosure, the color causing compounds present in the solvent is separated by distillation and the color causing compound free solvent is recovered and reused in the next cycle.

In the third step, the adsorbent is regenerated. After the color causing compounds have been displaced from the adsorbent bed, the solvent would still be present in the intra and inter particle voids/pores of the adsorbent. In an embodiment of the present disclosure, an inert gas such as nitrogen is passed over the adsorbent at a temperature ranging from 180 to 220°C for 4 to 6 hours to remove the solvent molecules from the adsorbent, thus, regenerating the adsorbent which can be used in the next cycle.

Regeneration of the adsorbent bed is confirmed by carrying out the Saybolt and/or ASTM color analysis of the raffinate HNP collected at regular interval of time.

The removal of the color causing compounds from HAB using the process of the present disclosure is carried out continuously at an ambient temperature. The process uses non-carcinogenic, eco-friendly solvents like HNP and n-nonane; and the solvents can be recovered and reused. An improvement from (-) 16 to (+) 16 in the Saybolt - color analysis can be achieved using the process in accordance with the present disclosure.

TECHNICAL ADVANCES

- The present disclosure provides a simple and economic process for the removal of color causing compounds from HAB using adsorbents.
- The process of the present disclosure can be carried out in the absence of carcinogenic solvents.
- The process of the present disclosure does not involve steam during the regeneration process and therefore, avoids generation of effluents having higher COD.
- The adsorbent used in the present disclosure can be regenerated and reused for removing the color causing compounds from HAB.

The exemplary embodiments herein quantify the benefits arising out of this disclosure and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the 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 will 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.

Any discussion of documents, acts, materials, devices, articles and 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.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications 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 modifications in the nature of the disclosure or the preferred embodiments 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.