Claims:WE CLAIM:
1. A system (100) for recovery of Acrylonitrile (ACRN) from an ATBS monomer slurry comprising:
an ACRN receiver tank (103) enabled to receive a filtrate containing crude acrylonitrile and other impurities from a filtration tank (102),
a first evaporator unit (A) configured to recover a first portion of pure ACRN upto 70%,
a second evaporator unit (B) for recovering remaining about 30% ACRN connected in series with the first evaporator unit (A);
a pure ACRN collection tank (111); and
a drain tank (112) configured to recover a filtrate residue comprising one or more impurities.

2. The system as claimed in claim 1, wherein the first evaporator unit (A) comprises a first evaporator apparatus (104), a vapour-liquid separator chamber (105), and a first condensation unit (106), and wherein the second evaporator unit (B) comprise a second evaporator apparatus (109), and a second condensation unit (110).

3. The system as claimed in claim 2, wherein the first evaporator unit (A) and the second evaporator unit (B) are connected through a continuous line conduit (113).

4. The system as claimed in claim 1, wherein the filtration tank (102) is a rotary pressure filtration tank.

5. The system as claimed in claim 3, wherein the first evaporator apparatus (104) and the second evaporator apparatus (109) are selected from at least one of rising film evaporator unit (RFE) and an agitated thin film evaporator (ATFE) unit.

6. The system as claimed in claim 2, wherein the first evaporator apparatus (104) and the first condensation unit (106) are connected through a vapour separator chamber (105) configured for recovery of upto 70% ACRN in a vapour from and transfer of remaining about 30% ACRN in liquid from to the second evaporator unit (B).

7. The system as claimed in claim 2, wherein the second evaporator apparatus (109) and the first condensation unit (106) are connected through a liquid ACRN receiver tank (108) configured for collection and transfer of remaining about 30% ACRN in liquid from.

8. The system as claimed in claim 1, wherein at least one of the first evaporator apparatus (104) and the second evaporator apparatus (109) comprises an ACRN polymerization inhibitor as MMeHQ inhibitor inhibiting ACRN polymerization.

9. The system as claimed in claim 3, wherein the continuous line conduit (113) is connected to a pure ACRN collection tank (111) configured for collection and transfer of recovered ACRN to an ATBS synthesis assembly.

10. The system as claimed in claim 2, wherein the first evaporator apparatus (104) and the second evaporator apparatus (109) are configured for recovery of pure ARCN from an upper portion of the said respective units.

11. The system as claimed in claim 2, wherein the first evaporator apparatus (104) and the second evaporator apparatus (109) are free of hydrophilic agent.

12. The system as claimed in claim 5, wherein the first evaporator apparatus (104) selected as rising film evaporator unit (RFE) comprises a low-pressure steam unit for heating and evaporating ACRN.

13. The system as claimed in claim 12, wherein the low-pressure steam unit is configured to maintain a temperature of the RFE between 60-100 0C at 1 atm pressure.

14. The system as claimed in claim 2, wherein second evaporator apparatus (109) is configured for continuous draining of residue from the bottom portion.

15. The system as claimed in claim 2, wherein the first condensation unit (106) and the second condensation unit (110) is a packed column type condenser unit.

16. The system as claimed in claim 1, wherein the system is configured to recover 97-99.9% of ACRN from the filtrate containing crude Acrylonitrile and other impurities.

17. The system as claimed in claim 1, comprising a conduit connection from pure ACRN collection tank to ATBS monomer reactor unit.

18. The system as claimed in claim 1, wherein the conduit connection from pure ACRN collection tank to ATBS monomer reaction unit is configured to recycle and incorporated 100% of the recovered pure ACRN in ATBS monomer preparation process.

19. A process (200) for recovery of pure acrylonitrile from an ATBS monomer slurry comprising:
loading (201) a filtrate of crude acrylonitrile to an ACRN receiver tank (103) from an outlet of a filtration tank (102);
passing (202) the filtrate of crude acrylonitrile to a first evaporator apparatus (104) to vaporize ACRN filtrate;
transferring (203) an evaporated ACRN filtrate to a vapor-liquid separator unit (105) to recover upto 70% ACRN in a vapour form and a balance of upto 30% ACRN remains in a liquid form;
receiving (204) a portion of upto 70% ACRN in a vapour form to a first condensation unit (106);
discharging (205) the remaining 30% ACRN filtrate in liquid form to a second evaporator apparatus (109);
retrieving (206) a remaining 30% portion of pure ACRN by evaporating the remaining 30% ACRN filtrate in liquid form in the second evaporator apparatus (109) and transferring an evaporated portion of ACRN to a second condensation unit (110);
separating (207) and collecting a residue from pure acrylonitrile in a drain tank (112) for preparing one or more by-products;
repeating (208) a cycle of transferring the remaining portion of a contaminated ACRN to at least one of the first evaporator unit (104) and the second evaporator unit (109) for a predefined number of times; and
recovering (209) a highly pure acrylonitrile yield between 97-99.9% from the filtrate of crude acrylonitrile.

20. The process of recovery of pure acrylonitrile as claimed in claim 19, wherein the loading (201) of a filtrate of crude acrylonitrile from an outlet of the filtration tank (102) to an ACRN receiver tank (103) comprises a centrifugal disc filtration mechanism.

21. The process of recovery of pure acrylonitrile as claimed in claim 19, wherein the step of transferring (203) comprises a sub-step of allowing passage of ACRN vapours through a vapour separator at a temperature between 55-70°C and vacuum pressure between 200-500 mmHg.

22. The process of recovery of pure acrylonitrile as claimed in claim 19, comprises a sub-step of inhibiting polymerization of pure ACRN by pumping a solution of MMeHQ at predefined rates from the top of the first evaporator apparatus (104) and the second evaporator apparatus (109), wherein a final content of remaining MMeHQ in Acrylonitrile is between 30-40 ppm.

Dated this 24th Day of December 2021

Priyank Gupta
Agent for the Applicant
IN/PA-1454

, Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
Title Of Invention:
SYSTEM AND PROCESS FOR ACRYLONITRILE RECOVERY DURING SYNTHESIS OF ACRYLAMIDO TERTIARY BUTYL SULFONIC ACID MONOMER

APPLICANT:
VINATI ORGANICS LIMITED

An Indian entity having address as,
Parinee Crescenzo, A Wing, 11th floor, 1102, G Block,
Behind MCA, Bandra Kurla Complex, Bandra (east), Mumbai 400051, Maharashtra, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATION AND PRIORITY
The present application claims no priority from any of the patent application.
FIELD OF INVENTION
The present invention relates to the field of recovery of acrylonitrile. More particularly, a system and process for recovery of acrylonitrile in an Acrylamido tertiary butyl sulfonic acid monomer preparation is disclosed.
BACKGROUND OF INVENTION
The subject matter discussed in the background section should not be assumed to be prior art merely because of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.

Polyacrylamides such as acrylamido tertiary butyl sulfonic acid monomer (hereinafter may be interchangeably referred to as ‘ATBS’) and its copolymers are vastly used in various applications such as enhanced oil recovery, as the sulfonated polymers containing ATBS can be used in higher temperature and salinity conditions and impart thickening and fluid properties. Acrylonitrile (hereinafter may be alternatively referred to as ‘ACRN’) is an essential component in a process of preparation of anionic vinyl monomers such as acrylamido tertiary butyl sulfonic acid (ATBS). The process of preparation of ATBS requires incorporation of excess amount Acrylonitrile.

Typically, Acrylonitrile liquid in excess is reacted with sulfonating agent and isobutylene for the formation of ATBS monomer slurry. The ATBS monomer is further filtered out from the ATBS monomer slurry, and the ACRN liquid with one or more types of dissolved impurities is transferred to effluent treatment plant. A total liquid discharge of the ACRN effluent may be harmful to the environment. Therefore, a recycled use of ACRN liquid is preferred over effluent discharge of the ACRN liquid. In state of the art, a recovery of ACRN is carried out by single stage distillation. The single stage distillation of ACRN does not remain efficient, as upto 40% of an impure ACRN is discarded in the ACRN recovery process. Also, in the said conventional process controlling the polymerization of ACRN at the time of evaporation is also difficult.

In state of the art, a method of neutralization of ACRN by alkali and removing the resulted salts has also been performed. This method involves additional effluent formation of alkali material as complete recovery of ACRN and simultaneous removal of impurities as a by-product may not be achieved.

Therefore, there is a long felt need to devise a system and method for recovery and recycled use of Acrylonitrile (ACRN) minimizing a total liquid discharge of a of ACRN as an effluent to an effluent treatment plant (ETP). Also, there is a long-standing need to develop a system and process to effect an environment friendly, simple, efficient, and cost-effective recovery of acrylonitrile from acrylamido tertiary butyl sulfonic acid (ATBS).

OBJECTIVES OF THE INVENTION
The main objective of the present invention is to provide an Acrylonitrile recovery system in a preparation of acrylamido tertiary butyl sulfonic acid monomer.

Another objective of the present invention is to provide a process of recovery of acrylonitrile in a preparation of acrylamido tertiary butyl sulfonic acid monomer.

Yet another objective of the present invention is to implement the acrylonitrile recovery system to achieve a zero total liquid discharge to effluent treatment plant and enabling recycled use of Acrylonitrile in the preparation of acrylamido tertiary butyl sulfonic acid monomer.

SUMMARY OF THE INVENTION
Before the present system, processes, method, and products are described in the said proposed invention, it is to be understood that the disclosed invention is not limited to the specific process, methods, and products as described herein, as there can be multiple possible embodiments which are not expressly illustrated in the present invention but may still be practicable within the scope of the invention.

This summary is provided to introduce concepts related to a system and process for recovery of acrylonitrile (ACRN) from an ABTS monomer slurry in an ATBS monomer synthesis and the concepts are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter not it is intended for use in determining or limiting the scope of the claimed subject matter.

The instant invention describes about a system for recovery of acrylonitrile from an ATBS monomer slurry. The instant invention further describes a process of recovery of pure acrylonitrile from an ATBS slurry.

In one embodiment of the present invention, a system for recovery of Acrylonitrile from an ATBS monomer slurry is disclosed. The system may comprise an ACRN receiver tank enabled to receive a filtrate containing crude acrylonitrile and other impurities from filtration tank. The system may comprise a first evaporator unit configured to recover a first portion of pure ACRN upto 70%. The system may comprise a second evaporation unit connected in series with the first evaporator unit for recovering remaining 30% ACRN. The system may comprise a pure ACRN collection tank. The system may comprise a drain tank configured to recover a filtrate residue comprising one or more impurities.
In another embodiment of the present invention, a process of recovery of pure acrylonitrile from an ATBS slurry is disclosed. The process may comprise a step of loading a filtrate of crude acrylonitrile to an ACRN receiver tank from an outlet of a filtration tank. The process may comprise a step of passing the filtrate of crude acrylonitrile a first evaporator unit to vaporize ACRN filtrate. The process may comprise a step of transferring an evaporated ACRN filtrate to a vapour liquid separator unit to recover upto 70% ACRN in a vapor form and balance of upto 30% ACRN remains in a liquid form. The process may comprise discharging the remaining 30% ACRN filtrate in liquid form to a second evaporation unit. The process may further comprise retrieving a remaining 30% portion of the pure ACRN by evaporating a remaining ACRN in the second evaporator unit. The process may comprise separating and collecting a residue from pure acrylonitrile in a drain tank for preparing one or more by-products. The process may comprise repeating the cycle of transferring the remaining portion of a contaminated ACRN to at least one of the first evaporator unit, and second evaporator unit for a predefined number of times. The process may further comprise recovering a highly pure acrylonitrile between 97-99.9% from the filtrate of crude acrylonitrile.
BRIEF DESCRIPTION OF DRAWINGS
The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 depicts a system (100) for recovery of Acrylonitrile (ACRN) from an ATBS monomer slurry, in accordance with an embodiment of the present invention.

Figure 2 depicts a process (200) for recovery of pure acrylonitrile from an ATBS slurry, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
Some embodiments of this disclosure, illustrating all its features, may now be discussed in detail. The words "comprising "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise, although any methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, wherein the exemplary methods are described. The disclosed embodiments are merely exemplary of the disclosure of the present invention, which may be embodied in various forms.
It may be understood by all readers of this written description that the example embodiments described herein and claimed hereafter may be suitably practiced in the absence of any recited feature, element or step that is, or is not, specifically disclosed herein. For instance, references in this written description to "one embodiment," "an embodiment," "an exemplary embodiment," and the like, indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. The disclosed embodiments are merely exemplary of various forms or combinations. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
No terminology in this application should be construed as indicating any non-claimed element as essential or critical. The use of any and all examples, or example language (e.g., "such as") provided herein, is intended merely to better illuminate example embodiments and does not pose a limitation on the scope of the claims appended hereto unless otherwise claimed.
Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Where a specific range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is included therein. All smaller sub-ranges are also included. The upper and lower limits of these smaller ranges are also included therein, subject to any specifically excluded limit in the stated range.
The main purpose of the disclosed invention is to provide a safe, easy and cost-effective system and process for an efficient recovery and reuse of pure acrylonitrile from ATBS slurry in ATBS synthesis process.

In one embodiment, in a process of synthesis of ATBS monomer various steps such as preparation of a moisture free sulfonating mixture comprising a predefined ratio of 30% oleum and 98% H2SO4, ¬preparation of acrylonitrile-sulphate in a buffer reactor, reaction of acrylonitrile sulphate with an isobutylene to form ATBS monomer slurry. The as prepared ATBS monomer slurry is further processed to separate and purify ATBS monomer cake, and to recover acrylonitrile from the ATBS monomer slurry. In another embodiment, a system and process for recovery of acrylonitrile from the ATBS monomer slurry is discussed herewith.

Referring to Figure 1, a system (100) for recovery of acrylonitrile (hereinafter may be interchangeably referred to as ‘ACRN’) from an acrylonitrile tertiary butyl sulfonic acid monomer crude slurry is illustrated in accordance with an embodiment of the present subject matter.
Accordingly, the present invention relates to a system (100) for recovery of acrylonitrile. Further the instant invention relates to a process for recovery of acrylonitrile from an ATBS monomer slurry by implementing the system (100).
In one embodiment, referring to the figure 1, the system (100) may comprise an ACRN filtrate hold tank (101). The said filtrate hold tank (101) is configured hold and store the ATBS slurry comprising crude acrylonitrile, crude form of ATBS monomer, and other impurities for further purification and recovery. The system (100) may further comprise a filtration tank (102) for separation of crude ACRN from crude ATBS monomer. The system (100) may comprise a comprise an ACRN receiver tank (103) enabled to receive a filtrate containing crude acrylonitrile and other impurities from a filtration tank (102). In one embodiment, the pressure filter tank (102) may be continuous rotary pressure filter tank.

In one embodiment, the system (100) may comprise a first evaporator unit (A) comprising a first evaporator apparatus (104), a vapor-liquid separator chamber (105) and a first condensation unit (106). The said first evaporator apparatus (104) may be configured to recover a first portion of pure ACRN upto 70%. In one embodiment, the first evaporator apparatus (104) may be a rising film evaporator unit (RFE) comprising a low-pressure steam unit for heating and evaporating ACRN. The said the low-pressure steam unit may be configured to maintain a temperature of the RFE between 60-100 0C at 1atm pressure.

In another embodiment, the first evaporator apparatus (104) and the first condensation unit (106) are connected through the vapour-liquid separator chamber (105). Further, the vapor-liquid separator chamber (105) may be configured for separation of upto a 70% of ACRN in a vapour form from a remaining 30% ACRN in a liquid form. The said 70% of the ACRN vapour may further be transferred to the first condensation unit (106). In one embodiment, the first condensation unit (106) may be a packed column type condenser unit configured for distillation and condensation of portion of 70% ACRN vapour.

The system (100) may comprise a second evaporator unit (109) connected in series with the first evaporator unit (104) via a line conduit (113). In one embodiment the vapour liquid separator unit (105) and the first condensation unit (106) are connected through bottom to the second evaporator unit (B). In another embodiment, a remaining about 30% ACRN in liquid may be transferred from the bottom of the vapour liquid separator unit (105) and the first condensation unit (106) to the liquid ACRN collection tank (108).

The remaining crude ACRN in liquid form may be transferred to the second evaporator unit (109) from bottom of both the vapour liquid separator unit (105) and the first condensation unit (106) via the liquid ACRN collection tank (108).

The said second evaporator apparatus (109) may be configured for vaporizing and recovering remaining 30% ACRN. In one embodiment, the second evaporator apparatus (109) may be an agitated thin film evaporator (ATFE) unit. The system (100) may further comprise second condensation unit (110). The said second condensation unit (110) may be a packed column type condenser unit configured for distillation and condensation of remaining portion of 30% ACRN vapour.

In one embodiment, the first evaporator unit (104) and the second evaporator unit are (109) free of hydrophilic agent. This is because, the crude ACRN with impurities is free of moisture or may comprise a minimal content of moisture. In the said ACRN recovery process, the content of moisture is eliminated by adjusting a ratio of sulfonating mixture at the time of reacting sulfonating mixture with ACRN and Isobutylene. The ratio of sulfonating mixture is adjusted between 0.10-0.25:1. As the ACRN receiver tank (103) is configured to receive a moisture-content free crude acrylonitrile and other impurities, the requirement of removal of moisture through hydrophilic agent is eliminated.

In one embodiment, at least one of the first evaporator apparatus (104) and the second evaporator apparatus (109) may comprise an ACRN polymerization inhibitor as MMeHQ inhibitor restricting and/or inhibiting the polymerization of ACRN.

The system (100) may comprise a pure ACRN collection tank (111) configured for collection of about 97-99.9% of pure ACRN liquid recovered from first condensation unit (106) and the second condensation unit (110) via a continuous conduit line (113). The system (100) may further comprise a drain tank (112) configured to recover a filtrate residue comprising one or more impurities. Since, Acrylonitrile is a component having lower boiling point than any other component in the mixture, recovery of ACRN by applying the process (200) (explained hereinafter referring to Figure 2) is carried out effectively.

In one embodiment, the system (100) may comprise a continuous conduit line (113) connected to the pure ACRN collection tank (111). The continuous conduit line (113) may further be configured for collection and transfer of recovered ACRN to an ATBS synthesis assembly (not shown). In yet another embodiment, the system (100) may be configured to recover 97-99.9% of ACRN from the filtrate containing crude Acrylonitrile and other impurities.

In one embodiment, the system (100) for recovery of ACRN from the ATBS monomer may comprise a conduit connection from pure ACRN collection tank to ATBS monomer reactor unit. The said conduit connection from pure ACRN collection tank to ATBS monomer reaction unit maybe configured to recycle and incorporated 100% of the recovered pure ACRN in ATBS monomer preparation process.

Referring to Figure 2, a process (200) for recovery of acrylonitrile from an ATBS monomer is depicted in accordance with an embodiment of the present invention. The process (200) may be carried out by the system (100) described above. In one embodiment, vacuum may be applied to the entire system (100) through a continuous conduit line (113). The said continuous conduit line (113), depicted as a dotted line is a conduit connected to a vacuum pump 114.

At step (201), a filtrate of crude acrylonitrile may be loaded to the ACRN receiver tank (103) from an outlet of a filtration tank (102). In one embodiment, the loading (201) of the filtrate of crude acrylonitrile from the outlet of a continuous rotary pressure filtration tank (102) to the ACRN receiver tank (103) may be carried out via a centrifugal disc filtration mechanism.

At step (202), the said filtrate of crude acrylonitrile may be passed to the first evaporator unit (A) comprising a first evaporator apparatus (104) in order to vaporize ACRN filtrate from the crude acrylonitrile. In one implementation, the first evaporator apparatus (104) may be a rising film evaporator (RFE).

At step (203), evaporated ACRN filtrate may be transferred to the vapour-liquid separator unit (105) to recover upto 70% ACRN in a vapour form and balance of up to 30% ACRN remains in a liquid form.

In one embodiment, the step of transferring (203) the evaporated ACRN filtrate to the vapour-liquid separator unit (105) comprises a sub-step of allowing passage of ACRN vapours through the vapour liquid separator unit (105) at a temperature between 55-70°C and vacuum pressure between 200-500 mmHg applied via the vacuum pump 114. The temperature between 55-70°C is maintained by applying low pressure steam mechanism at pressure of 3.5-4 kg/cm2. The low-pressure steam mechanism may be specifically applied for generation of uniform heat and to fulfil the optimum temperature requirement of 60-100°C, as a distillation temperature of ACRN liquid is 77°C.

At step (204), a portion of upto 70% ACRN in vapor form may be received at the first condensation unit (106) through the vapour-liquid separator unit (105).

At step (205), the remaining 30% ACRN filtrate in liquid form may be discharged towards the second evaporator unit (109) via the continuous conduit line (113). In one implementation, the first evaporator apparatus (104) may be an agitated thin film evaporator (ATFE).

At step (206), pure ACRN from the remaining 30% portion may be retrieved by evaporating the remaining 30% ACRN filtrate in liquid form in the second evaporator unit (B) comprising a second evaporator apparatus (109), and an evaporated portion of ACRN may be transferred to the second condensation unit (110).

In one embodiment of the present invention, the process (200) of recovery of pure acrylonitrile may comprise a sub-step of inhibiting polymerization of the pure ACRN by pumping a solution of an inhibitor such as monomethyl ether hydroquinone (hereinafter may be referred to as ‘MMeHQ’) at predefined feed rate. In one embodiment, the solution of MMeHQ is ACRN is fed from the top of at least one of first evaporator unit (105) and the second evaporator unit (109). In one embodiment, the predefined feed rate of the inhibitor MMeHQ may be controlled between 250-500 kg/hr comprising a 2500-5000 ppm of MMeHQ. In another embodiment, the predefined feed rate of the inhibitor MMeHQ may be controlled between 300-400 kg/hr comprising a 3000-4000 ppm of MMeHQ.

In one embodiment, the final content of remaining MMeHQ in the pure form of acrylonitrile is between 30-40 ppm. The content of the remaining MMeHQ in the pure form of ACRN is adjusted by pumping the solution of MMeHQ in the ACRN at predefined rate. The said minimal amount of 30-40 ppm MMeHQ is sufficient to avoid polymerization of ACRN in the ACRN recovery process as well as in recycled use of ACRN in ATBS monomer synthesis process.

At step (207), a residue may be separated and collected from the pure acrylonitrile (ACRN) in the drain tank (112) for preparing one or more by-products.

At step (208), the cycle of transferring the remaining portion of a contaminated ACRN to at least one of the first evaporator unit (104) and the second evaporator unit (109) may be repeated for a predefined number of times.

At step (209), a highly pure acrylonitrile yield between 97-99.9% may be recovered from the filtrate of crude acrylonitrile. In one embodiment, the residue separated from the pure ACRN may comprise by-products in form of mixture of monomers/polymers. The examples of by-products may include but not limited to acrylamides such as tertiary butyl acrylamide (TBA), Calcium and Sodium salts of sulfonated mixture monomers, and Co-polymer of acrylic acid & sulfonated mixture monomers, etc.

In one embodiment, the implementation of process (200) eliminates a requirement of neutralization of acrylonitrile for recycled use. The process (200) comprising a dual ACRN recovery system of RFE and ATFE based mechanism produces acrylonitrile with negligible acidity <100 ppm, which does not affect the ATBS monomer formation process by recycled use of ACRN.

The instant invention is further described by the following examples:

Experimental Details:
Example 1: recovery of acrylonitrile by implementing system (100) and process (200)
In one example, the system (100) comprising one or more components is enabled for recovery of Acrylonitrile from ATBS monomer slurry filtrate. At first vacuum is applied to the whole recovery system. The system (100) comprises of a first evaporation unit in form of a rising film evaporator (RFE) and a second evaporation unit in form of an agitated thin film evaporator. The ATBS monomer slurry filtrate is loaded and fed to the RFE from a filtrate hold tank. The filtrate is heated in the RFE by means of low-pressure steam and up to 65-70% of ACRN is evaporated in the RFE unit. The remaining 30-35% of ACRN in liquid form is eliminated from the RFE unit and the vapour-liquid separator and fed to a second evaporation unit (i.e., agitated thin film evaporator (ATFE) where the remaining pure acrylonitrile is evaporated, and the residue is drained of continuously from the bottom of the ATFE unit. In at least one of the RFE and ATFE units a predefined amount of 3000-4000 ppm polymerization inhibitor such as MMeHQ is added at a particular rate of 300-400 kg/hr from the top to avoid polymerization of ACRN and formation of any side-product. The evaporated ACRN from first the evaporator (i.e., RFE) and the second evaporator (i.e., ATFE) is passed through the first and second condensation units with packed columns connected to the evaporator units. The pure acrylonitrile is recovered in the acrylonitrile collection tank. Table 1 below illustrates the examples of % recovery of ACRN by implementing the proposed system (100) and the process (200).
# RFE feed, kg/hr ATFE feed, kg/hr RFE column top collection ATFE column top collection % recovery from RFE % recovery from ATFE Total % recovery
1 11300 3900 7522 3529 66.57% 31.23% 97.80%
2 11100 3900 6800 3550 61.26% 31.98% 93.24%
3 10500 3900 6800 3300 64.76% 31.43% 96.19%
4 11200 3900 7400 3500 66.07% 31.25% 97.32%
5 10300 3900 6700 3500 65.05% 33.98% 99.03%
6 10000 3900 6200 3400 62.00% 34.00% 97.00%
7 10200 3900 6400 3500 62.75% 34.31% 97.06%

In an embodiment, an effect of variation of one or more parameters such as variation is system and variation in system components was evaluated for ACRN recovery. It was observed that decrease/increase in temperature parameters by 10-20 degrees has no or minimal effect on % recovery of ACRN. Furthermore, the constant temperature of the system (100) is controlled by the controlling the steam flow rate.

In another embodiment, an incorporation of a single evaporator unit has reduced the final yield by 30-35%. Therefore, a double evaporator system was incorporated to recover maximum ACRN upto 99.9%.

In some embodiments of the present invention, the said system (100) and process (200) for recovery of Acrylonitrile (ACRN) from an ATBS monomer slurry in the synthesis of ATBS possesses following advantages but not limited to:
• Overall Recovery of acrylonitrile is in a range of 97.0% - 99.9%.
• The system (100) enables recovery of all the by-products along with ACRN and thereby zero liquid discharge (ZLD) to an effluent treatment plant is achieved.
• As the system (100) is configured to work under vacuum conditions, the heat requirement is reduced and thereby energy consumption is reduced.
• Minimal amount of impurity in the recovered acrylonitrile, enabling efficient reuse of ACRN in ATBS monomer synthesis process.
• Consistent purity in a recovered ACRN is achieved.

The embodiments, examples, and alternatives of the preceding paragraphs or the description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination thereof. Features described in connection with one embodiment apply to all embodiments, unless such features are incompatible.
List of Abbreviations:
ACRN-Acrylonitrile
ATBS- Acrylamido tertiary butyl sulfonic acid
TBA-Tertiary butyl acrylamide