Description:TECHNICAL FIELD
[001]. The present disclosure generally relates to the field of treating industrial waste. In particular, the present disclosure provides a process for removing impurities found in methanol, recovered from industrial effluents such as generated as a by-product during the production of 2-hydroxy sodium 5-sulpho isophthalate. The process comprises contacting a sample comprising the contaminated methanol with a mixed bed ion exchange resin, to obtain purified methanol.

BACKGROUND
[002]. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide. Methanol is a very good polar solvent and is used for many synthetic applications along with other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether and specialized chemicals.
[003]. In general, any single Polyethylene terephthalate plant - generates about 200MT/annum of contaminated methanol as a by-product during the production of 2-hydroxy sodium 5-sulpho isophthalate as an additive. This additive is also used for manufacturing cationic dyeable (CD) polyester/polymer for various applications by continuous polymerization (CP) process. During the synthesis of this additive, methanol is generated as a byproduct.
[004]. The methanol generated is acidic in nature having pH ranging between 3.8 to 4.2 with a moisture content of about 1%. Due to lower pH the overall quality of methanol is not suitable to use in the direct-methanol fuel cell (DMFC) application. Acidic methanol is usually neutralized with caustic solution for selling at a lower cost or for storing at -plant for safe handling. However, such methanol cannot be used for direct fuel cell applications.
[005]. In prior art, pure methanol is recovered from a mixture of impure methanol, ethanol and water using distillation process. However, such processes are cost intensive, having a multi-step and complex procedure. Also, such processes face difficulty in removing some organic impurities.
[006]. Thus, there is an unmet need in the art for developing simple, cost-effective and efficient process for purification of contaminated methanol generated at plant which will remove acidic as well as other contaminants thereby, improving the overall quality of purified methanol. The present disclosure aims to address the same.

SUMMARY
[007]. Accordingly, the present disclosure relates to a process for purification of contaminated methanol comprising the act of contacting a sample comprising contaminated methanol with an adsorbent to obtain purified methanol, wherein the adsorbent is a mixed bed ion exchange resin.
[008]. The obtained purified methanol according to the above described process has purity of at least 99% and conductivity of less than 0.5 µs/cm.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
[009]. In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:
[0010]. Figure 1 depicts the chemical structure of the mixed bed ion exchange resin Indion MB-12 employed in the process of the present disclosure.
[0011]. Figure 2 depicts flow diagram for the process of methanol purification as per the present disclosure.
[0012]. Figure 3 depicts breakthrough data of conductivity on INDION MB-12 resin using process methanol.
[0013]. Figure 4 depicts breakthrough data of pH on INDION MB-12 resin using process methanol.
[0014]. Figure 5 depicts breakthrough data of conductivity on Indion MB-12 resin using neutralized methanol.
[0015]. Figure 6 GC-MS analysis of contaminated methanol containing acetic acid.

DESCRIPTION OF THE DISCLOSURE
[0016]. The present disclosure aims to address the drawbacks of the art and provides for a highly efficient process to remove undesirable impurities from contaminated methanol. The process of the present disclosure aims to be cost-effective, ecofriendly without employing or generating hazardous chemicals, and suitable to be carried out at ambient temperature and atmospheric pressure.
[0017]. Before going into the detailed description, while the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate better understanding of the presently disclosed subject matter.
[0018]. As used herein, the terms "method" and “process” are employed interchangeably and are meant to convey their commonly known dictionary meaning.
[0019]. As used herein, the term “adsorbent of the present disclosure”, “mixed bed ion exchange resin” are used interchangeably to refer to adsorbent having characteristic features same or overlaps with MB12.
[0020]. As used herein, the term “sample” refers to the input feed containing the contaminated methanol, regardless of the quantity obtained/employed. The sample may be an industrial effluent containing contaminated methanol, obtained from industrial processes such as but not limiting to effluent generated during the production of 2-hydroxy sodium 5-sulpho isophthalate.
[0021]. As used herein, the term “contaminated methanol” refers to methanol which contains impurities associated with it, such as but not limiting to impurities like acetic acid, methyl acetate etc. Said term also refers to methanol associated with impurities which is produced as a by-product during the production of 2-hydroxy sodium 5-sulpho isophthalate.
[0022]. As used herein, the term “process methanol” is a subset of “contaminated methanol” and refers to methanol which is produced as a by-product in PET plants. In particular, at PET, 2-hydroxy sodium 5-sulpho isophthalate is manufactured as an additive from sodium salt of methyl ester of isophthalic acid and 2 mole of mono ethylene glycol in presence of sodium acetate as catalyst, at a temperature of 155? to 160?. During this process, about 204 MT/annum of impure methanol is generated as a by-product.
[0023]. As used herein, the expressions ‘purified methanol’ or ‘treated methanol’ are used interchangeably and to refer to the methanol obtained post treatment by the process of the present disclosure.
[0024]. As used herein, the expression ‘room temperature’ refers to temperature ranging from about 25 ? to about 40 ?,
[0025]. As used herein, the expression ‘‘atmospheric pressure’ refers to standard atmospheric pressure.
[0026]. The present disclosure provides for a process for purification of contaminated methanol. In an embodiment, the present disclosure relates to adsorption process for the purification of contaminated methanol at room temperature and atmospheric pressure.
[0027]. In an embodiment, the present disclosure provides for a process for purification of contaminated methanol generated as a by-product during one of PET production process reactions, particularly during the production of 2-hydroxy sodium 5-sulpho isophthalate. During this process different types of impurities are formed, such as but not limiting to methyl acetate and acetic acid etc. The generated contaminated methanol is an acidic in nature having pH of 3.8 to 4.2. Presence of these impurities and lower pH affect the overall quality of methanol obtained from such processes. Hence, to reuse methanol in fuel cell application it is required to purify the same.
[0028]. GC-MS analysis of contaminated methanol shows presence of acetic acid which causes lowering of pH, illustrated in Figure 6.
[0029]. In order to reuse and recycle methanol in the process of the present disclosure, it is essential to remove the impurities and obtain methanol with desired specifications. Based on impurities present, different types of adsorbents were explored viz., alumina, silica, ion exchange resin and activated carbon. However, the inventors of the present disclosure surprisingly found that the best results, in terms of removal of acidic impurities from methanol, were obtained upon using ion exchange having specific characteristic.
[0030]. In some embodiments, the present disclosure employs an ion exchange resin, preferably a mixed bed resin having anionic and cationic site, as an adsorbent to purify methanol. Using this resin removes all impurities and improves the quality of treated methanol rendering it suitable for the DMFC application.
[0031]. In some embodiments of the present disclosure, the chemical structure of the mixed bed ion exchange resin employed in the process of the present disclosure, Indion MB-12, is provided in Figure 1. Indion MB-12 is a mixed bed ion exchange resin. It is a mixture of highly purified and super regenerated strong acid cation and strong base anion resins in 1:2 stoichiometrically equivalent volume ratio of cation in H form and anion in OH form. Indion MB 12 is recommended for non-regenerable mixed bed application where reliable production of the highest quality water is required and where "as supplied" resin must have an absolute minimum of ionic and non-ionic contamination.
[0032]. In a typical process, adsorbent having granular form is loaded in a column or reactor through which contaminated methanol was passed at room temperature and atmospheric pressure. The treated methanol was checked for its pH, conductivity, and moisture. The spent adsorbent can be regenerated.
[0033]. In some embodiments of the present disclosure, the process for purification of contaminated methanol comprises the act of contacting a sample containing contaminated methanol with the ion exchange resin of the present disclosure, to obtain purified methanol.
[0034]. In an exemplary embodiment, the adsorbent ion exchange resin of the present disclosure of granule, shape is loaded/packed in a column or reactor though which contaminated methanol is passed at room temperature and atmospheric pressure. The treated methanol is subsequently analyzed for its percentage purity, conductivity, and pH.
[0035]. In some embodiments of the present disclosure, the process is carried out by using dynamic mode of adsorption or equilibrium mode of adsorption.
[0036]. In some embodiments of the present disclosure, in the equilibrium mode of adsorption, the contaminated methanol is kept in contact with the adsorbent for a period of about 0.5 hr to about 24 hr, and wherein the mixture is optionally stirred at about 50rpm to about 250rpm.
[0037]. In some embodiments of the present disclosure, the dynamic mode of adsorption is carried out in a glass column, or a reactor loaded with the ion exchange resin of the present disclosure.
[0038]. In an exemplary embodiment, the dynamic mode of adsorption is carried out in a glass column, such as but not limiting to a glass column. Contaminated methanol is passed through the column comprising the adsorbent of the present disclosure. Liquid hourly space velocity (LHSV) employed ranges from about 1 to about 40 h-1. In an embodiment the LHSV is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35 or 40 h-1.
[0039]. In another exemplary embodiment, the dynamic mode of adsorption is carried out in a reactor such as but not limiting to a packed bed reactor. The ion exchange resin adsorbent is loaded in the reactor. The adsorbent bed was packed properly by tapping.
[0040]. In some embodiments, the treated methanol is collected in storage tank, from where it is consumed in the process to manufacture the PET polymer.
[0041]. In some embodiments, once the adsorbent is exhausted, the bed is kept under nitrogen to desorb the trapped methanol from voids and pores of the ion exchange resin adsorbent and the spent adsorbent is unloaded from the bottom reactor.
[0042]. In some embodiments of the present disclosure, the process is carried out at a liquid hourly space velocity (LHSV) ranging from about 1h-1 to about 40h-1, preferably from about 1h-1 to about 4h-1.
[0043]. In some embodiments, the treated methanol sample is collected periodically and sent for analysis at Q.C. laboratory to monitor the % purity, pH and/or conductivity of the treated methanol, to assess the efficiency of the process.
[0044]. In some embodiments, the purified methanol obtained post treatment by the process of the present disclosure is suitable for reuse in industrial processes such as direct methanol fuel cell application.
[0045]. In some embodiments, the process for purification of contaminated methanol comprises the acts of:
- filtering a sample containing the contaminated methanol through a suitable filter, such as but not limiting to a micro filter, to obtain filtered sample, and
- contacting the filtered sample with the ion exchange resin of the present disclosure, to obtain purified methanol.
[0046]. In some embodiments, the process of the present disclosure is carried out at room temperature.
[0047]. In some embodiments, the process of the present disclosure is carried out at atmospheric pressure.
[0048]. After use in the process of the present disclosure, the ion exchange resin becomes saturated with contaminants. Therefore, the spent adsorbent needs to be regenerated for the further utilization. In some embodiments, the spent adsorbent of the present disclosure is regenerated for further utilization by techniques including but not limiting to heat regeneration.
[0049]. In an exemplary embodiment, the spent ion exchange resin is regenerated by technique including but not limited to chemical treatment.
[0050]. In some embodiments of the present disclosure, the purified methanol has a purity of at least 99%, preferably at least 99.5% and more preferably at least 99.85%.
[0051]. In some embodiments of the present disclosure, the purified methanol has a pH ranging from about 6 to about 7.
[0052]. In some embodiments of the present disclosure, the purified methanol has a conductivity of less than about 1µs/cm, preferably less than about 0.5µs/cm and more preferably less than about 0.25µs/cm.

ADVANTAGES/BENEFITS:
The process for purification of contaminated methanol and the adsorbent as described in the present disclosure has several advantages/benefits, including, but not limiting to the following:
1. Operated at ambient temperature and atmospheric pressure: Unlike methods of the prior art which require heating at high temperature, such as the distillation process for purification of methanol, the process of the present application does not require heating or high pressure, making the process simpler and more convenient.
2. The process of the present disclosure is thereby easy to handle and safe to operate.
3. Eco-friendly: Minimum loss and environment friendly process compared to reported conventional methods. The adsorptive process of the present disclosure is environmentally friendly as there is no hazardous chemicals used/generated in the process. The process also does not generate any side product or solid waste.
4. The process of the present disclosure maintains the plant integrity by removing corrosive acidic impurities from methanol.
5. Cost effective: The process of the present disclosure is highly economical compared to conventional techniques. Also, the continuous adsorptive purification process of the present disclosure would save huge revenue besides maintaining the plant process integrity.
6. Efficient purification of methanol: The process treats methanol with minimal loss and the treated methanol has high quality with desired specifications. Methanol obtained by the process of the present disclosure has high purity, i.e., at least 99% preferably at least 99.87%, and low conductivity i.e., less than about 1µs/cm, preferably less than about 0.25µs/cm.
7. Direct methanol fuel cell application: The process of the present disclosure improves the purity, pH and conductivity of contaminated methanol, rendering it suitable for direct methanol fuel cell application.
8. Commercially relevant: The developed process can be easily scaled up, is commercially viable and will create the value for the organization.
9. Regeneration of adsorbent: The adsorbent employed can be regenerated and reused.

[0053]. Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.
[0054]. The foregoing description of the specific embodiments fully reveals 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 in this disclosure 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.
[0055]. Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” wherever used, 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. Similarly, terms such as “include” or “have” or “contain” and all their variations are inclusive and 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.
[0056]. The terms "about" or “approximately” are used herein to mean approximately, in the region of, roughly, or around. When the term "about" is used in conjunction with a numerical value/range, it modifies that value/range by extending the boundaries above and below the numerical value(s) set forth. In general, the term "about" is used herein to modify a numerical value(s) or a measurable value(s) such as a parameter, an amount, a temporal duration, and the like, above and below the stated value(s) by a variance of +/-20% or less, +/-10% or less, +/-5% or less, +/-1% or less, and +/-0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention, and achieves the desired results and/or advantages as disclosed in the present disclosure. It is to be understood that the value to which the modifier “about” or “approximately” refers is itself also specifically, and preferably, disclosed.
[0057]. With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. As used in this specification and the appended claims, the singular forms “a,” “an” and “the” includes both singular and plural references unless the content clearly dictates otherwise. 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. As such, the terms “a” (or “an”), “one or more”, and “at least one” can be used interchangeably herein.
[0058]. Numerical ranges stated in the form ‘from x to y’ include the values mentioned and those values that lie within the range of the respective measurement accuracy as known to the skilled person. If several preferred numerical ranges are stated in this form, of course, all the ranges formed by a combination of the different end points are also included.
[0059]. As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.
[0060]. 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.
[0061]. 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.
[0062]. All references, articles, publications, general disclosures etc. cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication etc. cited herein is not, and should not be taken as, an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.
[0063]. Further, while the instant disclosure is susceptible to various modifications and alternative forms, specific aspects thereof has been shown by way of examples and drawings and are described in detail below. However, it should be understood that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention.

EXAMPLES
[0064]. The present disclosure is further described with reference to the following examples, which are only illustrative in nature and should not be construed to limit the scope of the present disclosure in any manner.
[0065]. Nomenclature Used in The Examples:
[0066]. Contaminated methanol: The contaminated methanol employed in the examples of the present application was obtained from polyester plant as a by-product during one of the PET production process reactions. In particular, at the PET-, 2-hydroxy sodium 5-sulpho isophthalate was manufactured as an additive from sodium salt of methyl ester of isophthalic acid and 2 moles of mono ethylene glycol in presence of sodium acetate as catalyst, at a temperature of 155? to 160?. During this process, about 204 MT/annum of impure methanol was generated as a by-product.
Indion MB-12 Indion -FFIP Indion 890 Tulsion T-66 Amberlite XAD-4
Make M/s Ion Exchange India Pvt. Ltd. Thermax Rohm & Haas
Appearance Spherical beads Translucent red brow beads Off white Spherical beads White Translucent Bead
Shipping Weight 700kg/m3 680 kg/m3 640kg/m3 680 kg/m3
Particle size (mm)
> 1.2 mm 5% ------ 5% 5% ------ 5%
< 0.3 mm 1% ------ 1% 1% ------ 5%
Uniformity co-efficient 1.7 Max. ------ 1.7 Max. 1.7 Max. ------ 2
Effective size (mm) 0.45-0.55 ------ 0.45-0.55 0.40-0.5 ------ 0.49-0.69
Chemical Properties Cation Resin Anion Resin Strong base anion Resin Weak base anion Resin Strong acid cation Resin Non-Ionic Resin
Matrix Cross-linked polystyrene Cross-linked polystyrene Styrene -EDMA copolymer Styrene divinyl co polymer Polystyrene copolymer Cross-linked aromatic polymer
Type Gel Gel ------- ------- ------- -------
Functional Group Sulphonic acid Quaternary ammonium Benzyl trimethyl amine Tertiary amines Nuclear Sulphonic group ------
Total exchange capacity (meq/ml) 1.9 1.0 1.2 1.4 ------ ------
Ionic conversion 99% in H form 90% in OH form ------ ------ Hydrogen ------
Moist. holding cap. 47-55% 48-58% 47-55% 52-56% 2% 54-60 %
Thermal stability Upto 120? Upto 60? 60? in OH form & 90? in Cl 60? in free base form & 80? in HCl forms 130? 150?
pH range 0-14 ------ 0-14 0 - 7 ------ 0 -14
[0067]. Adsorption Capacity: Adsorption capacity analysis was carried out at room temperature and atmospheric pressure.
[0068]. Pre-activation of ion exchange resin: Prior to evaluation studies, pre-activation of ion exchange resin is necessary. Pre-activation was carried out by taking about 100 g of resin and soaking it in about 200 ml of distilled water for about 30 minutes. The water-soaked resin was filled in a glass column. The soaked resin bed was further flushed with about 300 ml of distilled water with discharge rate of about 3ml/minute till the conductivity of the water at outlet is 0.7 microSiemens.
[0069]. Ion exchange resins: Different types of resins viz., Indion MB-12, Indion -FFIP and Indion 890 received from M/s India Ion Resin Ltd., Tulsion T-66 received from Thermax, and Amberlite XAD-4 received from Rohm & Haas were employed in the evaluation studies for methanol purification. The source and physico-chemical properties of these resins is provided in Table 1.
[0070]. Table 1: Physico-chemical properties of different Resins used for Methanol purification.

[0071]. Example 1: Mixed bed ion exchange resin
[0072]. Several trials were conducted to optimize process conditions and get the desired specification for purification of methanol. 70gm of Indion MB-12 resin with the column dimension 28mm OD and 200 mm in height was used. The adsorbent bed height was 140 mm with the discharge flow rate of 1.5 ml/min. Contaminated methanol was passed through this adsorbent. The conductivity and pH of treated methanol was checked and observed results was found to be satisfactorily. The observed adsorption capacity found to be about 190ml/g and the pH of the contaminated methanol changed from 6 to 7.

[0073]. Example 2: Equilibrium and dynamic study on ion exchange resins
[0074]. Several adsorbents including cation, anion and mixed bed ion-exchange resins and activated ion exchange resin (Act. Carbon PL-70 obtained from M/s Auro carbon, Vadodara, India) were assessed for purification of methanol by equilibrium and dynamic adsorption methodologies. Contaminated methanol obtained from plant was passed through columns comprising different adsorbents, as per the protocol described in Example 1. The details and results of the experiment are given in Table 2 below.
[0075]. However, it was observed that conductivity of methanol did not improve with the adsorbents: Indion -FFIP, Indion 890, Tulsion T-66, Amberlite XAD-4 resins and Activated carbon PL-70. However, among all the resins tested, the mixed bed resin (MB-12) showed significant improvement in the overall the conductivity (?1µs/cm) of impure methanol and in also neutralizing the pH of the impure methanol. The desired critical specification of untreated and treated methanol with the mixed bed resin MB-12 are provided in Table 3.
[0076]. Table 2: Various resins studied
Expt. No Method Ion exchange Resin Wt in gms Feed Methanol pH Methanol Purified (ml) Conductivity
(µs/cm)
1A Equilibrium XAD-4 Resin (As such) 2 6.7 50
8.4 (after treatment) 100 50
1B Equilibrium XAD-4 Resin (pre-activated) 2 6.7 50
6.6 100 50
2 Dynamic INDION FFIP (SAB) Resin 2 6.7 50
5.8 60 50
3 Dynamic TULSION T-66 Resin 2 6.7 50
5.8 60 50
4 Dynamic Act. Carbon PL-70 15 6.7 50
8.8 70 50
8.2 150 50
5 Dynamic INDION- 890 3 6.5 50 50

Properties Desired Limit for fuel Cell MeOH from process
Treated MeOH
pH 6-7 4.9 6-7
Conductivity (µs/cm) ?1 2.5 0.25
Purity (%) 99.85 75 99.87
[0077]. Table 3: Critical specification of untreated methanol and methanol treated with MB-12 resin

[0078]. Example 3: Process for purification of methanol with Indion MB-12 Resin
[0079]. Trials were conducted to optimize process conditions to get the desired specification of methanol.
[0080]. About 70 gm of MB-12 resin was used in a column having dimension of 28 mm OD and 200 mm height. The adsorbent bed height was 140 mm, and the discharge flow rate was 1.5ml/min. The details are tabulated in the Table 4.
[0081]. Table 4: Final optimization process using INDION MB-12 ion exchange resin using process methanol.
Exp. No. Feed Discharged Methanol (ml) pH Conductivity
(µs/cm)
6 Process Methanol 5.2 2.51
60 6.8 1.66
120 6.7 0.35
180 6.8 0.28
260 6.9 0.31
1440 6.6 0.34
1520 6.8 0.47
1600 6.3 0.34
1680 6.2 0.24

[0082]. Table 5: Final optimization process using INDION MB-12 ion exchange resin using neutralized methanol (acidic methanol is neutralized with caustic solution)
Exp. No. Discharged Methanol (ml) pH Conductivity
(µs/cm)
32 00 7.5 50.5
70 6.5 0.293
880 6.3 0.108
1600 6.3 0.241
3220 6.1 0.239
4010 6.0 0.268
4830 6.2 0.262
5640 6.2 0.196
6450 6.0 0.273
7220 6.1 0.281
8015 6.2 0.283
8825 6.1 0.293
9685 6.2 0.309
10045 6.2 0.570
10405 6.2 0.650
10625 6.2 0.958

[0083]. Further, to optimize the process for the purification of impure methanol, breakthrough experiments were carried out at room temperature and ambient pressure for depicting concentration of impurities in the feed and in the treated sample. The results are shown in Figure 3. The operating conditions and the amount of the adsorbent were kept the same (as mentioned in section 6.5). The adsorption capacity of the MB-12 ion exchange resin was found to be more than 85ml/g. Comparison of amount of feed processed g/g vs improvement in conductivity and pH are shown in Figures 3 and 4 respectively. Figure 3 indicates that the maximum amount of feed could be processed using the MB 12 resin. After 85ml/g feed processed the run was stopped due to shortage of feed. After stopping the run, the adsorbed methanol was drained off from bottom of the reactor. Nitrogen gas and/or dry air was used to drain the bed completely.

[0084]. Example 4: Study on different adsorbents
[0085]. A few studies were conducted to compare the efficacy of different adsorbents in the process of the present disclosure. Experiments were conducted by using dynamic/equilibrium adsorption.
[0086]. Experiment no. 1: In a dynamic process, contaminated methanol was passed through a glass column having diameter of 22.1 mm and height 150 mm by varying LHSV of 2, 6, 8, 10 and 40 h-1. About 10 gm of alumina adsorbent bed was prepared and through that contaminated methanol was passed. However, high adsorption capacity was observed in case of 2 LHSV. In case of equilibrium process, about 5 gm of adsorbent was taken in 250 ml of conical flask and to that contaminated methanol was added. The adsorption capacity was about 80ml/g with pH close to 7. However, the treated methanol has haziness due to attrition of alumina during the stirring.
[0087]. Experiment no. 2: Dynamic adsorption study was performed by taking 30 gm of ion exchange resin and packed in the glass column, through this contaminated methanol was passed at an LHSV of 2 h-1. The adsorption capacity and pH of the treated methanol was checked. The adsorption capacity was found to be about 30ml/g and pH was about 9.

[0088]. Referral Numerals:
Referral Numeral Description
100 Block diagram of the process of the present disclosure for purification of methanol
1 Input feed for impure methanol
2 Pump
3 Flow control valve or rotameter
4 Pre-filter (1 micron)
5 Drain
6 Pressure Gauge
7 Reactor
8 Adsorbent (ion exchange resin)
9 Ceramic ball support
10 Nitrogen
11 Purified methanol storge vessel
12 Filter

, Claims:1. A process for purification of contaminated methanol comprising the act of contacting a sample comprising contaminated methanol with an adsorbent to obtain purified methanol, wherein the adsorbent is a mixed bed ion exchange resin.
2. The process as claimed in claim 1, wherein the process is carried out at room temperature and atmospheric pressure.
3. The process as claimed in claim 1 or claim 2, wherein the process is carried out by using dynamic mode of adsorption or equilibrium mode of adsorption.
4. The process as claimed in claim 3, wherein the dynamic mode of adsorption is carried out in a glass column or rector loaded with the adsorbent, and by varying the liquid hourly space velocity (LHSV) in the range of 1h-1 to 40h-1.
5. The process as claimed in claim 3, wherein in the equilibrium mode of adsorption, the contaminated methanol is kept in contact with the adsorbent for a period of about 0.5 hr to about 24 hr, and wherein the mixture is optionally stirred at about 50rpm to about 250rpm.
6. The process as claimed in claim 1, wherein the adsorbent has a strong acid cation and strong base anion resins has about 1:2 stoichiometrically equivalent volume ratio of cation in H form and anion in OH form.
7. The process as claimed in claim 1, wherein the adsorbent has a crosslinked polystyrene matrix, and wherein the cation resin has a sulphonic acid functional group, and the anion resin has a quaternary ammonium functional group.
8. The process as claimed in claim 1, wherein the sample comprising the contaminated methanol is filtered prior to contacting the sample with the adsorbent.
9. The process as claimed in claim 1, wherein the contaminated methanol is generated as a by-product during the production of 2-hydroxy sodium 5-sulpho isophthalate or polyethylene terephthalate.
10. The process as claimed in claim 1, wherein the contaminant is selected from a group comprising methyl acetate, acetic acid and its derivatives and any combination thereof.
11. The process as claimed in any one of the preceding claims, wherein the purified methanol has a purity of at least 99%, preferably at least 99.5% and more preferably at least 99.85%; a pH of about 6 to about 7; and conductivity of less than about 1µs/cm, preferably less than about 0.5µs/cm and more preferably less than about 0.25µs/cm.

Dated this 07th day of June 2022
Signature:
Name: Sridhar R
To: Of K&S Partners, Bangalore
The Controller of Patents Agent for the Applicant
The Patent Office, at Mumbai IN/PA-2598