LIQUID PHASE REMOVAL OF TRACE OF IODIDE FROM AN ORGANIC MEDIA USING TERTIARY AMINE ION EXCHANGE ADSORBENT

Abstract

It is provided a process of removing iodides from an non-aqueous organic media comprising providing a weak base anion exchange adsorbent; and passing the organic media containing iodides through the adsorbent thereby removing the iodide from said organic media.

Claims

1. A process of removing CH.sub.3I from an organic media comprising less than 1000 ppmw of water, the process comprising: providing at least one weak base anion exchange adsorbent; and passing said organic media containing CH.sub.3I through said at least one adsorbent thereby removing the CH.sub.3I from said organic media, wherein CH3I is removed to less than about 1 ppm.

2-3. (canceled)

4. The process of claim 1, wherein the organic media is a liquid media, a gas, a fluid or a combination thereof.

5. The process of claim 1, wherein the organic media comprises methyl acetate.

6. The process of claim 1, wherein the organic media comprises methanol, ethyl acetate, ethylpropionate, methyl acetate, methanol, isopropyl acetate, n-propyl acetate, n-butyl acetate or a mixture thereof.

7-10. (canceled)

11. The process of claim 1, wherein said weak base anion exchange adsorbent is a adsorbent with primary amines, secondary amines and/or tertiary amines functional groups.

12. The process claim 1, wherein the weak base anion exchange adsorbent comprises the following structure: ##STR00004## wherein R.sup.1 is a backbone.

13. The process of claim 12, wherein R.sup.2 and R.sup.3 are H, CH.sub.3, or a combination thereof.

14. The process of claim 12, wherein the backbone is a polymer structure.

15. The process of claim 12, wherein the back bone is a polystyrene crosslinked divinylbenzene back bone.

16. The process of claim 1, wherein the weak base anion exchange adsorbent has a capacity of up to 2.0 equivalent/L.

17. The process of any one of claim[[s]] 1[[-16]], wherein the weak base anion exchange adsorbent has a capacity of 1.30 equivalent/L.

18. The process of claim 1, wherein said weak base anion exchange adsorbent in a PUROLITE® A100 adsorbent or an equivalent adsorbent.

19. The process of claim 18, wherein said weak base anion exchange adsorbent is a PUROLITE® A100PLUS, PUROLITE® A110, PUROLITE®A100S, PUROLITE® A120 S, Amberlite™ IRA96, and Amberlite™ HPR9700, or any adsorbent or solid substrate with such amine functional groups.

20. The process of claim 1, wherein said organic media passes through said adsorbent at a temperature of greater than 60° C.

21. The process of claim 1, wherein said organic media passes through said adsorbent at a temperature of less than 60° C.

22. The process of claim 1, wherein said organic media passes through said adsorbent at a temperature of less than about 50° C.

23. The process of any one of claim 1, wherein said organic media passes through said adsorbent at a temperature of less than about 40° C.

24. The process of claim 1, further comprising a first step of removing water from the organic media to a content of less than 1000 ppmw of water.

25. The process of claim 1, wherein the organic media comprises methanol and methyl acetate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Reference will now be made to the accompanying drawings.

[0030] FIG. 1 illustrates a schematic representation of a process of converting methanol into ethanol wherein the tertiary amine ion exchange adsorbent described herein is used to remove iodide contaminants in accordance to one embodiment.

DETAILED DESCRIPTION

[0031] It is provided a mean to remove iodide from an organic media using a tertiary amine ion exchange adsorbent. It is thus provided the use of a tertiary amine ion exchange adsorbent to remove iodide contaminants from an organic media following a carbonylation process.

[0032] In an embodiment, the organic media is in a gas phase and/or liquid phase, preferably liquid phase.

[0033] In an embodiment, the organic media is constituted of methyl acetate. Also encompassed are organic media comprising methanol, ethanol, ethyl acetate or other esters, which may include, but are not limited to, ethylpropionate, methyl acetate, isopropyl acetate, n-propyl acetate, n-butyl acetate or mixtures thereof.

[0034] As encompassed herein, iodide contaminants are generally alkyl iodides such as methyl iodide.

[0035] As illustrated in FIG. 1, an organic media containing methanol 10 and a carbon monoxide source 12, such as residual carbon monoxide from a syngas, are reacted 14 in a reactor (or carbonylation reactor) in the presence of a catalyst consisting essentially of rhodium or rhodium supported on a support of carbon or alumina for example, to produce methyl acetate and acetic acid. The produced methyl acetate is then distilled and purified, but traces of iodide contaminants may remain. The distilled methyl acetate is then passed through a guard bed 16, such as for example but not limited to in liquid phase, comprising the tertiary amine ion exchange adsorbent described herein in order to remove all traces of iodide contaminants before being hydrogenated 18 to produce ethanol 20. The liquid is preferably passed through at a predetermine rate. Feed rates are dependent on for example the amount of iodide impurity, the degree of purification required, the temperature, and the liquid feed. In an embodiment, the feed rate is between 0.5 to 50 bed volumes per hour.

[0036] Accordingly, in liquid phase, the impure methyl acetate/methanol stream can be passed through a bed of weak base anion exchange adsorbent as described herein. As known in the art, copper based catalysts are generally used to stimulate the hydrogenolysis reaction and such catalysts are sensitive to halogen (including organic and inorganic iodide). Thus removal of iodide contaminants as proposed herein allows to maximize the performance of copper catalysts during downstream hydrogenolysis reaction.

[0037] A weak base anion exchange adsorbent or tertiary amine adsorbent as encompassed herein is intended to mean a weakly basic adsorbent which has tertiary amine functional groups consisting generally of formula (A):

##STR00002##

wherein:

[0038] R.sup.1: is the polystyrene crosslinked divinylbenzene back bone (polymer structure) of the adsorbent (as shown in B), or any other back bone that can link amine functional groups.

[0039] R.sup.2 and R.sup.3 can be any R (but more typically CH.sub.3), but also H (i.e. secondary or primary amine groups).

[0040] The following generic reaction represents the chemical adsorption of the contaminant organic iodide (halogenoalkane or other organic halide) onto the amine functional group, where R.sup.4 is the CH.sub.3 (methyl) and X is the iodide (I), for the preferred specific case of methyl iodide (CH.sub.3I ). R.sup.4 is reacted (attached) to the amine functional group, making it a quaternary amine strong base. The new strong base function strongly link the iodide anion (I−) to the adsorbent, preventing it from being released back to the organic media.

##STR00003##

[0041] In an embodiment, the tertiary amine adsorbent as encompassed herein is a polystyrene crosslinked divinylbenzene tertiary amine adsorbent such as the PUROLITE® A100 or an equivalent, containing for example a capacity of 1.30 equivalent/L. Alternatively, also encompassed herein are adsorbents functionalized with tertiary amines known such as PUROLITE® A100PLUS, PUROLITE® A110, PUROLITE® A100S, PUROLITE® A120 S, Amberlite™ IRA96, and Amberlite™ HPR9700, but not limited to, since any adsorbent or solid substrate with such amine group would be effective at removal of such organic iodide.

[0042] Impure methyl acetate liquid stream is containing from up to 150 ppm, preferably from 15-to 150 ppm, of total iodide mainly considered to be organic iodides is to be treated to remove the iodide down to about 1 ppm or less. As encompassed herein, the iodide contaminate or impurity concentration is defined as the concentration of any molecular species containing iodide. For example, such species are HI, CH.sub.3I and/or C.sub.6H.sub.13I, C.sub.10H.sub.21I. In a particular embodiment, such species is CH.sub.3I. More particularly, the method described herein can be used to remove the concentration of one or more C.sub.1-C.sub.12 alkyl iodide, and more particularly one or more C.sub.1-C.sub.8 alkyl iodides, with increasing adsorption efficiency towards lower molecular weight iodide species. The method described herein allows to reduce the concentration of the iodide compounds to less than about 1 ppm up to less than about 500 ppb, when CH.sub.3I is the main form of residual iodide. Accordingly, as demonstrated herein, methyl Iodide is being almost totally removed. When other iodide species are present, the total iodide removal is higher than the methyl iodide removal, and thus the adsorbent described herein can remove other iodides species. Similar adsorption pathway applies to other alkyl iodides.

[0043] The liquid stream passes through the tertiary amine adsorbent as encompassed herein at a temperature of operation of for example less than 60° C., preferably of less than 50° C., more preferably at about 40° C., but not limited to.

[0044] While the present disclosure has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations, including such departures from the present disclosure as come within known or customary practice within the art and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.