KR20010105353A - Methods of extracting catalyst in solution in the manufacture of adipic acid - Google Patents

Abstract

The present invention relates to a method for extracting a metal catalyst from a reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst. According to this invention, almost all of the cyclohexane is removed and most of the adipic acid is also removed. Most of acetic acid is also removed without precipitating the catalyst to form a concentrate in solution. In a preferred embodiment of the present invention, the concentrate enters a countercurrent stream of water and cyclohexanone in countercurrent, resulting in an aqueous solution of a metal catalyst as an extract and a concentrate dissolved in cyclohexanone as a raffinate. Both solutions are additionally treated or recycled.

Description

METHODS OF EXTRACTING CATALYST IN SOLUTION IN THE MANUFACTURE OF ADIPIC ACID}

There are a number of references (both patents and papers) relating to the oxidation of hydrocarbons to make acid, the most important adipic acid. Adipic acid is used to produce nylon 66 fibers and resins, polyesters, polyurethanes and other compounds.

Adipic acid is prepared by various processes. Conventional processes involve oxidizing cyclohexane with oxygen to cyclohexanone and cyclohexanol (KA mixture) and oxidizing the KA mixture to adipic acid with nitric acid. Other processes include the "hydroperoxide process", the "boric acid process" and the "direct compatibility process", which directly oxidize cyclohexane to adipic acid with oxygen in the presence of solvents, catalysts and initiators or promoters. It includes.

Direct synthesis processes have been in the spotlight for a long time. However, there is little commercial success to date. One reason for this is that at first glance it looks very simple, but in reality it is very complex. This complexity results in noticeable contradictions, comments and observations in the various references.

It is well known that there is a mixture of two liquid phases at room temperature after the reaction according to the direct synthesis and a solid phase consisting mainly of adipic acid. The two liquid phases are called "Polar Phase" and "Non-Polar Phase". However, no attention was paid to the importance of these two liquid phases, except for separating adipic acid from the “top phase” and recycling these liquid materials to the reactor in part or in whole with or without further treatment.

It is also important that most of the research on direct synthesis has been carried out in batch mode, strictly speaking, for entirely practical purposes.

As described above, the organic compound is oxidized, for example, cyclohexanone, cyclohexanol. There are many references to producing intermediates such as cyclohexylhydroperoxide and / or acids such as adipic acid and the like.

Of the many references, the following may be considered representative of the provision of diacids and intermediate oxides.

U.S. Patent 5,463,119 (Kollar), U.S. Patent 5,374,767 (Drinkard et al.), U.S. Patent 5,321,157 (Kollar), U.S. Patent 3,987,100 (Barnette et al.), U.S. Patent 3,957,876 (Rapoport et al.), U.S. Patent 3,932,513 (Russell), U.S. Patent 3,530,185 (Pugi) ), US Patent 3,515,751 (Oberster et al.), US Patent 3,361,806 (Lidov et al.), US Patent 3,234,271 (Barker et al.), US Patent 3,231,608 (Kollar), US Patent 3,161,603 (Leyshon et al.), US Patent 2,565,087 (Porter et al.), USA Patent 2,557,282 (Hambiet et al.), US Patent 2,439,513 (Hamblet et al.), US Patent 2,223,494 (Loder et al.), US Patent 2,223,493 (Loder et al.).

DE 44 26 132 A1 (Kysela et al.) Discloses that in the presence of cobalt salts as a catalyst, cyclohexane is filtered in the liquid phase with air, and after the separation of adipic acid, cobalt salts are precipitated in the dehydration column. While dehydration of acetic acid in the process is described, the state of acetic acid returned to the beginning of the process is azeotropic distillation by addition of cyclohexane, and the residual moisture is evaporated and dehumidified to less than [sic] 0.3-0.7%. It is characterized in that.

PCT International Patent Publications WO 96/03365 (Costantini et al.) And US Pat. No. 5,756,837 (Costantini et al.) Describe a process for recycling a cobalt-containing catalyst by direct reaction of oxidizing cyclohexane to adipic acid. And the reaction mixture obtained by oxidation is treated by extracting at least a portion of glutaric acid and succinic acid formed during the reaction.

None of the above references or references known to the inventors disclose, suggest or imply an oxidation reaction in accordance with the complex and critical criteria and requirements in this invention, which are described and claimed herein, either alone or in combination.

The present invention relates to a method of oxidizing cyclohexane to adipic acid, and more particularly to a method of continuously extracting the catalyst into solution for recycling.

Referring to the following detailed description with reference to the drawings, the reader will better understand this invention.

1 shows a block diagram of a preferred embodiment of this invention in which catalyst extraction is carried out in a countercurrent stream,

Figure 2 shows a block diagram of another preferred embodiment of the present invention in which the catalyst extraction is carried out in a multistage extraction assembly.

As described above, the present invention relates to a method of oxidizing a hydrocarbon, such as cyclohexane, for example, to each intermediate product, such as, for example, adipic acid, and more particularly, continuously extracting the catalyst into solution for recycling. It is about how to. More specifically, the present invention relates to a method for extracting a metal catalyst from a reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst, the method comprising:

(a) removing almost all of the cyclohexane,

(b) removing most of the adipic acid,

(c) removing most (up to almost 100%) of acetic acid, taking care not to exceed the extent that the catalyst precipitates in solution and begins to form a concentrate,

(d) directing the concentrate to an intermediate region of the backflow stream having a lower region including a lower portion and an upper region and an intermediate region including the upper portion,

(e) directing cyclohexanone, which may comprise traces of water, to the lower region of the countercurrent stream,

(f) directing water, which may comprise traces of cyclohexanone, to the upper region of the countercurrent stream,

(g) removing the first liquid, ie raffinate, comprising most of the concentrate except for the catalyst from the top of the upper region, and

(h) removing the second liquid, ie extract, comprising most of the metal catalyst from the bottom of the lower region.

The metal catalyst is preferably a cobalt-containing compound. The metal catalyst, whether bound to the composite or to the moiety thereof, is substantially the metal itself and is preferably in the form of ions. As such, the metal may, for example, be bound to one moiety in step (a) and to another moiety in step (h), which will be mainly cobalt acetate in step (a) and mainly in step (h) Cobalt adiphosphate, cobalt glutarate or cobalt succinate or mixtures thereof.

Removal of cyclohexane can be performed during or before the removal of adipic acid, or both before and after the removal of adipic acid. Before or after means a step before or after the process, while during means the same step. For example, cyclohexane lowers the temperature and causes two distinct liquid states to be formed, a nonpolar state containing most of the cyclohexane and a polar state containing most of the acetic acid and adipic acid and other polar moieties. It is removed by decanting and removing non-polar materials and crystallizing and removing adipic acid. Another optional method is to remove cyclohexane during the instantaneous crystallization of adipic acid. Cyclohexane may be removed by distillation.

Preferably steps (d), (e), (f), (g) and (h) are performed simultaneously. Also, step (c) is preferably carried out by distillation. In step (c) a small amount of water may be added continuously or intermittently.

It is also preferred that in step (c) almost all of the acetic acid is removed and in step (h) almost all of the metal catalyst is removed.

If the catalyst is required to be removed almost completely, it is absolutely important to reduce or eliminate the emulsification tendency by keeping the temperature high enough in the portion of the back stream where only a small amount of catalyst is present, such as at the top of the back stream. .

The temperature at the top, middle and bottom may be about the same, preferably from 50 ° C. to 80 ° C.

However, it is more preferable that the upper temperature is higher than the middle temperature, and the intermediate temperature is higher than the lower temperature. More preferably, the upper temperature is in the range of 50 ° C to 90 ° C, the middle portion temperature is in the range of 30 ° C to 50 ° C, and the lower temperature is in the range of 10 ° C to 40 ° C.

The present invention also relates to a method of extracting a metal catalyst from a reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst, the method comprising:

(k) removing almost all of the cyclohexane,

(1) removing most of the adipic acid,

(m) precipitating the catalyst to remove most of the acetic acid without forming a concentrate in the solution,

(n) an intermediate stage of a backflow multistage assembly comprising a preliminary step comprising a forward mixing section and a forward separation section and a post step including a rear mixing section and a rear separation section and an intermediate step including an intermediate mixing section and an intermediate separation section. Guiding the concentrate,

(p) guiding cyclohexanone, which may contain traces of water, to the forward mixing section,

(q) directing water, which may contain traces of cyclohexanone, to the backmixing section,

(r) removing the raffinate comprising most of the concentrate except for the catalyst from the backside section, and

(s) removing the extract comprising most of the metal catalyst from the front separation section.

Step (m) is preferably carried out by distillation, in which case the method may additionally comprise adding water in step (m).

Separation is carried out at least partially in a centrifugation section at least in the rearward section.

According to one embodiment of this invention, the post step has a post step temperature, the intermediate step has a medium step temperature, the pre step has a pre step temperature, and the post step temperature, the intermediate step temperature and the pre step temperature are almost the same. Preferably such temperature is in the range of 50 ° C to 80 ° C.

In another embodiment, the after temperature is higher than the intermediate temperature and the intermediate temperature is higher than the previous temperature. Preferably, the post step temperature is in the range of 50 ° C to 90 ° C, the intermediate step temperature is in the range of 30 ° C to 50 ° C, and the prestep temperature is in the range of 10 ° C to 30 ° C.

According to this invention, it is preferred that almost all of the acetic acid is removed in step (m). It is also preferred that almost all of the metal catalyst is removed in step (s).

As described above, the metal catalyst is preferably a cobalt-containing compound. The metal catalyst is substantially the metal itself, preferably bound to the composite or to the moiety, and is preferably in ionic form. Thereby, the metal may, for example, be bound to one moiety in step (k) and to another moiety in step (s), which will be mainly cobalt acetate in step (k) and mainly in step (s) Cobalt adiphosphate, cobalt glutarate or cobalt succinate or mixtures thereof.

Preferably steps (n), (p), (q), (r) and (s) are carried out simultaneously. In addition, step (m) is preferably carried out by distillation. In step (m) a small amount of water may be added continuously or intermittently to maintain the solubility of the metal catalyst.

The methods of the invention react the resulting adipic acid with a reactant selected from the group consisting of polyols, polyamines and polyamides to form polyesters or polyamides or polymers of (polyimide and / or polyamideimide), respectively. Additionally, such polymers may be spun into fibers or mixed with fillers and / or other additives to form composites.

"Most" in the context of a moiety means at least 50%, up to almost 100% of such moiety by weight.

By " trace " in the context of a moiety means less than 50%, up to almost 0% of such moiety by weight.

"Upper phase" means "state of relatively small polar cyclohexanone containing trace amount of catalyst", and "lower phase" means "relative phase containing most of the catalyst." Means the state of water of great polarity. This applies not only to the case where the separator is a decanter that produces cyclohexanone in the upper state and water in the lower state, but also applies to the case where the separator is a centrifuge.

"Intermediate step" is any step that is not a previous step and a later step.

As described above, the present invention relates to, for example, a method and apparatus for oxidizing cyclohexane to adipic acid, and more particularly to a method of extracting a catalyst into a solution for recycling after the reaction.

Proper handling of catalysts in oxidation reactions has always been an important issue in the art. According to this invention, the catalyst is separated in the form of a dissolved liquid in an aqueous state and preferably returned to the reaction chamber with or without further treatment.

The inventors have oxidized to the required degree of conversion from cyclohexane to adipic acid and after the majority of the adipic acid and the remaining cyclohexane have been removed with water and at least most acetic acid, the reaction mixture has a critical amount of cyclohexanone and water. It was found that it could be maintained in a single phase liquid state without a solid before and after addition. Thereafter, the catalyst can be extracted by the addition of water or by the drop in temperature, and preferably returned to the reaction chamber with or without the addition treatment.

According to this invention, the catalyst separation process is remarkably improved by the technique described below.

Referring now to FIG. 1, there is shown a catalyst separation unit 10 comprising an evaporator, ie, a distillator 12, connected to an intermediate region 19 of the countercurrent extraction main complex 14 via a transfer line 16. The backflow extraction main complex 14 surrounds the extraction section complex 18. The backflow extraction main composite body 14 has a lower region 20 and an upper region 22 in addition to the intermediate region 19. The lower region 20 has a bottom 24 and the upper region 22 has a top 26. The water line 28 and the cyclohexanone line 30 are connected to the countercurrent extraction main complex 14, which is a catalyst solution line, that is, an extract line 32, and a concentrate solution line, that is, a raffinate line ( 34).

The evaporator, ie, the distillator 12, is connected to the steam line 15, and the optional addition line 13 and the line 11 of the treated reaction mixture are connected to the evaporator 12. The heater, ie the heat exchanger 17, is part of the evaporator 12.

The apparatuses in front and rear of the catalyst separation unit 10 are not shown in FIG. 1 because they are well described in most of the inventors' patents and applications described by reference in this application.

In the operation of this embodiment, the reaction mixture treated in the course of oxidation from cyclohexane to adipic acid is reacted to the reaction mixture line 11 (as exemplarily described in the inventors' patents and applications described by reference in this application). Through the evaporator, ie, the distillator 12. The treated reaction mixture is a mixture remaining after removing at least most of the adipic acid from the reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and preferably a cobalt mixture metal catalyst. The treated reaction mixture may contain most or minor amounts of unreacted cyclohexane. Cyclohexane can be removed by separating the reaction mixture into (i) a polar state containing most of acetic acid and adipic acid and other polar moieties and catalysts, and (ii) a nonpolar state containing most of the cyclohexane. In such a case, the nonpolar state can be recycled and most of the adipic acid can be removed from the polar state by crystallization. In this case, the remainder after removal of adipic acid constitutes the treated reaction mixture. In other cases, most or minor amounts of cyclohexane may be removed simultaneously with the instantaneous crystallization of adipic acid. In such a case, the remainder after removal of adipic acid constitutes the treated reaction mixture.

It should be noted that removing cyclohexane before the treated reaction mixture enters the evaporator, i.

The treated reaction mixture entering the evaporator 12 is concentrated to the required level by evaporating most of the acetic acid present. The cyclohexane present and most of the water is evaporated through the steam line 15 because the volatility is very high even before acetic acid is evaporated. It is very important that the concentrate produced by the evaporation of most acetic acid remains in the form of a liquid that can be pumped even if it is viscous through the transfer line 16.

In the course of evaporating acetic acid a small amount of water can be added continuously or intermittently via the optional addition line 13. The addition of water can be important in minimizing the amount of acetic acid in the concentrate in order to maintain the relative amount of the compounds in the concentrate, etc., depending on the conversion, thereby keeping the concentrate free of solids.

The concentrate enters into the extraction section complex 18 of the backwash extract complex 14, and within the extract section complex 18 there is a backflow stream 18 '.

The countercurrent stream 18 'has an intermediate region 19' corresponding to the intermediate region 19 of the countercurrent extracting main complex 14. Similarly, the backflow stream 18 'is the lower region 20' (corresponding to the lower region 20 of the backflow extraction main complex 14) and the upper region 22 '(the upper region of the backflow extraction main complex 14). (Corresponds to (22)). In addition, the lower region 20 'of the backflow stream 18' has a lower end 24 '(corresponding to the lower end 24 of the lower region 20 of the backflow extraction main complex 14). The upper region 22 'of the backflow stream 18' has an upper end 26 '(corresponding to the upper end 26 of the upper region 22 of the backflow extraction main complex 14).

As can be seen in FIG. 1, the backflow stream 18 ′ is generated by a plurality of secondary streams that have already entered or already existed in the backflow extraction main complex 14.

One of these secondary streams is a concentrate entering the middle region 19 'of the backflow stream 18'. Another secondary stream is a stream of cyclohexanone which is guided through cyclohexanone line 30 in the subregion 20 'of the backflow stream 18'. Another secondary stream is a stream of water that is guided through the water line 28 in the upper region 22 'of the backflow stream 18'.

Cyclohexanone has a specific gravity less than water and therefore moves upwards (in the direction from the lower zone 20 'to the upper zone 22' of the backflow stream 18 ') and the water moves downward (backward stream 18'). The direction toward the lower region 20 'from the upper region 22'. As the two secondary streams move in opposite directions, the composite of the backflow stream 18 'changes from position to position, resulting in a water phase containing at least the majority of the metal catalyst near the bottom 24' and the top ( 26 ') to a cyclohexanone state containing at least most of the concentrate except the catalyst. The water-state portion as an extract containing most of the catalyst is removed via the catalyst solution line, i.e., the extract line 32, and the cyclohexanone state portion is removed via the concentrate solution line, i.e. the raffinate line 34. do.

In this way, the dissolution of the concentrate takes place simultaneously with the extraction of the metal catalyst in solution form with water. The concentrate solution, i.e. raffinate and catalyst solution, i.e. extract, may be further processed or recycled as described in the inventors' aforementioned patents and patent applications.

Almost all of the metal catalyst can be extracted or removed through the catalyst solution line, i. E. The extraction line 32, by controlling the feed rate and temperature through the lines 16, 28, 30 described above.

Water entering the water line 28 may contain traces of cyclohexanone, and cyclohexanone entering the cyclohexanone line 30 may contain traces of water. Likewise, the water present in the extract line 32 or the catalyst solution in the extract contains traces of cyclohexanone, and the concentrate solution or raffinate present in the raffinate line 34 contains trace amounts of water.

In countercurrent streams with low concentrations of catalyst, such as the top 22 'of the countercurrent stream 18', emulsification of cyclohexanone and water containing miscellaneous products is prone to occur, as small amounts of catalyst are concentrated in the concentrate solution, That is, it is incorporated in the raffinate line 34. In order to significantly reduce or eliminate such trends, the temperature of the top 22 'must be above a certain threshold temperature which can be easily found in non-difficult experiments. As such, it can be maintained at a temperature above the critical temperature in all countercurrent streams 18 'or at least its top 22'. An easy way to control the temperature of the bottom 20 ', the middle 19' and the top 22 'of the back stream 18' is the cyclohexanone stream and the transfer line 16 of the cyclohexanone line 30. ) And the water stream of the water line (28), respectively.

If it is desired to keep all countercurrent streams at about the same temperature, the preferred temperature range is from 50 ° C to 80 ° C.

However, more preferably, the temperature range of the upper portion 22 'is maintained at 50 ° C to 90 ° C, and the temperature range of the middle portion 19' is maintained at 30 ° C to 50 ° C, and the temperature of the lower portion 20 '. The range is maintained at 10 ° C to 40 ° C. As described above, an easy way to achieve this is to control the temperature of the cyclohexanone stream of the cyclohexanone line 30, the concentrate stream of the transfer line 16 and the water stream of the water line 28, respectively. This is not necessarily necessary, and internal or external heating or cooling means and / or other temperature control means may be used for this purpose.

Referring now to FIG. 2, there is shown a catalyst separation unit 110 comprising an evaporator, ie, a distillation 112, connected to an intermediate stage 119 of the multi-stage countercurrent extraction assembly 114 via a transfer line 116. Intermediate step 119 includes an intermediate separator 118 and an intermediate mixer 118a. The multi-stage countercurrent extraction assembly has a previous step 120 and a later step 122 in addition to the intermediate step 119. The previous stage 120 has a front separator 124 and a front mixer 124a. Likewise, the later stage 122 has a back separator 126 and a back mixer 126a. The water line 128 is connected to the back mixer 126a, and the cyclohexanone line 130 is connected to the front mixer 124a. Extract line 132 is connected to the front separator 124, the raffinate line 134 is connected to the rear separator 126.

Also shown in FIG. 2 are intermediate steps 136 and 138 that include intermediate separators 140 and 142 and intermediate mixers 140a and 142a, respectively. However, the number of steps may be larger or smaller depending on the individual situation and the completeness of the extraction.

The mixer and separator are connected to each other by an inlet line and an outlet line as illustrated clearly in FIG. Some inlets are shown integrated together to form a single inlet to the mixer. But this is not essential. The inlet line can be individually and directly connected to the mixer. This direct connection is particularly preferred where there is a probability of solid precipitation. Pumps in lines for the movement of miscellaneous streams from one vessel to another are not shown for the sake of brevity, like other accessories, but they and their operation are well known in the art.

The separator may be a decanter, centrifuge or other separator suitable for separating two fluids from each other.

Various steps or portions of such steps (such as mixers, separators, inlets and outlets) may be heated or cooled by means well known in the art. Such heating means or cooling means are not shown in FIG. 1 for the sake of brevity.

The evaporator, ie, the distillator 112, is connected to the steam line 115, and the optional addition line 113 and the treated reaction mixture line 111 are connected to the evaporator 112. The heater, ie the heat exchanger 117, is part of the evaporator 112.

The apparatuses in front and rear of the catalyst extraction unit 110 are not shown in FIG. 2 because they are well described in the inventors' patents and patent applications described in this application by reference.

In the operation of this embodiment, the treated reaction mixture in the oxidation of cyclohexane to adipic acid (as described for example in the inventors' patents and applications described by reference in this application) is reacted to the reaction mixture line 111. Through the evaporator, that is, the distillation unit 112 enters. The treated reaction mixture is a mixture remaining after removing at least most of the adipic acid from the reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst, preferably a cobalt mixture. The treated reaction mixture may contain most or minor amounts of unreacted cyclohexane. Cyclohexane can also be removed by separating the reaction mixture into (i) a polar state containing most of acetic acid and adipic acid and other polar moieties and catalysts, and (ii) a nonpolar state containing most of the cyclohexane. In such cases, the nonpolar state can be recycled and most of the adipic acid can be removed by crystallization from the polar state. In this case, the residue after removal of adipic acid forms a treated reaction mixture. In other cases most or minor amounts of cyclohexane can be removed simultaneously with the instantaneous crystallization of adipic acid. In such a case, the residue after removal of adipic acid forms a treated reaction mixture.

Of course, cyclohexane can be removed by evaporation or other techniques.

It should be noted that removing the cyclohexane before the treated reaction mixture enters the evaporator, ie, distillator 112, is highly desirable but not necessary.

The treated reaction mixture entering the evaporator 112 is concentrated to the required level by evaporating most of the acetic acid present. The cyclohexane and most of the water present evaporate through the steam line 115 because the volatility is very high even before acetic acid is evaporated. It is very important that the concentrate produced by the evaporation of most acetic acid remains in the form of a liquid that can be pumped through the transfer line 116 even if it is viscous.

In the process of evaporating acetic acid, a small amount of water may be added continuously or intermittently via the optional addition line 113. The addition of water can be important in minimizing the amount of acetic acid in the concentrate in order to maintain the relative amount of the compounds in the concentrate, etc., depending on the conversion, thereby keeping the concentrate free of solids.

The concentrate enters the intermediate stage 119 of the multistage backflow assembly 114 via the transfer line 116, which is integrated with the stream in line 140 'and then with the stream in another line 142 ". Up to the intermediate mixer 118a. The streams from those three lines 116, 140 ', 142 "are well mixed in the mixer 118a, and the resulting mixture is separated through the line 118a'. 118), and the cyclohexanone is separated into the thick upper state and the water into the dark lower state. The lower state is led to the preceding mixer (intermediate mixer 140a) via line 118 ", and the upper state is guided to the trailing mixer (intermediate mixer 142a) via another line 118 '.

Cyclohexanone is fed to the front mixer 124a via line 130, where it is well mixed with the stream coming from the substate of the intermediate separator 140 via line 140 ". It is transferred to the front separator 124 through 124a 'and separated into a lower state exiting the assembly through line 132 and a higher state guided to the intermediate mixer 140a through another line 124'.

The substate exiting the assembly through line 132 is an extract in which most of the catalyst is an aqueous solution. It also contains a small amount of cyclohexanone.

In a later stage 122 of the assembly 114, water enters the mixer 126a via line 128, where it mixes well with the stream coming from the top of the intermediate separator 142 via line 142 ′. . The resulting mixture is then guided through line 126a 'to separator 126 to be separated into a lower state and a higher state. The lower state leads the line 126 ″ to the intermixer 142a and the upper state exits the assembly through the other line 134.

The upper state exiting assembly 114 through line 133 is raffinate, where the majority of the concentrate is cyclohexanone. There is also a small amount of water.

As shown in FIG. 2, the operation is followed by a subsequent step of extracting the catalyst to form the final water soluble catalyst extract and a subsequent step exiting the assembly 114 through line 132 and through the assembly 114 via line 134. It is based on the subsequent step leaving the concentrate raffinate, which is the exiting cyclohexanone.

As the solvent (water) moves from the rear separator 126 toward the front separator 124, the catalyst becomes thicker and leaves a raffinate that is gradually depleted, which in turn causes assembly 114 through line 134. Exit.

In this way, the dissolution of the concentrate entering the multi-stage countercurrent assembly via the transfer line 116 takes place simultaneously with the extraction of the metal catalyst in solution form with water. The raffinate and catalyst extract may be additionally treated or recycled as described in the inventors' aforementioned patents and patent applications.

The intermediate stage of the multistage reflux assembly or the guidance of the concentrate to the extractor (or the middle portion of a similar reflux strain) is important in maximizing the efficiency of catalyst extraction from the concentrate. The intermediate stage of the multistage countercurrent assembly, except the post stage 122, or guiding the concentrate to the extractor 114, allows a considerable amount of catalyst to already separate before final extraction takes place in the final separator 126. Guidance of the concentrate to the front stage 120 or to the extractor 114 of the multi-stage countercurrent assembly may cause a significant amount of concentrate moiety (not catalyst) to be incorporated into the catalyst extract exiting through line 132.

Almost all of the metal catalyst can be extracted or removed through the catalyst solution line, that is, the extract line 132, by the number of steps by controlling the feed rate through the lines 128 and 130 described above and the temperatures in the various steps.

Water entering the water line 128 may contain traces of cyclohexanone, and cyclohexanone entering the cyclohexanone line 130 may contain traces of water. Likewise, as described above, the catalyst extract present in the extract line 132 contains traces of cyclohexanone, and the raffinate present in the raffinate line 134 contains trace amounts of water.

The concentrations of the catalyst are much lower in the latter stages close to the later stage 122 of the countercurrent assembly 114, where the emulsification of cyclohexanone and water containing miscellaneous products is likely to occur, which is a small amount of catalyst. Is incorporated into the raffinate exiting the assembly via line 134. In order to significantly reduce or eliminate such trends, the temperatures at such later stages must be above a certain threshold temperature which can easily be found in non-difficult experiments. As such, at least all of the steps, such as later steps or later steps 122, can be maintained at a temperature above the critical temperature. One easy way to achieve this is to control the temperature of the miscellaneous streams by means well known in the art such as, for example, heaters, coolers or heat exchangers.

Of course, the separator or mixer may also be heated or cooled by similar techniques, such as by using external or internal heating or cooling devices and / or other temperature control means.

If it is desired to keep all countercurrent streams at about the same temperature, the preferred temperature range is from 50 ° C to 80 ° C.

However, more preferably, the temperature range of the subsequent step 122 is maintained at 50 ° C to 90 ° C, the temperature range of the intermediate step 119 is maintained at 30 ° C to 50 ° C, and the temperature range of the previous step 120 is It is maintained at 10 ° C to 40 ° C. When other intermediate stages are present, such intermediate stages are preferably maintained at a temperature between the temperatures of the intermediate stage and the end stage (front stage or rear stage) described above.

If unacceptable emulsification occurs in a later step 122 or elsewhere, a centrifuge such as separator 126 shown in FIG. 1 may be used in place of a simple decanter. Maintaining a temperature above the critical point of emulsification is not very important, at least when the centrifuge is used.

According to this invention, any liquid, gas or off-gases can be recycled wholly or partially from one section to another if necessary. In addition, any combination, any equivalent arrangement, or any combination of such equivalent arrangements, whether partially or wholly of the illustrated embodiments, may be utilized and are within the scope of this invention.

Although miscellaneous functions are preferably controlled by a computerized controller, according to the present invention, any kind of controller for controlling one or more functions may be used by manual control and / or even labor. Preferred computerized controllers include artificial intelligence systems (expert systems, neural networks and fuzzy logic systems well known in the art). Of these three types of artificial intelligence systems, the neural network learning the system collects information (eg, pressure, temperature, chemical or other analytical values) at various locations on the device, and returns this information (eg, pressure). Depending on the rate of descent, reaction rate, reactivity, etc., this information is then programmed with other available data to determine what action to take each moment. The expert system is programmed based on the experience of a skilled person. Fuzzy logic systems rely on intuitive laws in addition to rule of thumb.

Oxidation according to this invention is a harmless oxidation whose oxidation product is not carbon monoxide and carbon dioxide and mixtures thereof but for example adipic acid and the like. Of course, small amounts of these compounds may be formed with the oxidation product, which may be a mixture of products of one kind or of a variety of products.

General information regarding adipic acid that is particularly suitable for precipitation in accordance with the process of this invention can be found in a number of US patents and other references. These references are not restrictive but include the following by way of example.

U.S. Patent 2,223,493; 2,589,648; 2,285,914; 3,231,608; 3,234,271; 3,361,806; 3,390, ®; 3,530,185; 3,649,685; 3,657,334; 3,957,876; 3,987,100; 4,032,569; 4,105,856; 4,158,739 (glutaric acid); 4,263,453; 4,331,608; 4,606,863; 4,902,827; 5,221,800; And 5,321,157.

Diacids (e.g. adipic acid, phthalic acid, isophthalic acid, terephthalic acid and like) or other suitable compounds with a third reactant selected from the group consisting of polyols, polyamines and polyamides according to techniques well known in the art. It may be reacted together to form polyester or polyamide or polymer of (polyimide and / or polyamideimide), respectively. Preferably polyols, polyamines and polyamides are mainly diols, diamines and diamides in order to avoid excessive crosslinking. The polymer obtained from this reaction can be spun into fibers by techniques well known in the art. The polymer can be mixed with fillers and / or other polymers to make various composites.

The illustrations demonstrating the practice of this invention should not be construed as limiting the scope of this invention in any way, but are provided for illustrative purposes only. In addition, the preferred embodiments described in detail above may be implemented individually or in combination as with other embodiments falling within the scope of the invention by common sense or expertise. In addition, any description attempted in the detailed description is intended to be considered in detail and not in detail. Each of the zones of the embodiments can also be implemented in accordance with this invention, either individually or in combination with other zones. Such combinations are also within the scope of this invention. In addition, any example in the detailed description is intended to be considered as not limiting the invention.

Claims (21)

A method of extracting a metal catalyst from a reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst, (a) removing almost all of the cyclohexane, (b) removing most of the adipic acid, (c) precipitating the catalyst to remove most of the acetic acid without forming a concentrate in the solution, (d) directing the concentrate to said intermediate portion of the reflux stream having a lower portion having a lower portion and an upper portion and an intermediate portion having an upper portion, (e) directing cyclohexanone, which may comprise traces of water, to the bottom of the countercurrent stream, (f) directing water, which may comprise traces of cyclohexanone, to the top of the countercurrent stream, (g) removing the first liquid, ie raffinate, comprising most of the concentrate except for the catalyst from the top of the top, and (h) removing the second liquid, ie extract, comprising most of the metal catalyst from the bottom of the lower portion. The method according to claim 1, The steps (d) and (e) and (f) and (g) and (h) are performed simultaneously. The method according to any one of claims 1 to 2, Wherein said step (c) is carried out by distillation. The method according to any one of claims 1 to 3, And additionally adding water in step (c). The method according to any one of claims 1 to 4, Wherein in step (c) almost all of the acetic acid is removed. The method according to any one of claims 1 to 5, Wherein in step (h) almost all of the metal catalyst is removed. The method according to any one of claims 1 to 6, The upper part has an upper temperature and the middle part has an intermediate part temperature and the lower part has a lower temperature, And wherein said upper temperature, said intermediate temperature and said lower temperature are approximately equal. The method according to any one of claims 1 to 6, The upper part has an upper temperature and the middle part has an intermediate part temperature and the lower part has a lower temperature, And wherein the upper temperature is higher than the middle portion temperature. The method according to claim 8, And wherein said intermediate temperature is higher than said lower temperature. The method according to any one of claims 1 to 9, Reacting adipic acid with a polyol and a reactant selected from the group consisting of polyamines and polyamides to form polyesters or polyamides or polymers of (polyimide and / or polyamideimide), respectively, Additionally spinning the polymer into fibers or mixing with fillers or other additives or both to form a composite. A method of extracting a metal catalyst from a reaction mixture produced by oxidizing cyclohexane to adipic acid in the presence of acetic acid and a metal catalyst, (k) removing almost all of the cyclohexane, (l) removing most of the adipic acid, (m) precipitating the catalyst to remove most of the acetic acid without forming a concentrate in the solution, (n) the intermediate stage of the backflow multistage assembly comprising a preceding step comprising a forward mixing section and a forward separating section and a later step comprising a rear mixing section and a rear separating section and an intermediate step including an intermediate mixing section and an intermediate separation section. Guiding the concentrate to, (p) guiding cyclohexanone, which may contain traces of water, to the forward mixing section, (q) directing water, which may contain traces of cyclohexanone, to the backmixing section, (r) removing the raffinate comprising most of the concentrate except for the catalyst from the backside section, and (s) removing the extract comprising the majority of the metal catalyst from the forward separation section. The method according to claim 11, The step (m) is characterized in that carried out by distillation. The method according to any one of claims 11 to 12, Further comprising the step of adding water in step (m). The method according to any one of claims 11 to 13, At least part of the rearward separation section, wherein the separation is performed at least in part by a centrifugation step. The method according to any one of claims 11 to 14, The rear stage has a rear stage temperature and the intermediate stage has a middle stage temperature and the front stage has a front stage temperature, And wherein the rear step temperature, the intermediate step temperature, and the previous step temperature are substantially the same. The method according to claim 15, And wherein said approximately equal temperature range is from 50 ° C to 80 ° C. The method according to any one of claims 1 to 14, The rear stage has a rear stage temperature and the intermediate stage has a middle stage temperature and the front stage has a front stage temperature, And the intermediate step temperature is higher than the post step temperature and the intermediate step temperature, and the intermediate step temperature is higher than the previous step temperature. The method according to claim 17, The range of the post-step temperature is 50 ℃ to 90 ℃, the range of the intermediate stage temperature is 30 ℃ to 50 ℃, characterized in that the range of the previous stage temperature is 10 ℃ to 40 ℃. The method according to any one of claims 1 to 18, Wherein in step (m) almost all of the acetic acid is removed. The method according to any one of claims 1 to 19, Wherein in step (s) almost all of the metal catalyst is removed. The method according to any one of claims 11 to 20, Reacting adipic acid with a polyol and a reactant selected from the group consisting of polyamines and polyamides to form polyesters or polyamides or polymers of (polyimide and / or polyamideimide), respectively, Additionally spinning the polymer into fibers or mixing with fillers or other additives or both to form a composite.