FR2475036A1 - PROCESS FOR IMPROVING THE QUALITY OF SATURATED ALIPHATIC MONOCARBOXYLIC ACIDS FROM 7 TO 9 CARBON ATOMS - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR IMPROVING THE QUALITY OF SATURATED MONOCARBOXYLIC ACIDS C-C, PRODUCED BY OXIDATION OF THE CORRESPONDING ALDEHYDES. ACCORDING TO THE INVENTION, AFTER ITS RECOVERY BY DISTILLATION OR OTHER PROCESS, THE ACIDIC PRODUCT IS SUBJECT TO HYDROGENATION IN THE PRESENCE OF A PALLADIUM CATALYST UNDER CONDITIONS WHERE MODERATE TEMPERATURE AND PRESSURE ARE COMBINED SUCH AS THE TEMPERATURE VARIES BY 20 AT APPROXIMATELY 50C AND HYDROGEN PRESSURES VARY FROM ABOUT 1 TO 5 BARS. PALLADIUM IS ESPECIALLY KNOWN FOR ITS ABILITY TO REMOVE IMPURITIES, ESPECIALLY ODORING IMPURITIES APPEARING DURING THE OXIDATION REACTION. THE EQUIPMENT USED ACCORDING TO THE PROCESS OF THE PRESENT INVENTION CAN BE ANY EQUIPMENT NORMALLY USED FOR HYDROGENATION, EITHER IN SEPARATE OPERATION, OR IN CONTINUOUS OPERATION. THIS EQUIPMENT INCLUDES A PRESSURE UNIT CONTAINING A SECTION CONTAINING THE CATALYST AND THROUGH WHICH THE ACID TO BE TREATED OVERFLOWS OR RUWS, AS APPLICABLE, IN AN ATMOSPHERE CHARGED WITH HYDROGEN. THE TREATED OR HYDROGEN PRODUCT IS THEN RECOVERED. THE PRESENT INVENTION APPLIES IN PARTICULAR TO THE ORGANIC CHEMISTRY INDUSTRY.

Description

The present invention relates to a method for improving the quality

  of the aliphatic monocarboxylic acid -substituted from 7 to 9am caboneprhydogenaticn, in the final phase, the acid product in the presence of a palladium catalyst at moderate temperature and pressure. There are many references to techniques

  hydrogenation of unsaturated hydrocarbons.

  Typical of these references are U.S. Patent Nos. 1,023,753; 1,174,245; 2,331,915; Nos. 3,123,574 and 3,198,816, which describe various processes for the hydrogenation of unsaturated fatty oils using various forms of palladium catalysts. However, these references

  do not mention hydrogenation as a purification step

  fication of saturated acids. U.S. Patent 3,271,410 discloses a process for improving the quality of a hydrogenated fatty acid by catalyzing by rehydrogenation of this fatty acid,

  in the presence of a palladium catalyst at temperatures of

  high temperatures (930 ° C. to 260 ° C.) and at pressures of 0.74 to 344 bar. More impurities can occur during hydrogenation at elevated temperatures than at moderate temperatures and pressures. This is why the desired end product is distilled from the product.

  hydrogenated rather than hydrogenated in the final phase.

  US Pat. No. 3,775,450 discloses the hydrogenation of 5-10 ° C aliphatic acids produced by nitric acid oxidation at temperatures ranging from room temperature to 3000 ° C, and at elevated hydrogen pressures. from 7 to 138 bars. Palladium catalysts are satisfactory as hydrogenation catalysts. High temperatures and high hydrogen content generally result in the production of additional impurities and the desired products are obtained by distillation rather than by final stage hydrogenation. Finally, U.S. Patent 2,884,451 discloses a process for purifying a crude acid mixture produced by oxidation of paraffinic hydrocarbons to form

  aliphatic acids having 1 to 4 carbon atoms.

  The desired acid is first removed by distillation

  reaction mixture and then hydrogenated by the

  a typical hydrogenation catalyst. Both palladium and platinum catalysts are known for their ability to remove impurities at room temperature and at atmospheric pressure, particularly odor and impurity impurities.

  reducing nature, formed during the oxidation reaction

  tion. However, this patent does not say anything about the purification of higher acids produced or not by oxidation of the corresponding aldehydes, which acids are themselves very fragrant. It would seem unreasonable to assume that these higher acids also contain impurities different from those contained in C1-C4 acids produced by the oxidation of paraffinic hydrocarbons. In addition, U.S. Patent No. 2,884,451 does not indicate whether palladium is a

  more efficient catalyst than platinum for purifying

  cation by hydrogenation of the acids other than the Ci-C4 acids, and particularly in the hydrogenation of purified C7-C9 acids according to

  the process of the present invention.

  We have now found a method for improving the qubitity of the aliphatic monocarboxylic acids formed by the oxidation of the corresponding C7-C9 aldehydes. After recovery by distillation or other process, the acid product is hydrogenated in the presence of a palladium catalyst under mild temperature and pressure conditions are combined so that the temperature varies from 200 C to 50 C and pressures

  hydrogen from about 1 to about 5 bar.

  In the production of saturated aliphatic acid monocarboxylic acids having 7 to 9 carbon atoms, a small amount of undesirable impurities may be produced and transported with the desired product even if it employs complete distillation or other recovery systems for purification.

  of the product. These impurities, whether they are sub-

  Unsaturated organic products or other reducible materials may give the end product undesirable characteristics. For example, such impurities can cause the formation of undesirable color bodies in the acid product. These impurities also react to the materials with which the acid products are used or react, forming other thermally unstable impurities.

and chemically.

  The present invention relates to a process for improving the quality of C7-C9 saturated monocarboxylic-l-aliphatic acids produced by oxidation of the corresponding C7-C9 aldehydes. Generally, this process involves the hydrogenation of saturated C - C 9 acids at exceptionally mild temperature and hydrogen pressure conditions using a palladium catalyst. The C7-C9 aldehydes used to produce the corresponding acids purified by the process of this invention can be prepared by catalytic hydroformylation of C6-C8 alkenes such as n-hexene, n-heptene or n-octeene in the presence of a suitable catalyst. with rock oxide and hydrogen; see, for example, U.S. Patent No. 3,239,566 to Slaugh et al .; U.S.A. Patent No. 3,511,880 to Booth; U.S.A. 4,158,020 to Stautzenberger et al., among others. The present invention can be used advantageously as a final step (ie without distillation or subsequent recovery system) to obtain high quality saturated C-1 acids, since no impurities

  does not occur under these mild hydrogenation conditions.

  The side salt, which is highly unsaturated, has a very low iodine content and can be an indication of how the acids will react with respect to thermal stability and

color development.

  The acids purified by the process of this invention are produced by oxidation of n-heptanal, n-octanal and n-nonanal in the presence of a catalyst such as manganese, copper or a combination of both, followed by distillation to obtain the desired acid product containing small amounts of impurities. According to the process of the invention, the C7-C9 acids can be hydrogenated slowly and in the final phase at moderate temperature and pressure to eliminate the harmful effects of the impurities and not produce additional impurities as shown by the chromatographic investigations.

typical gas phase.

  The process of this invention involves the use of mild hydrogenation at low temperature and low hydrogenation pressure. The temperatures used in the hydrogenation stage can be between about 20 ° C. and 50 ° C. for prehydroxis. The hydrogenation pressures can be between about 1 and 5 bar, preferably about 1.4 bar at

4 bars.

  The hydrogenation catalyst used for the present invention contains palladium under various

  shapes such as dumpling pellet powders and the like.

  As catalyst, unsupported palladium or palladium supported by silica, rre, cdakieselguhr or the like can be used. Particularly preferred catalyst is palladium saipporté by a pellet of coal. When supported palladium catalysts are used, the amount of palladium on the support can range from about 0.01% to 10% by weight or more based on the total catalyst, preferably about

0.5% to 5% on the same basis.

  The amount of catalyst present should be sufficient to allow the dilution to be as low as possible from the point of view of ecoromics. The amount of palladium used can vary from about 0.001% to about 1% by weight (without the weight

  of the support) on the basis of the amount of monocar-

  saturated aliphatic boxylic acid to be treated. Normally, the amount of palladium used will vary from about 0.001% to about 0.15% by weight of the total amount of acid to be treated. A most desirable catalyst is 0.5 wt.% Palladium on mesh, 4 x 8 mesh to obtain at least about 0.01 wt.% Palladium on the surface.

all the treated acid.

  The equipment used according to the process of this invention may be any equipment normally used for hydrogenation, either in continuously continuous operations. A Parr bomb or equivalent piece of equipment may be used in discoetinue operation. Necessarily, filtration of the catalyst from the hydrogenated product is required for this hydrogenation process. Continuous hydrogenation processes can be carried out either in runoff bed

  (unrestricted mass transfer) or in bed overflowing

  (limited mass transfer) and the same equipment can be used for both processes. This equipment comprises a pressure unit containing a section which contacts the catalyst and through which the acid to be treated overflows or flows, as the case may be, in a hydrogen-charged atmosphere. The treated or hydrogenated product is then recovered. The production of fine powders of catalyst, possible by the overflow bed process, is minimized by the trickle bed process and, therefore, the trickle bed technique is

the preferred embodiment.

  The following examples are presented as

  a specific illustration of the present invention.

  It will be understood, however, that the invention is not limited

  to the specific details indicated in the examples.

-2475036

EXAMPLES I to 8

  Nonylic acid produced by oxidation of n

  nonanal in the presence of a combination of manganese acetate

  ganesis and cupric acetate as catalysts, was distilled from the reaction mixture and then processed into a series of operations according to the following method: a Parr glass bomb (having a volume of about 300 milliliters) was charged with about 100 milliliters of nonyl acid (iodine value 0.047 meq / g) and 10 milliliters of catalyst

  hydrogenation, and then pressurized with hydrogen.

  After stirring for a specified time at room temperature, (about 20 ° C) the hydrogen was vented to the atmosphere and the contents of the reactor were filtered (0.451 Millipore filter) and analyzed for iodine value. indicates differences in the use of palladium on carbon and platinum on carbon as catalysts

hydrogenation.

TABLE 1

  COMPARISON OF PLATINUM AND PALLADIUM CATALYSTS FOR HYDROGENATION OF ACID

nonyl

  Catalyst Pressure H2 (Bars) Residence time (Mn) Indioe of iodine (meq / g) Nonyl food

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

  Acid% Platinum on carbon% Palladium on carbon% Platinum on carbon% Palladium on carbon 0.5% Platinum on carbon 0.5% Palladium on carbon 0.5% Platinum on carbon 0.5% Palladium on carbon X * 0 , 047 4,13 4, 13 4, 13 4, 13 4,13 4, 13 4, 13 4, 13 0.015 0.006 0.010 0.004 0.027 0.011 0.016 0.004 -J, Co 0s * Iodine number = amount of iodine in milli-equivalents absorbed per 1 gram of nonyl acid as determined by the Wijs method according to ASTM D 1959 The comparison of palladium on charcoal and platinum on charcoal for the hydrogenation of nonyl acid indicates that at moderate room temperature (about C) and at low hydrogen pressure, palladium-on-charcoal catalysts are more efficient at reducing the iodine value than the equivalent platinum-on-carbon catalysts.

  WIJS METHOD FOR IODINE INDEX ACCORDING TO STANDARD

ASTM D 1959

  A 500 ml iodine baton is filled with a 15 gram sample, 25 milliliters of carbon tetrachloride solvent and 20 milliliters of Wijs * solution. The balloon is then plugged and placed in a dark room for thirty minutes. After removing the baloon from the darkroom, 20 milliliters of potassium iodine solution ** and 100 milliliters of distilled water are added. The content of the balloon is then titrated

  0.1 N thiosulfate to a starch endpoint.

  A blank, omitting the only sample will be

  performed simultaneously with each group of samples.

  Calculation: iodine number (BS) x N x 12.69 (meq / g) = weight of the sample o B = titration of the blank S = titration of the sample N = normality of the thiosulphate solution * the solution de Wijs consists of 5 milliliters of reactive quality iodine monochloride in one liter

of glacial acetic acid.

  ** 15% by weight of reactive quality potassium iodide

in distilled water.

EXAMPLES 9 to 12

  Heptylic acid produced by oxidation of n

  heptanal in the presence of a combination of manganese acetate and cupric acetate catalysts was distilled from the reaction mixture and then underwent a series of treatments according to the following process A Parr glass bomb (approximate volume 300 milliliters) was charged with 100 milliliters of heptyl acid (iodine number 0.012 meq / g) and 10 milliliters of hydrogenation catalyst and then pressurized with hydrogen. After stirring for a determined period of time at room temperature (approximately 200 ° C.), the hydrogen was released into the atmosphere and the contents of the reactor were filtered (millipore filter 0.45) and

analyzed for the iodine index.

  Table 2 shows the differences obtained using palladium on carbon and platinum on

  coal as hydrogenation catalysts.

J ,,. 4.-

TABLE 2

  Comparison of platinum and palladium as catalysts for acid hydride

heptyl

  Catalyst Pressure H2 (Bars) Residence time (Mn) Iodine value Heptylic acid supply

Example 9

Example 10

Example 11

Example 12

0.5% Palladium on charcoal

0, 5%

  Platinum on carbon% Palladium on carbon% Platinum on carbon 4.13 0, 012 4.13 0.006 4.13 4.13 o 0.008 0.002 0.004 rlo n as l1

EXAMPLE 13

  In a trickle bed hydrogenation reactor containing a catalyst bed of 50.8 x 304.8 mm to 0.5% palladium on carbon of mesh size 4 x 8 mesh, nonyl acid produced in accordance with Examples I to 8 run above the analyzer at a controlled rate. Pressure

  of hydrogen from the reactor is 1.38 bar and the temperature

  hydrogenation is 30 C. Table 3 shows the results obtained for the hydrogenation of

  nonyl acid under various conditions.

TABLE 3

  HYDROGENATION OF NONYLIC ACID ON RUN-OFF BED

  Mass Flow * (Kg / m2 dry) Iodine Number Meq / g Product Feed

0.53 0.05 0.015

0.30 0.05 0.020

0.23 0.05 0.015

0.15 0.05 0.015

0.08 0.05 0.009

  * Liquid feed rate per cross-section

  unit-kilograms per m2 per second.

  Table 3 indicates that the quality of the nonyl acid can be improved by a continuous process

of soft hydrogenation.

EXAMPLE 14

  Using identical hydrogenation equipment under the reaction conditions of Example 13 and

  replacing the heptylic acid produced according to description

  Examples 9 to 12 with nonyl acid, the following results are obtained:

TABLE 4

  HYDROGENATION OF HEPTYLIC ACID ON RUN-OFF BED

  Mass Flow Iodine Number (Kg / m2 dry) Meq / g Feed Product

0.15 0.011 0.004

  Table 4 shows that the quality of heptylic acid can be improved by a continuous process

of soft hydrogenation.

EXAMPLE 15

  In theory, the hydrogenation can be done before or after final column treatment. In addition, hydrogenation of the product of the oxidation of n-heptanal or n-nonanal prior to distillation would be highly desirable from the starting point at which distillation to obtain the desired acid product would act as protection against training

  of powdersfines of the catalyst in the finished product.

  A blapat-hydrogenation comparison and the pre-bydrognatkian of the methylenic acid was performed on the bed of

  runoff described in Example 14.

  The nonyl acid reaction product obtained from the n-nononal oxidation was separated into two parts. Part of this reaction product was hydrogenated in the trickle bed reactor described in Example 14 under the same hydrogenation and catalyst conditions. The product was then distilled to give a product that could be called a pre-hydrogenated product. The other part of the product

  reaction of nonylylic acid was first distilled

  to isolate nonyl acid from the remaining reaction products. The distilled nonyl acid was then hydrogenated in the hydrogenation equipment at

  run-off bed according to the description of example 14

  under hydrogenation conditions and with a catalytic

  lyser to obtain a product that could be called a post-hydrogenated product. The following results were obtained: Reaction product of nonyl acid Nonyl acid Nonylated distilled nonhydrogenic acid post-prehydrogenated hydrogenated hydrogenated Iodine Meq / g 0.048 0.010 0.025

  The above data show that pre-hydrogenation

  is less effective than post-hydrogenation in reducing iodine value. However both products are more satisfactory than the product

  reaction of distilled nonhydrogenated nonylic acid.

  It was observed that the reaction product at the pre-hydrogenation stage rapidly deactivates the hydrogenation catalyst while there was no deactivation at the final post-hydrogenation stage according to the present invention. Therefore, the pre-hydrogenation process can not be considered reliable because of the deactivation of the hydrogenation catalyst. In all the examples described above, illustrating the processes of the present invention, no additional product has been observed in the hydrogenated products of heptylic and nonyl acids as shown by the typical gas chromatograms. Of course, the invention is not at all limited to the embodiment described and shown which has been given only as an example. In particular, it includes all means constituting equivalents

  described techniques, as well as their combinations.

  sounds, if they are executed according to his spirit and implemented as part of the protection

as claimed.

Claims (7)

R E V E N D I C A T I 0 N S   1. A process for improving the quality of C7-C7-saturated aliphatic monocarboxylic acids produced by oxidation of the corresponding C7-C9 aldehydes and recovery of the desired product, characterized in that the hydrogenation of said acid product is carried out as final phase in the presence a palladium catalyst at a hydrogen pressure of from about 1 to about 5 bar and at a temperature of about 20 to 50 C. 2. Method according to claim 1 characterized in that the catalyst is palladium on carbon and in that the amount of palladium varies from 0.1 to % by weight of the total catalyst.   3. Method according to claim I characterized in that the temperature varies from about 25 C to 350. 4. Process according to claim 1, characterized in that the hydrogen pressure varies from approximately 1 4 bars to 4 bars.   5. Method according to claim 2, characterized in that the catalyst is a palladium on carbon and in that the amount of palladium varies from approximately   0.5 to about 5% by weight, of the total weight of the catalyst.   6. Process according to claim 5, characterized in that the hydrogenated saturated monocarboxylic acid is heptylic acid.   7. Process according to claim 5, characterized in that the hydrogenated saturated monocarboxylic acid is nonyl acid.