MXPA06004995A - Method for the production of formic acid formates - Google Patents

Abstract

The invention relates to a method for the production of formic acid formates, wherein a flowing liquid (I) containing formic acid, and a flowing liquid (II) containing a metal formate, are provided. The flowing liquids (I) and (II) are guided to a rectification column such that a higher or equal guiding point for the liquid flow (II) is selected for the rectification column for the liquid flow (I). The liquid flows (I) and (II) in the rectification column are mixed by separating water via the head of the rectification column and the liquid flow is withdrawn from the rectification column, said liquid flow containing the formic acid formate. The invention is characterised in that the liquid flow is obtained as a melt containing at least 0.5 wt.%water.

Description

METHOD FOR THE PRODUCTION OF FORMATS OF ACID FORMATIC The invention relates to a process for preparing acid formats and to the use of the acid formats prepared by the method for preserving and / or acidifying plant and / or animal materials, for treating biological waste. and as an additive in animal nutrition or as a growth promoter for animals. The acid formats have an antimicrobial action and are used, for example, to preserve and also to acidify plant and animal materials, for example fats, agricultural products or meat, to treat biological residues or as an additive for animal nutrition. The acid formats are compounds and mixtures containing anions format (HC00 ~), cations (Mx +) and formic acid (HCOOH). They may be present together in the form of a solid or a liquid and may optionally comprise other components, for example other salts, additives or solvents, for example water. In general, the acid formats can be represented by the formula HCOO ~ Mx + 1 / x * and HCOOH (I), wherein M is an organic or inorganic, monovalent or polyvalent cation, X is a positive integer and refers to the cation charge e "y" provides the mole fraction of formic acid based on the anion format. The mole fraction of formic acid based on the anion format and "is generally from 0.01 to 100, preferably from 0.05 to 20, particularly preferably from 0.5 to 5, and especially from 0.9 to 3.1.The nature of the inorganic or organic cation Mx + it is in principle irrelevant provided that said cation has stability under the conditions in which the acid format must be handled, this includes, for example, the stability with respect to the reducing anion formate.Since inorganic cations are the cations of monovalent metals and / or polyvalent metals of groups 1 to 14 of the Periodic Table of the Elements, for example, lithium (Li +), sodium (Na +), potassium (K +), cesium (Cs +), magnesium (Mg2 +), calcium (Ca2 + ), estonian (Sr2 +) and barium (Ba2 +), preferably sodium (Na +), potassium (K +), cesium (Cs +), and calcium (Ca2 +) Possible organic cations are unsubstituted ammonium (NH4 +) and ammonium substituted by one or more Radicals that contain car which may optionally be linked together, for example, methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, pyrrolidinium, N-methylpyrrolidinium, piperidinium, N-methylpiperidinium or pyridinium. An organic radical containing carbon is an aliphatic, aromatic or araliphatic substituted or unsubstituted radical having from 1 to 30 carbon atoms. This radical may contain one or more heteroatoms, such as oxygen, nitrogen, sulfur or phosphorus, for example -0-, -S-, -NR-, -CO-, -N =, -PR- and / or -PR2 and / or can be substituted or one or more functional groups containing, for example, oxygen, nitrogen, sulfur and / or allogene, for example by fluorine, chlorine, bromine iodine and / or a cyano group (the radical R in this case it is in the same way an organic radical containing carbon). The organic radical containing carbon can be a monovalent or polyvalent radical, for example a divalent or trivalent radical. Several processes are known to prepare acid formats. In these processes, in general, a liquid stream I comprising formic acid and also a liquid stream II comprising a metal format are prepared and said liquid streams I and II are mixed to obtain a product stream containing acid format that it is optionally further processed. A process of this type is disclosed, for example, in DE-A 102 37 379. According to this document, the streams containing formic acid and metal form are combined, preferably to a column, which is advantageously operated in such a manner. that a part of the solvent fed, in general water, is removed. In this procedure, a bottom product can be obtained which contains acid format having a water content of 0.5 to 30% by weight, particularly having a water content generally less than or equal to 1% by weight. In contrast, in spite of the advantages expected in the further processing of the product stream containing acid format, a person skilled in the art could not have known until now that it was possible to obtain a product stream having a content of water remarkably lower compared to the known processes directly from the column in which the stream containing formic acid and the stream containing metal format are mixed. Accordingly, a process has been found for preparing acid formats wherein they are prepared: a liquid stream I comprising formic acid and a liquid stream II comprising a metallic format, the liquid streams I and II are fed to a rectification column in such a way that a feed point is selected to the highest rectification column or at the same height for the liquid stream II as compared to the liquid stream I, the liquid streams I and II are mixed in the rectification column, removing water from the head of the rectification column and extracting from the rectification column a bottom stream containing the acid format, the bottom stream is produced in the form of a melt containing less than 0.5% by weight of water. In a preferred embodiment of the process, a liquid stream I is prepared which contains relatively highly concentrated formic acid, that is to say it comprises at least 85% by weight of formic acid. Particularly preferably, the liquid stream I comprises at least 94% by weight, in particular 99% by weight, of formic acid. Advantageously in this case, commercially available types of formic acid are used, for example formic acid having a purity of 85%, 94%, or 99%. The liquid stream I mentioned above comprising formic acid is preferably an aqueous stream. The inventors recognized that when concentrated formic acid solutions are used, a lower residual water content can be obtained in the target product, which is extracted as a melt from the rectification column, where the liquid streams I and II are mixed , in particular a residual water content of less than 0.3% by weight, preferably within a range of 0.2 to 0.1% by weight, and especially from 0.1 to 0.5% by weight. The inventors also recognized that, with the tendency to decrease the water content in the liquid stream I, the other conditions remaining unchanged in the rectification column, decreases the water content in the melt extracted through the bottom.

The lower content of residual water in the melt has a decisive influence on the storage stability of the final product formulated, acid diformate: the lower the residual water content in the final product, the lower the tendency to the formation of cake 0 lumps An additional advantage compared to a process that has a higher water content in a liquid stream 1 is that, in order to obtain a melt having the same low water content, a smaller number of theoretical plates is sufficient, said number is in particular reduced from approximately 4 to 8 theoretical plates. Correspondingly, the rectification column can also be constructed in smaller size and therefore capital and operating costs can be reduced. Preferably, the liquid streams I and II are each aqueous streams. The process is not limited to the specific ways of preparing liquid streams I and II. Preferably, these may be provided in accordance with that described in DE-A 103 21 733 which is hereby explicitly incorporated in its entirety by reference in the contents of the present application. The liquid stream I can be obtained, for example, by partial hydrolysis of ethyl formate, which is indicated below by the abbreviation MeFo (process step (a) of DE-A 103 21 733) and distillation of unreacted MeFo and methanol. The liquid stream II can be obtained, for example, through the process variants described in DE-A 103 21 733. Accordingly, a stream comprising MeFo- and methanol can be converted, in a step of process c) in stream II containing metal format and containing water, by i) the reaction with a basic compound having a pKa of the conjugate acid of the corresponding dissociation state of = 3, in accordance with the measured at 25 ° C in aqueous solution, in the presence of water and ii) removal of methanol by distillation. For a more detailed description of process step c), reference is made to said DE-A 103 21 733. In a further alternative, it is possible to produce stream II containing metal format by carbonylation of the corresponding metal hydroxide . Said process is described in DE-A 102 37 380, the contents of which are hereby explicitly incorporated herein by reference in the present application. In the next process step for the preparation of acid formats, the prepared stream I containing formic acid and the prepared stream II containing the metal format are mixed in a rectification column. In this case it is possible and possibly advantageous to subject the liquid stream I containing formic acid and / or the liquid stream I containing metal format before mixing in the rectification column, to a formic acid concentration or metal format, in particular by removing a part of the water present by evaporation, preferably by distillation. It has been found that it is essential for the operation for the operation of the rectification column to select a higher or at least identical feed point for the liquid stream I as compared to the liquid stream I. The inventors have found that the presence of metal format in the widest possible regions of the column, especially in regions above the feed of the stream containing formic acid, is important for the substantial removal of water from the bottom stream. In this case it is essential that the metal format, in the column system, act as a tracer for the formic acid. Preference is given to an operation of the rectification column in which the background temperature in the rectification column is limited to a value lower than 135 ° C, in particular lower than a value of 125 ° C. For this purpose, a person skilled in the art will adjust the head pressure in the column accordingly, taking into account family considerations, especially the pressure drop that occurs in the column. In a preferred process variant, the feed point for the liquid stream I is selected at or above the uppermost separation stage of the rectification column, with correspondingly lower capital costs. In addition, or alternatively, the operating conditions in the column can be affected by the choice of the proportions of the liquid streams II and I; the proportion of the liquid streams II and I can be selected in such a way that the molar ratio between the metal form of the liquid stream I and the formic acid of the liquid stream I is greater than 1, lower preferably between 0.95 and 1.05, As a result, the losses of formic acid in the overhead stream of the rectification column may be limited, without requiring some enrichment in the rectification column for this purpose. In this case, it is possible to extract virtually pure water. In the selection of internal separation fittings For the rectification column, it is advantageous to take into account internal additives of low pressure drop with, at the same time, a good separation efficiency, preferably ordered packing. The number of theoretical es of the rectification column is calculated according to general methods usual in this field. For the present separation task, preference is given in general to a number of theoretical es comprised between 5 and 15. The invention also relates to the use of acid formats prepared through the process of the present invention for preserving and / or acidifying t and / or animal materials, to treat biological waste or as additives in animal nutrition and / or as growth promoters for animals. The extraction of the valuable material, the acid format, in the form of a melt having a water content of less than 0.5% by weight, in the process of the present invention as soon as the liquid streams containing the same are mixed in the column. Formic acid and metal format offers significant economic advantages. In particular, for the additional treatment of the melt extracted from the rectification column, apparatus different from the known apparatuses for the additional processing of product streams with a higher content in water are required which are less complicated and less susceptible to faults, especially cooling rollers or cooling belts, cooling es or granulation towers. This decreases capital costs compared to ts for conventional processes that have a higher water content in the product stream. Additional product steps, such as solid / liquid separations, crystallization and subsequent drying that are required in the known processes are unnecessary. The invention will be described in more detail below with reference to a drawing and example modalities. In the drawings: Figure 1 shows a diagrammatic representation of a "first embodiment of a t for carrying out the process of the invention and Figure 2 shows the diagrammatic representation of a further preferred embodiment of a t for carrying out the process of the present invention In the first embodiment of the process of the invention shown diagrammatically in Figure 1, a rectification column R is fed with an aqueous stream II comprising a metal format and underneath it is fed with a aqueous stream I comprising formic acid Above the feed of aqueous stream II an enrichment portion is ed In the rectification column R, the aqueous streams I and II are mixed and an overhead stream which contains predominantly water is extracted , said current is condensed in a condenser K in the upper part of the column, it is applied again partially to the column na as reflux and the rest is discharged. From the bottom of the column a melt comprising less than 0.5% by weight of water is extracted and solidified in or in a downstream apparatus E. From the downstream apparatus E, optionally after treatment in a compactor that does not shown, the product of desired particle size is extracted. The preferred embodiment shown in Figure 2 differs from the embodiment in Figure 1 by the aqueous stream II applied to the upper tray of the rectification column R. In this embodiment, the rectification column R therefore does not have an enrichment part. In this process variant, also, substantially pure water can be extracted in the upper part of the rectification column, provided that the ratio between the liquid streams II and I is selected in such a way that the molar ratio between the metal format from liquid stream II and formic acid from liquid stream I is greater than or equal to 1. Sample modalities In a laboratory column consisting of three or two sections each with a diameter of 30 mm, each with 10 bubble cap trays, potassium diformate fusions were produced. The column was operated in the form of a column of pure exhaustion. The feeds consisted of 75% aqueous potassium format in the upper tray of the column and aqueous formic acid, five trays down. Formic acid and potassium formate were fed stoichiometrically. Potassium diformate with different water contents was discharged at the bottom and at the top of the column was discharged virtually pure water containing formic acid residues of less than 1000 ppm. In the examples, the concentration of formic acid was varied in the feed. In addition, at each concentration of formic acid, a first experiment (indicated below by means of the suffix A) was carried out at a higher head pressure, and an additional experiment was carried out (indicated below with the suffix B) at a lower head pressure. Example 1A The concentration of formic acid in the feed was 30% by weight. The column consisted of 32 sections: the pressure drop in the column was approximately 35 mbar. The column was operated at a head pressure of 50 mbar. The background temperatures were between 132 and 135 ° C. In the melting at the bottom of the column, water contents of approximately 0.45% by weight were reached. Example IB The concentration of formic acid in the feed, the number of column sections and the pressure drop in the column remained unchanged with respect to example 1A. The column was operated at a head pressure of 20 mbar and a bottom temperature between 122 and 127 ° C. A melt with a water content of approximately 0.35% by weight was extracted from the bottom of the column. Example 2 A The formic acid concentration in the feed was 85% by weight. The column consisted of two sections; the pressure drop in the column was approximately 25 mbar. The column was operated at a head pressure of approximately 35 mbar. At a bottom temperature of about 126 ° C, water contents between 0.18 and 0.2% by weight were reached in the melt of potassium diformate extracted from the bottom of the column. Example 2 B The concentration of formic acid in the feed, the number of column sections and also the pressure drop in the column remained unchanged with respect to example 2 A. The pressure decreased to about 25 mbar. At a bottom temperature within a range of 124 to 12 ° C, water contents of about 0.08 to about 0.12% by weight were reached in the melt of potassium diformate extracted from the bottom of the column. Example 3 A The formic acid concentration in the feed was 94% by weight. The number of column sections and the pressure drop corresponded to that observed in example 2 A. The column was operated at a head pressure of approximately 35 mbar. At a bottom temperature of 126 to 128 ° C, water contents of about 0.08 to 0.1% by weight were reached in the melt of potassium diformate extracted from the bottom of the column. Example 3 B The formic acid concentration remained unchanged compared to Example 2 A. The number of column sections and also the pressure drop corresponded to that observed in example 2 A. The head pressure was reduced to approximately 25 mbar. At a bottom temperature of 124 to 126 ° C, a water content of about 0.05 to 0.7% by weight was reached in the melt of potassium diformate extracted from the bottom of the column. Example 4 A The formic acid concentration in the feed was 99% by weight. The number of column sections and also the pressure drop corresponded to that observed in example 2 A. The column was operated at a head pressure of approximately 35 mbar. At bottom temperatures of 124 to 126 ° C, water contents of about 0.05 to 0.8% by weight were reached in the melt of potassium diformate extracted from the bottom of the column. Example 4 B At a formic acid concentration without change in feed, head pressure was reduced to about 25 mbar. The number of column sections and also the pressure drop corresponded to that observed in example 2 A. The background temperatures and also the water content in the potassium diformate fusion extracted from the bottom of the column were in the same range as described in example 3 A. In the high concentration of formic acid used in examples 3 A and 3 B, no significant effect of the head pressure on the water content in the melt extracted from the bottom of the the column for a variation of head pressure from 35 mbar to 25 mbar. Examples 2 A, 2 B, 3 A, 3 B, 4 A, and 4 B show that in the preferred process using highly concentrated formic acid as initial stream I, particularly low water contents were reached in the melt extracted from the bottom of the column.

Claims (11)

1. CLAIMS 1. A process for preparing acid formats wherein they are prepared: a liquid stream I comprising formic acid and a liquid stream II comprising a metallic format, the liquid streams I and II are fed to a rectification column in such a way if a feed point is selected to the highest rectification column or at the same height for the liquid stream II in comparison, with the liquid stream I, the liquid streams I and II are mixed in the rectification column, removing water from the At the head of the rectification column and a bottom stream containing the acid format is extracted from the rectification column, the bottom stream is produced in the form of a melt containing less than 0.5% by weight of water.
2. 2. A process according to claim 1, wherein the formic acid content of the liquid stream I is at least 85% by weight.
3. 3. A process according to claim 2, wherein the formic acid content of the liquid stream I is at least 94% by weight, preferably at least 99% by weight.
4. 4. A process according to any of claims 1 to 3, wherein the liquid streams I and II are aqueous streams.
5. 5. A process according to any of claims 1 to 4, wherein the bottom stream comprises less than 0.3% by weight of water, preferably between 0.2 and 0.1% by weight of water, particularly preferably from 0.1 to 0.05. % by weight of water.
6. 6. A process according to any of claims 1 to 5, wherein the background temperature in the rectification column is limited to a value below 135 ° C.
7. 7. A process according to claim 6, wherein the background temperature in the rectification column is limited to a value below 125 ° C.
8. 8. A process according to any of claims 1 to 7, wherein the feed point for the liquid stream II is selected in the extreme upper separation stage of the rectification column or above said extreme upper separation stage.
9. 9. A process according to any of claims 1 to 8, wherein the ratio between the liquid stream II and the liquid stream I is selected in such a way that the molar ratio between the metal format coming from the liquid stream II and the formic acid coming from the liquid stream I is within a range of 0.95 to 1.05, preferably 1.
10. 10. A process according to any of claims 1 to 9, wherein the rectification column is equipped with internal separation fittings. of low pressure drop, preferably with ordered packing.
11. 11. A process according to any of claims 1 to 10, wherein the number of theoretical plates of the rectification column is selected from 5 to 15. SUMMARY OF THE INVENTION A process for the preparation of acid formats is proposed wherein: a liquid stream I comprising formic acid and a liquid stream II comprising a metallic format, the liquid streams I and II are fed to a liquid stream. a rectification column in such a way that a feed point is selected to the highest rectification column or at the same level for the liquid stream II as compared to the liquid stream I, the liquid streams I and II are mixed in the column of rectification, water being removed from the head of the rectification column and a bottom stream containing the acid format being extracted from the rectification column, the bottom stream occurring in the form of a melt containing less than 0.5% by weight of Water.