Process for preventing the deposition of polymers in a process for purifying (meth)acrylic acid

Abstract

This invention produces technical (meth)acrylic acid without being confronted with problems of fouling of systems to purify the crude reaction mixture of (meth)acrylic acid synthesis, due to the presence of glyoxal formed during synthesis. The invention is based on the addition or generation of quinoline derivative in a glyoxal-containing (meth)acrylic acid flow in a quinoline/glyoxal derivative molar ratio ranging from 0.1 to 5, during the purification steps, said quinoline compound with one of formulas (I) or (II): ##STR00001##
wherein, groups R.sub.1, R.sub.2, R.sub.3, and R.sub.4 independently denote a hydrogen atom or a C.sub.1-C.sub.6, or R.sub.1 et R.sub.2 C-alkyl group combine and together with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, preferably a phenyl group, and/or R.sub.3 and R.sub.4 combine and with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, preferably a phenyl group.

Claims

1. A process for preventing deposition of polymeric compounds during (meth)acrylic acid purification operations, wherein to at least one (meth)acrylic acid flow containing at least glyoxal as impurity, is added, at least one quinone derivative corresponding to one of formulas (I) or (II): ##STR00005## wherein, groups R.sub.1, R.sub.2, R.sub.3, and R.sub.4 independently denote a hydrogen atom or a C.sub.1-C.sub.6, or R.sub.1 et R.sub.2 C-alkyl group combine and together with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, and/or R.sub.3 and R.sub.4 combine and with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, said quinone derivative being added at a content expressed by the quinone/glyoxal derivative molar ratio of between 0.1 and 5. wherein the quinone derivative is generated in situ in said (meth)acrylic acid flow, from a hydroquinone derivative or a catechol derivative, and an oxidizing compound.

2. The process according to claim 1, wherein the quinone derivative is introduced directly in liquid form, in solution in an aqueous solvent or in solution in (meth)acrylic acid.

3. The process according to claim 1, wherein the quinone derivative is selected from 1,2-benzoquinone, 1,4-benzoquinone, naphthaquinone and anthraquinone.

4. The process according to claim 1, wherein the quinone derivative is 1,4-benzoquinone generated in situ from hydroquinone and 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (4-OH-tempo).

5. The process according to claim 1 wherein (meth)acrylic acid is of petrochemical origin.

6. The process according to claim 1 wherein (meth)acrylic acid is at least partially of renewable origin.

7. The process according to that claim 1 wherein said (meth)acrylic acid flow derives from a purification process comprising the extraction of (meth)acrylic acid by counter-current absorption in the form of an aqueous solution of (meth)acrylic acid.

8. The process according to claim 1 wherein said (meth)acrylic acid flow derives from a purification process comprising the extraction of (meth)acrylic acid by counter-current absorption at medium of a hydrophobic heavy solvent.

9. The process according to claim 1 wherein the said (meth)acrylic acid flow derives from a purification process without external organic solvent.

10. The process according to claim 1 wherein said (meth)acrylic acid flow contains at least 10% weight (meth)acrylic acid.

11. The process according to claim 1 wherein said (meth)acrylic acid flow contains at least 10 ppm of glyoxal.

12. The process according to claim 1 wherein said (meth)acrylic acid flow additionally contains at least one polymerization inhibitor.

13. The process according to claim 1 wherein the quinone derivative is added at a content expressed by the molar quinone/glyoxal derivative ratio of between 0.2 and 5.

14. The process according to claim 1 wherein said (meth)acrylic acid flow is a liquid feed flow for a distillation column, a distillation column condensate, or a distillation column reflux.

Description

DETAILED PRESENTATION OF THE INVENTION

(1) The purpose of the invention is to produce technical (meth)acrylic acid without being confronted with the problem of fouling of the systems used to purify the crude reaction mixture of (meth)acrylic acid synthesis, in particular due to the presence of glyoxal formed during the synthesis process.

(2) The invention is based on the addition of a quinoline derivative corresponding to one of the formulas (I) or (II) in a (meth)acrylic acid flow containing glyoxal during the purification steps, the quinoline/glyoxal derivative molar ratio being between 0.1 and 5.

(3) The term (meth)acrylic acid includes acrylic acid and methacrylic acid. Preferably, the (meth)acrylic acid is acrylic acid.

(4) The (meth)acrylic acid may be of petrochemical origin or at least partly of renewable origin.

(5) According to one embodiment of the invention, acrylic acid is derived from a production process using propylene or propane as a raw material.

(6) According to one embodiment of the invention, acrylic acid is obtained from a process using ethylene and CO.sub.2 as raw materials.

(7) According to one embodiment of the invention, acrylic acid is derived from a process using acetic acid as raw material.

(8) According to one embodiment of the invention, the methacrylic acid is obtained from isobutylene and/or tert-butanol, butane and/or isobutane.

(9) According to one embodiment of the invention, acrylic acid is derived from a production process using glycerol or glycerine as raw material.

(10) According to one embodiment of the invention, the acrylic acid is derived from a process for the dehydration of lactic acid or ammonium lactate, or of a process for the dehydration of 3-hydroxypropionic acid or of its ammonium salt. These compounds may be derived from the fermentation of biomass and/or sugars.

(11) The above mentioned synthesis processes all lead to the formation of crude (meth)acrylic acid, meaning to a reaction mixture constituted, apart from (meth)acrylic acid: of incondensable light compounds under commonly used temperature and pressure conditions: nitrogen, unconverted oxygen, carbon monoxide and carbon dioxide formed in small quantities by ultimate oxidation or rotating in a circle, by recycling, in the process, of condensable light compounds: in particular water, generated by the synthesis reaction or as diluent, unconverted acroleine light aldehydes, such as formaldehyde, acetaldehyde and glyoxal, formic acid and acetic acid, heavy compounds: furfuraldehyde, benzaldehyde, maleic acid and anhydride, benzoic acid, 2-butenoic acid, phenol, protoanemonin.

(12) By definition, a light compound is a compound whose boiling point is lower than that of (meth)acrylic acid under the pressure conditions used. A heavy compound is a compound whose boiling point is higher than that of (meth)acrylic acid under the pressure conditions used.

(13) In the following description of the invention, for the sake of simplification, reference will be made to acrylic acid only, but the characteristics and advantages of the invention also apply to methacrylic acid.

(14) The second manufacturing stage involves recovering the acrylic acid contained in the crude reaction mixture to turn it into technical acrylic acid.

(15) According to a first embodiment of the invention, the process for the recovery/purification of acrylic acid comprises the extraction of acrylic acid by counter-current absorption in the form of an aqueous solution of acrylic acid, generally followed by a dehydration step which is carried out in the presence of an acrylic acid solvent immiscible with water, but may in combination with water, form an azeotrope. A dehydration step by azeotropic distillation with the solvent enables the obtention of a separation of water effective and less expensive energy. It may also be coupled with liquid-liquid extraction separation.

(16) According to a second embodiment of the invention, the process for the recovery/purification of acrylic acid comprises the extraction of acrylic acid by counter-current absorption using a hydrophobic heavy solvent, generally followed by the separation by distillation of a mixture containing acrylic acid solution in the hydrophobic heavy solvent.

(17) These acrylic acid recovery/purification processes which furthermore carry out several distillation steps to eliminate the light and/or heavy compounds, are known in the prior art, and are for example described in patent documents WO10/031949 and WO11/114051 relating to the synthesis of acrylic acid from glycerol, to which reference may be made in the context of the present invention.

(18) According to another embodiment of the invention, the process for recovering/purifying acrylic acid does not use an external organic solvent. For example, the process as described in patent EP 2066613 B1 may be used, with just two distillation columnsa dehydration column and a finishing columnwithout introducing a solvent. Alternatively, the partial condensation method described in US2016/090347 may be used.

(19) Whatever the recovery/purification process used to recover technical acrylic acid, the glyoxal present as impurity in the medium to be treated is found in different flows during the various process operations. Indeed, it is a rather light compound, most of which is eliminated at the same time as acetic acid, but a sufficiently large part also distils with acrylic acid.

(20) The flow of acrylic acid into which a quinoline derivative is introduced to prevent the formation of insoluble polymers is preferably a liquid flow.

(21) This liquid flow may be a distillation column feed flow, or a distillation column condensate, or a distillation column reflux, in the purification process.

(22) Said acrylic acid flow generally comprises at least 10% by weight of acrylic acid, preferably at least 30% by weight, in particular at least 50% by weight of acrylic acid, and may comprise up to 99.5% by weight of acrylic acid.

(23) Said flow of acrylic acid further comprises at least 10 ppm of glyoxal, and may comprise a glyoxal content ranging from 10 to 5000 ppm.

(24) The acrylic acid content in the flows may be determined by gas phase or liquid phase chromatography and the glyoxal content can be determined by liquid chromatography.

(25) Said flow of acrylic acid may furthermore comprise at least one polymerization inhibitor, for example in particular from 50 ppm to 5% by weight, in particular from 0.01% to 3% by weight, relative to the medium containing the acrylic acid. The polymerisation inhibitor(s) may be selected from phenolic derivatives such as hydroquinone and its derivatives like hydroquinone methyl ether; 2,6-di-tert-butyl-4-methylphenol (BHT); and 2,4-dimethyl-6-tert-butylphenol (Topanol A); phenothiazine and its derivatives; manganese salts, such as manganese acetate; thiocarbamic or dithiocarbamic acid salts, such as metal thiocarbamates and dithiocarbamates, like copper di-n-butyldithiocarbamate; N-oxyl compounds, as 4-hydroxy-2,2,6,6-tetramethylpiperidinoxyl (4-OH-TEMPO); compounds having nitroso groups, including N-nitroso phenylhydroxylamine and its ammonium salts; amine compounds such as para-phenylenediamine derivatives.

(26) According to a particular embodiment of the invention, the flow of acrylic acid comprises phenothiazine as a polymerization inhibitor, at a content ranging from 50 ppm to 5% by weight, especially from 100 ppm to 1% by weight.

(27) The quinoline derivative corresponding to one of formulas (I) or (II) above is generally introduced in liquid form, in solution in an aqueous solvent, or in solution in acrylic acid.

(28) 1,4-Benzoquinone is preferably used as quinoline compound.

(29) Alternatively, the quinoline derivative may be generated in situ in the acrylic acid flow, in particular from a hydroquinone derivative or a catechol derivative, and an oxidizing compound, according to the following reaction schemes:

(30) ##STR00003##

(31) wherein, groups R.sub.1, R.sub.2, R.sub.3 and R.sub.4 meet the definitions defined above.

(32) According to one embodiment, groups R.sub.1 to R.sub.4 are the hydrogen atom, the in situ quinoline derivative generation being made from hydroquinone or catechol.

(33) This embodiment may be advantageous in order to avoid the delicate handling of certain quinol derivatives.

(34) Oxidation may be carried out using an oxidizing compound selected, for example, from metal salts, especially manganese or copper salts, or N-oxyl derivatives, in particular 4-OH-Tempo.

(35) According to a preferred embodiment of the invention, 1,4-benzoquinone is generated in situ by oxidation of the hydroquinone using an oxidizing compound such as 4-OH-Tempo, according to the following reaction:

(36) ##STR00004##

(37) The hydroxyl by-product generated at the same time as benzoquinone does not distil with acrylic acid because it is a higher boiling point compound, hence, it does not pollute the final technical acrylic acid.

(38) This embodiment is particularly advantageous because hydroquinone is a polymerization inhibitor widely used in acrylic acid manufacturing processes, and may already be present in the various acrylic acid flows comprising glyoxal. The formation of polymeric deposits during acrylic acid purification operations can be avoided by simply adding 4-OH-Tempo, in the form of a low-toxicity aqueous solution commercially available, with benzoquinone being generated in situ.

(39) The quinoline derivative content introduced into the acrylic acid flow to prevent fouling of the plant, expressed by quinoline/glyoxal derivative molar ratio is between 0.1 and 5. Preferably quinoline derivative is introduced so that quinoline/glyoxal molar ratio is between 0.2 and 5, preferably between 0.2 and 3, in particular between 0.5 and 2.

(40) According to a preferred embodiment of the invention a quinoline derivative, preferably 1,4-benzoquinone is introduced, or generated in situ.

(41) According to a preferred embodiment of the invention, a quinoline derivative, preferably 1,4-benzoquinone, is introduced into or generated in situ to feed the distillation column(s) in which acetic acid and glyoxal is concentrated in a process for producing acrylic acid from propylene.

(42) According to a preferred embodiment of the invention, a quinoline derivative, preferably benzoquinone, is introduced into an acrylic acid flow comprising from 90 to 99.5% by weight of acrylic acid, from 10 to 1000 ppm glyoxal and 100 to 10,000 ppm phenothiazine.

(43) The acrylic acid purifying process according to the invention comprising the adding of at least one quinoline derivative in a flow containing at least acrylic acid and at least glyoxal, can easily be part of any acrylic acid synthesis process.

(44) The following examples illustrate the present invention without limiting its scope.

EXPERIMENTAL PART

(45) The following abbreviations are used in the examples:

(46) BQ: 1,4-benzoquinone (CAS 106-51-4)

(47) NQ: Naphthalene (CAS 130-15-4)

(48) HQ: hydroquinone (CAS 123-31-9)

(49) PTZ: phenothiazine (CAS 92-84-2)

(50) 4HT: 4-OH-Tempo (CAS 2226-96-2)

Example 1

(51) 500 g of glacial acrylic acid was placed in a 2 litre flask and supplemented with 1000 ppm phenothiazine (PTZ).

(52) Various additions of glyoxal, in its commercial form of 40% by weight aqueous solution, were made, and the effect of different compounds in this medium was observed under the following conditions:

(53) The medium was placed in an oil bath at 110 C. under 230 mbar for 2 h. A 5 ml/min air bubble was applied for the duration of the experiment. At the end of the experiment, the liquid phase was emptied and any solids present were recovered, dried under vacuum and weighed.

(54) The various tests are summarised in table 1 below.

(55) TABLE-US-00001 TABLE 1 Glyoxal added (l of 40% Added compound (s) aqueous Glyoxal added Amount Mass of solid Testing solution) mmol/l Type Quantity (ppm) (mmol/l) measured (g) 1 references 0 0 / 0 0 2 20 0.37 / 0 1 3 50 0.93 / 0 11 4 100 1.86 / 0 >40 5 comparative 50 0.93 PTZ 20 0.11 13 6 50 0.93 PTZ 50 0.26 15 7 50 0.93 PTZ 100 0.53 15 8 100 1.86 PTZ 100 0.53 >40 9 100 1.86 PTZ 200 1.06 >40 10 100 1.86 PTZ 500 2.64 >40 11 50 0.93 HQ 20 0.19 11 12 50 0.93 HQ 50 0.48 10 13 50 0.93 HQ 100 0.95 10 14 100 1.86 HQ 100 0.95 >40 15 100 1.86 HQ 200 1.91 >40 16 100 1.86 HQ 500 4.77 >40 17 50 0.93 4HT 20 0.11 11 18 50 0.93 4HT 50 0.29 11 19 50 0.93 4HT 100 0.57 10 20 100 1.86 4HT 100 0.57 >40 21 100 1.86 4HT 200 1.14 >40 22 100 1.86 4HT 500 2.85 35 23 invention 50 0.93 BQ 20 0.19 4 24 50 0.93 BQ 50 0.49 0.7 25 50 0.93 BQ 100 0.97 0.3 26 100 1.86 BQ 100 0.97 25 27 100 1.86 BQ 200 1.94 0.5 28 100 1.86 BQ 500 4.86 0.2 29 100 1.86 NQ 150 1.00 14 30 100 1.86 NQ 300 1.99 2 31 invention 50 0.93 HQ 100 0.95 7 4HT 50 0.29 32 50 0.93 HQ 100 0.95 3 4HT 100 0.57 33 50 0.93 HQ 100 0.95 0.4 4HT 200 1.14 34 50 0.93 HQ 100 0.95 0.3 4HT 500 2.85 35 100 1.86 HQ 200 1.91 35 4HT 200 1.14 36 100 1.86 HQ 200 1.91 0.7 4HT 500 2.85

(56) The presence of more or less significant amounts of solids in the medium makes it possible to characterise the probability of fouling on an industrial scale.

(57) As shown in reference tests 1 to 4, polymerisation of acrylic acid occurs when glyoxal is present in the medium, even in the presence of 1000 ppm PTZ.

(58) The addition of an additional amount of PTZ (tests 5 to 10) does not prevent the polymerization of acrylic acid.

(59) With a separate addition of hydroquinone or 4-OH-Tempo, even at 500 ppm in acrylic acid, the formation of insoluble solids in the medium was noticed (tests 11 to 22).

(60) Benzoquinone and naphthaquinone have sufficiently inhibited the polymerization of acrylic acid to prevent the formation of insoluble solids that can lead to fouling of the plant (tests 23 to 30).

(61) The simultaneous addition of hydroquinone and 4-OH-Tempo in proportions enabling the generation of benzoquinone in situ at different levels leads to the same result (tests 31 to 36).

Example 2: Use of Benzoquinone as-it, Continuous Test

(62) An industrial flow of acrylic acid containing about 50 ppm of glyoxal (0.91 mmol/l), 200 ppm HQ (1.91 mmol/l) and supplemented with 1000 ppm of PTZ was injected at a rate of 100 g/h in a glass thermosiphon reboiler of approximately 200 ml, surmounted by a total reflux condenser and equipped with an overflow (i.e. a residence time of 2 h). The reboiler operates at 110 C. in the liquid under a pressure of 380 mbar. The fouling of the reboiler was visually observed, in the absence of benzoquinone, and in the presence of 100 or 200 ppm of benzoquinone (respectively 0.97 mmol/l and 1.94 mmol/l).

(63) After 1.5 hours of operation in the absence of benzoquinone, the experiment had to be stopped due to heavy fouling of the reboiler.

(64) In the presence of benzoquinone, the experimental set-up was still clean after 8 hours of experience.

Example 3: Use of the In Situ Generated Benzoquinone, Continuous Test

(65) An industrial flow of acrylic acid containing about 50 ppm of glyoxal (0.91 mmol/l), 200 ppm HQ (1.91 mmol/l) and supplemented with 1000 ppm of PTZ was injected at a rate of 100 g/h in a glass thermosiphon reboiler of approximately 200 ml, surmounted by a total reflux condenser and equipped with an overflow (i.e. a residence time of 2 h). The reboiler operates at 110 C. in the liquid under a pressure of 380 mbar. The fouling of the reboiler was visually observed, without further additions, and adding 200 and 500 ppm of 4-OH-Tempo (respectively 1.14 mmol/l and 2.85 mmol/l), in order to generate benzoquinone in situ from the HQ already contained in the medium.

(66) After 1.5 hours of operation in the absence of 4-OH-Tempo, the experiment had to be stopped because of heavy fouling of the reboiler.

(67) In the presence of 4-OH-Tempo to generate benzoquinone, the experimental set-up was still clean after 8 hours of experience.