RU2043332C1 - Process for recovering n-butyric aldehyde from propylene hydroformylation product - Google Patents

Abstract

FIELD: petrochemical synthesis. SUBSTANCE: the product: n-butyric aldehyde. Recovery conditions: rectification; the separating agent includes paraffin C₇,-hydrocarbons; the separating agent to butylformates weight ratio is (1-8):1; the starting material: n-butyric aldehyde, isobutyric aldehyde, pentane-hexane fraction, butylformates, butanols, dimeric and trimeric products, and water. EFFECT: improved recovery process. 2 cl, 12 tbl

Description

 The invention relates to chemical technology, more precisely, to an improved method for the separation of n-butyric aldehyde (NMA) from mixtures containing isobutyric aldehyde (IMA), pentane-hexane fraction of saturated hydrocarbons (PHF), butyl formates, which form azeotropic systems with NMA.

 The bulk of NMA in industry is obtained by the technology of oxosynthesis based on the reaction of hydroformation of propylene using cobalt hydrocarbonyls as a catalyst. As a solvent, hydroformylation reactions for processes in which a commodity NMA is obtained use toluene, butanols, trimeric fractions of oxosynthesis, i.e. solvents that do not form azeotropic systems with NMA and have significantly higher boiling points.

 Large-scale plant for the production of n- and iso-butanols, includes a stage of hydroformylation of propylene on a cobalt-containing catalyst using PHP as a reaction solvent, a stage of distillation of aldehydes, water, PHF, butanols, butyl formates and other impurities on the evaporator from the catalyst, a stage of hydrogenation of distillation followed by the isolation of butanols and PHF distillation.

 Ways to isolate NMA from products containing IMA, PHF, water, butyl formates were not detected. It was previously noted that it is difficult to isolate NMA from these mixtures and this explains why PHF is not used as a solvent for hydroformylation reactions when obtaining NMA oxosynthesis as a target product, despite the advantages of this solvent in terms of selectivity and conversion of the reaction, as well as its low cost.

 The difficulty in isolating NMA from mixtures containing IMA, water, butyl formates, n-hexane and isohexanes (the latter are part of PHF) is that the presence of isohexanes and n-hexane in the mixture significantly reduces the relative volatility of the components in the NMA systems butyl formates, which makes these components are difficult to separate by simple rectification (i.e. without a separating agent.

 Known methods for the separation of boiling oxygen-containing products by distillation using separating agents. In one of the works for the separation of boiling components of alcohols, aldehydes, ethers as R. a. they recommend the use of formamides specially synthesized for this purpose, and dimethylacetamide, lactic acid monoethylamine, glycolic acid diethylamide are used for another purpose. The materials of these methods do not provide specific data (quality of separation products, yield) for mixtures of aldehydes and esters. Nevertheless, the most effective R.a. of the recommended ones were tested for the isolation of intangible intangible substances from mixtures with PHF. As follows from the data of the following example 7, the separating effect of furfural is the most effective of these R. low: the purity of the allocated intangibles is 97.4%; the yield from the potential is 89.2 wt.

 The disadvantage of these R.a. is their high thermolability, corrosiveness, high cost, most of them are bought for currency. A known method of separating NMA from a hydroformylation product of propylene using toluene as a reaction solvent and containing NMA, IMA, butyl alcohols, butyl formates, water, toluene, dimeric and trimeric products (prototype).

The specified product is sent to the power of distillation column K-1 with an efficiency of 40 tons operating at a top pressure of 1000 mmHg cube 1280 mmHg top temperature 73-75 ^о С, cube 170 ^о С, with irrigation multiplicity 1.5.

 Gases are separated at the top of the column, which are separated and removed from the system, IMA 21.76% NMA 75.37 wt. water 1.91 wt. butyl alcohols 0.27 wt. butyl formates 0.23 wt. butyl ethers 0.06 wt. butyric acid 0.03 wt.

 Lateral selection in the vapor phase from the stripping section of the column allocate, wt. toluene 72.26; IMA 0.5; NMA 1.76; isobutanol 11.65; n-butanol 8.49; dimers 2.04; butyl formates 3.06; butyric acid 0.24.

 At the bottom of the column output product containing toluene 9.64 wt. the rest is dimers, trimers and cobalt salts.

The top product of the K-1 column is sent to the feed of the K-2 column with an efficiency of 50 t.t. operating at a top pressure of 1000 mmHg bottom 1350 mm RT. Art. the temperature of the top is 65-70 ^о С, the bottom is 95-100 ^о С, the irrigation ratio is 14.0.

 At the top of the K-2 column, isobutyric aldehyde of the composition, wt. propane 0.75; propylene 0.07; IMA 95.83; NMA 0.91; water 2.44.

 At the bottom of the column allocate the target intangible assets, composition, wt. IMA 0.98; NMA 97.99; isobutanol 0.35; toluene 0.26; butyl formates 0.30; butyric acid 0.04; butyl esters 0.08.

 The output of NMA from the potential content of 96.4 wt.

 The disadvantage of this method is the low purity and yield of the target NMA, isolated from the hydroformylation product containing PHF and butyl formates. This follows from the data of example 5 of this application. Even when using highly efficient columns operating at high irrigation rates, the purity of the NMA produced is 94.59 wt. yield 90.9 wt.

The purpose of the invention is to increase the yield and purity of NMA released from propylene hydroformylation products containing IMA, PHF, water, butyl formates and other impurities. The essence of the proposed method is as follows. The product of hydroformylation of propylene composition, wt. IMA 13-18 NMA 48-59 Isobutanol 0.5-1.3 n-Butanol 0.8-1.6 PHF 13-25 Butyl formates 1.2-2.0 Oily acids 0.2-0.6 Butyl esters 0 , 03-0.08 Water 0.8-2.0 Dimers 1-3
The group chromatographic composition of PHF used at the Salavat NHC, including 0.01-0.12 wt. C ₄ hydrocarbons; 55-80 wt. C ₅ hydrocarbons; 20-45 wt. C ₆ hydrocarbons are fed to the distillation column K-1 with an efficiency of 30-40 t.t. operating at a pressure of 1.1-1.7 atmospheres, in the presence of a separating agent (p.a.). As a p.a. use n-heptane, isoheptanes in a mixture or individually, taken in an amount in which the mass ratio of R. a is established in the column feed. butyl formates in the range (1-8): 1. At the top of the K-1 column, IMA, water, PHP with impurities of butyl formates, butanols, and NMA (3-5% of the potential) are isolated. The specified distillate is directed to hydrogenation in order to obtain butanols. PHF and R.A. isolated from the hydrogenation product by distillation and recycled to the process.

The bottoms product of the K-1 column contains NMA, butanols, non-separated NAK-1 butyl formates, dimeric products, butyric acids, which feed the K-2 columns with an efficiency of 20-30 tons operated at a reflux ratio of 3-4, the top temperature of 75-82 ^{° C,} 113-120 ° ^C cube

The target NMA is isolated at the top of the K-2 column, butanols, dimers, butyric acids are sent at the bottom, which are sent to hydrogenation and rectification in order to obtain C ₈ alcohols.

 The lower limit of the claimed ratio of R.A. butyl formates is determined by the intended purpose the allocation of NMA with a purity of not less than 98.0 wt. The upper limit of economic considerations: an increase in the number of p.a. inexpedient, because it does not affect a further increase in the effect.

 A common feature of the proposed and known method is a two-column scheme for the allocation of NMA from the product of propylene hydroformylation. An essential distinguishing feature is the organization of a rectification scheme. In the proposed method, at the top of the K-1 column, all IMA, PHF, water and most of the butyl formates are isolated, the majority of NMA is withdrawn as a bottoms product of the column. In the known method, PHF, IMA, water, butyl formates and the majority of NMA are isolated at the top of the K-1 column.

 The target NMA in the proposed method is isolated at the top of the K-2 column, in the known method at the bottom.

The second significant distinguishing feature of the proposed method is the rectification process in a K-1 column in the presence of C ₇ paraffins as a separating agent, taken in a mass ratio with butyl formates equal to (1-8): 1.

 Use of R.A. in the specified ratio can improve the quality and yield of the target product.

 A comparison of the following examples 1,4,5 shows that when using p. a. in the ratio with butyl formate and equal to 5: 1, the purity of the released NMA is 99.21 wt. yield 96.0 wt. Without the use of R.A. purity NMA 97.07 wt. yield 88 wt. when working according to the known method, the purity of 94.59 wt. yield 90.9 wt.

The separating effect of C ₇ paraffin hydrocarbons in the NMA systems of butyl formates in the presence of PHF is not an obvious fact and cannot be predicted theoretically; data on phase equilibria in the NMA system of butyl formates of PHF water C ₇ paraffin hydrocarbons are absent in the literature, which does not allow simulating the computer separation under consideration , i.e. the proposed solution meets the criterion of non-obviousness.

 The proposed method for the allocation of intangibles is easily implemented on two distillation columns.

 Thus, the proposed method allows to increase the purity of the allocated NMA from 94.6 to 99.2 wt. potential yield from 89 to 96 wt.

 The main results of examples 1-9 are shown in the summary table.10.

 PRI me R 1 (average values of the claimed parameters).

The product of hydroformylation of propylene composition, wt. IMA 14.01 NMA 49.72 Isobutanol 0.86 n-Butanol 10.67 PHF 19.68 Dimers 2.22 Water 0.99 Butyl formates 1.38 Oily acids 0.42 Butyl ethers 0.05 in the amount of 1106.2 kg / h are sent to the 20th plate of a distillation column having 60 valve plates. Together with the raw materials, the columns are introduced into the diet as r.a. 76.5 kg / h of paraffins C ₇ , composition, wt. 2,2-dimethylpentane 14.9; 2-methylhexane 32.7; 3-methylhexane 26.4; n-heptane 18.0, admixtures of paraffins C ₆ , C ₈ 3.8; cyclo-C ₆ -C ₈ 4,2 extracted from rectification clear pryamogennoy gasoline fraction 62-105 ° ^C.

 The ratio of R.A. and butyl formates 5: 1.

The efficiency of the column in theoretical plates is 30 tons the reflux ratio 6.0, the top pressure of 1.3 atm, 1.7 atm bottom, top temperature of 62 ^{° C,} bottom 88 ° ^C.

 As the distillate of the K-1 column, 486.9 kg / h of the product of the composition shown in Table 1 of the material balance of the experiment are isolated.

Said product is subjected to hydrogenation at alyumotsinkhromovom catalyst at a pressure of 308 atm, a temperature of 320 ^{° C,} at a volumetric feed rate of the liquid aldehyde product 2.0 h ^-1. The result is a hydrogenated composition, wt. IMA 0.92; NMA 0.12; isobutanol 30.9; n-butanol 2.62. PGF 45.63; water 2.38; butyl formates 0.11; R.A. 17.32.

 The specified product is sent to the feed distillation column with an efficiency of 30 tons working at a reflux ratio of 5.0, with a top pressure of 0.3 ati, a bottom of 0.45 ati. At the top of the column, PHF is recovered, returned to the hydroformylation stage, with a side stream in the liquid phase with 12 t from the top of the column bottom butanol sent for purification according to the scheme applicable at the Salavat NHC.

The bottoms product of the K-1 column containing NMA, butanols, butyl formates not separated into K-1, dimeric products; butyric acids are sent to the power of the K-2 column with an efficiency of 26 tons operated at a reflux ratio of 3.6, a temperature of 76 ^{° C} top, cube 118 ^C. As the top K-2 is isolated target NMA purity 99.21 wt. with a yield of potential of 96.0 wt. The component-wise material balance of experience is given in Table 1.

 PRI me R 2 (the lower boundary of the ratio of RA and butyl formates).

 The raw material composition shown in example 1 is subjected to separation analogously to example 1 with the difference that the ratio of R.A. and butyl formates in the K-1 column corresponds to the lower claimed boundary, namely 1: 1.

 The component-wise material balance of experience is given in Table 2.

 As a result, NMAs with a purity of 98.0% are isolated with a yield of 94.0 wt.

PRI me R 3 (the upper boundary of the ratio of R.A. and butyl formates)
The raw material composition shown in example 1 is subjected to separation analogously to example 1 with the difference that the ratio of R.A. and butyl formates in the K-1 column corresponds to the upper claimed boundary, namely 8: 1.

 The component-wise material balance of experience is given in Table 3.

 As a result, NMAs with a purity of 99.27 wt. with a yield of 96.4 wt.

 PRI me R 4 (comparative, distillation without s.a.).

 The raw material of the composition shown in example 1 is subjected to separation analogously to example 1 with the difference that the separating agent is not introduced into the K-1 column.

 The component-wise material balance of experience is given in Table 4.

 As a result, NMAs with a purity of 97.07 wt. with a yield of 88 wt.

 PRI me R 5 (according to the prototype method).

The raw material composition shown in example 1, is subjected to separation on a column with an efficiency of 40 tons operating at a top pressure of 998 mmHg cube 1248 mm RT. Art. top temperature of 69.2 ^{° C,} cube 168 ^{° C,} at a reflux ratio of 1.5.

The distillate product of the K-1 column is sent to the feed of the K-2 column with an efficiency of 50 t.t. operating at an upper pressure of 993 mmHg bottom 1344 mmHg top temperature of 67 ^{° C,} bottom 97 ^{° C,} a reflux ratio of 14.0.

 At the bottom of the K-2 column, the target NMA is displayed.

 The component-wise material balance of experience is given in Table 5.

 As a result, NMAs with a purity of 94.59 wt. with a yield of 90.9 wt. During the experiment in the K-1 column with a column efficiency of 60 tons and a reflux ratio of 8.0, and in the K-2 column with an efficiency of 73 tons and reflux number 23.0, NMA is isolated with a purity of 96.1 wt. with a yield of 92.1 wt. those. increasing the efficiency of the column and the reflux ratio does not lead to a significant improvement in separation.

 PRI me R 6 (comparative, according to the prototype method, the raw material does not contain PHF).

 The raw material composition shown in table 6 and not containing PHF, shared analogously to example 5.

 The component-wise balance of experience is given in Table 6. As a result, NMA with a purity of 98.0 wt. with a yield of potential of 96.5 wt.

 A comparison of the data of examples 5 and 6 shows that the presence of PHF in the raw material worsens the rate of NMA release by a known method.

 PRI me R 7 (comparative, by the method-analogue).

 The raw material of the composition shown in example 1, is subjected to separation analogously to example 1 with the difference that as p.a. in the K-1 column, furfural is used. The ratio of R.A. and raw materials 5: 1. The target NMA is isolated at the top of the K-2 column.

 The component-wise material balance of experience is given in Table 7.

 As a result, NMAs with a purity of 97.44 wt. with a yield of 89.3 wt.

 PRI me R 8 (another composition of the raw materials for separation).

 The raw materials of the composition shown in table 8, different from that shown in example 1, which is obtained by changing the mode of the stages of hydroformylation of propylene and oxidative decobaltization, is subjected to separation analogously to example 1.

 The component-wise material balance of experience is given in Table 8.

 As a result, the target NMA is isolated with a purity of 99.31 wt. with a yield of 94.8 wt.

 PRI me R 9 (R.A. 2-methylhexane).

The raw material of the composition shown in example 8 is subjected to separation analogously to example 8 with the difference that as p.a. use individual paraffin C ₇ 2-methylhexane.

 The component-wise material balance of experience is given in Table 9.

 As a result, the target NMA is isolated with a purity of 99.31 wt. with a yield of potential of 94.1 wt.

 PRI me R 10 (comparative, the raw material of example 1, a separating agent-2-methylhexane).

The raw material of the composition shown in example 1 is subjected to separation analogously to example 1 with the difference that the individual isoparaffin C ₇ 2-methylhexane is used as the separating agent. The component-wise material balance of experience is given in Table 10. As a result, the target n-butyraldehyde is isolated with a purity of 99.29 wt. with a yield of 95.3 wt.

 PRI me R 11 (comparative, raw material of example 1, a separating agent-n-heptane).

 The raw material of the composition shown in example 1, is subjected to separation analogously to example 1 with the difference that n-heptane is used as the separating agent. The component-wise material balance of experience is given in Table 11. As a result, the target n-butyraldehyde is isolated with a purity of 99.18 wt. with a yield of 93.8 wt.

 Summary data for the examples are given in table. 12.

Claims (2)

1. METHOD FOR ISOLATING N-OIL ALDEHYDE FROM A PROPYLENE HYDROFORMILIZATION PRODUCT, containing, in addition to n-butyraldehyde, isobutyric aldehyde, pentane-hexane fraction, butyl formates, butanols, dimeric and trimeric products, which are different from water, water, and the first column is carried out in the presence of a resolving agent - paraffinic hydrocarbon composition C ₇ at a mass ratio in the column feed separating agent: butyl formate (1-8): 1, with separation along the top of the first column separating aga that, pentane-hexane fraction, isobutyraldehyde, water and butyl formate, and on top of the second column of the target n-butyraldehyde. 2. The method according to claim 1, characterized in that 2-methylhexane, 3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane in a mixture or individually are used as paraffin hydrocarbons of composition C ₇ .

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