RU2284313C1 - Butanol-butyl formate fraction processing method - Google Patents

Abstract

FIELD: industrial organic synthesis and catalysts.

SUBSTANCE: invention relates to a method for processing of butanol-butyl formate fraction obtained in propylene hydroformylation process, which method comprises reduction of butanol-butyl formate fractions with hydrogen at 200-280°C, pressure 1-30 atm, and volumetric feedstock and hydrogen supply rate 0.1-0.5 and 50-500 h-1, respectively. Reaction is carried out on catalyst having following chemical analysis, wt %: copper oxide 48.0-63.0, zinc oxide 9.0-18.1, chromium oxide 19.0-34.8, graphite 1.0-5.1 and activity index below 40 to form butyl alcohols and carbon oxide as final products. Method allows using real non-diluted butanol-butyl formate fractions and achieving following results: conversion of butyl formates 94.5-99.5%, content of methanol and high-boiling products in hydrogenate 0.8-1.5 and 2.9-3.5%, respectively.

EFFECT: enhanced process efficiency.

4 tbl, 2 ex

Description

The invention relates to the field of petrochemical synthesis, more specifically to methods for producing butyl alcohols by decomposition of butyl formates on heterogeneous catalysts.

In industry, butyl alcohols are mainly obtained by hydrogenation of butyric aldehydes - products of the propylene hydroformylation process. Among the most significant by-products of this process are butyl formates, the amount of which is 2-8 wt.% Of the total oxygen-containing compounds obtained by hydroformylation. Since butyl formates form azeotropic mixtures with butanols, their presence significantly complicates the isolation of the latter in pure form at the stage of rectification of alcohols. Therefore, the bulk of butyl formates are preliminarily selected, at the stage of rectification of decobaltized mixtures of hydroformylation products in the form of a butanol-butyl formate fraction (BBP fraction), in which the content of the main components is (wt.%): Butanol 30-50, butyl formate 35-65, ethers 1-5, high boiling products (VKP) 0.5-2. In the presence of an acceptable method for the processing of butyl formates into butanols, this fraction can serve as a significant source of additional quantities of commodity alcohols. The aim of the present invention is to provide an effective method for processing BBP fractions.

Known methods for the chemical cleavage of butyl formates by heating in the presence of alkalis, acids, ion-exchange resins or alkaline salts of lower carboxylic acids (Shmuk R., Daute R. et al., Sat. Production of oil aldehydes and butyl alcohols. Part 1, L., VNIINeftekhim, 1970, p. 86-99). Using these methods, butyl formates are decomposed to butanols, CO, CO ₂ , H ₂ O. However, this method of processing butyl formates is characterized by the presence of a large amount of wastewater contaminated with salts of organic and mineral acids and, as industrial practice has shown, has proved to be economically disadvantageous.

It is economically feasible to break down butyl formates in the presence of heterogeneous catalysts in a hydrogen atmosphere. In this case, the conversion of butyl formates can proceed in two directions:

1) the decomposition of formates with the formation of butanols and carbon monoxide and

2) hydrogenation to alcohols - butanols and methanol. The amount of the latter in the BBP fraction hydrogenate can reach 20 wt.%, Which significantly complicates the isolation of commodity butanol from it, and the BBP fraction hydrogenate containing 70-80 wt.% C ₄ alcohols is used in this case mainly as an oxygen-containing additive to gasolines .

To obtain an additional quantity of commercial butanol from the BBP fraction, it is advisable to carry out its decomposition in the first direction. Nickel catalysts (copper-nickel, nickel on alumina or silica with alkaline modifiers) provide almost complete conversion of alkyl formates at atmospheric pressure, a space feed rate of 0.2-0.5 h ^-1 and temperatures up to 160 ° C with the release of by-products (simple butyl ethers, butyl ethers of butyric acids) up to 2 wt.%. However, these catalysts in the presence of already small amounts of butyric acids (constantly present in the fraction) quickly lose their activity, the fall of which must be compensated by an increase in temperature. The latter caused a sharp increase in the number of VKP: at 160 ° С - 2%, at 170 ° С - 12%, at 180 ° С-22%.

Iron-chromium catalysts are more stable during the decomposition of butyl formates (GDR Patent No. 109372, 12 C 5/02). These catalysts are applicable for the decomposition of butyl formates at temperatures above 250 ° C and are characterized by low selectivity. At 275 ° C and atmospheric pressure, the loss of C ₄ alcohols already reaches 16%. To increase the selectivity of the process at temperatures of 250-320 ° C, pressures of 1-250 atm, it was proposed to add water in the amount of 1-5 moles per mole of formate to the feedstock (SU 566449, C 07 C 29/24). However, this significantly complicates the stage of rectification and increases the loss of target products, because water forms azeotropic mixtures with butanol.

A known catalyst for the hydrogenation of mixtures of carbonyl compounds, consisting in unreduced form of oxides of copper, iron, aluminum and manganese (US Patent 5,243,095, C 07 C 29/147, C 07 C 29/132). At temperatures of 250-350 ° C and pressures of 105-316 atm, the catalyst allows hydrogenation of aldehydes, ketones, carboxylic acids and their esters to the corresponding alcohols. However, at such relatively high hydrogen pressures, the conversion of formates on this catalyst will take place in the aforementioned undesirable direction.

The closest solution to the problem in its technical essence is a method for producing butyl alcohols by hydrogenation of products of hydroformylation of propylene (SU 1087510 С 07 С 31/12; С 07 С 29/14 - prototype), which use a skeletal catalyst containing nickel, molybdenum, copper and aluminum in the following ratio of components, wt.%:

nickel 35-45 molybdenum 0.5-10 copper 1-15 aluminum rest.

According to this method, the process of hydrogenating a mixture of hydroformylation products of the propane propylene fraction, including oil aldehydes, butyl alcohols, water, dibutyl ether, dibutyl butyral, butyl butyrate, 2-ethylhexenal and 2-ethylhexanal, is carried out at temperatures of 110-140 ° C, pressures of 300-310 at feed rates of raw materials and hydrogen, respectively 3-6 and 6-17 h ^-1 . The catalyst is characterized by increased activity, providing at such relatively high feed rates, the conversion of oil aldehydes is 96-99% and the total yield of alcohols is 80-103%. The disadvantage of this method, as described above, is the need to work with a high hydrogen pressure, in which formates (if present in the feed) will be hydrogenated to butanols and undesired methanol. In addition, the use of skeletal catalysts is associated with the need to utilize a large amount of alkali-contaminated wastewater generated during the catalyst activation stage.

We propose a method for the decomposition of butyl formates present in the BBP fraction at a temperature of 200-280 ° C, a pressure of 1-30 at, bulk feed rates of hydrogen and hydrogen, respectively 0.1-0.5 and 50-500 h ^-1 on a brand catalyst K-140 having the following characteristics:

- Chemical composition (wt.%):

copper oxide 48.0-63.0 zinc oxide 9.0-18.1 chromium oxide 19.0-34.8 graphite 3.0-5.1

- The activity index is less than 40 (the conversion of ethyl acetate in the reaction of its hydrogenation in a flowing laboratory apparatus at a pressure of 1 atm, a temperature of 240 ° C, a volumetric feed rate of 0.2 h ^-1 , a molar ratio of hydrogen: ether = 10: 1 - test reaction to assess the activity of copper-chromium catalysts for the hydrogenation of carbonyl-containing compounds, including catalyst K-140 (TU 2172-013-2392878-98; Koshelev Yu.N. et al., Oil refining and petrochemistry, 1986, No. 3, p.16-17 )

The catalyst is preliminarily reduced at elevated temperature in nitrogen circulating at a speed of 500-4000 h ^-1 and at a pressure of 0.05-3 atm, followed by a gradual replacement of nitrogen by hydrogen (SU 2178781, С 07 С 29/141, 31/125) .

Distinctive features of the proposed method is the use of a catalyst other than in the known chemical composition and having reduced activity in the hydrogenation reaction.

The advantage of the proposed method lies in the possibility of working with real undiluted BBP fractions with the following indicators: conversion of butyl formates 94.5-99.5%, methanol content in the hydrogenate 0.8-1.5 wt.%, VKP 2.9-3 5 wt.%.

Industrial applicability of the proposed method is illustrated by the following examples.

Example 1

Three samples of 50 cm ^{3 of} catalyst K-140, deactivated during long-term operation during the hydrogenation of isobutyric aldehyde into isobutanol and passivated in a known manner, by passing nitrogen, with an oxygen content of 0.1-3 vol.% At a temperature of 200-220 ° C ( A reference guide to catalysts for the production of ammonia and hydrogen, edited by V.P. Semenov. - L .: Chemistry, 1973, p.213), respectively, are selected from the upper, middle and lower shelves of an industrial reactor. Samples had the following characteristics. Chemical composition (the same for all major components), wt.%: Copper oxide - 57.5; zinc oxide - 12.9; chromium oxide - 23.8. Activity index: sample from the upper shelf - 28%, from the middle shelf - 31%, from the lower - 38%. The fresh sample before loading into the reactor had an index of 46% (according to the Technical Conditions, a fresh K-140 grade catalyst of acceptable quality should have an activity index greater than or equal to 40%).

The samples are alternately loaded into a laboratory flow unit, restored with a mixture of hydrogen with nitrogen, gradually raising the temperature to 240 ° C, and tested in the process of decomposition of a sample of industrial BBP fraction under the following conditions:

The first sample is a temperature of 200 ° C, a pressure of 20 atm, and volumetric feed rates of liquid feed and hydrogen, respectively, 0.1 and 500 h ^-1 .

The second sample is a temperature of 240 ° C, a pressure of 5 atm, and volumetric feed rates of liquid raw materials and hydrogen, respectively 0.3 and 250 h ^-1 .

The third sample is a temperature of 280 ° C, a pressure of 1 atm, and volumetric feed rates of liquid feed and hydrogen, respectively, 0.5 and 50 h ^-1 .

The compositions of raw materials, hydrogenates and the conversion of butyl formates are shown in table 1.

Table 2 presents the material balance of the experiment using sample No. 3 as a catalyst. The balance is given without taking into account hydrogen, the share of which among the substances that took part in chemical transformations is only 0.03-0.05%. In the table. Figure 2 also shows the yield of butanols calculated on converted formates and oil aldehydes.

The hydrogenated experiment with sample No. 3 was subjected to distillation on a laboratory column with twenty theoretical plates. Isobutanol and n-butanol were isolated, which in terms of quality satisfy the requirements of GOST 9536-79, amendment 1-3 (1 grade) and GOST 5208-81, amendment. 1-3 (1 grade) with yields of 68% and 80%, respectively.

Example 2

The example illustrates the inefficiency of the use of catalysts active in the hydrogenation reaction during the decomposition of industrial BBP fractions.

Two fresh samples of K-140 catalyst of various industrial batches with a volume of 50 cm ³ each (samples nos. 4 and 5) are alternately loaded into a laboratory flow unit. Samples had the following characteristics. Sample No. 4 in chemical composition and activity index fully corresponded to the fresh catalyst sample from Example 1. The chemical composition of sample No. 5, wt.%: Copper oxide - 58.1, zinc oxide - 11.5, chromium oxide - 22.4; the activity index value is 42. The samples are restored analogously to example 1 and are tested in the process of decomposition of the BBP fraction under the same conditions for both, identical to the experience with sample No. 3 of example 1: temperature 280 ° C, pressure 1 atm, volumetric feed rates of liquid raw materials and hydrogen respectively 0.5 and 50 h ^-1 .

The test results are presented in table.3. It can be seen that when using fresh (active) K-140 catalyst samples under the conditions of the proposed method for processing the BBP fraction, the process is characterized by almost complete conversion of formates and aldehydes, but lower selectivity due to the formation of increased amounts of unidentified impurities, esters and high boiling products. Moreover, in the most active sample No. 4 there are significantly more by-products than on less active No. 5 and especially No. 3. The yield of alcohols in the experiment with sample No. 4 was: isobutanol - 80.0%, n-butanol - 78.4, which is significantly less than with sample No. 3. In addition, significant amounts of methyl alcohol, which are undesirable at the stage of purification of butanols, are present in hydrogenates using active catalysts.

Table 1 Component composition Raw materials, wt.% Hydrogenate, wt.% Sample 1 Sample 2 Sample 3 Water 0.12 0.16 0.13 0.14 Methanol - 5.83 1.55 0.79 Isobutyric Aldehyde 0.42 0.12 0.18 0.23 N-butyric aldehyde 1.22 0.12 0.23 0.31 Isobutanol 21.64 47.45 49.39 49.45 N-butanol 13.17 34.03 39.30 40.72 Isobutyl formate 29.41 1,67 0.60 0.11 N-butyl formate 31.26 1.75 0.71 0.15 Sum of Butyric Acids traces 0.01 0.01 0.01 Amount not identified. 0.45 1.00 0.73 0.73 impurities The sum of the ethers C ₈ 1,53 4.63 4.24 4.39 Sum of high boilers 0.78 3.23 2.93 2.97 components The conversion of boot formates,%: Isobutyl formate 94.32 97.95 99.62 N-butyl formate 94.40 97.72 99.52

table 2 Component composition Uploaded, g Received, g Carbon monoxide - 17.10 Water 0.12 0.12 Methanol - 0.65 Isobutyric Aldehyde 0.42 0.19 N-butyric aldehyde 1.22 0.26 Isobutanol 21.64 41.02 N-butanol 13.17 33.76 Isobutyl formate 29.41 0.09 N-butyl formate 31.26 0.12 Sum of Butyric Acids traces 0.01 Amount not identified. 0.45 0.59 impurities The sum of the ethers C ₈ 1,53 3.63 Sum of high boiling foods 0.78 2.46 TOTAL: 100.00 100.00 The yield of butanols,%: Isobutanol 95.6 N-butanol 92.4

Table 3 Component composition Raw materials, wt.% Hydrogenate, wt.% Sample 4 Sample 5 Water 0.12 2.13 1,57 Methanol - 11.14 10.13 Isobutyric Aldehyde 0.42 - - N-butyric aldehyde 1.22 - - Isobutanol 21.64 39.10 42.1 N-butanol 13.17 32.75 33.5 Isobutyl formate 29.41 - traces N-butyl formate 31.26 - traces Σ butyric acids traces 0.26 0.15 Σ unidentified. impurities 0.45 3.83 3.57 Σ C ₈ ethers 1,53 6.40 5.26 Σ high boiling components 0.78 4.39 3.72 Total: 100.0 100.0 100.0

Table 4 Component composition Uploaded, g Received, g Carbon monoxide - 12.50 Water 0.12 0.16 Methanol - 4.20 Isobutyric Aldehyde 0.42 0.23 N-butyric aldehyde 1.22 0.31 Isobutanol 21.64 34.17 N-butanol 13.17 31.07 Isobutyl formate 29.41 0.75 N-butyl formate 31.26 1.00 Sum of Butyric Acids traces 0.02 Amount not identified. impurities 0.45 0.88 The sum of ethers With ₈ 1,53 9.48 Sum of high boiling components 0.78 5.23 TOTAL: 100.00 100.00 The yield of butanols,%; Isobutanol 61.94 N-butanol 83.80

Claims (1)

The method of decomposition of butanol-butyl formate fractions of the process of hydroformylation of propylene by reduction with hydrogen at a temperature of 200-280 ° C, a pressure of 1-30 at, bulk feed rates of hydrogen and 0.1-0.5 and 50-500 h ^-1, respectively, characterized in that the process is carried out to obtain the final products of butyl alcohols and carbon monoxide on a catalyst having the following chemical composition, wt.%: Copper oxide 48.0-63.0 Zinc oxide 9.0-18.1 Chromium oxide 19.0-34.8 Graphite 3.0-5.1 and activity index less than 40.