CS264710B1 - A method for producing cumene from by-products of phenol production by cumene - Google Patents

Abstract

Method for the production of cumene from by-products arising during the production of phenol from cumene by hydrogenation of alpha-methylstyrene on palladium or nickel catalysts. By the method of producing cumene for the production of phenol by hydrogenating the cumene-alpha-methylstyrene fraction isolated from the organic fraction from the bottom of the crude acetone rectification column on palladium or nickel-based catalysts at a hydrogen pressure of 1 to 4 MPa, withdrawing the catalyst 1 to 1.5 liters of fraction per 1 liter of catalyst at temperatures of 105 to 130 °C, while the cumene-alpha-methylstyrene fraction flows down the catalyst in the form of a film from top to bottom and the obtained hydrogenate contains alpha-methylstyrene below 0.05 wt.%.

Description

The invention relates to a method for producing cumene from by-products arising in the production of phenol from cumene by hydrogenation of the cumene-alpha-methylstyrene fraction isolated from the by-products by distillation.

In the production of phenol from cumene, in addition to phenol and acetone as the main products, there are also by-products such as alpha-methyl-styrene, mesityl oxide, phoron, benzofurans, tertiary butylbenzene, diacetone alcohol, acetophenone, which are separated from phenol in the azeotropic distillation column of phenol with water as azeotropes, water-phenol, water-cumene, alpha-methylstyrene, mesityl oxide, acetone, alcohol, etc. This mixture, because it contains the highest concentration of alpha-methylstyrene, is often referred to in practice as the alpha-methylstyrene fraction and the corresponding column as the alpha-methylstyrene column.

This alpha-methylstyrene fraction according to previously known methods is extracted several times with sodium hydroxide before the actual hydrogenation, dried and distilled in order to obtain the cumene-alpha-methylstyrene fraction, which is then hydrogenated in the liquid or gas phase with hydrogen on catalysts containing cobalt-molybdenum or nickel or Pd (palladium) and their compounds at a pressure of 8 to 12 MPa and a temperature of 160 to 180 °C.

The disadvantage of the above methods is that water forms an azeotrope not only with the previously mentioned hydrocarbons, but also with phenol, and that the system consists of 95% by weight of phenol and the alpha-methylstyrene fraction thus obtained contains a high concentration of phenol, which must be laboriously removed before the actual hydrogenation by repeated extraction with sodium hydroxide to form sodium phenolate, from which the phenol must then be released with strong inorganic acids to form a large amount of sulfate waters containing phenol, which must then be laboriously removed with organic solvents.

The presence of sulfate in wastewater results in very frequent and intensive fouling of the extraction equipment. Another disadvantage is that hydrogenation of alpha-methylstyrene in the gas phase is energy and material intensive and under given reaction conditions part of the alpha-methylstyrene polymerizes, reducing the activity of the catalyst and hydrogenation in the liquid phase due to the low solubility of hydrogen in the reaction system requires higher pressures and temperatures with a low catalyst loading, usually 0.5 to 0.6 l of alpha-methylstyrene fraction per 1 liter of catalyst.

The invention provides a solution to eliminate the aforementioned shortcomings. The method of producing cumene from by-products arising in the production of phenol by the cumene method by hydrogenation of the alpha-methylstyrene fraction according to the invention consists in using for hydrogenation an organic fraction taken from the bottom of the crude acetone rectification column, which contains a concentration of phenol several times lower than the alpha-methylstyrene fraction of the azeotropic distillation column, which contains 70 to 80% of the total amount of alpha-methylstyrene arising in the production of phenol, which is then, after extracting a small amount of phenol and isolating the cumene-alpha-methylstyrene fraction, hydrogenated with hydrogen on a catalyst containing nickel or palladium or their compounds at a temperature of 105 to 120 °C and a pressure of 0.5 to 3.5 MPa with a draw-off of 1 to 1.5 l of raw material per 1 l of catalyst, while the injected cumene-alpha-methylstyrene fraction into the hydrogenation reactor is sprayed using a special device so that flows down the catalyst in the form of a fine film from top to bottom, thereby achieving a high hydrogen concentration in the reaction system and rapid diffusion of hydrogen to the active centers of the catalyst. Cumene at the reactor outlet contains alpha-methylstyrene in a concentration below 0.5% by weight.

The advantage of producing cumene according to the invention is evident from the following examples.

Example 1 - comparative

From column No. 4 alpha-methylstyrene, 1,000 g of organic fraction with the composition: acetone 24.1% by weight is taken.

mesityl oxide 2.4% by weight.

cumene 5.6 % mass alphamethylstyrene 19.0 % mass mestylene 0.2 % mass how are you, dear? 0.3 % mass benzofurans 1.1 mass dimethylphenylcarbinol 0.8 % mass acetophenone 3.0 % mass phenol 45.6 % mass

On a column with a 40 to 50 TP and a reflux ratio of 5, the fraction is distilled so that an acetone fraction is obtained, then a mesityl oxide fraction and finally an alpha-methylstyrene fraction with the composition: cumene 45.4% by weight.

alphamethylstyrene 50.2% by weight

mesityl oxide 0.02% by weight.

water 0.2% by weight.

From this fraction, the phenol is extracted with 10% sodium hydroxide and then again distilled to remove water and traces of alkali which would deactivate the catalyst. A cumene-alphamethylstyrene fraction is obtained with the following composition:

cumene alphamethylstyrene mesityl oxide

46.20% by weight 53.79% by weight

0.01% by weight.

which is injected into the bottom of the reactor containing 1,000 ml of Pd catalyst at a rate of 500 ml/h. The reactor is heated to a temperature of 135 °C, the pressure of hydrogen, which is also supplied to the bottom of the reactor, is 5.2 MPa. From the top of the reactor, a hydrogenate with the composition:

cumene 98.2% by weight.

alpha-methylstyrene dimers 0.4 wt.%

isopropylcyclohexane 0.08% wt.

Example 2

A fraction with the following composition is taken from the bottom of the acetone column:

acetone 28.8% mass mesityl oxide 2.2% mass cumene 30.63 % by weight alphamethylstyrene 35.65 % by weight acetophenone 1.52 % by weight dimethylphenylcarbinol 0.28 % by weight phenol 0.92 % by weight

The small amount of phenol present is extracted from the mixture with an aqueous solution of sodium hydroxide and the acetone, mesityl oxide and alpha-methylstyrene-cumene fractions are distilled off on a column with a 30-40 TP and a reflux ratio of 1 with the following composition:

cumene 43.4% by weight.

alphamethylstyrene 56.58% wt.

mesityl oxide 0.02% by weight.

which is used for hydrogenation on a Pd catalyst as in Example 1. The mixture is injected into the upper part of the reactor and flows down in the form of a film over the catalyst from top to bottom. Hydrogen is fed into the lower part of the reactor in 30% excess of theory. The temperature in the reactor is 115 °C and the pressure is 1.6 MPa. The amount of injected raw material is 1 liter/h. Hydrogenate of the composition is taken from the lower part of the reactor:

cumene dimers alphamethylstyrene alphamethylstyrene isopropylcyclohexane

99.91% wt. 0.02% wt. 0.05% wt. 0.02% wt.

Example 3

The cumene-alphamethylstyrene fraction of the composition given in Example 2 is hydrogenated over a Ni catalyst as in Example 2, except that the temperature in the reactor is 150°C and the pressure is 4.5 MPa. A hydrogenate of the composition is taken from the bottom of the reactor:

cumene dimers alphamethylstyrene alpha-methylstyrene isopropylcyclohexane

99.8% wt. 0.03% wt. 0.15% wt. 0.025% wt.

Example

Under the conditions as in Example 2, 1,500 ml of cumene-alphamethylstyrene fraction is injected, which is diluted with 500 ml of circulating hydrogenate before entering the reactor. At the outlet of the reactor, hydrogenate of the composition:

cumene dimers-alphamethylstyrene alpha-methylstyrene isopropylcyclohexane

99.9% wt. 0.02% wt. 0.05% wt. 0.02% wt.

As is evident from Examples 1 to 4, the production of cumene according to the invention is simpler, less energy-intensive and the purity of the cumene obtained is higher.

Claims (1)

EXAMPLE 3 The cumene-alfamethylstyrene fraction of Example 2 is hydrogenated on a Nicatalyst as in Example 2, except for a temperature in the reactor of 150 ° C and a pressure of 4.5 MPa. The hydrogenate of the composition is removed from the bottom of the reactor: cumene dimers alfamethylstyrene alpha-methylstyrene isopropylcyclohexane 99.8% w / w 0.03% w / w 0.15% w / w 0.025% w / w. EXAMPLE Under the conditions of Example 2, 1500 ml of cumene-alpha-methylstyrene fraction are injected, which is diluted with 500 ml of the circulating hydrogenate prior to entering the reactor. The hydrogenate of the composition is collected at the outlet of the reactor: cumene dimers-alfamethylstyrene alpha-methylstyrene isopropylcyclohexane 99.9% w / w 0.02% w / w 0.05% w / w 0.02% w / w. As can be seen from Examples 1 to 4, the production of cumene according to the invention is simpler, less energy intensive and the purity of the cumene obtained is higher. BEFORE THE INVENTION The process for producing cumene from the by-products of phenol production from cumene, characterized in that an alpha-methylstyrene fraction from the bottom of the rectification column of crude acetone is used for hydrogenation, which is freed from phenol before hydrogenation. the alpha-methylstyrene fraction, which is then hydrogenated with hydrogen in the presence of a nickel or palladium catalyst or compounds thereof at a temperature of 105 to 130 ° C and a pressure of 1.5 to 4 MPa to attract a catalyst of 1.2 to 1.5 L of alpha-methylstyrene fraction per liter of catalyst wherein the alpha-methylstyrene fraction flows in the form of a fine film over the catalyst downstream. Severografia, n. P., MOST Price £ 2.40 p