SU211432A1 - METHOD OF CLEANING PHENOL - Google Patents

Description

There are known methods for purifying phenol, an acid-catalyzed guluch-enyl cleavage of hydroperoxide, obtained by oxidation of a secondary alkylated aromatic hydrocarbon, and, in particular, methods for purifying phenol obtained by acid dissolution of hydroperoxide formed during cumene oxidation.

Phenol (Produced by partial oxidation of cumene to cumene hydroperoxide, followed by acid catalyzed cleavage of hydroperoxide; the result is a reaction mixture containing phenol, acetone and unreacted cumene. This mixture is cleaved from the decomposition and then fractionated to separate the phenolic product from the higher and lower boiling point components of the reaction mixture. Even when the iC is operating, the effective;; riting column in the fraction of phenol contains small but harmful amounts impurities resulting from the oxidation, cleavage and separation of phenol. The impurities that remain in the fepol fraction consist of carbonyl compounds, including diacetone alcohol, oxyacetone, acetone trimers and the main product of acetone collation, mesityl oxide, which is practically not separated from phenol by simple distillation methods. Carbonyl compounds are harmful even in small quantities, as they tend to color, which leads to the unacceptability of the phenolic product in many industrial applications x. According to the proposed method, in order to substantially remove impurities containing carbonyl compounds from the phenolic framed acid, the latter is treated at an elevated temperature in the presence of a catalyst and

2-10 weight. % water. The catalyst consists of oxides of aluminum, silicon, zirconium.

The phenol purification process is carried out as follows. To form an alpha-hydroperoxide derivative of a secondary alkylated aromatic hydrocarbon, it is partially oxidized. This derivative is cleaved by acid and catalyzed to form phenol and aliphatic ketone. Obtained by splitting the reaction mixture

neutralize. Then, a fraction containing phenol and impurities in which carbonyl compounds are found is separated from it. This process is characterized by the fact that some of these impurities are separated from the phenolic

by adding water to the fraction; contacting the mixture at elevated temperature with a catalytic mixture selected from the group consisting of silicic anhydride - alumina, silicic anhydride - zirconium anhydride, silicic anhydride - alumina oxide - zirconium anhydride to convert these carbonyl compounds into compounds with lower kinenium points, and distilling these compounds from phenol.

Water or steam is added to the phenol fraction. Moreover, the water-phenol mixture is brought into contact with the catalytic 1 mixture at flooding temperature. Vodophenol mixture should contain 2-20 wt. % water or narra corresponding to the equivalent amount of water. This mixture is brought into contact with the catalytic mixture at 150-250 ° C. Phenol is predominantly processed in the bulk phase, although usually some vapor phase of phenol is also present. The optimum contact time is determined by the partially applied temperature and catalytic mixture. A contact time equivalent to a fluid hourly space velocity of from 0.1 to 5.0, and preferably from 0.2 to 2.0, is appropriate. Usually, a pressure in the range of atmospheric is applied up to 17 atm, although the exact value of pressure is not critical.

Catalytic mixtures include, in particular, mixtures of silicic anhydride and alumina. The nzhm are bentonite type silicates of aluminum silicate, activated by acid treatment. However, preference should be given to synthetically manufactured mixtures of silicic anhydride and alumina containing 60-95% and more preferably 70-90% of silicic anhydride. These mixtures are readily prepared by known methods.

One of these methods consists in co-precipitating and co-gelling the silicic anhydride and alumina from the common solution. For example, aqueous solutions of sodium silicate (ordinary water glass) and aluminum sulphate are mixed, and a sufficient amount of acid (hydrochloric or sulfuric) is added to the mixture to form a precipitate or gel. Another method is that the silica gel is impregnated with a suitable aluminum compound which can later be converted to alumina. For example, aluminum hydroxide precipitates from an aqueous solution of a suitable aluminum salt, such as aluminum sulphate, in the presence of silica gel, submerged in solution. The resulting salt is then heated at an elevated temperature, and the impregnated hydroxide is converted into alumina by thermal decomposition. Alternatively, the silica gel may be impregnated with a decomposable aluminum salt, which forms upon subsequent heating of the alumina. Aluminum nitrate can be impregnated with silica gel by immersing the gel in an aqueous solution of aluminum nitrate; mini.

A mixture of silicic anhydride and alumina, prepared according to methods, is usually washed with water to remove soluble salts from it, and then dried at 95-200 ° C. After that, the mixture is calcined at 475,800 ° C (preferably 600-700 ° C). can be produced in any suitable atmosphere. Usually, calcination is carried out in the presence of air or other oxidizing agents, although it can also be reduced in a reducing atmosphere, such as hydrogen or in an inert atmosphere, like nitrogen.

Although silicic anhydride — alumina is the preferred catalytic mixture, some other mixtures, but “silicic anhydride — zirconium anhydride, aluminum oxide, zirconium lngride, and silicic anhydride — alumina} w — zirconium anhydride, exhibit

desirable catalytic properties and may

to be consumed.

Treatment of the phenol fraction with water with a pug of its contact with a silica anhydride-alumina catalyst and separation of the carbonyl compounds that are conversion products from phenol can be carried out in two separate steps or in one step. In the process being described, impurities containing carbonyl compounds are converted to products with a lower boiling point, which are easily distilled from the phenol or separated from it by a gas absorber, such as nitrogen, or a combination of a scavenger and distillation. Other impurities, which may be in phenol, are separated in this case in accordance with the present process. For example, in the separation of excess water from phenol by distillation methods, methylbenzofuran, which is usually in trace amounts, is recovered as part of the steam distillate.

Example 1. Phenol, which was fractionally distilled from the neutralized reaction mixture after the cleavage of cumene hydroneoxide, contained, according to the gas-liquid chrO | Mathematical analysis, oxide

.meetila. Phenol mixed with steam was passed through a vertical tubular reactor containing 200 cm in a fixed bed or 120 g tablets of 3.2 mm in size, consisting of 88% silica anhydride and 12%

alumina. The reactor was approximately at atmospheric pressure and at 190 ° C, with the proportions of phenol and steam being adjusted so as to obtain streams with varying amounts of water. Flowing out

from pea, the product was discharged continuously and o.h. The following analyzes of the incoming raw materials and the products obtained show that mesityl oxide has largely evolved into acetone, which

and sn

40 2.0

%

0,0010

0,0010 0,1940 0,1940

with. %

0.14675 0.1193 0.0060 0.0041

: P re p 2. The phenol fraction recovered by Distillation of the neutralized reaction mixture from the cleavage of hydroperoxide contains carbonyl impurities, mainly mesityl oxide, but also diacetone alcohol, oxyacetone, and acetone trimer. This fraction was processed to convert complex carbonyl compounds to acetone. The phenol fraction was mixed with about 10 of you. % water. Then the phenol was passed through a heated vapor pipe to the vertical tubular reactor with a liquid hourly space velocity of 0.5. In the reactor there was a fixed layer of tablets, which occupied a volume of 100 ohz and containing 76% silicic anhydride and 24% alumina oxide. The reactor was under a pressure of about 5 atm and at a temperature of 205 ° C. The following analyzes of the raw materials of the products obtained also show a significant conversion of mesityl oxide to acetone, as well as the formation of various other compounds, more volatile than phenol, which can again be removed by distillation.

III

raw materials, weight %

0,0036

0.0036 acetone 0.1489 0.1489

mesityl oxide 0.0915 0.0915 different

product analysis, weight. %:

0.1788 0.1606 acetone 0.0063 0.0067

Mesityl oxide 0.1349 0.1868 different

PRI me R 3. The fraction of phenol, extracted

100 5.0 disgillides to neutralize the reaction mixture or the cleavage of cumene hydroperoxide, was converted into a phenolic product containing separable impurities, using a mixture containing about 90% silica anhydride as a catalyst. 200 s.iz of catalyst in the form of 3.2 mm balls were located in a fixed bed in a vertical tubular reactor. Phenol was supplied. In peaiKTOp together with lars, in order to obtain a vodnogoioli feed material containing about 5 wt. % water. Water-phenolic feedstock arrived with a liquid hourly space velocity of about 1; the reactor was maintained at a temperature of about 190 ° C and a pressure of about 3.4 atm. The product exiting the reactor was analyzed as shown below.

Analysis of raw materials %

Product analysis, wt. %

acetone 0.18

acetone0.01

mesityl oxide 0.16

mesityl oxide 0.1 different0.3 different0.14

In this example, a less accurate 30 analysis method was applied.

However, here we see almost complete conversion of mesityl oxide to acetone.

Subject invention

35

1. A method of purifying phenol obtained by decomposing isopropylbenzene hydroperoxide followed by separation of the phenol fraction, treating it at an elevated temperature in the presence of KaTavTn3aTopa consisting of aluminum and silicon oxides, characterized in that the process is carried out in the presence of 2 -10 weight. % water.

2. Method for and. 1, characterized in that zirconium oxide is incorporated into the catalyst.