CS270694B1 - A method of alkylating phenol and derivatives thereof - Google Patents

Abstract

The method of alkylation of phenols and their derivatives with at least one free ortho-position to hydroxyl by the action of an aliphatic alcohol in the gas phase at a temperature of 27o to 4oo °C and a pressure of 0.1 to 1.0 MPa takes place in the presence of a solid catalyst, which is an alloy of iron and vanadium oxides, further containing oxides from the group Ti, Cr, Mg, Mn, £i or a sulfate anion.

Description

The invention relates to processes for the alkylation of phenol and its derivative by the action of an aliphatic alcohol in the presence of a catalyst.

Alkylation of phenol with methanol or other low molecular weight alcohols to alkyl derivatives of phenol is a known and relatively widespread industrial process. In particular, the alkylation of phenol with methanol to the corresponding ortho-derivatives, i.e. ortho-cresol and 2,6-xylenol (2,6-dimethylphenol), is finding increasing application in industrial practice.

Ortho-cresol or a mixture of ortho-cresol and 2,6-xylenol can be successfully prepared by reacting phenol with methanol in the gas phase on alumina as a catalyst. In the case where it is necessary to produce only 2,6-xylenol, or both mentioned ortho-derivatives, with a high relative yield of 2,6-xylenol (approximately over 40 mol%), alumina is no longer suitable as a catalyst due to its low selectivity.

In the past, a number of types of catalysts have been developed to catalyze the alkylation of phenol with methanol, or dimethyl ether, to the hydroxyl ortho position with higher selectivity than γ-alumina. It is known to use a mixture of Mg and Mn oxides, catalysts based on Fe oxides with the addition of oxides of other elements, acting as promoters, are also used. Vanadium is a highly effective promoter. Usually, the catalyst is modified with multiple promoters.

Oxide ferric catalysts for the alkylation of phenols are prepared according to known methods by precipitating solutions of iron salts, most often ferric nitrate, with an alkali solution. its salts to a pre-prepared ferrous mass by saturation. The resulting catalyst is usually shaped by tabulation, extrusion, or only granulation.

Iron oxide catalysts catalyze the alkylation of phenol with high overall selectivity relative to phenol and high selectivity to the ortho position relative to the phenol of the phenol. Usually, however, also significantly catalyze the decomposition of the alkylating agent, i.e. a lower aliphatic alcohol, gaseous products, especially CH ^ CO ^ ^ ^ 2 * Example ^ounces of alcohol increases significantly with increasing temperature.

The alkylation of phenols with a lower aliphatic alcohol is usually carried out at temperatures of 35 DEG to 39 DEG C. using the ferrous alkylation catalysts known to date. Under these conditions, a satisfactory alkylation rate is usually achieved, but about 20 to 60% of the injected methanol decomposes into low-value gaseous products, which increases the cost of the process.

The disadvantages of the hitherto known processes are eliminated by the process according to the invention. Process for the alkylation of phenols and their derivatives with at least one free ortho-position to the hydroxyl by the action of an aliphatic alcohol on phenol or its derivatives in the gas phase at a temperature of 27o to 400 ° C, preferably 300 to 35o ° C, a pressure of 0.1 to 1.0 MPa , preferably 0.1 to 0.2 MPa, in the presence of a solid catalyst according to the invention, the starting reaction mixture is introduced into a catalyst which is an alloy of iron oxide and vanadium in an atomic ratio of Fe: V = 1: 0.4 to 1: 2.5, which optionally contains at least one oxide of an element from the group Ti, Cr, Mg, Mn, Si in an amount corresponding to the atomic ratio of each element present in said series to iron by a maximum of 0.1: 1, and / or sulphate anion in an amount corresponding to a molar ratio of SO 2: 1 to a maximum of 0.2: 1.

In the process according to the invention, the catalyst is prepared by melting a mixture of oxides of iron, vanadium or an oxide of one or more elements from the above series of promoters or sulphate of one of the above elements or by oxidative melting of a mixture of iron, vanadium or another of said series of metals. After solidification, the alloy is crushed and sorted into grain of the required size,

The alkylation in the process according to the invention takes place at a temperature of 28 ° to 40 ° C, preferably 31 ° to 35 ° C and at a pressure of 0.1 to 1.0 MPa, preferably 0.1 MPa.

The advantage of the process according to the invention is the possibility of conducting the alkylation process at a lower temperature compared to known processes, while maintaining satisfactory productivity. Another advantage over known processes

CS 270694 B1 is a lower decomposition of the aliphatic alcohol used, which improves the economy of the process.

Example 1

In the preparation of the catalyst for the alkylation of phenol or a derivative thereof, a ground fine powder of iron oxide, prepared by precipitating a solution of technical grade Fe 2 SO 4) with ammonium carbonate solution in a known manner, containing Ti, Mg, Mn oxides and residual sulfate ions, is mixed. with vanadium oxide in a weight ratio of about 1: 1. The mixture is poured into a crucible and heated to 80 ° C in an electric oven within 90 minutes. The mixture is kept at this temperature in the molten state for about 6 minutes. It is then poured into a porcelain bowl, allowed to cool and crushed. Fractions of 3 to 5 mm are separated from the crushed mass. The catalyst mass thus prepared has, for example, the following composition:

Fe ^ ⁰ ^ ^5o 55 wt.%, ^V 2 ° 5 ⁴ ^ ^{40 wt} .% · TiO ^ ¹ wt.

MnO 1 wt.%, Max., SO ^ 1.5 wt.%, Max., SiO 2 .0.8 wt.%, Max.

Alkylation of this catalyst proceeds as follows:

50 g of the catalyst prepared in the above manner are introduced into a stainless steel reactor with an inner diameter of 20 mm, equipped with a temperature measurement in the axis and a temperature measurement in a permeation bath. A raw material evaporator is connected to the reactor (a cylindrical vessel made of stainless steel, which is connected to the reactor at the top). The reactor and the evaporator are located in a common heat exchange bath. The feedstock (a 1: 5: 1 molar ratio of phenol, methanol and water) is injected into the evaporator, the vapor from the top of the evaporator passes to the top of the reactor above the catalyst bed, the product from the bottom of the reactor is in air and then in water. the cooling is cooled to a temperature of about 25 ° C, in a simple separator the liquid phase is separated from the gaseous one. Residues of non-volatile compounds are separated from the gas phase by freezing at -30 ° C in a two-necked flask immersed in an alcohol-solid CO 2 mixture. The liquid fractions condensed in the freezer are added to the main part of the liquid product. The individual phenolic compounds are determined chromatographically in the liquid product. The following table gives an example of the conditions and results of such an experiment.

T F ^F i X ^v i ^V 2 From 3oo 298 0.242 0.348 84, p 14, p o, oo4 3oo 132 o, lo7 0.686 71.2 25.6 o, oo4 3oo 92 o, o75 o, 94o 49.7 47.4 o, oo4 31o 29 7 o, 24 1 0.532 81.1 17, p 0.006 310 loo o, o81 0.962 31.7 64.7 0.006 310 84 0.068 o, 97o 13.9 74.5 o, oo5 320 295 0.239 o, 739 71.6 26.9 o, oo9 32o 131 o, lo7 0.998 2.0 94.1 0.013 32o lol o, o82 0.999 0.0 97.3 0.014

Symbols:

T (° C)

F (ml. G “ ^1. H ^-1 ) temperature in the middle of the catalyst bed feed of raw material (phenol: methanol: water» 1: 5: 1 molar)

CS 27o694 Bl

^F i (> < ^x ) injection of phenol per unit weight of kitilizer X degree of phenol conversion ^v i (% moth.) yield of o-cresol (based on reacted phenol) ^V 2 (% moth.) yield of "2,6-xylenol (based on reacted phenol) From (1 <· B- ¹ ) the amount of off-gas per unit weight of catalyst

Example 2

In the preparation of the catalyst, 5 kg of bar steel ČSN No. 12ol3 is placed in a crucible equipped with an oxygen supply, the steel is heated to melting point either by electric heating or by a flame and the oxygen supply is started at a rate of 8 to 9 rn ^ / h. Molten steel is oxidized by oxygen to iron oxides. The heat released by this reaction keeps the mixture in a molten state. After complete melting of the mixture (approx. 25 min. From the start of the oxygen supply), 5 kg of granular ^{α mixture is added with} oxygen supply and occasional stirring for another hour.

The avalanche is then poured onto a cold steel plate. After cooling, the alloy is crushed and a 3 to 5 mm fraction is sorted out, which is used for alkylation.

Catalyst composition:

Fe O 46.6 wt.

FeO 25.9 wt

V ₂ O ₅ 26.6 wt.

SiO 2, 0.5% w / h

MnO o, 8 wt

Alkylation

The alkylation was performed in the same manner as in Example 1, and the following table summarizes the typical conditions and results.

T F ^F i X ^v i ^V 2 From 32o 248 0.192 0.484 82.3 16.4 o, o3 32o 131 o, lo2 0.852 58.7 38.9 o, o2 32o 96 o, o74 0.974 17.0 79.1 0.04 33o 236 0.184 0.794 62.9 35.1 o, o5 33o 134 o, lo4 o, 98o 14.5 82.3 o, o5 33o 8o o, o62 0.996 o, l 93.3 o, o9 34o 244 0.189 o, 842 53.7 44.1 o, ll 34o 16o 0.124 o, 98o 14.4 82.2 o, o9 34o 65 0.066 0.999 o, 2 92.1 0.08 Importance the symbols used are the same as \ from Example 1.

Claims (1)

OBJECT OF THE INVENTION Process for the alkylation of phenols and their derivatives with at least one free ortho-position relative to the hydroxyl by the action of an aliphatic alcohol on phenol or its derivatives in the gas phase at a temperature of 270 to 40 ° C, preferably 30 to 35 ° C, a pressure of 0.1 to 1. o MPa, preferably 0.1 to 0.2 MPa, in the presence of a solid catalyst, characterized in that the starting reaction mixture is introduced into a catalyst which is an alloy of iron oxides and vanadium with an atomic ratio of Fe: V <1: 0.4 to 1: 2.5, which optionally contains at least one oxide of elements from the group Ti, Cr, Mg, Mn, Si in an amount corresponding to the atomic ratio of each element present in said series to iron by a maximum of 0.1: 1 and / or sulphate anion in an amount corresponding to a molar ratio of 50: Fe at most 0.2: 1.