CS234493B1 - Method of phenol preparation by means of benzoic acid oxidation in gas phase - Google Patents

Abstract

The invention is within the organic field technology. It solves the process for the preparation of phenol by oxidizing benzoic acid in gaseous phase. It solves the process for the preparation of phenol by oxidation benzoic acid in the shallow phase at 250 to 350 ° C when molar the ratio of reactants benzoic acid : water: oxygen is 0.6 to 2.5: 40 to 70: 1.5 to 2.5 with spatial velocity benzoic acid 0.01 to 0.22 kgh_1kg catalyst. According to the invention, the reaction is carried out in the presence of catalysts of the oxide type of formula I Cu Cu - M * - M2 - 0 I deposited on the alumine carrier 2-1 surface 40 to 190 m g, where M i is 0.01 up to 10.9% by weight of lead, bismuth, iron, cobalt, chromium and Mg is 0.9 to 10% by weight of bismuth, molybdenum, alkali metals, metals II. b. subgroups with a medium content of 1.5 to 9.5% by weight and which specific surface before use it is 30 to 100 m ^ g ”^.

Description

The invention relates to a process for the preparation of phenol by gas phase oxidation of benzoic acid.

According to previously known processes, part of the world's phenol production is production from toluene, where benzoic acid is an intermediate. The production of phenol by this liquid phase process is industrially realized by Dow. The reaction is carried out at a temperature of 230 to 270 ° C, at atmospheric pressure and the catalytic action of copper benzoate in the presence of magnesium oxide. The disadvantage of this process is that high boiling pitch products are formed which cannot be separated from the catalyst and thereby result in considerable losses. This disadvantage is overcome by the gas-phase preparation process in the presence of solid catalysts. In the patent literature work has been reported to monitor the reaction in the presence of several catalytic systems under vacuum at a temperature range of 200 to 400 ° C, mainly at atmospheric pressure, but also by applying a higher pressure / Qerm. Offen pat. The authors used CuO-based catalyst systems supported on silica gel as well as in the presence of a cobalt oxide activator / Barnard R.D., Meyer R. H. U.S. Pat. 2,852,567 (1958); honey powder coated on magnesium oxide / Belg. pat. 627,445 (1963); a combined catalyst consisting of Cu, V, Li,

Mg, Na / Belg. pat. 621,999 / 1963 //; a Cu-Cr-X-Ba-O type catalyst wherein X is Zn, Fe, Co, Mo, W, In, Te deposited on diatomaceous earth or silica gel / Jap. 81, 40, 628 (1981), and Jap. pat. 81, 25, 126 (1981). The effect of a higher pressure of 2,234,493 kDC was observed on a CuO-ZrOg-KgO catalyst, respectively.

NagO deposited on ui-alumine. Atypical catalyst, where the active ingredient is molybdenum oxide and / or other metals of activators and promoters. applied to alumine were used by Japanese authors / Jap. pat. 147, 736 (1981) //.

The above drawbacks are eliminated in the process for the preparation of phenol by the gas phase oxidation of benzoic acid according to the invention at a temperature of 250 to 35 ° C, each molar ratio of the reactants benzoic acid: water: oxygen being 0.6 to

2.5: 40 to 70: 1.5 to 2.5 with a benzoic acid space velocity of 0.01 to 0.22 kgh ^ kg ^{3, a} catalyst whose essence is that the reaction * is carried out in the presence of an oxide type catalyst Cu - 1 - Mg - 0/1 / supported on a carrier. The carrier is an alumina having a specific surface area of 40 to 190 b ^{2 11} , wherein M je is 0.01 to 10.9% by weight of lead, bismuth, iron, cobalt, chromium and Mg by weight of bismuth, molybdenum, alkali metals II.b. Sub-groups with a media content of 1.5 to 9.5% by weight and whose specific surface area before use is 30 to 100 m ² g ~

Under optimal reaction conditions and molar ratios of the components fed to the reactor, the catalysts of the invention retain activity for several tens of hours. In the event of a decrease in activity, the catalyst can be reactivated in the presence of molecular oxygen directly in the reactor without the addition of other components. Catalysts are prepared by impregnation (24 h) of a carrier - alumina - with an aqueous solution of the respective salts and after evaporation, drying is calcined for 3-11 h at 450-800 ° C, depending on the type of metal compound. The advantage of using these catalysts is higher phenol yield, higher process selectivity and longer catalyst life.

Further advantages of using these catalysts are illustrated in more detail in the examples.

Example 1

234 493

A 26 mm diameter glass reactor, 60 cm in length, was charged with 47 g of a catalyst having a particle size of 1 to 1.6 matt. The catalyst contained 3.99 wt% Cu, 4.6 wt% Cu. Pb and 4.1% wt® K on alumina and its specific surface area was 61 mg · Prepared as follows: alumina with a specific surface area of 120 m ² g-^ was impregnated (24 h) with an aqueous solution of copper nitrate and dried after evaporation of water and calcined at 73 ° C for 3.5 h. The obtained catalyst was further impregnated with aqueous lead nitrate solution (24 h) and after evaporation of water and also dried and calcined at 65 ° C for 3.5 h. Finally, the catalyst was impregnated (24 h) with an aqueous potassium hydroxide solution. After evaporation of the water, drying, it was calcined again at 540 ° C for 11 h. The working conditions were as follows: temperature Catalyst was 300-4, the molar ratio of benzoic acid: water: oxygen (in the form of air), which was fed to the top of the reactor was 1: 60: 2. Reactor was cooled and captured in a condenser® The identification of the components of the reaction mixture was carried out by mass spectrometry and their quantitative determination by gas chromatography · The content of generated carbon dioxide and oxygen consumed in the off-gas by gas chromatography was also monitored ·

After a 2.5 hour induction period, a steady state conversion of benzoic acid, phenol yield and byproducts was achieved, as well as carbon dioxide generation and oxygen consumption rates. The by-products were diphenyl + diphenyl oxide (6%) and benzene. Catalyst activity did not change over 21 hrs ·

Example 2

The procedure and conditions were the same as in Example 1, but the catalyst except for 3.99 wt% Cu and 4.6 wt% Cu. Pb contained 2.3 wt. Li on alumina and its specific surface area was 55 mg · The preparation procedure was the same as in Example 1, except for K and Li

4,234,493 was applied to the catalyst by impregnation (24 h) with an aqueous solution of lithium nitrate and, after evaporation of water, drying, was calcined at 65 ° C for 3.5 h. Under these conditions, the steady state reaction was achieved after 1.5 hours induction period at conversion of benzoic acid of 83% to phenol with a yield of 57%. By-products were dipeptyl + diphenyloxide (8%) and benzene. Catalyst activity did not change over 32 h. It can be seen from Examples 1 and 2 that the promoter significantly affects the activity of the catalyst, enhances its activity and selectivity of the reaction.

Example 3

The procedure and conditions were the same as in Example 1 but the catalyst except for 3.99 wt. Cu and 4.6 wt. The Pb contained 4.48% wt.

Bi on alumine carrier. The specific surface area of the catalyst was 53 mg. Steady state reaction, which is achieved after * 4?

A 1.5 hour induction period produced phenol with a selectivity of 82.6%, with a benzoic acid conversion of 52%. The by-products were diphenyl + diphenyl oxide (7%) and benzene®.

Example 4

The procedure and conditions were the same as in Example 1, but the catalyst contained 3.99 wt. Cu, 4.48% wt. Bi, 2.3 wt. Li on alumina. The specific surface area of the catalyst was 64 m g. After 1.5 h induction period the reaction stabilized and the phenol formed with a selectivity of 51.7 at a benzoic acid conversion of 70%. By-products were diphenyl + diphenyloxide (6%) and benzene. Catalyst activity did not change over 20 h.

Example 5

The conditions and procedure were the same as in Example 1, but the catalyst contained 3.99 wt. Cu, 4.48% wt. Bi and 4.37 wt. Cd on alumina. The specific surface area of the catalyst was 62.5 m g · P · minute induction period and the reaction was started and the parameters of the experiment stabilized and maintained without changing the activity of the catalyst for 19 h. Under these conditions arose

5,234,493 at a benzoic acid conversion of 33% phenol with a selectivity of 88%. The by-products were predominantly diphenyl oxide and benzene. Comparing examples 3,4 and 5, it can be seen that the presence of metal components on the catalyst surface has a significant effect on its activity.

Example 6

The conditions and procedure of Example 1, the catalyst of the reaction contained 3.99% by weight Gu _0, 3.67% by weight. Co and 4.37 wt. Mg 2 —1 on alumina support. The specific surface area of the catalyst was 64.2 mg. Under these conditions, the induction period of the reaction was 3 h, during which the oxidation was carried out at steady state. The conversion of benzoic acid 42% gave phenol with a yield of 27%. The catalyst began to lose activity after 23 hours.

Claims (1)

OBJECT OF THE INVENTION 234 493 Process for the preparation of phenol by gas-phase oxidation of benzoic acid at a temperature of 250 to 35 ° C and a molar ratio of the reactants of benzoic acid: water: oxygen of 0.6 to 2.5: 40 to 70: 1.5 to 2.5 and of the space velocity of the acid 0.01 to 0.22 kgh kg of catalyst, characterized in that the reaction aa is carried out in the presence of an oxide type catalyst of the formula I Cu - - m ₂ - 0/1 / deposited on an alumine support having a specific surface area of 40 to 190 B ² g ¹ , where M ^ is 0.01 to 10.9% by weight of lead, bismuth, iron, cobalt, chromium and ligand is 0.4 to 10% by weight of molybdenum bismuth, alkali metals, alkaline earth metals, metals II.b. subgroup and having a content of 1.5 to 1.5 9.5% by weight, the specific surface area of the catalyst being 30 to 100 Β ² β ^-1 .