JPH06508616A - Production method of phenol - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Production method of phenol The present invention relates to the oxidation of corresponding aryl carboxylic acids in the gas phase in the presence of Cu-containing catalysts. The present invention relates to a method for producing phenol through decarboxylation.

The production of phenol by oxidative decarboxylation has been known for a long time. Ora British Patent No. 762738, which corresponds to Nda Patent No. 90.684, is have already disclosed such a method, in which oxidation, decarboxylation as well as and hydrolysis in a single step at a temperature of at least 200°C, preferably between 230 and 250°C. It is being implemented in the process.

A number of patents have been issued in recent years related to this method, and these The disadvantage is that it is difficult to suppress the formation of a significant number of by-products, especially tar-like products. The purpose is to

It is proposed that the reaction be carried out in the gas phase over a solid copper-containing catalyst to prevent tar formation. proposed; for example, Dutch Patent No. 107561 and Dutch Patent No. See specification no. 110374. Similar to the patents mentioned below, these mainly focus on catalyst optimization. (e.g. Dutch Patent No. 7810528, European Patent No. 7810528) Patent No. 52839 and European Patent No. 40452), tar does not disclose a system in which the production of is substantially suppressed. in all cases , for a while (then the catalyst will be covered with a black tar-like coating, which is particularly noticeable). appears to affect its activity.

The process according to the invention comprises the process of preparing a substantially complete reaction mixture in the gas phase from the corresponding arylcarboxylic acid. To provide a method for producing phenol while preventing the formation of tar.

Therefore, a method with both high manufacturing selectivity and economically attractive aspects is available. It will be done.

The method of the invention is characterized by carrying out the following manufacturing steps: a) Oxidant-containing gas under conditions such that tar formation is essentially absent. feeding the mixture to the catalyst bed; b) While excluding oxygen, supply aryl carboxylic acid and steam to generate phenol in the gas phase. form a rule.

By carrying out the method in this way, a two-step process is obtained: first, the oxidation is then combined with reduction of the catalyst to form phenol.

In this case, in the following, arylcarboxylic acids are defined as compounds having the following structural formula: in which R1 to R6 are hydrogen (in this case at least R1 or R6 is hydrogen), or an organic group with so-called Hammett constants of −1 and + It is anything between 2. This Hammett or σ value is This description represents a measure of the influence of substituents on the reactivity of phosphoric acids. March (J, March) ^dvanced Organic Chemi stry, 1989, pp. 242-250, especially table 4 on page 244. I can put it out.

The groups that can be used here are the following: di-C-alkyl having 1 to 6 atoms, cycloa alkyl, aryl, arylalkyl, amino, halogen, nitro.

Esters and anhydrides of (1) are also suitable, groups such as naphthalene carbon Linked to each other through a ring system, as in the case of acids (unsubstituted or substituted) can be done. Polyarylcarbohydrates such as trimellitic acid and pyromellitic acid phosphoric acid may also be used as a starting material. Mixtures of the above-mentioned aryl carboxylic acids are also included in the invention. It can be used in the following methods.

The invention particularly relates to converting unsubstituted benzoic acid (R1 to R6=hydrogen) into corresponding unsubstituted unsubstituted Concerning a method for converting into phenol.

The oxidation of copper-containing catalysts, including converting copper to Cu(II), is the first step of the present invention. This is the reaction process. An increase in the degree of copper oxidation results.

The oxidation of copper-containing catalysts proceeds particularly well when carried out using oxygen-containing gases. . Air, whether oxygen-enriched or oxygen-depleted, is suitable for this purpose. Very well used vine. Containing other oxidizing gases, e.g. N20 or O3 It also uses gas. The pressure used is not critical, but generally High pressure will be selected to facilitate. Therefore, between 0.1 and 2.5 MPa The pressure is appropriate.

This oxidation step should be carried out in such a way that (substantially) no tar is formed. Ru. This can be achieved by various means. For example, phenol is no longer adsorbed on the catalyst. so that the catalyst is essentially free of phenol. It is maintained. This can be done by stripping with steam or inert gas at the end of the second step. This is achieved by Or, for example, the catalyst temperature in this step is 200°C Hereinafter, it is preferably maintained between 150 and 190°C (because the oxidation rate of Cu is The temperature is high, and tar formation continues until the temperature exceeds 200℃ in the presence of phenol. (This is because it is not true.) Of course, not all copper is converted to Cu(n) type. Higher temperatures (e.g. 191-270°C) are used to increase the temperature of the reaction mixture. It is also possible to keep the contact time between oxygen and oxygen short (eg 01-5 minutes).

The catalyst consists of, for example, oxides of silicon, titanium or cadmium, carbon Apply on the carrier. Preferably, the catalyst is used immobilized on a carrier. Silica is good Suitably used as a carrier. The catalyst loading is generally between 5 and 40% by weight on the support. It is metal. A high degree of loading contributes to a high conversion rate per unit volume.

It is advantageous to use a catalyst containing a Co-Catalyst in addition to copper. can be. This cocatalyst is particularly suitable for elements from Groups Ⅰ to 1 of the periodic table. and the group of lanthanides and actinides.

These components affect the copper oxidation performance of the catalyst.

The catalyst may include, for example, copper, zirconium and, if desired, sodium, potassium, etc. from alkali metals or alkaline earth metals such as Constructed. Furthermore, rare earths (atomic number 37 to 71), or zirconium, Silver, vanadium, chromium, molybdenum, hafnium and tungsten or the like Mixtures of may be used in combination with copper.

Examples of suitable catalyst systems include EP 52 839; 40452, Dutch Patent No. 7810528, Dutch Patent No. No. 110374 and Dutch Patent No. 107561. Ru. In general, all catalysts suitable for gas phase reactions can be used according to the invention described herein. can be used in a two-step process.

The two-step process in the method of the invention consists of a combination of reduction and phenol production. At this time, carbon dioxide is released.

Unlike the method described in Dutch Patent No. 283.477, reduction and The production of phenol is carried out in the absence of oxygen. Since there is no oxygen present, this re-oxidation of the Cu-containing catalyst in the process process, and therefore There is no reaction between phenol and its intermediate products and any oxidized catalyst products. Does not occur. This prevents the formation of tar.

The amount of steam in the second step of the process of the present invention is relative to the amount of Cu(■)benzoate. It is advantageous to use amounts which are at least equivalent molar. Preferably, (2- or more is used in excess, generally sufficient to ensure high yields) is used in a 4-fold excess.

The pressure at which the second manufacturing step is carried out is not critical, but the pressure may be increased above atmospheric pressure. The advantage of this is that it has a favorable influence on the reaction kinetics. applied The pressure applied is generally in the range 0.1 to 2.511 Pa; higher pressures is acceptable, but does not result in a substantial improvement in its manufacturing process.

It is advantageous to work up the reaction mixture obtained to promote phenol production. Ru. This is achieved by using an acid ion exchanger in a fixed bed reactor. Nice vine.

The reaction product undergoes quality improvement operations to separate and recover the resulting phenol. will be done. This can be done by methods known per se, for example by distillation.

The bottom fluid of distillation, which contains unconverted aryl carboxylic acids, is If necessary, it can be recycled to the manufacturing process after the purification step.

The catalyst can be applied in fixed or moving bed form. The two-step reaction can be carried out intermittently. can be used to continuously supply oxygen-containing gas for a short time, e.g. to a fixed bed reactor, and then A second step is carried out with the oxygen removed. After setting the conditions for the catalyst for the first step, the oxidation gas mixture is again supplied. A two-step process, or multiple oxidation steps The second reaction is carried out in the first reactor of the reactor system and then preferably in a moving bed. It can be carried out continuously by feeding the catalyst into a vessel where the second step takes place. Can also be done. In that case, the reactor can be completely adapted to the desired requirements.

The method of the present invention is particularly suitable for producing unsubstituted phenol from unsubstituted benzoic acid. suitable. This phenol can be used, for example, for phenol-formaldehyde resins. and as a starting material for caprolactam, as a starting material for nylon-6, and as a starting material for caprolactam. is used for the production of bisphenol-A.

The invention is illustrated in the following examples, which do not limit the invention. It should not be interpreted as such.

Example The test was conducted using the experimental equipment shown in the attached drawings, in which A is the evaporator. Air generator (H20/N2 mixture), B is benzoic acid evaporator and C is air supply device represents. Three streams go to the reaction bed. E, F and G are coolers, which are used for reaction mixture. The mixture is cooled to 130°C, 8°C and -80°C, respectively. H is the released mixture This is the analysis site. The reactor is approximately 2.5 meters long and is made of silica filled with copper oxide! ! full of Consists of a filled floor. Gas flows from A, B and C are adjustable and from E to The product in H is analyzed by gas chromatography (GC) and high pressure liquid chromatography. was analyzed using HPLC (HPLC).

Example! The catalyst was oxidized with air for 30 seconds. Benzoic acid and steam were then supplied for 240 seconds. . The temperature of the catalyst bed was 250°C. The retention time of acid and vapor in the column is 4 It was seconds. The conversion rate of benzoic acid was 20%.

At the end of the working cycle, only steam is used to remove absorbed phenol. Supplied for 2 seconds. The selectivity to phenol was 96% and benzene was 4%. It was. At the end of five working cycles the catalyst was extracted with ether. In HPLC analysis , no formation of tar products on the catalyst was demonstrated.

Example■ Same amounts of steam and benzoic acid were applied as in Example I with a retention time of 2 seconds on the column. The temperature was increased to 300°C for 60 seconds. The conversion rate is 40%, and the selection to phenol is The selectivity was 91% and 9% to benzene. No tar was produced.

international search report international search report Continuation of front page (81) Designated countries EP (AT, BE, CH, DE.

DK, ES, FR, GB, GR, IT, LU, MC, NL, SE), 0A (BF , BJ, CF, CG, CI, CM, GA, GN, ML, MR, SN, TD, TG. ), AU, BB, BG, BR, CA, C3, FI, HU, JP.

KP, KR, LK, MG, MN, MW, No, PL, RO, RU, SD

Claims (12)

[Claims] 1. Oxidation of the corresponding aryl carboxylic acid in the gas phase in the presence of a Cu-containing catalyst In the method for producing phenol by decarboxylating the a) Oxidant-containing gas mixture under conditions such that tar formation is substantially absent. feeding the compound to the catalyst bed; b) Arylcarboxylic acid from which oxygen has been removed and phenol in the gas phase by supplying steam Production of phenol, characterized by carrying out a process consisting of producing Law. 2. 2. A process according to claim 1, wherein the oxidation of the catalyst is carried out with an oxygen-containing gas. 3. 3. A method according to claim 1 or 2, wherein the Cu-containing catalyst contains a co-catalyst. 4. carrying out the oxidation with an insufficient amount of oxidant compared to the amount of Cu in the catalyst; A method according to any one of claims 1 to 3. 5. Claims in which the catalyst applied in step a) is essentially free of phenol The method according to any one of Items 1 to 4. 6. 6. At the end of step a), the phenol is removed from the catalyst. How to put it on. 7. From claim 1, wherein the temperature of the catalyst bed is between 120 and 190°C during step a). 4. The method described in any one of items 4 to 4. 8. 5. According to any one of claims 1 to 4, step a) is carried out for 0.1 to 5 minutes. the method of. 9. carrying out step a) with essentially equimolar amounts of steam relative to the amount of Cu(II); A method according to any one of claims 1 to 8. 10. Claims 1 to 9, wherein step b) is carried out at a temperature of 250 to 350°C. The method according to any one of the above. 11. From claim 1, wherein the arylcarboxylic acid is used as unsubstituted benzoic acid. 10. The method according to any one of items 1 to 10. 12. A method substantially as described in the specification and examples.