Method for production of phenol and its derivatives

 

(57) Abstract:

The invention relates to a method for production of phenol and its derivatives by oxidation of benzene and its derivatives nitrogen oxide in the presence of heterogeneous catalysts. The oxidation of benzene and its derivatives are nitrous oxide when 225-450oIn the presence of zeolite catalyst, which is pre-activated at elevated temperatures by two-stage heat treatment. In the first stage, the catalyst was incubated for 4-6 h at 350-450oWith in a stream of nitrogen or air, and the second stage is heated under 450-1100oC for 1-3 h in the continuous current of inert gas or air. Activated zeolite catalyst is cooled to 350oC. this results In the increased stability of the catalyst and increases the selectivity of the process. 7 table.

The invention relates to the field of organic synthesis, in particular to a method for production of phenol and its derivatives by oxidation of benzene and its derivatives nitrogen oxide in the presence of heterogeneous catalysts. As heterogeneous catalysts used in industrial zeolites, modified by special treatments.

The most famous oxide ka is Italia not provide high selectivity and yield of the target product. The best results were obtained on the phosphates of various metals. In particular, the use of ZnPO4as catalyst for the oxidation of benzene to phenol in the presence of alcohols at a temperature of 550-600oC is allowed to reach the output of phenol to about 25%, but the selectivity was low at 60% (Japan Patent N 56-77234, 56-87527, 1981). In addition, the disadvantage of using phosphate catalysts in the oxidation of benzene is the high consumption of alcohol.

Known oxide catalysts for direct oxidation of benzene with nitrous oxide (N2O) at a temperature of 500-600oC based on vanadium, molybdenum-, tungsten-oxide systems (lwamoto et. al. J. Phys. Chem. V. 87. N 6. P. 903. 1983). The maximum yield of phenol on such catalysts in the presence of excess water vapor is about 7-8% with a selectivity of 70-72%. Low selectivity and yield of phenol, the use of high reaction temperatures and water vapor are the main disadvantages of the described catalyst.

There are also zeolite catalysts for the selective oxidation of benzene and its derivatives using N2O as oxidant (E. Suzuki, K. Nakashiro, Y. Ono, Chem.Lett. N 6. P. 953. 1988; M. Gubelmann, et. al. , Eur. Pat. 341, 165, 1989; US Pat. N 5001280, 1990). As catalysts for the oxidation of benzoe (ZSM-5). So in the oxidation of benzene with nitrous oxide on the zeolite HZSM-5 at 400oC (M: Gubelmann, et. al. Eur. Pat. 341165, 1989) phenol with output up to 16% with a selectivity close to 98-99%. The disadvantage of these catalysts is the low conversion and accordingly, the output of phenol and low selectivity at high temperatures of reaction.

Know the use of zeolite catalysts of the type pentasil (ZSM-5, ZSM-II, ZSM-12, ZSM-23), mordenite, zeolite and EU-1 (A. S. Kharitonov, G. I. Panov, K. G. lone, et. al. US Patent N 5055623, 1991), modified at the stage of synthesis of small additions of iron ions. The results obtained in the oxidation of benzene with nitrous oxide at 350-400oC and contact time of 2-4 seconds. (the volumetric rate of liquid benzene 0.4 h-1). When the molar ratio of benzene: nitrous oxide 1:4 output phenol reached 20-30% with a selectivity of about 90-97%. The disadvantages of these catalysts are the necessity of introducing iron into the zeolite and monitor its condition, small values of the flow rate of benzene and large contact times to achieve acceptable, but still not enough high yields of the target products, and low selectivity at elevated temperatures (450oC).

Closest to the proposed method, one is related to the nitrous oxide at a temperature of 225-450oC in the presence of iron-containing zeolite catalyst pre-treated at a temperature of 350-950oC in a gas-vapor stream, containing 0.1-100 mol.% H2O.

(Patent RU N 2074164, C 07 C 37/60, June, 1997,

Application N 94013071/04, C 07 C 37/60, BI N 36, 27.12.95 year).

Processing according to the method of the zeolite catalyst does not lead to a large increase in its activity.

The technical result of the claimed method for production of phenol and its derivatives is to increase process efficiency by increasing the stability of the catalyst and selectivity, as well as increasing the yield of the target product - phenols.

To achieve the technical result in the method for production of phenol and its derivatives by oxidation of benzene and its derivatives with nitrous oxide at 225-450oC in the presence of a zeolite catalyst, previously activated at elevated temperatures, prior activation of the zeolite catalyst is carried out by two-stage heat treatment, the first of which it was incubated for 4-6 hours at 350-450% in a stream of nitrogen or air and the second heat during 450-1100oC for 1-3 hours in continuous current trade is ASS="ptx2">

According to the present invention, the source samples for the preparation of zeolite catalysts are industrial forms of zeolites, such as:

(1) zeolites with a high content of SiO2ZSM - 5, ZSM-11, and others, prepared for example as described in U.S. Pat N 3702886;

(2) the zeolite H-mordenite;

(3) isomorphically substituted pentasil type ferrosilicate, gallosilikata etc.;

More preferred is the use of zeolite ZSM (ZSM-5, ZSM-11, ZSM-12, ZSM-23 and others) with a ratio Si/Al or Si/Me (M=Ga,...) is greater than 20 and especially from 40 to 100.

According to the present invention of the industrial zeolite was transferred to the acid form by treatment with inorganic or organic acid. For best results the Na-form of the zeolite is treated with acid (normality of 0.1 n to 2 n), in the range from 10 ml to 100 ml per 1 g of the zeolite. Such processing may be carried out in one stage or, preferably, in several stages.

The acid form of the zeolite may also be received by the exchange of industrial zeolite with an aqueous solution of ammonium salt, such as nitrate or chloride. For this purpose, the Na-form of zeolite ZSM treated with 0.1 - 2 N. the solution of ammonium salt.

Nitrous oxide is used as the mixture of nitrous oxide in a molar ratio of nitrous oxide/benzene from 1 to 10, usually, about 4 - 5. The reaction mainly takes place at a temperature of from 300 to 500oC.

The products formed in the reactor, can be a mixture of phenol and dihydroxybenzenes, and other oxidation products. They are condensed, are identified and analyzed by any of known methods (gas chromatography, liquid chromatography, mass spectrometry or a combination).

To further illustrate the invention and its advantages, the following are typical examples, and it should be understood that these examples are given for illustration only and not as limiting.

In these examples, use the following parameters (in percent): C = conversion, S = selectivity, Y = output (x S).

Example 1.

The original synthesis of zeolite HZSM-5 was carried out as described in U.S. Pat. USA N 3702886.

Experimental conditions for the oxidation of benzene with nitrous oxide:

the gas phase continuous stream

the catalyst is HZSM-5 (SiO2/Al2O3= 42)

standard temperature pre-treatment - 350oC

temperature dihydroxypropane- 450, 650, 750, 850, 920 or 110oC

the reaction temperature - 350oC

molatore HZSM-5 (SiO2/Al2O3= 42), diffuse, 400 mg of quartz with the same particle size, is placed in the reactor in the form of a tube made of quartz or stainless steel (inner diameter 7 mm). The catalyst was prepared in two stages. The first stage consisted in the heat treatment of the catalyst for 5 hours at 350oC in a stream of nitrogen or air (60 ml/min) in a tube furnace. The second stage consisted in degidroksilirovanie by heating the catalyst for 2 hours at a higher temperature, 450, 650, 750, 850, 920 or 1100oC continuous current of inert gas or air. After this treatment the catalyst was cooled to the reaction temperature (350oC) in a stream of inert gas. The reaction was carried out in a continuous stream through a feed mixture consisting of benzene, nitric oxide and helium (nitrogen) at a flow rate of benzene (liquid) 0.5 to 2 h-1and the time of contact of the gas mixture 1-4 sec.

Data conversion, selectivity and yield of phenol, depending on the temperature dihydroxypropane presented in table 1. The parameters C, S and Y were measured 30 min after start of the reaction. Also in table 1 are values of the degree of deactivation (%), namely, reducing the conversion for the following mperature 1000-1100oC is the destruction of the structure of zeolite HZSM-5 and, as a result, there is a decline of activity.

Example 2.

Sample preparation and catalytic study was carried out as described in example 1. The reaction was carried out at a temperature of 450oC.

The obtained data are presented in table 2.

These data suggest that at high reaction temperature (about 450oC) activity and, especially, the selectivity of the catalyst increased with increasing temperature dihydroxypropane. Thus, for catalyst developed in this invention, the reaction of the direct oxidation of benzene to phenol proceeds with high yields and selectivity close to 100 , even at high temperatures of reaction.

Examples 3 and 4.

The preparation of the catalyst and its catalytic study was carried out as described in examples 1 and 2, respectively, except for the type of catalyst. In order to determine the dependence of the catalytic parameters on the ratio Si/Al in the structure, zeolite HZSM-5 with SiO2Al2O3= 100 (example 3) was investigated in comparison with zeolite HZSM-5 with SiO2/Al2O3= 42 (example 4). The results are shown in varitelnogo dihydroxypropane zeolite and temperature of the reaction direct oxidation of benzene.

Example 5.

Zeolite HZSM-5 (SiO2/Al2O3= 42), prepared by treatment with acid or exchange with NH4-ions, as in example 1 was hot at 450oC for 5 hours (Cycle 1), and then 2 hours at 800oC in a stream of air. After this treatment the catalyst was cooled to room temperature and was maintained in contact with water vapor for 24 hours (Cycle 2). Thereafter, the catalyst was again hot at 450, 650 or 800oC for 2 hours, and then held the oxidation reaction of benzene with nitric oxide NO in 350oC, as described in example 1. The results of the catalytic experiments are presented in table 4.

These data show that the catalyst, once prepared under conditions of high temperature dihydroxypropane, even after subsequent hydration and subsequent standard calcination at 450 - 500oC shows a higher activity than the fresh catalyst prepared in standard conditions (450oC).

Examples 6 and 7.

The catalyst according to example 3 in an amount of 250 mg (fraction 0.5-1.0 mm) diluted with crushed quartz (750 mg) and the mixture is placed in the reactor. As the substrate is benzene (example 6) or phenol (at 430oC. using benzene as substrate with the release of 60% and a selectivity of 97% of the mixture containing phenol (75%) and a mixture (25%) o-, p-diphenols (pyrocatechin and hydroquinone in the ratio 1: 4). The oxidation of the phenol obtained a mixture of o-, m-, p-diphenols in the ratio of 1:0,5:4 with a total yield of 75%.

Examples 8-13.

The catalyst of examples 1 and 2 in the amount of 500 mg, the grain size 0.25-0.5 mm, is placed in flow-through installation. Saturator filled with substrate: florasulam, o-, m-, or p-differentlal, p-axilla, toluene, ethylbenzene, styrene (examples 8-13, respectively). The ratio of helium gas mixture: air: nitrous oxide is 1:3:5. The volumetric rate of the substrate is 1-3 h-1. Analysis catalyzate was conducted chromatomasspectrometry. Data on oxidation are presented in tables 5-7. Several values of the conversion tables correspond to different reaction times of 10, 40, and 70 min-conversion of alkyl benzenes (tab. 7) decreases over time and with increasing reaction temperature, which is associated with deactivation of the catalyst. The oxidation of fervently formed mixture containing predominantly para-isomer of terfenol up to 75% in the absence of m-isomer.

Example 14.

Zeolite type NCM include-5, theoC for 5 hours and at 750oC for 2 hours. Using this catalyst was carried out the oxidation of fervently when flow rate 2.3 h, the reaction temperature 400oC, the gas mixture air:N2O:He=3:5:2 ratio of N2O:substrate=1:4. The output of tortenelem amounted to 20% with selectivity of 97%. Among tortenelem dominated by p-isomer 70%.

These examples show that the developed catalysts for the oxidation of benzene and its derivatives into the corresponding phenols using nitrous oxide have the following advantages over known catalysts reported in patents:

(1) conversion of benzene on the developed catalysts can be increased from 8 to 30% up to 50 - 75% without reducing the selectivity ( 98 - 100%);

(2) the selectivity of the formation of phenol at high reaction temperature (400-450oC) can be increased from 30 to 40% to 95 - 100% at the output of the phenol to 75%;

(3) the stability and lifetime of the catalyst can be significantly improved by prior prior to catalytic testing stage high temperature dihydroxypropane zeolites;

(4) high yield and selectivity of the formation of phenol can be achieved without videoage cases (haloidbenzenes, phenol) shows high selectivity and regioselectivity in p-isomers formed phenols.

Method for production of phenol and its derivatives by oxidation of benzene and its derivatives with nitrous oxide at 225 - 450oC in the presence of a zeolite catalyst, previously activated at elevated temperature, characterized in that prior activation of the zeolite catalyst is carried out by two-stage heat treatment, the first of which it was incubated for 4 to 6 hours at 350 - 450oC in a stream of nitrogen or air, and the second heated at 450 - 1100oC for 1 to 3 h in a continuous current of inert gas or air, followed by cooling of the activated zeolite catalyst to 350oC.

 

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