The activation method of the zeolite catalysts for the oxidative hydroxylation of aromatic compounds

 

(57) Abstract:

The invention relates to the field of organic synthesis, more specifically to a method for production of phenol and its derivatives by catalytic oxidation of benzene and its derivatives. Describes how the activation of the zeolite catalysts for the oxidative hydroxylation of aromatic compounds nitrous oxide at 300-1000oWith in a reducing atmosphere when the content of the reducing agent in the gas-diluent from 0.01 to 100 mol. %. In use as a reducing agent carbon monoxide, ammonia, hydrogen, methane, ethane, methanol, ethanol, and other organic and inorganic compounds or mixtures thereof with reducing properties. Reducing atmosphere contains water vapor in a concentration of from 1 to 99 mol. %. Activation of conduct in respect of the deactivated catalyst to restore its activity and further use in the catalytic process. The activation method of the zeolite catalyst in a reducing atmosphere allows 1.5-2 times increase of the activity of these systems in the reaction of oxidative hydroxylation of aromatic compounds nitrous oxide. The catalyst lost activity during explose continue to use these catalysts for the oxidation of aromatic compounds nitrous oxide order to obtain the corresponding hydroxy. 4 C.p. f-crystals, 8 PL.

The invention relates to the field of organic synthesis, more specifically to a method for production of phenol and its derivatives by catalytic oxidation of benzene and its derivatives.

The introduction of a hydroxyl group in the aromatic ring is one of the most difficult tasks in organic synthesis. The simplest reaction of this type, the oxidation of benzene to phenol, at present, by using the so-called Kumanovo process consisting of three stages. Numerous attempts to make a direct oxidation of benzene to phenol with molecular oxygen has not led to success. Interaction with oxygen leads to the destruction of the benzene ring and a low selectivity to phenol. Attempts by the oxidation of benzene derivatives are even less successful.

In 1983 he opened a new method of one-step hydroxylation of aromatic compounds using as oxidant nitrous oxide (Iwamoto M. , Matsukami K., Kagawa S. Catalytic oxidation by oxide radical ions. 1. One-step hydroxylation of benzene to phenol over group 5 and 6 oxides supported on silica gel. //J. Phys. Chem. 1983. - v.87. - p. 903).

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In equation (1) X= H, HE, F, Cl, CH3WITH2H5or any other radical, the replacement of one or bore which we which provide a selectivity close to 100% (Suzuki E., Nukashiro K., Ono Y. Hydroxylation of benzene with dinitrogen monoxide over H-ZSM-5 zeolite. //Chem. Lett. 1988. - 6. - p. 953-956. US Patent 5055623, C 07 C 37/60, Oct. 8, 1991; US Patent 5110995, C 07 C 37/60, Mau 5, 1992).

On this basis, developed a new process of direct oxidation of benzene to phenol, which has successfully passed the pilot test and considered as a potential alternative semolina process (Uriarte A. K., M. Rodkin, A., Gross, M. J., A. Kharitonov, S., Panov, G. I. Direct Hydroxylation of Benzene to Phenol by nitrous Oxide // Stud. Surf. Sci. Catal., Elsevier, 1997. - V. 110. - p. 857-864).

However, zeolite catalysts have several disadvantages, which include:

a) low activity;

b) gradual deactivation, leading to replacement of the catalyst.

Addressing these deficiencies would significantly increase the effectiveness of zeolite catalysts.

There are two methods that are used for increasing the activity of zeolites in the reactions of hydroxylation of aromatic compounds nitrous oxide: a high-temperature calcination in air in the temperature range of 350-1100o(V. Zholobenko. Preparation of phenol over dehydroxylation HZSM-5 zeolites. Mendeleev Commun. , 1993, 1, p. 28-29; EP 0889018 A1, C 07 C 37/60, June 30, 1998) and processing of water vapor in the area of the carrier gas. However, the effect of increasing the activity produced by these methods is not high enough.

The Way (V. Zholobenko. Preparation of phenol over dehydroxylation HZSM-5 zeolites. //Mendeleev Commun. , 1993, 1, p. 28-29) chosen as a prototype.

The present invention solves both the problem of increasing the activity of the parent zeolite catalyst, and the task of restoring its activity after decontamination in the conditions of the catalytic reaction.

This is achieved by the activation method of the zeolite catalysts for the oxidative hydroxylation of aromatic compounds nitrous oxide at 300-1000oWith in a reducing atmosphere when the content of the reducing agent in the gas-diluent from 0.01 to 100 mol. %. In use as a reducing agent carbon monoxide, ammonia, hydrogen, methane, ethane, methanol, ethanol, and other organic and inorganic compounds or mixtures thereof with reducing properties. Reducing atmosphere contains water vapor in a concentration of from 1 to 99 mol. %. Activation of conduct in respect of the deactivated catalyst to restore its activity and further use in the catalytic process.

Restorative treatment is R is the capabilities of the synthesis of ammonia or hydrogenation of various organic compounds. Sometimes reductive treatment is also used for zeolite catalysts to increase their activity in the reactions in a reducing atmosphere, excluding the presence of an oxidant. Thus, in (US Patent 4002578, B 01 J 029/06, Jan. 11, 1977) describes a method of activation of zeolites containing metals of group VIII by treatment in hydrogen at 250-650oC. This treatment increases the catalytic activity of zeolites in the hydrogenation reactions. In the patent (US Patent 4539305, B 01 J 029/28, Sep.3, 1985) is similar to the recovery processing of metal-containing zeolite catalysts is to increase their activity in the process of reforming. In the patent (US Patent 4326994, B 01 J 029/28, April 27, 1980) declared the activation method of the zeolite by treatment with water vapor, especially in the presence of ammonia. This improves the catalytic properties of the zeolite in the reactions of cracking, hydrocracking, alkylation, dealkylation, isomerization and aromatization of hydrocarbons.

However, there are cases when recovery processing would be applicable to the zeolite or other systems designed for future use as catalysts for oxidation reactions, because such a treatment would be contrary to the common okeh temperatures (above 300oC). Contact the recovered catalyst with a hydrogen peroxide solution at this temperature will inevitably lead to oxidation, in doing so, advanced restorative treatment is useless or even harmful.

However, experiments performed by us showed that the use of zeolites in the reaction of oxidative hydroxylation of aromatic compounds with N2O is a special case. In this case, the processing of the zeolite catalyst in a reducing atmosphere leads to irreversible activating effect, which is stored under conditions of oxidative reactions.

As a hypothesis explaining this unusual phenomenon can be assumed that the activity of the zeolite is associated with the presence of reduced forms of any transition metal, for example iron. This metal may be present either in the form of uncontrolled impurities or intentionally introduced into the zeolite. Being set in restored condition at the stage of activation, the metal acquires the ability to take such positions in the zeolite matrix, which ensures the stability of the new state even in the presence of an oxidant.

The use of reductant DL is, had previously been carried out and from the available literature data, it has a positive effect cannot be predicted.

The present invention describes a method of activating a zeolite catalyst by pre-treatment in the atmosphere containing a reducing agent. In addition, the invention also provides for the use of such restorative treatment for reactivation, i.e., increasing the activity of the catalyst is subjected to aging as a result of its use in the oxidation of benzene and other aromatic compounds nitrous oxide.

According to this invention, the zeolite catalyst can activate or reactivit in a reducing atmosphere to increase the effectiveness of its actions in the reactions of hydroxylation of aromatic compounds with nitrous oxide. In particular, activated or reactivated thus the catalyst can be used in the process of one-step oxidation of benzene to phenol at a temperature varying between 250 and 600oWith the description of which is given in the patent (US Patent 5055623, C 07 C 37/60, Oct. 8, 1991; US Patent 5110995, C 07 C 37/60, May 5, 1992; EP 0889018 A1, C 07 C 37/60, June 30, 1998; US Patent 5672777, C 07 C 37/60, Sep. 30, 1997; DE 19634406 A1, C 07 B 41/02, March 12, 1998). In one embodiment, the implementation of this is s water.

The zeolite catalyst may include zeolites of different chemical composition with the structure of pentasil, beta, and other types of zeolites, for example, claimed in the patent (US Patent 5055623, C 07 C 37/60, Oct. 8, 199; US Patent 5110995, C 07 C 37/60, May 5, 1992; EP 0889018 Al, C 07 C 37/60, J 30, 1998; DE 19634406 A1, C 07 B 41/02, March 12, 1998). When this zeolite may not include or include specially designed additives of one or more metals from the number of items 2, 3, 4, 5 or 6 period of the Periodic system. Preferably one of the metals were iron, as described in the patent (US Patent 5110995, C 07 C 37/60, May 5, 1992).

The zeolite catalyst may be prepared in known conventional methods, the application of which leads to the formation of the crystalline structure of the zeolite, for example, as described in the aforementioned patents. When this additive metal may be made at the stage of synthesis of the zeolite, or by various postsinapticheskih treatments, for example by impregnation or chemical deposition from the gas phase. The catalyst may be used in molded and unmolded. As a binder for the moulding can be applied generally used for this purpose oxides, such as oxides of Al, Si, Ti, etc. or their obrabotke under the influence of the reducing atmosphere. Such recovery processing can be carried out both before and after forming catalyst. As a reducing agent can be hydrogen, ammonia, carbon monoxide, methane, ethane, benzene, methanol, ethanol, or any other organic or inorganic substance capable of reductive atmosphere. Can also be used in mixtures of two or more substances-reducing agents. The concentration of reducing agent can vary from about 0.01 mol. % to 100 mol. % It is desirable that the concentration of the reducing agent does not exceed the lower explosive limit with air to avoid the formation of explosive mixtures in the case of emergency depressurization equipment.

Reducing atmosphere may include water vapor. The concentration of water vapor in the reducing atmosphere can vary from about 1 mol. % to an estimated 99.9 mol. %; preferably from about 10 mol. % to about 90 mol. %, and most preferably from about 30 mol. % to about 60 mol. %. If necessary in a reducing atmosphere may be added to the inert gas, the concentration of which m is approximately 30-60 mol. % water vapor, and the rest inert gas.

Activation and reactivation of the catalyst in a reducing atmosphere may be carried out in the temperature range of from approximately 300oWith up to approximately 1000oWith; preferably from about 400oWith up to approximately 900oC; more preferably from about 500oWith up to approximately 700oC.

The duration of the impact of reducing atmosphere on the catalyst varies depending on its composition, temperature and chemical composition of the catalyst. Typically, the duration of exposure should not exceed about 50 hours, preferably a length of from about 10 to about 30 hours, the preferred length of from about 1 to about 5 hours. The optimal duration of activation and reactivation in each case can easily be determined experimentally by a person who is familiar with this area of study.

As mentioned above, the catalyst activated in accordance with the present invention may be used in the hydroxylation of aromatic compounds. Activation can be carried out in the same reactor in which catalic, The 07 With 27/60, Oct. 8, 199; US Patent 5110995, C 07 C 37/60, May 5, 1992; US Patent 5756861, C 07 C 37/00, May 26,1998), the scope of which is fully incorporated into the present patent application with references. In a typical case, the reaction is carried out with a molar deficiency of nitrous oxide. The reaction mixture fed to the catalyst, in addition to the aromatic compounds and nitrous oxide, may contain other gases used for dilution of the reaction mixture, and various impurities. Normally gaseous diluents do not hinder the flow of the target formation reaction gidrauxilirovannogo aromatic product, for example phenol, and, as a rule, contain helium, argon, nitrogen, carbon dioxide or other gases, or a mixture thereof. In the composition of impurities may contain substances that prevent the target reaction get gidrauxilirovannogo aromatic product by participating in adverse reactions, either by poisoning of the catalyst. Preferably, the concentration of contaminants was as low as possible, but given the practical difficulties of ensuring high purity gases in an industrial environment, a certain low level of contaminants can be considered valid. Impurities normally found in industrial gas streams, which at the nia, nitric oxide, nitrogen dioxide and volatile organic compounds.

In the process of hydroxylation over a zeolite catalyst, activated in a reducing atmosphere, in addition to benzene, can be used other aromatic compounds such as phenol, torbenson, chlorobenzene, toluene, ethylbenzene, etc., In particular, the process of hydroxylation can be used for the preparation of aromatic polyols, such as hydroquinone, resorcinol and pyrocatechin by oxidation of phenol. However, aromatic polyols can be formed by oxidation of benzene by additional oxidation of the formed phenol. Undesirable formation of polyols can be avoided by using a low ratio of nitrous oxide to an aromatic compound, for example, about 0.5 or lower, and also reducing the contact time. On the contrary, the concentration of the mixture of polyols can be increased by increasing the contact time. In the General case, it is preferable to maintain the contact time with the catalyst at a low level, to prevent the formation of undesirable polyols. The optimum contact time can easily be determined prepared in the field by the employee by varying the reaction conditions, composition of the reaction mixture, obtura in accordance with this invention is its performance in the process of hydroxylation of aromatic compounds increases significantly (e.g., up to 2 times).

In another embodiment, the present invention is achieved by reactivation of the deactivated zeolite catalyst by treatment in a reducing atmosphere. Such reductive reactivation can be carried out in respect of the zeolite catalysts used in the above-mentioned processes hydroxylation of aromatic compounds. During hydroxylation gradual sakakawea the surface of the zeolite catalyst. This leads to the need for periodic regeneration of the catalyst by burning the coke, which is accompanied by heating of the catalyst to high temperatures, sometimes exceeding 600oC. Effect of such high temperatures in combination with water vapor, which are formed during the combustion of coke, leads to the gradual deactivation of the zeolite and the need for its replacement with fresh catalyst. Restorative treatment in accordance with this invention, allows you to reactivate this deactivated catalyst and re-use it in the catalytic process. The reactivation of the catalyst is carried out in accordance with the present invention under the same conditions and in the same reset is and the proposed method activation carried out on zeolite catalysts of different chemical composition, cooked in various ways, with a binder and without binder. Testing of catalytic properties held in the reactions of oxidation of benzene to phenol and toluene in the cresol in the installation of flow type.

For a better understanding of this invention the following are examples of its use for activation and reactivation of zeolite catalysts.

Examples 1-3 (comparative, prototype)

For conducting experiments using Fe-containing zeolite catalyst with the structure of ZSM-11. The catalyst has the following composition: SiO2/Al2O3=40; CFe= 0.08 wt. %; CNa=0,02 wt. %; ANDwet=350 m2/g Catalyst synthesized by the methods of hydrothermal synthesis with the introduction of iron in the original gel in accordance with the patent (US Patent 5110995, C 07 C 37/60, May 5, 1992). After burning organic additives at a temperature of 550oWith and translation of the zeolite in the H form a catalyst to activate subjected to further calcination at one of the temperatures specified in the table. 1. To test the catalytic properties of activated catalyst (2 cm3in the form of fractions of 0.5-1.0 mm is loaded into a quartz tubular reactor with an inner diameter of 7 mm, the Reactor is heated to a temperature of 400oWith a and B>6, the rest is helium. The composition of the reaction mixture after the reactor periodically analyze chromatographic method. From the obtained data, calculate the performance of the catalyst for phenol. Performance values measured within 1 hour after the start of operation of the catalyst are shown in table. 1 (examples 1-3).

It is seen that the source zeolite, calcined at 550oWith, has a low activity (example 1). Its performance for phenol is only 1.5 mmol/g hour. With increasing temperature calcination activity increases (examples 2-3).

Examples 4-6

The catalyst FeZSM-11 of the same chemical composition as in examples 1-3, are synthesized in accordance with the patent (US Patent 5110995, C 07 C 37/60, May 5, 1992). After burning organic additives at a temperature of 550oWith and translation of the zeolite in the H form, the catalyst was activated in a stream Not containing 6 mol. % of carbon monoxide. After activation, the catalyst was tested in the oxidation of benzene to phenol by nitrous oxide in identical conditions as described in examples 1-3. The results are given in table. 2.

Examples 7-12 (comparative)

High-temperature activation of zeolite catalysts in the presence of water vapor (US Patent to highlight the actual effect of the reducing agent in the recovery thermoprotei activation of pre-made examples 7-12, The zeolite catalyst with the structure of ZSM-5 is prepared in accordance with the patent (US Patent 5110995, C 07 C 37/60, May 5, 1992). The catalyst does not contain a specially introduced Fe or any other transition metal and has the following chemical composition: SiO2/Al2O3=80; CNa=0,01 wt. %. The surface of the catalyst BET is 400 m2/g, micropore volume - 0,140 cm3/year After burning organic additives and translation in the H-form of the catalyst is subjected to thermoprotei activation in accordance with the patent (US Patent 5672777, C 07 C 37/60, Sep. 30, 1997) when one of the temperatures indicated in the examples 8-12 (PL. 3). Activation is carried out for 2 hours in a stream of helium containing 50 mol. % H2O. As can be seen from a comparison with the results of the experiment 7 conducted with neaktivirovannye catalyst, termoparnaya activation significantly increases the catalytic activity of the zeolite. Examples 7-12 then used for comparison with reconstructive thermoprotei activation carried out in the presence of water vapor and a reducing gas (examples 13-17).

Examples 13-17

These examples in comparison with examples 7-12 illustrate the positive effect of reducing agent on the stage thermoprotei activation zeal Oh, 6 mol. %, The rest is helium. From the results shown in the table. 4, it is seen that the presence of a reducing gas in the activating mixture significantly increases the catalytic activity of the zeolite. Depending on the activation temperature performance for phenol increases from 10 to 75%.

Examples 18 to 21

These examples illustrate the effect of the nature of the reducing agent used at the stage thermoprotei activation. In these examples, samples of zeolite ZSM-5 prepared in the same manner as in example 15, except that when activated, instead of carbon monoxide as a reductant use ammonia (example 19), hydrogen (examples 20, 21) and methane (example 22).

From the results shown in table. 5, it is seen that the presence of a reducing agent in all cases increases the catalytic activity of ZSM-5. His performance is going to be increased about two times: from 5.1 mmol PhOH/g h in example 10 (activation without reductant) to 9.0-10.5 mmol/g h in examples 18-21. The concentration and nature of the reducing agent does not have a major impact on the value of the activating effect. This opens up a wide possibility when choosing a suitable reductant, as among the organic and among near the ATEM catalyst is subjected to decontamination by prolonged high temperature treatment in the presence of water vapor. This treatment simulates the real conditions of aging of the catalyst in the process of its operation. As can be seen from the table. 6, the catalyst when it really loses a significant proportion of its activity, its performance drops from 4.3 mmol PhOH/g hour (example 11) to 1.9 mmol PhOH/g hour (example 22).

Decontamination of the sample in this experiment is carried out with the purpose to further test the possibility of reactivation using restorative treatment (see example 23).

Example 23

This example illustrates the possibility of reactivation of the deactivated zeolite. To this end decontaminated sample of ZSM-5 after example 22, in which he showed low catalytic activity, is subjected to reduction treatment at a temperature of 775oWith the current helium containing 12 mol. %. This treatment several times increases the catalytic activity of the sample and leads to the restoration of its performance for phenol (PL. 6).

Thus, activation of the zeolite catalyst in a reducing atmosphere allows 1.5-2 times increase of the activity of these systems in the reaction of oxidative hydroxylation of aromatic compounds nitrous oxide. The catalyst lost activity in the ore, that allows you to continue to use these catalysts for the oxidation of aromatic compounds nitrous oxide order to obtain the corresponding hydroxy.

Examples 23-24 (Confirmation of potential use to activate the reducing agent with a concentration of from 0.01 to 100 mol. %)

Examples 23-24 illustrate a possible use for the activation of the reducing agent with a concentration of from 0.01 to 100 mol. %. To this end, the catalyst FeZSM-11 is prepared as in example 5 except that in example 23 activation is carried out in a stream of helium containing 0.01 mol. %, And in example 24 activation is carried out in the thread clean. After activation, the catalyst was tested in the oxidation of benzene to phenol by nitrous oxide in identical conditions as described in examples 1-3. The results are given in table. 7.

Examples 25-28 (Confirm the possibility of using for activation of the catalyst substances of different chemical nature, with reducing properties)

These examples illustrate the effect of the nature of the reducing agent to the activation process. To this end, the catalyst FeZSM-11 is prepared as in example 5, except that when activated as a reducing agent inst/SUB>. After activation, the catalyst was tested in the oxidation of benzene to phenol by nitrous oxide in identical conditions as described in examples 1-3. The results are given in table. 8.

As examples 25-28 the presence of a reducing agent in the activating mixture has a positive effect compared with calcining the catalyst in air (example 2). The changes in the chemical nature of the reducing agent has only a minor impact on the magnitude of the effect. The nature of the reducing agent does not have much influence on the quantity of the activating effect when thermoprotei activation (examples 18-21). This means that for activation of the catalyst can be used any of organic and inorganic compounds and their mixtures with reducing properties.

1. The activation method of the zeolite catalysts for the oxidative hydroxylation of aromatic compounds nitrous oxide at 300-1000o, Characterized in that the activation of the catalysts are in a reducing atmosphere.

2. The method according to p. 1, characterized in that the content of reducing agent in the gas-solvent is from 0.01 to 100 mol. %.

3. The method according to p. 1, characterized in that as restore the systematic compounds or mixtures thereof, with reducing properties.

4. The method according to p. 1, wherein the reducing atmosphere contains water vapor in a concentration of from 1 to 99 mol. %.

5. The method according to PP. 1-4, characterized in that the activation of conduct in respect of the deactivated catalysts in order to restore their activity and further use in the catalytic process.

 

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