KR100231372B1 - Catalyst for production of phenol and its derivatives - Google Patents

Abstract

The present invention is effective under nitrogen of about 500 to 1000 ° C., effective for two hours of hydrothermal treatment, useful for preparing phenol and its derivatives by oxidative hydroxylation of benzene and its derivatives with nitrous oxide at 225 to 450 ° C. A zeolite catalyst substantially enhanced by hot water treatment using a gas containing 3 to 100 mole percent water vapor.

Description

Catalysts for the production of phenols and derivatives thereof

Photocatalysts ranging from vanadium pentoxide on silica to zeolites such as ZSM-5 and ZSM-11 zeolites and phenols by partial oxidation of benzene using nitrous oxide at high temperatures from 300 ° C to 450 ° C. Manufacturing methods have been disclosed. If benzene is replaced with benzene derivatives such as chlorobenzene, fluobenzene, toluene or ethylbenzene, the corresponding substituted phenols can be produced. When the phenol itself is a substituted benzene, the reaction product includes dihydroxy benzenes such as hydroquinone, resorcinol and catechol. Phenols and their derivatives such as dihydricphenols, chlorophenols, nitrophenols, cresols and other hydroxy containing aromatic compounds are valuable products with a wide range of industrial applications. The most common essential chemicals of this class are phenols, which are mainly used in the manufacture of phenolic resins, caprolactams, nitrophenols and chlorophenols. For the past decade, simple and efficient synthesis of phenol and its derivatives has been studied. Iwamoto et al., Physical and Chemical Papers (ACS), vol. 87, NO. 6, (1983) P. 903-905 One-step hydroxylation of aromatic compounds is carried out using nitrous oxide as the oxidant in the presence of conventional catalysts for partial oxidation, such as oxides of vanadium, molybdenum and tungsten. It can be described. Iwamoto carried out the reaction at 550 ° C. with a benzene conversion of 10% and a selectivity to phenol of 72%. These results are considerably better than before, but still prove to be insufficient for practical use of the method, and more efficient systems are required.

The use of new types of catalysts, such as highly silica aluminosilicates with zeolite structures, for the hydroxyation of benzene is described by Suzuki et al. In the Japanese Chemical Society (1988) P. 953-956; By Gubbelman et al. In US Pat. No. 5,055,623; In US Pat. No. 5,110,995 reported by Karitonov et al. The hydroxylation reaction of benzene and other aromatic compounds in the presence of this zeolite catalyst was carried out at 300-400 ° C. with a selectivity to phenol of 90-100%. However, catalytic activity was quite inadequate for the commercial utility of this technique.

Researchers have continued to explore new ways to introduce different types of catalyst pretreatment to enhance zeolite efficiency and / or improve reaction phase parameters. In this regard, Zorobenko writes in Mendelev Column (1993) NO. 1 P28-29 reported a method for preparing phenol using a zeolite catalyst which is activated by hot firing in air. The disadvantage of this zorobenco method is that the catalytic activity does not increase at all at the firing temperature of 700 ° C or lower. More specifically, the activating effect is significant at higher temperatures (750 ° C. or higher), and therefore the zorobenco method is practically difficult to use.

What is described herein relates to improved catalysts used to prepare phenols and their derivatives by one-step oxidative hydroxylation of benzene or other aromatic compounds with nitrous oxide and methods of making such catalysts.

[Summary of invention]

The present invention solves various problems associated with insufficient performance and efficiency of zeolite catalysts in the nitrous oxide hydroxylation reaction of benzene and its derivatives to produce phenol and its derivatives. These problems are surprisingly solved by the use of activated zeolite catalysts in a simple and efficient manner such as, for example, exposure to steam at high temperatures.

[Detailed Description of Preferred Embodiments]

The present invention provides an improved zeolite catalyst for the oxidative hydroxylation of corresponding aromatic compounds using nitrous oxide to prepare phenols and derivatives thereof. The catalytic performance of such zeolite catalysts is enhanced by the process of the invention in which the zeolite catalyst is treated with a vapor comprising a gas phase at 350-950 ° C. The content of water vapor in the gas phase is not critical, which can range from low levels of water vapor in the diluent gas to essentially pure water vapor. For example, the gas phase may contain as low as 3 mole percent water vapor in the air or preferably inert diluent gas phase, preferably including nitrogen, argon, helium, carbon dioxide, or the like or mixtures thereof. The gas phase, of course, must not contain essentially any components harmful to the catalyst. The gas phase may preferably contain higher amounts of water vapor, for example up to 100 mol%, for example 10 mol% or more. The duration of high temperature exposure of the catalyst to water vapor can vary depending on the desired degree of enhancement, which can be readily determined by routine experimentation.

Zeolites which can be improved by the process of the invention preferably include ZSM-5 and ZSM-11 zeolites which are in acidic form and which contain iron. These zeolites are known in the art, are used in various commercial processes and can be easily purchased from catalyst vendors such as UOP, Mobil. Commercial zeolite catalysts are provided in porous matrices of alumina or silica to provide permanent pellets that resist abrasion in a packing or fluidized bed reactor. It has been found that the process of the invention is advantageously applied to zeolites in powder or pellet form.

Zeolite catalysts with improved performance prepared by the process of the present invention are characterized in that oxidation of aromatic compounds such as benzene and benzene derivatives, such as chlorobenzene, fluorobenzene, toluene, ethylbenzene and similar compounds including phenol, etc. Particularly useful for the reaction. This oxidation reaction is accomplished by passing a feed gas mixture of phenol, nitrous oxide and any diluent gas, such as nitrogen, argon, carbon dioxide, etc., over a zeolite catalyst at a temperature of 225-450 ° C. or higher, for example 500 ° C. Reaction conditions, including feed gas composition, reaction temperature and flow rate, may be determined by those skilled in the art depending on the desired reaction parameters such as selectivity of phenol production, conversion of nitrous oxide, phenol concentration in biogas, catalyst productivity, and the like. Can be changed. For example, the molar ratio of nitrous oxide to benzene in the feed gas mixture can be in the range of 100: 1 to 1: 100. In some preferred embodiments, it is advantageous to carry out the reaction with molar excess aromatic compounds.

According to one aspect of the present invention, the hydrothermally treated zeolite catalyst has a characteristic of lowering the benzene conversion rate during phenol production due to the desired catalytic conversion, that is, oxidation of benzene with nitrous oxide at 350 ° C. Preferred catalysts of the present invention, such as ZSM-5 or ZSM-11 zeolite catalysts, have a ratio of at least 40% of the benzene conversion after a 3 hour continuous process to the initial benzene conversion. For more preferred catalysts, this ratio will be at least 50%. In the following examples, catalysts are exemplified for this ratio to be about 70%.

Hydrothermally treated catalysts of the present invention can be identified as resistant to hydrothermal treatment. For example, the iron-containing acidified zeolite catalyst of the present invention is a catalytic hydride of benzene for preparing phenol in a gas stream consisting of 75 mol% helium, 5 mol% benzene and 20 mol% nitrous oxide at 350 ° C. When used in the oxidization reaction, the conversion rate of benzene is not increased to 10% or more even by hot water treatment at 600 ° C. for 2 hours with a gas composed of 50 mol% air and 50 mol% water.

The advantages of the present invention are illustrated by the following examples, wherein the enhanced performance of zeolites is illustrated by the oxidation of benzene with nitrous oxide.

Example 1

SiO ₂ per mole of 4.3 × 10 _-4 mol of Fe ₂ O ₃ and 2.3 × 10 ^-2 mole of Al ₂ O ₃ to the zeolite catalyst SiO ₂ as a base material including a method disclosed by U.S. Patent No. 5,110,955 arc Kariya sat Smirnoff It was prepared according to. After the organic template material was burned out, the zeolite was treated with acid, transformed into H-type, and calcined by inflowing dry air at 550 ° C. for 2 hours. To test the catalytic properties, a tubular reactor was prepared by adding about 2 cc of zeolite in 0.5-1.0 mm fraction to a quartz tube with an internal diameter of 0.7 cm. The zeolite-filled tubular reactor was heated to 350 ° C. and a reactor mixture containing 5 mol% benzene and 20 mol% nitrous oxide in helium was fed. The product gas flowing from the reactor was analyzed periodically by gas chromatography. Gas analysis data were used to calculate benzene conversion (X) and selectivity for phenol (S), which are shown in Table 1. The catalyst was observed to be deactivated during the reaction due to coke precipitation. Twenty minutes after the feed gas was introduced into the reactor, 8.5% initial benzene conversion was measured to determine X _o and 92.5% initial selectivity So. After 3 hours of continuous operation, the benzene conversion was determined to be 3.0%, indicating lower catalytic activity. The ratio of benzene conversion to initial benzene conversion (X / X _o ) 35% characterizes the catalyst stability during the reaction operation. give. No decrease in selectivity was observed in any reaction process.

Example 2

The catalyst substantially prepared in the method of Example 1 was subjected to hydrothermal treatment for 2 hours by exposing to air containing 50% water at 500 ° C. for 2 hours in the presence of air containing 50 mol% water. According to the properties of the hydrothermally treated catalyst shown in Table 1, the initial benzene conversion was substantially increased to 18.5%.

[Examples 3 to 8]

These examples illustrate the invention by varying the hot water treatment temperature.

In these examples, the catalyst samples were prepared by the method of Example 2, except that the hydrothermal treatment at a temperature of 550 ~ 1000 ℃. According to the observed catalytic properties shown in Table 1, the optimum hydrothermal treatment temperature can be readily determined by routine experimentation to provide catalysts with desired initial or long term conversion properties. More surprisingly, as the benzene conversion increased from 8.5% to 37% with hydrothermal treatment, the catalyst stability also increased to factor 2, ie X / X _o increased from 35% to 70%. This treatment at very high temperatures around 1000 ° C. is not recommended because it significantly reduces the catalytic activity.

TABLE 1

EXAMPLES 9-12

These examples illustrate the invention by varying the water content of the hot water treatment gas. Catalyst samples in these examples were prepared essentially according to the method of Example 2, except that the hot water treatment was carried out with treated gases containing 2.5-100 mol% water vapor at 600 ° C. The catalyst data shown in Table 2 shows that it is possible to provide catalysts with substantially increased process efficiency as the water vapor concentration in the hot water treatment gas increases. For example, as the benzene conversion was increased from 8.5% to 38.5%, the degree of recognition increased and the selectivity increased somewhat. In Example 9, hydrothermal treatment was carried out under similar conditions to calcinate the catalyst in air, for example at 2.5 mole percent water vapor. Comparison of Example 9 with Example 1 shows that the concentration of water is not sufficient for significant activation of the catalyst.

TABLE 2

[Examples 14-16]

These examples illustrate the beneficial effect of the process of the present invention on a variety of catalysts useful in the preparation of phenols by the hydroxylation of benzene with nitrous oxide. Zeolites with the compositions shown in Table 3 were evaluated both to determine initial bezel conversion and phenol selectivity. The zeolite was then subjected to hydrothermal treatment by exposing it to a gas at 500 ° C. containing 50 mol% water for 2 hours. It can be seen that such hydrothermal treatment enhances the process properties according to various zeolite compositions.

TABLE 3

These examples illustrate the nature of the proposed invention, but are never exclusive, and the optimal conditions of hydrothermal treatment activation (temperature, time, steam, concentration, etc.) depend on different types of catalysts and reactions using these catalysts. Therefore, it may vary. In particular, the high efficiency of the activated catalysts not only allows the reaction to proceed under excess nitrogen dioxide, but also under conditions where the molar ratio of excess aromatic compounds, such as aromatic compounds to nitrous oxide, is 100: 1. You can. The advantage of running the reaction in excess aromatics is that under these conditions complete conversion of nitrous oxide can be achieved. In this case, there is no need to separate unreacted nitrous oxide, which leads to significant technical unification.

While particular embodiments have been described herein, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the following claims are intended to cover all such modifications within the spirit of the invention as a whole.

Claims (17)

The zeolite catalyst for promoting the oxidation reaction of benzene by nitrous oxide, comprising the step of enhancing the activity of the zeolite catalyst by treating with hot water gas containing 3 to 100 mol% of water at 350 to 950 ° C. Manufacturing method. The method of claim 1, wherein the zeolite catalyst is a ZSM-5 or ZSM-11 zeolite catalyst. 3. A process according to claim 2 wherein the catalyst is an iron containing acidified zeolite. 4. A process according to claim 3 wherein the gas contains at least 10 mole percent water. The method of claim 4. The temperature of the gas is at least 500 ° C. Zeolite catalyst prepared by the method according to claim 1. The process of claim 6 wherein the catalyst is initially subjected to catalytic hydroxylation of benzene to produce phenol in a gas stream consisting of 75 mol% helium, 5 mol% benzene and 20 mol% nitrous oxide at 350 ° C. 8. A catalyst characterized by a ZSM-5 or ZSM-11 zeolite catalyst which stabilizes the benzene conversion such that the ratio of benzene conversion after 3 hours continuous process to benzene conversion is at least 40%. A phenol comprising the step of reacting benzene or a derivative thereof with nitrous oxide in the presence of a zeolite catalyst which is hydrothermally treated with a gas containing 3 to 100 mol% of water at 350 to 950 ° C to enhance catalytic activity. Method for producing a derivative thereof. The method of claim 8, wherein the zeolite catalyst is a ZSM-5 or ZSM-11 zeolite catalyst. 10. The process of claim 9, wherein the catalyst is an iron containing acidified zeolite. The method of claim 10, wherein the gas contains at least 10 mol% water. 12. The method of claim 11 wherein the temperature of the gas is at least 500 ° C. The method of claim 5, wherein the temperature of the gas is at least 550 ° C. 7. The method of claim 13, wherein the temperature of the gas is at least 600 ° C. The method of claim 12, wherein the temperature of the gas is at least 550 ° C. 16. The method of claim 15, wherein the temperature of the gas is at least 600 ° C. Zeolite catalyst prepared by the manufacturing method according to claim 14.