KR19990083611A - Selective oxidation and the synthesis of hydroxyl-containing aromatic compounds - Google Patents

Abstract

The present invention relates to a process for preparing hydroxyl containing aromatic compounds in a single step by selective catalytic oxidation of aromatic compounds.

Description

Selective oxidation and the synthesis of hydroxyl-containing aromatic compounds

The present invention relates to a process for preparing hydroxyl containing aromatic compounds in a single step by selective catalytic oxidation of aromatic hydrocarbons.

To date, it has not been possible to directly convert benzene to the corresponding hydroxyl compound in a single step and high yield by selective oxidation to produce hydroxyl containing aromatic compounds such as phenols. The aromatic ring was not attacked by the oxidant at all, or was degraded by the oxidant. The main products produced were carbon dioxide and coke.

So far, from an economic point of view, it has only been possible to introduce hydroxyl groups into the aromatic system through a number of intermediate steps.

Cumene processes are industrially established for producing phenols starting from benzene. In this step, in general, cumene produced from benzene and propene is subjected to peroxidation, and then the oxidation product is decomposed into phenol and acetone.

In addition, a benzoic acid process starting from toluene is used, in which a phenol can be obtained by decarboxylation of the benzoic acid prepared from toluene. However, the decarboxylation step, i.e. the step of removing the originally bound carbon, loses the market advantage of toluene over benzene in this initial step. Therefore, this process is only suitable for the case where the desired product is benzoic acid and when the phenol can be produced using the extra production equipment.

For example, other processes for preparing phenol through chlorobenzene (chlorination or oxychlorination of benzene) or sulfonation processes (processes for preparing benzenesulphonic acid) have proven uneconomical. Some of the reasons are unsatisfactory selectivity, corrosion problems and the generation of undesired by-products.

The cyclohexanol process (hydration process of cyclohexene in the first stage) is also uneconomical. This process requires too many steps to produce the desired product phenol.

For this reason, most of the phenols in the world are produced through the cumene process described above. However, because acetone is also produced in this process, the cost efficiency of this process depends on the prices of phenol and acetone.

Many attempts have been focused on the selective oxidation of benzene or benzene derivatives so that the dependence on acetone produced as a byproduct can be neglected. However, for example, US Pat. Nos. 5,055,623, 5,672,777 and 5,110,995 describe the oxidation of benzene with dinitrogen monoxide over suitable catalysts.

The oxidative properties of benzene with dinitrogen monoxide on vanadium oxide / molybdenum oxide / tungsten oxide catalysts have already been known since 1992 (Iwamoto). In 1988, ZSM-5 type zeolite catalysts (Gubelmann, Rhone-Poulenc) were developed to directly oxidize benzene using dinitrogen monoxide. Basically, the mode of action of zeolites is due to the microporous channel system where the pore diameter is equal to the size of the molecules to be oxidized.

The use of ZSM-5 type iron-containing zeolite catalysts for oxidizing benzene with dinitrogen monoxide is described in the literature. Volodin, Bolshov and Panov, J. Phys. Chem. 1994, 98, 7548-7550.

In addition, the following documents describe oxidation on zeolites, in particular zeolites of the ZSM-5 type. See also: 3rd World Congress on Oxidation, 1997 Elsevier Science BV, RK Graselli et al., (Editors), M. Hafele et al. (University of Erlangen-Nuremberg) and GI Panov et al., Applied Catalysis A: General 98 (1993) 1-20.

The most developed reaction from the point of view of process engineering is the reaction of dinitrogen monoxide on acid zeolites of the ZSM-5 type and ZSM-11 type with the addition of various metals (eg iron). This reaction is generally carried out at 300 to 450 ° C. under atmospheric pressure.

The disadvantage of zeolites is that because they are completely crystalline structures, they cannot be applied continuously by varying the pore size for the molecule to be oxidized, and can only be applied stepwise depending on the crystal type established. This means that zeolites cannot be specifically applied to each oxidation problem. Zeolites cannot substantially change the surface porosity, which, when immobilized, allows for certain reaction mechanisms. Documents such as US Pat. Nos. 5,110,995 and 5,055,623 describe one type of zeolites (pentasil ZSM-5 and ZSM-11) for preparing various phenol derivatives. Although zeolites or acidic zeolites can be modified with a variety of metals, this does not completely solve the problems described above but can at best improve them. Thus, for example, in acidic zeolites, sodium atoms and hydrogen atoms can be replaced. In the case of iron-containing zeolites, the activity is not lowered at all, whereas when iron is replaced with aluminum, the activity is lowered by replacing sodium and hydrogen atoms. However, overall conversion and selectivity are still unsatisfactory.

Changing other parameters, such as increasing the reaction temperature (zeolites are thought to be thermally stable below about 800 ° C.), increases the benzene conversion, but also further reduces selectivity and further deactivates the catalyst. Increasing the partial pressure of N ₂ O can also increase the benzene conversion, but in this case also the selectivity is reduced. Increasing the partial pressure of benzene can only improve gradually at best. Selectivity and production of phenol are slightly increased. Nevertheless, it is still desirable to further increase selectivity and conversion.

Generally, the activity is degraded by relatively rapid coking of the catalyst occurring at the applied temperature, so the catalyst must be regenerated relatively frequently (every about 48 hours).

The dinitrogen monoxide used to catalytically oxidize benzene in the process described above should be very high purity. Contaminants such as oxygen or hydrophilic gases (water vapor or ammonia) can completely inactivate the zeolite catalyst. Only inert gases such as Group 0 gases or nitrogen may be acceptable as mixtures.

In the case of dinitrogen monoxide, various raw materials are suitable. Catalytic decomposition of ammonium nitrate at 100 to 160 ° C. using manganese, copper, lead, bismuth, cobalt and nickel catalysts yields a mixture of dinitrogen monoxide, nitric oxide and nitrogen dioxide, which is used to directly oxidize benzene. It cannot be used.

It is rather easier to oxidize ammonia with oxygen on a platinum oxide or bismuth oxide catalyst at 200 to 500 ° C. and to react nitrogen oxide with carbon monoxide on a platinum catalyst. In the first case, however, water is produced as a byproduct, and in the second case carbon dioxide is produced as a byproduct. Dinitrogen monoxide thus prepared cannot be directly used for benzene oxidation. Likewise, dinitrogen monoxide generated in the production of adipic acid cannot be used directly for benzene oxidation and a separate purification step must be performed. Oxygen and NO _x present in the exhaust gases are particularly disturbing.

Attention should be paid to the purity of dinitrogen monoxide with respect to the fact that the zeolite's catalytic activity decreases when the zeolite absorbs water. Certain zeolite structures may be hydroaminated by dealumination, but in this case the selection of suitable zeolites is further limited. In addition, dealumination is an additional process step, forming undesirable amorphous components in the zeolite. In addition, since the dealumination degree cannot be set specifically, it must be measured experimentally in this process. This means that oxidizers of inconsistent quality grades, for example different steam mixtures, cannot be used.

It is therefore an object of the present invention to provide an economical method for catalytically oxidizing aromatic compounds with high selectivity to obtain the corresponding hydroxyl compounds even when the quality of dinitrogen monoxide is low.

Surprisingly, it has been found that porous glass can act as an excellent catalyst for the catalytic oxidation of aromatic compounds, even when using contaminated dinitrogen monoxide, to obtain the corresponding hydroxyl compound.

Accordingly, the present invention relates to a process for preparing hydroxyl-containing aromatic compounds, including catalytically oxidizing the aromatic compound in the presence of porous glass using a dinitrogen monoxide containing gas at a temperature of 100 to 800 ° C.

The process according to the invention can be optimized by using porous glass depending on the respective respective conditions of use, for example the quality of dinitrogen monoxide or aromatic compound type to be used.

The present invention is an example because a specialized book on high selectivity to phenols with high benzene conversions suggests "specific" zeolites, for example pentasil type zeolites (eg ZSM-5 and ZSM-11). It is bad.

Since these zeolites have a three-dimensional structure ("cage structure"), the surface area is large. However, since the pore system of porous glass used in the method according to the invention has a significantly different structure, the catalytic activity is substantially lower (if any), as compared to zeolites, since in general three-dimensional access is not possible. Can be expected.

The degree of catalysis caused by the method of manufacture or the composition of the porous glass used in the present invention may still remain unanswered, but using a low quality dinitrogen monoxide by the method according to the present invention Even with very high selectivity, conversion rates can be increased.

The dinitrogen monoxide-containing gas used in the present invention may be a mixture of 5 to 100 vol% dinitrogen monoxide with 0 to 95 vol% of other gases.

In addition, the dinitrogen monoxide content of the gas used in the process according to the invention may be from 80 to 100% by volume, the content of other gases may be from 0 to 20% by volume.

As other gases, air, oxygen, nitrogen, group 0 gases, carbon dioxide, water vapor, ammonia or mixtures thereof can be used.

The dinitrogen monoxide-containing gas used in the present invention may contain, for example, an organic impurity or an inorganic impurity from the oxidation process (the reaction system itself in the production of N ₂ O or the N ₂ O-containing exhaust gas generated in the production of adipic acid). Can be.

In certain embodiments of the present invention, the aromatic compound used is benzene, but other aromatic compounds such as toluene, xylene or halogenated benzene and polynuclear aromatic compounds such as naphthalene can also be oxidized.

Surprisingly, on the surface of non-polar modified porous glass, it is observed that benzene conversion below 375 ° C. (eg 350 ° C.) is substantially as high as benzene conversion above 375 ° C. The selectivity also increases at lower temperatures, as expected. In the case of zeolite catalyst systems, the benzene conversion generally decreases considerably as the temperature is lowered. Thus, under equivalent conditions, zeolites act considerably less advantageously.

The process according to the invention is preferably carried out at 200 to 700 ° C, particularly preferably at 250 to 550 ° C. Porous glass and microporous amorphous mixed metal oxides used in the process according to the invention can be prepared according to DE 195 06 843 A1.

The porous glass used in the process according to the invention is produced by the sol-gel method.

In one embodiment of the present invention, the porous glass comprises from 50 to 100% by weight of oxides of Group 3, 4, 3 or 4 elements of the Periodic Table of Elements, including lanthanide and actinide do.

In another aspect of the invention, the mixed metal oxide matrix of the porous glass comprises at least 50% by weight of titanium, silicon, vanadium, aluminum, zirconium or cerium element compounds and / or molybdenum, tin, zinc, vanadium, manganese, iron, cobalt, Nickel, arsenic, lead, antimony, bismuth, ruthenium, rhenium, chromium, tungsten, niobium, hafnium, lanthanum, cerium, gadolinium, gallium, indium, thallium, silver, copper, lithium, potassium, sodium, beryllium, magnesium, calcium It may comprise up to 50% by weight of an oxide of one or more metals selected from the group consisting of strontium and barium (very advantageous for atomic distribution).

Preferably, the mixed metal oxide matrix of the porous glass is one selected from the group consisting of SiO ₂ , TiO ₂ , Al ₂ O ₃ , vanadium oxide, zirconium oxide, cerium oxide, spinel, mullite, silicon carbide, silicon nitride and titanium nitrite At least two compounds, particularly preferably at least two compounds.

In addition, the mixed metal oxide matrix further comprises up to 10% by weight of the metal of one of platinum, rhodium, iridium, osmium, silver, gold, copper, nickel, palladium and cobalt in a highly dispersed form, either in the metal state or in the oxidized state. can do.

The porous glass can be obtained by linearly polymerizing or polycondensing the hydrolyzable soluble compounds of the above-mentioned metals and their oxides using an acid or a fluoride as a catalyst. Preferably, alkoxy, mixed alkoxyalkyl, alkoxyoxo or acetylacetonate derivatives of the metals or metal oxides described above are used in the sol-gel method in the acidic to neutral pH range. It is then gently dried and calcined slowly, and calcination is terminated at a temperature between 120 and 800 ° C.

Another method for preparing this type of compound is the pyrolysis process. See K. W. Terry et al., J. Am. Chem. Soc. 1997, 119, 9745-9756. However, compared with the sol-gel method, the disadvantage of this method is that the likelihood of change during manufacture is reduced, so that only very small proportions of elements in the final product are possible.

Non-polar porous glass or hydrophobic porous glass is produced, for example, according to DE 195 45 042 A1. The polarity of the inner surface and the outer surface of the porous glass is, for example, the sol-gel process of alkylsilanes or aryloxysilanes of the formula R'-Si (OR) ₃ type having It can be fixed by co-condensation with other compounds.

R and R 'may be the same or different and are preferably aliphatic hydrocarbon radicals of up to 6 carbon atoms, for example methyl, ethyl or isopropyl groups, or phenyl radicals.

Metal oxides reacted with such non-hydrolyzable groups are described above. As ligands of the starting compounds, ie soluble metal compounds, halides, alkoxides, oxyalkoxides, carbonates, oxalates, nitrates, sulfates, sulfonates, acetylacetonates, glycolates or aminoalkoxylates are preferably used. . The base material is SiO ₂ , Al ₂ O ₃ , TiO ₂ or ZrO ₂ .

The use of hydrophobized porous glass is advantageous because the selectivity is constant and high, especially when the moisture content of dinitrogen monoxide is high,

Not only porous glass but also flux may be used. These are considered to mean support systems or mixtures thereof based on SiO ₂ or Al ₂ O ₃ . In addition, as described in the examples, a mixture of porous glass and (crystalline) zeolite can be used without lowering benzene conversion and selectivity.

The pore size and total surface area of the glass used are important. Average pore size should be between 0.1 and 1 nm, as reported by Horvath and Kawazoe. J. Chem. Eng. Jpn. 16 (1983) 470 ff.].

The total surface area of the porous glass in the dry state is measured by the BET method according to the literature, in each case preferably 50 m ² / g or more, particularly preferably 50 to 5,000 m ² / g, very preferably 75 to 1,500 m ² / g (WF Maier et al., Tetrahedron 51 (1995) 3787 ff.).

Example

1. Preparation of Porous Glass

1.1 Zirconium Dioxide-Silicon Dioxide Glass

1 ml of tetrabutoxyzirconium, 10 ml of tetraethoxysilane and 8 ml of ethanol are successively dissolved in order, and 2 ml of 8N hydrochloric acid is added while stirring. After the gel was formed, the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then heated to 250 ° C. at a heating rate of 0.2 ° C./min and then at this temperature. Calculate for an additional 3 hours. The product shows a uniform pore distribution.

BET Surface Area: 500m ² / g

Pore Diameter: 0.74nm

1.2 Aluminum oxide-zirconium dioxide-silicon dioxide glass

0.45 ml of tetraisobutylaluminum, 2.01 ml of tetra-n-propoxyzirconium, 27.5 ml of tetraethoxysilane, and 25 ml of ethanol are successively dissolved, and 4.5 ml of 0.4N hydrochloric acid is added with stirring over 10 minutes. During this time, the temperature rises to 55 ° C. After the gel was formed, it was slowly pre-dried at room temperature, then the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then 300 ° C. at a heating rate of 0.2 ° C./min. Heated to and then calcined for an additional 3 hours at this temperature. The product shows a constant pore distribution.

BET Surface Area: 290m ² / g

Pore diameter: 0.69nm

1.3 Zirconium Dioxide-Silicon Dioxide Glass

1 ml of tetrabutoxyzirconium, 10 ml of tetraethoxysilane, and 8.4 ml of ethanol are successively dissolved in order, and 2 ml of 2N hydrochloric acid is added with stirring. After the gel was formed, the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then heated to 250 ° C. at a heating rate of 0.2 ° C./min and then at this temperature. Calculate for an additional 3 hours. The product shows a constant pore distribution.

BET Surface Area: 250m ² / g

Pore diameter: 0.65nm

1.4 Vanadium Oxide-Silicon Dioxide Glass

1.2 g of vanadil acetylacetonate, 10 ml of tetraethoxysilane and 8 ml of ethanol are successively dissolved in order, and 2 ml of 8N hydrochloric acid is added with stirring. After the gel was formed, the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then heated to 250 ° C. at a heating rate of 0.2 ° C./min and then at this temperature. Calculate for an additional 3 hours. The product shows a constant pore distribution.

BET surface area: 550m ² / g

Pore diameter: 0.66nm

1.5 iron-containing silicon dioxide glass

1.2 g of iron acetylacetonate, 10 ml of tetraethoxysilane, and 8 ml of ethanol are successively dissolved in order, and 2 ml of 8N hydrochloric acid is added with stirring. After the gel was formed, the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then heated to 230 ° C. at a heating rate of 0.2 ° C./min and then at this temperature. Calculate for an additional 5 hours. The product shows a constant pore distribution.

BET surface area: 520m ² / g

Pore diameter: 0.62nm

1.6 Titanium Dioxide-Silicon Dioxide Glass

0.14 ml of tetraethoxytitanium, 1.2 g of acetylacetonate, 10 ml of tetraethoxysilane, and 8 ml of ethanol are successively dissolved, and 1.8 ml of 8N hydrochloric acid is added with stirring. After the gel was formed, the material was heated to 65 ° C. at a heating rate of 0.5 ° C./min, held at 65 ° C. for 3 hours, and then heated to 250 ° C. at a heating rate of 0.2 ° C./min and then at this temperature. Calculate for an additional 3 hours. The product shows a constant pore distribution.

BET surface area: 480m ² / g

Pore diameter: 0.67nm

1.7 Hydrophobized Titanium Dioxide-Silicon Dioxide-Methyl Silicon Sesquioxide Glass

0.133 ml of tetraisopropoxytitane, 8 ml of tetraethoxysilane, 1.8 ml of methyltriethoxysilane and 7.9 ml of ethanol are successively dissolved, and 1.98 ml of 8N hydrochloric acid is added with stirring. After the gel was formed and cured, the gel was heated to 65 ° C. at a heating rate of 0.2 ° C./min, held at 65 ° C. for 3 hours, and then heated to 250 ° C. at a heating rate of 0.2 ° C./min, Calcin for an additional 3 hours at this temperature. The product shows a constant pore distribution.

BET surface area: 540m ² / g

Pore diameter: 0.70nm

1.8 Silicon Dioxide-Methylsilicon Sesquioxide Glass with Hydrophobic Iron

8 ml of tetraethoxysilane, 1.8 ml of methyltriethoxysilane, 0.5 g of iron acetylacetonate, and 8 ml of ethanol were dissolved in succession, and 2 ml of 8N hydrochloric acid was added with stirring. After the gel was formed and cured, the gel was heated to 65 ° C. under a protective gas at a heating rate of 0.2 ° C./min, held at 65 ° C. for 3 hours, and then heated to 230 ° C. at a heating rate of 0.2 ° C./min. And then calcined for an additional 5 hours at this temperature. The product shows a constant pore distribution.

BET surface area: 420m ² / g

Pore diameter: 0.61nm

2. Reaction of catalyst with benzene and dinitrogen monoxide / accompanying gas

2.1 Experimental Conditions

A 2 cm ³ catalyst was charged into a 8 mm inner tubular reactor. The catalyst is prepulverized to a particle diameter of 500 to 1,000 mu m. The reaction compartment is heated to a preset temperature. Monitor the temperature through the thermometer. Benzene and gas are added continuously in gaseous form and the gas flow rate is set to 60 cm ³ / min. The pressure is in the range of 760 mmHg. In this case, the molar ratio of benzene to oxidant in the gas compartment is 1: 5. In laboratory experiments, the carrier gas used is nitrogen. Gas composition is analyzed by GC / MS system. As the zeolite, Fe-ZSM-5 purchased from UOP Company and ZSM-5 (containing no iron) purchased from VAW Company are used.

2.2 Results

Experiment number catalyst Temperature (℃) Composition of oxidant (% by volume) Benzene Conversion (%) Selectivity (%) Not in accordance with the present invention One. Ferrous Zeolite ZSM-5 375 100 N ₂ O 7 97 Not in accordance with the present invention 2. Ferrous Zeolite ZSM-5 425 100 N ₂ O 13 85 Not in accordance with the present invention 3. Zeolite ZSM-5 375 99 N ₂ O / 1 H ₂ O 0 0 According to the present invention 4. 1.1 375 99 N ₂ O / 1 H ₂ O 0.5 50 According to the present invention 5. 100% ZSM-5 / 100% 1.1 375 99 N ₂ O / 1 H ₂ O 2 59 According to the present invention 6. 1.1 375 100 N ₂ O 2 55 According to the present invention 7. 1.2 375 100 N ₂ O 2 67 According to the present invention 8. 1.3 375 100 N ₂ O One 55 According to the present invention 9. 1.4 375 100 N ₂ O 2 49 According to the present invention 10. 1.5 375 100 N ₂ O 11 89 According to the present invention 11. 1.6 375 100 N ₂ O One 51 According to the present invention 12. 1.7 375 100 N ₂ O 6 91 According to the present invention 13. 1.8 375 100 N ₂ O 13 95 According to the present invention 14. 1.8 350 100 N ₂ O 12 99 According to the present invention 15. 1.8 375 90 N ₂ O / 10 H ₂ O 10 96 Not in accordance with the present invention 16. Iron-containing zeolite ZSM-5 375 90 N ₂ O / 10 H ₂ O 0 0 According to the present invention 17. 1.8 375 99 N ₂ O / 1 NH ₃ 3 85 According to the present invention 18. 1.8 375 95 N ₂ O / 5 air 4 92 According to the present invention 19. 1.8 375 99 N ₂ O / 1 O ₂ 5 79

The present invention enables the catalytic oxidation of aromatic compounds with high selectivity to economically obtain the corresponding hydroxyl containing aromatic compounds.

Claims (12)

A method for producing a hydroxyl-containing aromatic compound, comprising catalytically oxidizing the aromatic compound using a dinitrogen monoxide-containing gas at a temperature of 100 to 800 ° C. in the presence of porous glass. The process of claim 1 wherein the aromatic compound used is benzene. The process according to claim 1 or 2, wherein the dinitrogen monoxide containing gas comprises 5 to 100% by volume dinitrogen monoxide and 0 to 95% by volume of other gases. The process of claim 1 or 2, wherein the dinitrogen monoxide containing gas comprises 80 to 100 vol% dinitrogen monoxide and 0 to 20 vol% other gases. The process according to claim 3 or 4, wherein the other gas consists of air, oxygen, nitrogen, group 0 gas, carbon dioxide, water vapor, ammonia and mixtures thereof. The method according to any one of claims 1 to 5, wherein the average pore size of the porous glass is 0.1 to 1.0 nm. The process according to claim 1, wherein the catalytic oxidation is carried out at a temperature of 200 to 700 ° C. 8. The process of claim 7 wherein the catalytic oxidation is carried out at a temperature of 250 to 550 ° C. The method according to any one of claims 1 to 8, wherein the total surface area of the porous glass is at least 50 m ² / g in the dry state. 10. The method of claim 9, wherein the total surface area of the porous glass in the dry state is from 50 to 5,000 m ² / g. 10. The method of claim 9, wherein the total surface area of the porous glass is 75 to 1500 m ² / g in the dry state. 12. Group 3, 4, 3 of the Periodic Table of Elements according to any one of claims 1 to 11, wherein the porous glass is prepared by the sol-gel method and comprises lanthanide and actinide. A method comprising at least 50% by weight of oxides of subgroup or subgroup elements.