JP5973436B2 - Catalyst for oxidizing o-xylene and / or naphthalene to phthalic anhydride - Google Patents

Description

  The present invention is a catalyst for the oxidation of o-xylene and / or naphthalene to phthalic anhydride, using antimony trioxide arranged continuously in a reaction tube and containing a significant proportion of white ore. The present invention relates to a catalyst having a plurality of produced catalyst regions. The invention further relates to a gas phase oxidation process in which a gas stream comprising at least one hydrocarbon and oxygen molecules is passed to a catalyst produced using antimony trioxide containing a significant proportion of white ore.

  Many carboxylic acids and / or carboxylic anhydrides are produced industrially in a fixed bed reactor by catalytic gas phase oxidation of hydrocarbons such as benzene, xylene, naphthalene, toluene or durene. In this method, for example, benzoic acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid or pyromellitic anhydride can be obtained. Usually, the mixture of the oxygen-containing gas and the starting material to be oxidized is passed through a tube in which the catalyst bed is present. In order to adjust the temperature, the tube is surrounded by a heat transfer medium, for example a salt melt.

  Coated catalysts in which the catalytically active composition is applied to an inert support material such as steatite in the form of a shell have been found to be useful as catalysts for these oxidation reactions. In general, the catalyst has a layer of active composition having essentially the same chemical composition and applied in the form of a shell. It is also possible to apply two or more different layers of the active composition to the carrier in succession. These are called two-layer or multi-layer catalysts (see, for example, Patent Document 1 (DE19839001A1)).

  As catalytically active components of the catalytically active compositions of these coated catalysts, titanium dioxide and vanadium pentoxide are generally used. Also, a small amount of many other oxidized compounds (including cesium oxide, phosphorus oxide and antimony oxide) that act as promoters and affect the activity and selectivity of the catalyst may be present in the catalytically active composition. .

A particularly high PAn yield is obtained when a specific V ₂ O ₅ / Sb ₂ O ₃ ratio is set and the antimony trioxide has a predetermined average particle size as in Patent Document 2 (EP 1636161). The resulting catalyst can be obtained.

  The presence of antimony oxide increases PAn selectivity; this effect is thought to be a separation of the vanadium sites.

  The antimony oxide used in the active composition of the catalyst may be various antimony (III), antimony (IV) and antimony (V) compounds; usually antimony trioxide or antimony pentoxide is used. Patent Document 3 (EP 528771) describes the use of antimony pentoxide, and Patent Document 4 (US 2009/306409) and Patent Document 5 (EP 1636161) disclose the use of antimony trioxide.

  Compared with antimony tetroxide and antimony pentoxide, antimony trioxide has a property of being well dispersed on titanium dioxide, so that the catalyst distribution is remarkably improved. Antimony trioxide is usually used as a pure mannite phase (see Schubert, U.-A. et al., Topics in Catalysis, 2001, vol. 15 (2-4), pages 195-200). Apart from the cubic form of beanite, there is also an orthorhombic modification of antimony trioxide, which is known as Baansu (Golunski, SE et al., Appl. Catal., 1989, vol.48, 123-135).

DE19839001A1 EP1636161 EP5222871 US2009 / 306409 EP1636161

  There remains a need for catalysts for gas phase oxidation that can provide very high conversion at high selectivity with the catalyst.

  The object of the present invention is a catalyst for the oxidation of o-xylene and / or naphthalene to phthalic anhydride, which has a high yield of phthalic anhydride with a low content of o-xylene and phthalide at low salt bath temperatures. It is to improve the catalyst that makes it possible.

  This object is achieved by a catalyst for the oxidation of o-xylene and / or naphthalene to phthalic anhydride, produced using antimony trioxide containing a significant proportion of white andesite.

  The object of the present invention is a catalyst for the oxidation of o-xylene and / or naphthalene to phthalic anhydride, the signal height at 2 theta = 27.7 ° and 28.4 ° in the powder X-ray diffraction pattern. It is to provide a catalyst characterized in that it is produced using antimony trioxide having a signal height ratio at 2 Theta = 28.4 ° to the sum of at least 0.02.

The signal at 2 theta = 27.7 ° is an indicator of samarmo nt ite (see ASTM Index, No. 5-0534 / 7), and the signal at 2 theta = 28.4 ° is (see ASTM Index, No. 11-689). The signal height is obtained by the difference between the maximum intensity of each signal and the measurement background.

  In a preferred embodiment of the invention, the catalyst has a signal height at 2 theta = 28.4 ° relative to the sum of the signal height at 2 theta = 27.7 ° and 28.4 ° in the powder X-ray diffraction pattern. Is produced using antimony trioxide having a ratio of at least 0.03, particularly preferably at least 0.05.

  The antimony trioxide with a high content of white ore to be used in the present invention can be used to produce one or more catalytic regions. In a preferred embodiment of the present invention, the catalyst has three, four or five regions, and antimony trioxide with a high white-anite content is used to produce at least one region.

  The catalyst of the present invention can be used in combination with a suitable upstream and / or downstream bed and with an intermediate zone, for example to avoid high hot spot temperatures, the upstream and / or downstream bed and intermediate The region may typically include materials that are catalytically inert or less active.

  The catalyst of the present invention is usually a coated catalyst in which the catalytically active composition is applied to an inert support material in the form of a shell.

As the inert support material, use substantially all the support materials in the prior art which are advantageously used in the manufacture of coated catalysts for the oxidation of aromatic hydrocarbons to aldehydes, carboxylic acids and / or carboxylic anhydrides For example, quartz (SiO ₂ ), porcelain, magnesium oxide, tin dioxide, silicon carbide, rutile, alumina (Al ₂ O ₃ ), aluminum silicate, steatite (magnesium silicate), zirconium silicate Cerium silicate or a mixture of these carrier materials. These catalyst supports can be used in the form of, for example, a spherical product, a ring product, a pellet product, a spiral product, a tubular product, an extrudate, or a crushed material. The dimensions of these catalyst supports correspond to the dimensions of the catalyst supports normally used to produce a coated catalyst for the gas phase reaction of aromatic hydrocarbons. It is preferred to use steatite in the form of a sphere having a diameter of 3-6 mm or in the form of a ring having an outer diameter of 5-9 mm and a length of 3-8 mm and a wall thickness of 1-2 mm.

  The catalyst of the present invention comprises a catalytically active composition that includes at least vanadium oxide and titanium dioxide and can be applied to the support material in one or more layers. In this case, the various layers can differ in their chemical composition.

This catalytically active composition comprises 1 to 40% by mass of vanadium oxide calculated as V ₂ O ₅ and 60 to 99% by mass of titanium dioxide calculated as TiO _{2 with} respect to the total amount of the catalytically active composition. It is preferable to include. In a preferred embodiment, the catalytically active composition comprises 1% by weight or less of a cesium compound calculated as Cs, 1% by weight or less of a phosphorus compound calculated as P, and antimony oxide calculated as Sb ₂ O _3. You may further contain 10 mass% or less. All numerical values relating to the chemical composition of the catalytically active composition are based on the latter calcination state, for example, the state after calcination of the catalyst at 450 ° C. for 1 hour.

Titanium dioxide is usually used in the anatase form for catalytic actives. Titanium dioxide preferably has a BET surface area of 15 to 60 m ² / g, in particular 15 to 45 m ² / g, particularly preferably 13 to 28 m ² / g. The titanium oxide used may be a single titanium dioxide or a mixture of a plurality of titanium dioxides. In the latter case, the value of the load average BET surface area determines the contribution of the individual titanium dioxide. Titanium dioxide used may, for example, it is advantageous BET surface area TiO ₂ and BET surface area is 5 to 15 m ² / g is a mixture of TiO ₂ is 15 to 50 m ² / g.

  Suitable vanadium sources are in particular vanadium pentoxide or ammonium metavanadate. Suitable antimony sources are various antimony trioxides having a significant white andesite content. Possible phosphorus sources are in particular phosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate or phosphate ester, and in particular ammonium dihydrogen phosphate. Suitable cesium sources are oxides or hydroxides or salts that can be thermally converted to oxides, such as carboxylates, in particular acetates, malonates or oxalates, carbonates, bicarbonates, sulfates Salt or nitrate.

  Apart from optionally added cesium and phosphorus, the catalytically active composition can act as a promoter, for example many other oxidations that affect its activity and selectivity, for example by reducing or increasing the activity of the catalyst. A small amount of the compound may be contained. Examples of such promoters are alkali metals, in addition to the cesium mentioned above, in particular lithium, potassium and rubidium (these are usually used in the form of their oxides or hydroxides), thallium (I) oxide, Aluminum oxide, zirconium oxide, iron oxide, nickel oxide, cobalt oxide, manganese oxide, tin oxide, silver oxide, copper oxide, chromium oxide, molybdenum oxide, tungsten oxide, iridium oxide, tantalum oxide, niobium oxide, arsenic oxide, tetraoxide Antimony, antimony pentoxide and cerium oxide.

  Among the above accelerators, it is more preferable to use niobium and tungsten oxides as additives in an amount of 0.01 to 0.50% by mass based on the catalytically active composition.

The formation of the layer of the coated catalyst is advantageously carried out by spraying a suspension of TiO ₂ and V ₂ O ₅ optionally containing the above promoter element source onto a fluidized support. In order to disperse suspended solid agglomerates and obtain a homogeneous suspension, it is preferable to stir the suspension for a sufficiently long time before coating, for example 2 to 30 hours, in particular 12 to 25 hours. . This suspension usually has a solids content of 20-50% by weight. The suspension medium is usually aqueous, eg water per se, or an aqueous mixture with water-miscible organic solvents (eg methanol, ethanol, isopropanol, formamide, etc.).

  Usually an organic binder, preferably a copolymer of acrylic acid-maleic acid, vinyl acetate-vinyl laurate, vinyl acetate-acrylate, styrene-acrylate and vinyl acetate-ethylene (advantageously in the form of an aqueous dispersion) Is added to the suspension. The binder is commercially available as an aqueous dispersion having a solid content of, for example, 35 to 65% by mass. The amount of such binder dispersion used is usually from 2 to 45% by weight, preferably from 5 to 35% by weight, particularly preferably from 7 to 20% by weight, based on the weight of the suspension.

  The carrier is fluidized in a rising gas stream, in particular in air, for example in a fluid bed apparatus or moving bed apparatus. These devices usually comprise a conical or spherical container into which flowing gas is introduced from below or from above via a dip tube. The suspension is sprayed onto the fluidized bed from above, from the side or from below via a nozzle. It is advantageous to use risers arranged in the center of the dip tube or concentrically. A high gas velocity that feeds the carrier particles upward is used inside the riser. In the outer ring, the gas velocity is slightly above the relaxed velocity. As a result, the particles move vertically in a circulating manner. A suitable fluid bed apparatus is described, for example, in DE-A 4006935.

  In the coating of the catalyst support having the catalytically active composition, a coating temperature of 20 to 500 ° C. is usually employed, and the coating can be performed under atmospheric pressure or reduced pressure. Usually, the coating is carried out at 0 ° C. to 200 ° C., preferably 20 to 150 ° C., in particular 60 to 120 ° C.

  The layer thickness of the catalytically active composition is usually 0.02 to 0.2 mm, preferably 0.05 to 0.15 mm. The proportion of the active composition in the catalyst is usually 5 to 25% by mass, usually 7 to 15% by mass.

  By heat-treating the previous catalyst thus obtained at a temperature of> 200 ° C. to 500 ° C., the binder is released from the applied layer by pyrolysis and / or combustion. The heat treatment is preferably performed in situ in the gas phase oxidation reactor.

  The present invention further provides a gas stream comprising at least one hydrocarbon and oxygen molecules, wherein 2 theta = 28 relative to the sum of the signal heights at 2 theta = 27.7 ° and 28.4 ° in the powder X-ray diffraction pattern. Provided is a gas phase oxidation process that passes through a catalyst made using antimony trioxide having a signal height ratio at 4 ° of at least 0.02.

  A preferred embodiment of the present invention is a method for vapor phase oxidation of o-xylene and / or naphthalene to phthalic anhydride, wherein a gas stream comprising o-xylene and / or naphthalene and oxygen molecules is subjected to a powder X-ray diffraction pattern. Manufactured using antimony trioxide wherein the ratio of the signal height at 2 theta = 28.4 ° to the sum of the signal height at 2 theta = 27.7 ° and 28.4 ° is at least 0.02. It is the method of sending to the made catalyst.

Measurement of white andesite content and antimony content in antimony trioxide:
The measurement was performed by a powder X-ray diffraction method. For this reason, the antimony trioxide powder was measured with a “D5000 Theta / Theta” powder X-ray diffractometer manufactured by Siemens. The measurement parameters are as follows:

  The signal height is obtained by the difference between the maximum intensity of each signal and the measurement background. Signals at 2 theta = 27.7 ° (Ban'an, signal height a) and 28.4 ° (Hakuan, signal height b) were employed to measure the content of Hakuan. The content of Hakuan ore is b / (a + b), and the content of Hang'an ore is a / (a + b).

Example 1 (Invention)
Catalyst zone CZ1:
Cesium carbonate 3.38 g, titanium dioxide 459.3g (Fuji TA 100C, anatase, BET surface areas ^20m 2 ^/g),196.9g titanium dioxide (Fuji TA 100, anatase, BET surface ^7m 2 / g) and 51 .4 g of vanadium pentoxide and 13.2 g of antimony trioxide (Merck Selectipur 7835, white anite content = 0.18, beanite content 0.82, 99.5% Sb ₂ O ₃ content, 300 mass ppm As, 500 mass ppm Pb, 50 mass ppm Fe, average particle diameter 2 μm) was suspended in 1869 g of demineralized water, stirred for 18 hours, and uniformly distributed. 78.4 g of organic binder containing a copolymer of vinyl acetate and vinyl laurate was added to this suspension in the form of a 50% strength by weight aqueous dispersion. In a fluidized bed apparatus, 820 g of this suspension was sprayed onto 2 kg of steatite (magnesium silicate) in a ring shape with dimensions of 7 mm × 7 mm × 4 mm and dried. After calcining the catalyst for 1 hour at 450 ° C., the amount of active composition applied to the steatite ring was 9.1%. The chemical composition of the active composition analyzed was 7.1% V ₂ O ₅ , 1.8% Sb ₂ O ₃ , 0.38% Cs, the rest being TiO ₂ .

Catalytic zone CZ2:
Manufactured in the same way as CZ1 by changing the chemical composition of the suspension. After calcining the catalyst at 450 ° C. for 1 hour, the amount of active composition applied to the steatite ring was 8.5%. The chemical composition of the analyzed active composition was 7.95% V ₂ O ₅ , 2.7% Sb ₂ O ₃ , 0.31% Cs, the rest being TiO with an average BET surface area of 18 m ² / g. ₂ .

Catalyst region CZ3:
Manufactured in the same way as CZ1 by changing the chemical composition of the suspension. After calcining the catalyst at 450 ° C. for 1 hour, the amount of active composition applied to the steatite ring was 8.5%. The chemical composition of the active composition analyzed was 7.1% V ₂ O ₅ , 2.4% Sb ₂ O ₃ , 0.10% Cs, the remainder being TiO ₂ with an average BET surface area of 17 m ² / g. Met.

Catalytic zone CZ4
Manufactured in the same way as CZ1, using a modified chemical composition of the suspension and using Fuji TA 100CT (anatase, BET surface area 27 m ² / g) instead of Fuji TA 100C. After calcining the catalyst for 1 hour at 450 ° C., the amount of active composition applied to the steatite ring was 9.1%. The chemical composition of the active composition analyzed was 20% V ₂ O ₅ , 0.38% P, the remainder being TiO ₂ with an average BET surface area of 23 m ² / g.

Example 2 (non-present invention)
Catalytic zone CZ5:
Antimony trioxide grade with low content of white mine (for example, Tricox white mine content of Antraco = 0.015, content of banyanite = 0.985, 99.3% Sb ₂ O ₃ content , 0.3 mass% As ₂ O ₃ , 0.18 mass% PbO, 0.02 mass% iron oxide, average particle size 1.5 μm).

Catalyst region CZ6:
Antimony trioxide grade with low content of white mine (for example, Tricox white mine content of Antraco = 0.015, content of banyanite = 0.985, 99.3% Sb ₂ O ₃ content , 0.3 mass% As ₂ O ₃ , 0.18 mass% PbO, 0.02 mass% iron oxide, average particle size 1.5 μm).

Catalytic zone CZ7:
Antimony trioxide grade with low content of white mine (for example, Tricox white mine content of Antraco = 0.015, content of banyanite = 0.985, 99.3% Sb ₂ O ₃ content , 0.3 wt% As ₂ O ₃ , 0.18 wt% PbO, 0.02 wt% iron oxide, average particle size 1.5 μm).

Example 3 (Oxylene to phthalic anhydride oxidation on a model tube scale according to the invention)
Catalytic oxidation of o-xylene to phthalic anhydride was carried out in a salt bath cooling tube reactor having a tube with an inner diameter of 25 mm. From the reactor inlet to the reactor outlet, 130 cm CZ1, 70 cm CZ2, 60 cm CZ3 and 60 cm CZ4 were introduced into an iron tube having a length of 3.5 m and an inner diameter of 25 mm. The iron tube was surrounded by a salt melt to adjust the temperature; a sheath thermocouple with an outer diameter of 4 mm and a built-in pull-out element functioned to measure the catalyst temperature.

4.0 standard m ³ / h air with a 99.2 wt% concentration of o-xylene loading of 30-100 g / standard m ³ was passed down from the top of the tube. This gave the results summarized in Table 1 ("PAn yield" is the amount in weight percent of the amount of phthalic anhydride obtained for 100% concentration of o-xylene).

Example 4 (oxidation of o-xylene to phthalic anhydride on a model tube scale (non-present invention))
See Example 3 except that a catalyst bed comprising 130 cm CZ5, 70 cm CZ6, 60 cm CZ7 and 60 cm CZ4 from the reactor inlet to the reactor outlet was used.

Comparison of Examples 3 and 4 in Table 1 shows that the catalytic activity of the catalyst in Example 3 is higher than that of Example 4. Therefore, Example 3 salt bath temperature of (the present invention) can be further reduced, o- xylene and P A n yields a low content of phthalide is significantly higher than Example 4 (non-invention).

Example 5 (Oxylene oxidation to phthalic anhydride on the industrial scale (invention))
Catalytic oxidation of o-xylene to phthalic anhydride was carried out in a salt bath cooled tube reactor having 15105 tubes with an inner diameter of 25 mm. From the reactor inlet to the reactor outlet, 130 cm CZ1, 90 cm CZ2, 60 cm CZ3 and 60 cm CZ4 were introduced. A thermoelectric was attached to a part of the reactor tube to record the temperature data. 4.0 standard m ³ / h air with 0-100 g / standard m ³ o-xylene loading (purity about 99% by weight) was passed through the tube. The PAn yield was measured in the gas at the outlet of the reactor, and Table 2 shows the mass% (kg of PAn per kg of reacted o-xylene) with respect to 100% concentration of o-xylene.

Example 6 (Oxylene oxidation to phthalic anhydride on an industrial scale (non-inventive))
See Example 5 except that a catalyst bed comprising 130 cm CZ5, 90 cm CZ6, 60 cm CZ7 and 60 cm CZ4 from the reactor inlet to the reactor outlet was used.

  Comparison of Examples 5 and 6 in Table 2 shows that the catalytic activity of the catalyst of Example 5 is higher than that of Example 6. Therefore, the salt bath temperature in Example 5 (invention) can be further reduced, and the PAn yield with a low content of o-xylene and phthalide is significantly higher than in Example 6 (non-invention).

Claims (6)

A catalyst for oxidizing o-xylene and / or naphthalene to phthalic anhydride,
Antimony trioxide having a ratio of the signal height at 2 theta = 28.4 ° to the sum of the signal height at 2 theta = 27.7 ° and 28.4 ° in the powder X-ray diffraction pattern is at least 0.02. And a catalyst produced using titanium dioxide and vanadium pentoxide . A gas stream comprising o-xylene and / or naphthalene and oxygen molecules is obtained at 2 theta = 28.4 ° relative to the sum of the signal heights at 2 theta = 27.7 ° and 28.4 ° in the powder X-ray diffraction pattern. A gas phase oxidation process that passes to a catalyst made using antimony trioxide and titanium dioxide and vanadium pentoxide having a signal height ratio of at least 0.02. The catalyst of claim 1, wherein the height ratio is at least 0.05. The catalyst according to claim 1 or 3, comprising 1 to 40% by mass of the vanadium pentoxide and 60 to 99% by mass of the titanium dioxide with respect to the total amount of the catalytically active composition. The titanium dioxide is 15-60m ² Catalyst according to any one of claims 1, 3 and 4, having a BET surface area of / g. The gas phase oxidation method according to claim 2, wherein the catalyst is the catalyst according to any one of claims 3 to 5.