TW201132614A - Method for the gas-phase oxidation of hydrocarbons - Google Patents

Abstract

The invention relates to a method for the gas-phase oxidation of aromatic hydrocarbons using a catalyst charge, wherein the catalyst charge is housed in a heating bed and wherein the method comprises: (a) setting the temperature of the heating bed at 365 DEG C to 395 DEG C; (b) passing from 0.5 to 5.0 Nm3/n air through the catalyst charge until the temperature of the heating bed has fallen by 5 DEG C to 10 DEG C, c) passing from 0.5 to 5.0 Nm3/h air with a hydrocarbon load of from 10 to 110 g/Nm3 air through the catalyst charge, with the result that, seen in direction of flow of the air, a hotspot with a temperature of from 430 DEG C to less than 470 DEG C forms in the last 10 to 25% of same.

Description

201132614 VI. INSTRUCTIONS: The present invention relates to a gas phase oxidation zone for tobacco. Currently, many acids, acid retardants, and phthalic anhydride are used in industrial bed reactors by hydrocarbons such as aromatic Catalytic gas phase oxidation of a hydrocarbon such as benzene'-o-xylene-di-xylene or p-xylene, T.'s or a 1,M,5-tetramethylbenzene, a dilute hydrocarbon and a sulphuric acid Examples of products produced by means of such methods are, in particular, terephthalic acid, non-tautic acid, formic acid 'sandic acid needle, phthalic acid liver, isophthalic acid or benzoic acid. Specifically, 'using a catalyst based on oxidative starvation and/or dioxins, and using a mixed metal oxide-based catalyst in the case of a hydrocarbon or a terpene hydrocarbon. The reaction wherein a local temperature maximum is formed within the catalyst charge, also referred to as a "hot spot". These hot spots may be detrimental because the catalyst can be irreversibly destroyed when the temperature is too high. "catalyst charge" in this article Refers to a plurality of individual catalysts in the reactor, and thus refers to a supported catalyst or a supported catalyst molded body. The terms "catalyst", "supported catalyst", "support catalyst", etc. The definitions in "Winnacker-Kiichler Chemische Technik, Prozesse und Produkte, Vol. 1, 5th edition, wiley-VCH, 2004" are used herein. In addition to simple catalyst loading, several layers of activity and/or selectivity are included. 201132614 Catalyst charge of different catalysts (so-called multi-layer catalyst systems) is also used in the prior art, for example for the oxidation of o-xylene and/or naphthalene to o-parabens (=PA). In this case it is necessary It is ensured that the activity of the individual catalyst layers is suitable for the reaction process along the reactor axis (i.e. between the layers of the different active layers), in which case a high yield of PA can be obtained, while the yield of the undesirable intermediate benzoquinone is exhausted. It may be small. Generally speaking, in this multi-layer catalyst system, the first catalyst layer (the layer closest to the inlet of the reactor) shows minimal activity. This is because the highest educt concentration and thus the highest reaction rate are present in the region near the inlet of the reactor. Since the heat is released during the chemical reaction, the reaction gas is thus heated up to a position in the catalyst (at the so-called hot spot) The energy produced by the reaction is exactly equal to the energy released to the coolant. The catalysis/tongue of the first layer will cause an uncontrolled increase in the temperature of the hot spot, which usually leads to a decrease in selectivity or even a so-called "runaway" One of the basic aspects that must be considered in designing the activity of individual catalyst layers is the hot spot location in the catalyst charge, or the hot spot location in the first catalyst layer in the case of a multilayer catalyst. Since the catalyst activity decreases as the operating time increases, the hot spot position moves further toward the reactor outlet. This can actually continue to the extent that in a multi-layer catalyst system hotspots enter the second layer from the first layer row, or even into the next subsequent layer (or vice versa). Since the correlation of the product yield is significantly reduced in this case, the catalyst usually has to be replaced, resulting in a loss of yield due to the waiting time. Such a multilayer catalyst system for the oxidation of o-xylene and/or naphthalene to phthalic anhydride is described, for example, in EP 1 〇 84 115 B1, in which the activity of individual catalyst layers is self-reactor inlet according to the publication 201132614 The reactor outlet continues to increase. This is achieved by increasing the active mass in combination with reducing the alkali metal content of the catalyst. The catalyst layer immediately adjacent to the catalyst inlet has the lowest active material content and the highest alkali metal content. DE 103 23 818 A1 discloses a multilayer catalyst system having at least 3 continuous catalyst layers for the oxidation of o-xylene and/or naphthalene to phthalic anhydride, which allows the activity of individual catalyst layers to be lateral from the reactor inlet The outlet side of the reactor continues to increase. This is achieved by making the BET surface area of the Ti?2 acting as a catalyst in the layer at the reactor inlet smaller than the BET surface area in the subsequent layer, wherein the maximum BET surface area is in the region of the reactor outlet. DE 103 23 461 A1 proposes a multilayer catalyst system for the oxidation of o-diphenylbenzene and/or naphthalene to phthalic anhydride, wherein the activity of the individual catalyst layers increases from the inlet side of the reactor to the outlet side of the reactor, wherein The ratio of the catalytically active compound % 〇 5 in one layer is between 3 5:1 and 51. DE 103 23 817 A1 describes a multilayer catalyst system having at least 3 continuous catalyst layers for the oxidation of o-xylene and/or naphthalene to phthalic anhydride, wherein the activity of the individual catalyst layers is laterally reacted from the inlet of the reactor The exit side of the device continues to increase. The catalyst layer closest to the reactor outlet contains greater than 10 Wt 〇 /. It is V2〇5 and contains a phosphate in a single layer form. Because of the aging process, all catalysts lose their activity as their lifespan increases. This mainly occurs in the main reaction zone, i.e. in the gas inlet zone' because, as already mentioned, there is a maximum temperature negative at this location. Main reverse: The zone continues to travel deep into the catalyst bed during the life of the catalyst. As a result, the intermediates and by-products could not be completely converted. This is because the main reaction zone is currently located in the less selective and more active catalyst bed zone or catalyst layer. The quality of the product of the resulting oxidation product is thus gradually deteriorated. It is possible to counteract the reduction in conversion and the quality of the product by increasing the reaction temperature, for example by increasing the temperature of the heated bed and/or by reducing the amount of air while maintaining the same hydrocarbon loading (for example with o-dioxin). Poor, however, it must accept a reduction in the amount of product. If the amount of air is reduced while the hydrocarbon loading is kept the same, the hot spot moves "up". The location and temperature of the hot spot can be controlled, for example, by a targeted starting-up of the oxidation catalyst. In this regard, DE-A 22 12 947 describes a method for producing phthalic anhydride, wherein the salt bath is initially set at 37 (temperature of rc to 41 〇〇c to make at least 1 每小时 per hour) Litre air and at least 33 每 of per-Nm3 air pass through the pipeline to produce a hot spot temperature of 450 to 465 ° C in the first third of the catalyst layer calculated from the gas inlet point. On the other hand, DE- A 25 46 268 discloses a process for producing phthalic anhydride in which the catalyst charge is maintained at a temperature of 360 to 4 ° C in a salt bath, wherein the amount of air supplied is 4.5 Nm 3 and the loading is 36.8 to 60.3 g of o-xylene per Nm3 of air. DE-A 198 24 532 describes a method for producing phthalic acid needles in which the xylene loading is run-up on several days of an air volume of 4.0 Nm3. The period is increased from 40 g per Nm 3 of air to 80 g. EP-B 985 648 further discloses a similar method according to which the air amount is 2 to 3 Nm 3 and the amount of air per 1 m 3 of air is 1 to 140 g of o-dimethyl 7 201132614 Benzene loading produces phthalic acid needles. Finally, DE 10 2005 031 465 provides a method wherein the catalyst charge is initiated at a temperature of from 360 ° C to 400 ° C, the amount of air is from i 〇 to 3 5 Nm 3 /h and the hydrocarbon loading is from 20 to 65 g/Nm 3 , wherein the first 7% is 2〇% of the catalyst charge forms a temperature of 39 〇. (: to 45 〇 < t or less. Although the attack has set the effect of the location and temperature of the hot spot, in view of the two factors PA yield and quality and catalyst deactivation are very important and still need to be optimized. Therefore, it is an object of the present invention to provide a gas phase oxidation for aromatic hydrocarbons, especially for the production of phthalic acid (pA). <Method, with which the product yield and product f can be improved. All catalyst layers will also be optimally activated for the respective reactions to be carried out therein, and further the deactivation of the catalyst needs to be further slowed down. The object is achieved by the method according to the scope of the patent application. Preferred embodiments are found in the scope of the appended claims. A preferred embodiment of the invention relates to a method for using a catalyst charge for a phase-oxidized aromatic hydrocarbon. The catalysis Charger = where the process comprises the steps of: a) setting the temperature of the heated bed: to 395 C; b) allowing the hydrocarbon loading to be between 0.5 and 5 〇Nm3/h of air per _3 air to (10) g. ;y : 25: The length of the catalyst charge is formed in the direction of air flow: its temperature is 40 (TC, preferably 4UrC to 47 〇t or less. 201132614 The amount of air remains constant at least until the hot spot moves to π from the air. a, j is moved to the position of 30 to 80 em on the inlet side. Air In another step d), the small upper J is connected to. The reduction, or according to an alternative embodiment, continues to be, for example, a salt bath containing the catalyst charge. It is obvious that the catalyst renter has a catalyst layer of at least one catalyst layer, preferably at least two catalyst layers exhibiting different activities and/or selectivity in this case. - Thus, the initiation of the reactor containing the catalyst charge is carried out in several steps. In the first step a), the suitable temperature of the heated bed is first set. The force...bed heat source is then decoupled so that it is only thermally connected to the reactor. In a further step b), the predetermined first-hour air volume is fed into the reactor. At this stage, the air still does not carry hydrocarbons. The temperature of the heated bed slowly drops. Once the second drop is about 5C to 10C, the air to be passed through the reactor bed is enriched in hydrocarbons in the next step c). In this way, it is achieved that a hot spot is formed in the rear portion (i.e., downstream) of the reactor. This has been shown to be superior in terms of reaction quality' because there are fewer undesirable by-products formed overall. The temperature maximum or hot spot then goes forward, i.e., toward the air inlet side while increasing the hydrocarbon loading. In the next step d), the air can now be reduced in flux through the catalyst charge. The reaction zone is further advanced in the reactor' so that the catalyst layer near the reactor inlet is fully activated. The load can also be increased in step d) as appropriate. After the activation of the catalyst layer 'in another step e) 'the amount of air is again increased to the amount required for the process (the amount of air of interest)' wherein in this step e), the loading of o-diphenylbenzene can also be increased . In this manner, the maximum reaction zone is optimally formed in the fully activated catalyst charge over the entire length 201132614. It should be noted that the method according to the specific example of the present invention uses a catalyst charge (i.e., with more than one layer of a catalyst, a so-called multi-layer multi-layer system). In the multilayer catalyst loading, the catalytic layer is selected such that the activity first decreases from the gas inlet side to the gas should be * l α 1 and then increases again. When, for example, the catalyst charge has four layers, the following arrangement of the individual catalyst layers is selected: wherein the first catalyst layer located on the gas or coffee is selected to exhibit activity higher than the side of the mouth of the flute. The activity is then increased again from the second catalyst layer via the layer of the catalyst layer. Preferably, the positional position of the catalytic gas inlet side 30 and one is selected such that the effect from the two gas feeds and, as the case may be, the increase in the amount of loading depends on the layer ... moving toward the first catalyst layer to also optimally activate this The amount of air supplied in one and c) is, for example, between ο.% gamma (two: the value of the value), and in other specific examples is between two. Between and 'for example, 2. 5 to 4.5 Nm3 / h. Within the specified range, such as "a quantity may be 3.0 to 4. pass, or 3_〇 to 4 2Nm3 / h, example, t4.1Nm3 / h. All specified ranges have been specifically in accordance with the present invention Satisfactory results are displayed within the framework. The loss of G Μ points occupying the desired position in the final (four) chemical layer. The experience of β can be between 2 and 48 hours, specifically between w and 26 Between the hours. In the specific example, the amount of air in step d) is reduced as appropriate.

S 10 201132614 is carried out slowly, for example in an equidistant step with a phase of 0.05 to N.5 Nm3/h or initially with a larger phase and with a smaller phase accompanied by a gas reduction, wherein the amount of air can be introduced: Intermediate stage. & special-period remains fixed in step b), the hydrocarbon loading can be, for example, between 1〇 and (10), or 10 to 0〇g/Nm3, enter-step #9ς &<> Between 25 and 60 g/Nm 3 , 3 〇 to 55 g/Nm 3 , or 30 to 45 g/Nm 3 . As the loading of o-xylene increases, the temperature of the shellfish is increased, and the temperature must be reduced accordingly to adapt the cold effect to the increasing conversion rate. The salt bath temperature preferably decreases from about 39 generations to about 35 (TC. However, the temperature may also drop from 39 〇t to 3 thief to (4) C, for example from 390. (: to 37 (TC to 375 ° C. It has been mentioned that, according to an embodiment of the invention, the hydrocarbon loading can be increased in steps b), two: e). The increase in the loading in step d) can be, for example, 5 to 6 after the T air reduction step Minutes. This increase can also be carried out in two stages, for example at a stage of 〇5 to 1〇g/Nm3. In this regard, the initial phase is performed in a larger phase and then in a smaller phase. The same is about. It is possible to incorporate smoke load blame periodically to achieve a certain degree of stability. The value of 40 to 12 〇g/Nm3 has proven to be suitable as the purpose I. The load is also used after the stable reaction is established. The amount of load at the end of the boot process. In step d) ifo carrier's air quantity can be reduced synchronously or asynchronously to increase hydrocarbon negative. In the case of unsynchronized reduction, it is advantageous to first reduce the amount of air and then to adapt the negative cut. In step *, step e) ct 〒' air volume can be increased synchronously or asynchronously to increase the hydrocarbon negative 201132614 load. In the case of unsynchronized addition, it is advantageous to first increase the amount of air and then adjust the amount of load. Using a method according to one or more specific examples of the invention, as already mentioned, at the end of step C) 'in the last 5% to 3%, preferably 10% to 25% of the total catalyst charge In the final layer (in the case of a multilayer catalyst) and thus in the region of the outlet side of the reactor, a hot spot temperature of 4 〇 (rc, preferably 41 〇 to 470 C) is formed. The hot spot position is preferably at the end of the catalyst charge. In the region of 13% to 20% of the length, the hot spot temperature can be between 4 〇〇 and 〇 47 ° ° C, especially between 41 (rc and 45 〇〇 C4 43 〇 between it and 45 〇. During the reduction of air in step d), the amount of air is preferably reduced to 2.8 to 3.3 Nm3/h, for example to 2_9 to 31 Nm3/h. The hot spot is from the outlet side of the reactor or from the middle of the catalyst layer at this time. The position used (for example, expressed in geometric dimensions at 80 cm from the start of the catalyst charge) is moved to the air inlet side by the catalyst charge. Within the framework of the process, it should be ensured that in all areas along the length of the reactor during this process Hotspot; the profit is always above 400 ° C, or above 41 (rc, or at 43 〇t And below 45 Torr. At the end of step d), the hot spot is stable over the first 7% to 3% of the length of the catalyst charge, preferably at a geometry of about 3 〇 6 () (10) from the catalyst loading starting point. Representation. According to one embodiment of the invention, the amount of air may then be increased to the amount of target air in step 0. The amount of air of interest is the amount of air that is subsequently statically operated for the reactor used in the present invention. For example, between 2.8 and 4. 〇Nm3/h. The increase can be carried out step by step, for example, by 〇5, such as 3 。 from the slave. In this way, the optimal catalytic activity of the total catalyst charge 12 201132614 and selectivity are achieved. Finally, after step C), in a subsequent step d), the hydrocarbon loading can be gradually increased to the desired loading, with the salt bath temperature being reduced as appropriate. This can be carried out, for example, in the step of 2 to 0.1 g/Nm3. The purpose of adjusting the salt bath temperature is to limit the hot spot temperature to at most 47 〇 < t, however, it should be confirmed that the hot spot position is not below the top of the catalyst charge of 1 〇 _ 3 〇 %. Specific examples of the invention can be used to produce benzoic acid, maleic anhydride, acrolein, acrylic acid, metacrolidine, methacrylic acid, o-dicarboxylic acid anhydride, isophthalic acid, para-benzoic acid Dicarboxylic acid, stupid tetrahydride, naphthalic anhydride or nicotinic acid. For example, o-quinone and/or naphthalene can be oxidized to phthalic anhydride in this manner. Within the framework of the present invention, as described above, a catalyst charge consisting of several layers of different active and selective catalysts (multilayer catalyst systems) may be used, wherein the catalyst activity is preferably first reduced from the gas inlet to the gas outlet and subsequently increased . Such a multilayer catalyst system is described, for example, in DE i 〇 2〇〇5 〇〇 9 473. It is generally possible to use from 2 to 6 catalyst layers, especially from 3 to 5 catalyst layers. The first layer may, for example, comprise from 5% to 15% of the total catalyst charge and the second layer comprise from 20% to 60%. In principle, the smaller the number of layers in a multilayer catalyst system, the greater the proportion of catalyst charge in the second layer. The start of the catalyst charge is typically carried out at an inlet ab〇ve_atm〇spheric pressure range of 〇.65 bar. This pressure range can also be used within the framework of the present invention. In a multilayer catalyst system suitable for the production of a phthalic acid if, the 13 201132614

1 . 〇Wt% alkali metal and the remaining Ti〇2 (a catalyst of anatase 1.0 wt% P, 〇·1 to 1.1 active material (relative to the total catalyst), to I5 wt% V2〇5, 〇 Up to 5 wt%, 2, 3, anatase form, wherein planer is preferably used as the alkali metal.

Mixtures of titanium dioxide having different BET surface areas in mineral form may also be used in place of pure titanium dioxide, wherein the resulting BET surface area should be such that it has the values mentioned above. It is also possible to equip different catalyst layers with titanium dioxide having different BET surface areas. In order to increase the catalyst activity from the gas inlet, the BET surface area of the titanium dioxide used increases from the first layer to the gas inlet to the gas outlet. For example, at least 30%, especially at least 40% and at most 80% of the total pore volume of the titanium dioxide is formed by pores having a radius between 60 and 400 nm. The pores having a radius greater than 4 Å are preferably less than about 30%, especially about 22%, and especially preferably less than 20%, based on the total pore volume of the titanium dioxide used. With respect to the smaller pore radius, it is preferable that 30% or less of the total pore volume of Ti〇2, particularly 2 〇Q/q or less, is formed by pores having a radius of 3.7 to 60 nm. A particularly preferred range for this pore size herein is from about 10 to 30%, especially from 12 to 20%, of the total pore volume. In this regard, it should be noted that, unless otherwise stated, the pore volume or ratio quoted is based on measurements using mercury porosimetry (according to DIN 66 1 33). In each case, the total pore volume quoted is with the aid of mercury

S 14 201132614 The porosity measurement is related to the total pore volume measured between 7500 and 3.7 nm pore radius dimensions. Within the framework of the present invention, the titanium dioxide used for the catalyst charge can exhibit a particle size distribution (the Dx value is, in this case, the value of the larger or smaller particle diameter of the particles in each case): Dl value : less than or equal to 〇 is clawed; 〇 5 〇 value: less than or equal to isym; ^ value: less than or equal to 々 " melon. The D90 value is preferably between about 肖·5 〇 2〇/zm, especially between about i and ι〇 P, particularly preferably between about 2 and 5" m. The titanium dioxide used in the electron micrographs preferably has an open cell or sponge structure in which the primary particles or crystallites are larger than 3 % by weight, especially greater than 5 G%, and the structures are combined into an agglomerate. It is envisaged that the gas phase oxidation reaction conditions which are particularly advantageous are created by the special structure of the two gas/(匕夕,士四主》k ϋ 虱 ,, which is reflected by the pore radius distribution. Specifications are difficult: in terms of -------% price, i.e. different titanium dioxide having different dirty surface areas, porosity and/or particle size distribution can also be used in the catalyst used in the process of the invention. View, = 75% less 'especially all of the titanium dioxide used should have the BET surface area and porosity as the original meaning, and preferably the particle size distribution. Depending on the type of oxidation reaction to be carried out, familiar with this item. The components well known to the skilled person may be included in or in place of the titanium dioxide or the titanium dioxide: the active material 3 of the catalyst therein. For example, such catalysts are, for example, in EPG 964 744 B. The oxidation capacity is hereby incorporated by reference. The disclosure of the inner and inner cans is incorporated into the specification. One example of such oxides & θ g曰 example is a V2 having a small particle size to promote dispersion on titanium dioxide 15 201132614 s material. For example, at least 90% of the particles used may have a diameter of from 20 or less than 20 μm. For this purpose, reference is also made to DE 103 44 846 A1, which is also described in the prior art for increasing catalyst productivity. Agents can also be used within the framework of the process of the invention. Such promoters include, inter alia, alkali and alkaline earth metals, cerium, lanthanum, phosphorus, iron, lanthanum, cerium, indium, silver, tungsten, tin, lead and/or铋 and a mixture of two or more of the above components. For example, DE 2 1 59 441 A describes a catalyst which, besides the anatase form of titanium dioxide, also has from 1 to 30 wt% of pentoxide and two The composition of cerium oxide. The list of suitable accelerators can also be found in w〇2004/103561, page 5, lines 29 to 37, also with reference to the patent. The activity and selectivity of the catalyst can be affected by individual promoters, especially Decreasing or increasing the activity. The promoter for increasing selectivity includes, for example, metal oxides and phosphorus oxide compounds, especially phosphorus pentoxide. In the catalyst used in the process of the invention, the first catalyst layer and the second catalyst The phosphorus compound is optionally contained. The purpose of this configuration is to achieve high activity, wherein the selectivity in the subsequent catalyst layer (layer 3 and subsequent layers) is suitably adjusted, for example, by the presence of a filling compound. In this case, it may be advantageous to have only the last layer containing a phosphorus compound. As described, for example, in De 103 23 461 A, vanadium (calculated as V 2 〇 5) in the catalyst of the first layer and/or the catalyst of the second layer The ratio of 锑 (calculated as ShCh) is between about 3.5:1 and 5: 1. The base content (e.g., Cs content) of the catalyst used in the framework of the present invention is, for example, constant or from the second layer to the last layer. (on the gas outlet side)

S 16 201132614 Decrease. Particularly preferably, the last catalyst layer is free of alkali metals. The specific composition of the catalyst layer for producing phthalic acid liver is described, for example, in WO 04/103944. A number of methods suitable for generating catalysts that can be used within the framework of the present invention are described in the prior art. The so-called sheath catalyst can be produced by applying a thin layer of an active component of 50 to 500 v m to an inert carrier as described, for example, in US 2, 〇 35, 6 〇 6. A ball or hollow cylinder is especially mentioned as a carrier. These shaped bodies produce a high packing density at low pressure loss and reduce the risk of filling errors when pouring the catalyst into the reaction tube of the oxidation reactor. For example, bismuth silicate, tantalum carbide, porcelain, alumina, magnesia, tin oxide, rutile, aluminum silicate, magnesium ruthenate (steatite), bismuth citrate or bismuth ruthenate Or a mixture thereof can be used as the carrier material. For example, a shell catalyst such as that described in DE-A-16 42 938 or DE-A 17 69 998 can also be used. In order to manufacture such a catalyst, a component of a catalytically active substance and/or a precursor compound thereof, which contains an aqueous solvent and/or an organic solvent, is heated in a heated coating drum at a high temperature. A liquid or suspension (often referred to as "mash") is sprayed onto the support material until the catalytically active material reaches the desired level. According to DE 2 1 06 796, the catalytically active material can be coated (coated) on an inert carrier in a fluid bed coater. The advantage of coating the support in a fluidized bed is that the thickness of the sheet which acts as a catalyst in the catalytic performance of the catalyst 17 201132614 is highly uniform. For example, according to 12 8 756 756, DE 198 28 583 or DE 197 09 589, a suspension or solution of the active ingredient is sprayed onto the heated carrier in a fluidized bed at 80 to 2 Torr. A particularly uniform coating is obtained. Unlike the coating in the coating drum 'When a hollow cylinder is used as the carrier in the specified fluidized bed method, the inside of the hollow cylinder can also be uniformly coated. In the fluidized bed process specified, the method according to DE 197 09 589 is particularly advantageous, since a predominantly horizontal circular movement by means of the carrier along a uniform coating also results in a lesser degree of wear of the device parts. In the coating process, an aqueous solution or suspension of the active component and an organic binder (preferably vinyl acetate/vinyl laurate, vinyl acetate/ethylene or styrene/acrylate copolymer) is passed through one or more The nozzle is sprayed onto the heated fluidized carrier. The spray fluid can be applied to the location where the product is at the highest speed, whereby the spray material can be evenly distributed. The spraying process is continued until the suspension is used up or the necessary amount of active ingredient is applied to the carrier. The catalytically active material of the catalyst can be coated, for example, in a fluidized bed or fluidized bed by means of a suitable binder. Suitable binders include organic binders well known to those skilled in the art such as vinyl acetate/vinyl laurate, vinyl acetate/acrylate, styrene/acrylate, vinyl acetate, preferably in the form of an aqueous dispersion. / maleate and copolymer of vinyl acetate / ethylene. An organic polymerization or copolymerization adhesive, in particular, a vinyl acetate copolymer adhesive is particularly preferred. The binder used is added to the catalytically active material in a conventional amount, for example, in a proportion of about 1Q to 2% by weight relative to the solid content of the catalytically active material. Refer to eP 744 214 for this. If the catalytically active material has been applied at an elevated temperature of about i5 (rc 18 201132614), as is known in the art, it is also possible to carry out the carrier coating in the absence of an organic binder. According to de 21 〇 6 7961, when using When the dispensing agent is given, the coating temperature which can be used is, for example, between about 50 C and 450 C. When the reactor filled with the catalyst is activated, the binder used is burned out shortly after heating the catalyst. Adhesives are mainly used to enhance the adhesion of catalytically active materials on the support and to reduce wear during catalyst transport and filling. Other possibilities for producing a ruthenium catalyst for the catalytic gas phase oxidation of aromatic hydrocarbons to carboxylic acids and/or carboxylic anhydrides The process is described, for example, in w〇98/〇〇778 and EP-A 7 1 4 700. According to such methods, firstly in the presence of an auxiliary for catalyst production, the catalytically active metal oxide and/or The solution and/or suspension of the precursor compound produces a powder, which is then applied as a shell to the support in order to produce a catalyst (as appropriate after conditioning and optionally) After the treatment) to produce a catalytically active metal oxide, the support thus coated is subsequently subjected to a heat treatment to produce a catalytically active metal oxide or subjected to a treatment for removing volatile components. When a reactor suitable for the process of the invention is produced, first The catalyst charge is poured into the reaction tubes of the reactor, which are kept externally at the reaction temperature, kept at the reaction temperature, for example by means of a heated bed, in particular by means of a salt bath. The method of producing o-phthalic anhydride from o-xylene and/or naphthalene is also well known to those skilled in the art based on the prior art, especially in Ullmann's Encyclopedia of Industrial Chemistry, Section A. 2, Volume, 1992, 181. Towae, W. Enke, R. Hckh, N. 19 201132614

A summary statement in Bhargana "Phthalic Acid and Derivatives", which is incorporated herein by reference. By way of example, the boundary conditions known from the above references by WO 〇 A 98/37967 or WO 99/61433 can be selected to achieve a stable operating state of oxidation 'so that a fully activated reactor has been achieved or that the method of the invention has been carried out The status of the step. In a stable operation, 'at a temperature of usually 300 to 450 ° C, preferably 320 to 420 ° C and particularly preferably 340 to 40 (at a temperature of TC and at a pressure of usually 〇1 to 25, preferably 0.3 to 1.5 bar). Under the pressure above the force, the reaction gas is charged through the catalyst at a space velocity of usually 75 〇 to 500 Hz. The reaction gas supplied to the catalyst is usually mixed with an oxygen-containing gas (for example, air) (the oxygen-containing gas) In addition to oxygen, a suitable reaction moderator and/or diluent such as steam, carbon dioxide and/or nitrogen may be contained in combination with the aromatic hydrocarbon to be oxidized, wherein the oxygen-containing gas may contain usually 1 to 〇〇 Preferably, it is from 2 to 50 and particularly preferably from 10 to 30 m〇l% of oxygen, from 30 to 30, preferably from 0 to 10 mol% of water vapor and from 〇 to 5 Torr, preferably from 〇 to 1% by weight of carbon dioxide, the balance being I The gas is generated to generate a reaction gas, usually filled with 3 to 15 g of aromatic hydrocarbons to be oxidized per Nm 3 of gas. The catalysts containing up to 4 layers which can be used in the framework of the method of the present invention are given below. An example of material.

98 wt%, especially at least 99 wt%, », preferably at least 95 wt%, more preferably at least better than at least 99.5 wt%, especially 1 wt%

S 20 201132614 Τι02 composition. The BET surface area of Ti02 is between 15 and about 45 m2/g. The first catalyst layer covers a length ratio of 5 to 25%, particularly preferably 10. 25%, of the total length of all of the catalyst layers present. The active material of the catalyst of the second catalyst layer contains V205, 〇 to 5 wt0 / 〇 Sb203, 0·2 to 0.75 wt0 / 〇 Cs, 〇 to 2wt ° / between 5 and i 5 wt%. Nt>2〇5 and 〇 to i wt〇/〇 p. The remainder of the active material consists of at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight, especially at least 99% by weight, more preferably at least 99.5% by weight, especially i〇〇wt% Ti〇2. Ti 〇 2 has a BET surface area between 15 and about 25 m2/g. The second catalyst layer covers a length ratio of about 15 to 6 %, preferably 2 to 60% or 20 to 50% of the total length of all of the catalyst layers present. The active material of the catalyst of the third catalyst layer contains 5 to 15 wt% of V205, 0 to 4 wt% of Sb203, 0.05 to 0.5 wt% of Cs, and 〇 to 2 wt%.

Nb2〇5, 〇 to 丨wt% p. The remainder of the active material is at least, preferably at least 95% by weight, more preferably at least 98% by weight. /. In particular, at least 99 wt%, more preferably at least 99.5 wt%, especially 100 wt% Ti〇2 composition. Ti〇2 has a BET surface area between about 15 and 25 m2/g. The third layer covers a length ratio of from about 1% to about 3% of the total length of all of the catalyst layers present, especially when at least one other catalyst layer also abuts the third layer. If the third layer is the last layer, that is, the layer closest to the outlet of the reactor, the length ratio of the third layer is preferably from 2 to 50%. The active material of the catalyst of the fourth catalyst layer is optionally selected to contain 5 to. 25wt% v2〇5, 〇 to fine % 讥2〇3, 〇 to 〇 a, 〇 to 2wt% P, 〇 to j wt% Nb2〇5. The remainder of the active material consists of at least 100%, preferably at least 95% by weight, more preferably at least minus, especially at least 21 201132614 99% by weight, more preferably at least 99.5% by weight, especially 100% by weight of Ti〇2. If the fourth layer is the last catalyst layer on the gas outlet side of the reactor, the Ti 〇 2 BET surface area which is slightly higher than the Ti 〇 2 BET surface area of the layer located closer to the gas inlet side is preferably 'between Within the range of 15 to about 45 m2/g. The fourth catalyst layer covers a length ratio of from about 10 to 50%, particularly preferably from 1 to 40%, of the total length of all of the catalyst layers present. The fifth catalyst layer is not usually necessary but may be used. As already mentioned, catalysts which do not have a phosphorus compound in the catalytically active material in the intermediate and optionally first catalyst layers may have particularly good activity' while having very high selectivity. Further preferably, at least 0.05% by weight of the catalytically active material in the first and intermediate catalyst layers is formed from at least one metallization. The metal test is particularly preferred. The resulting catalyst charge is temperature treated or calcined (conditioned) in a conventional manner prior to use. It has been demonstrated that if the catalyst is calcined in a gas containing helium 2, in particular in air at at least 390 ° C for at least 24 hours, in particular at 24 ° C for between 24 and 72 hours, It is then advantageous. The temperature should preferably not exceed 500. (:, especially 470. (: However, other calcination conditions that appear to be suitable for those skilled in the art may be used in principle. The following method is used to determine the catalyst charge that can be used within the framework of the present invention. Parameters: 1. BET surface area · This is determined using the BET method according to DIN 6 6132; this BET method is disclosed, for example, in J. Am. Chem, Soc. 60, 309 (193 8).

S 22 201132614 2. Pore radius distribution: The pore radius distribution of Ti〇2 used is measured by the mercury porosimetry method according to DIN 66133. Maximum pressure _ 2, 〇〇〇巴, p〇r〇simeter 4 〇〇〇 (Firma P〇rotec, DE), according to the manufacturer's details. 3. Particle size: The particle size is based on the laser diffraction method using Fritsch Particle Sizer

Analysette 22 Economy (Fritsch, DE) is based on the manufacturer's details and sample pretreatment: the sample is homogenized in deionized water without additional aid and treated with ultrasonic for 5 minutes. The BET surface area, pore radius distribution, pore volume, and particle size distribution are each determined using an uncalcined material dried in a vacuum at 15 (r) for titanium dioxide. The details of the BET surface area of the catalyst or catalyst layer given in this specification are also BET surface area for the Ti〇2 material used in each case (drying in vacuum under i 5 〇 <>c, not calcined, see above). Usually the 'BET surface area of the catalyst is from the Ti 所 used. The bet surface area of 2 is determined by the fact that the bet surface area varies to some extent by the addition of other catalytically active components. This is well known to those skilled in the art. The proportion of active material (in the absence of a binder, the catalytically active material) The ratio) in each case is related to the ratio (in wt%) of the catalytically active material to the total weight of the catalyst comprising the support in the respective catalyst layers, which is measured after 4 hours in air at 4001. 4. Catalyst test: The highest temperature measured in the entire catalyst bed is referred to in this specification as 23 201132614 as a hot spot. Hotspots, ie the highest temperatures in each of the further considered catalyst layers. The invention will now be explained in more detail by means of the following non-limiting examples. The manufacture consists of the layers of catalysts A, B, C and D. Four-layer catalyst in order to produce a ratio of active material with 9.5 wt% and 75 wt% vanadium pentoxide, 3.2 wt% antimony trioxide, 〇.4 wt% planer (calculated as 铯), 0.2 wt% phosphorus (with phosphorus) Calculate) and the catalyst A of the remaining titanium dioxide composition, at a temperature of 70 C, in a so-called fluidized bed coater, i7.〇g pentoxide, 7.0 g of antimony trioxide, M g sulfuric acid, ι· 65 g of ammonium dihydrogen phosphate, 194.9 g of titanium dioxide having a BET surface area of 21 m 2 /g, i〇2.1 g of water and a 5 % by weight dispersion of a vinyl acetate/ethylene copolymer (eg from Air)

The Vinnapas® series of adhesives from Products and 2000 g of water suspension were coated with 2000 g of a hollow cylindrical block talc having a size of 8 X 6 X 5 mm. The active substance is applied in the form of a thin layer. In order to produce a ratio of active material with 8.6 wt% and 7.5 wt% bismuth pentoxide, 3.2 wt% antimony trioxide, 〇.4 〇 wt% planer (calculated by planing), 0.2 wt0 / bismuth phosphorus (calculated as phosphorus) And the catalyst B of the remaining titanium dioxide composition, at a temperature of 70 ° C in a so-called fluidized bed coater with 17 〇g vanadium pentoxide, 7.0 g of antimony trioxide, MgSO g of barium sulfate, L65 g of phosphoric acid Ammonium hydroxide, 194.9 g of titanium dioxide having a BET surface area of 21 m 2 /g, i 〇 2. lg of water and a 5 % by weight dispersion of a vinyl acetate/ethylene copolymer (eg from Air)

The adhesive of the Vinnapas® family of Products and 2000 g of water suspension was coated with 2000 g of a block talc in the form of a hollow cylinder of size 8 x 6 X 5 mm. The active substance is applied in the form of a thin layer.

S 24 201132614 in order to produce a proportion of active material with 8 wt% and 7.5 wt% vanadium pentoxide, 3.2 wt% antimony trioxide, 〇.2 〇 wt% planer (calculated by planing), 〇. 2 wt% phosphorus (to Catalyst C of phosphorus composition) and the composition of the remaining titanium dioxide, at a temperature of 70 ° C in a so-called fluidized bed coater with 15.1 g of vanadium pentoxide, 6.3 g of antimony trioxide, ruthenium. 1.47g of ammonium dihydrogen phosphate, 173.7 g of titanium dioxide having a BET surface area of 21 m 2 /g, l lg of water and a 50% dispersion of a vinyl acetate/ethylene copolymer (for example, the Vinnapas® family of products from Air Products) The suspension of 2000 g of water and 2000 g of water was coated with 2000 g of a block talc in the form of a hollow cylinder having a size of 8 X 6 X 5 mm. The active substance is applied in the form of a thin layer. In order to produce a catalyst D having a composition of 8% by weight of active material and 7.5 wt% of pentoxide, 3.2 wt% of oxidized bismuth, 〇.2 wt% (calculated) and the remaining titanium dioxide, at 7 (rc) At the temperature, in a so-called fluidized bed coater, 15.1 g of vanadium pentoxide, 6 25 g of aluminum oxide, 1.47 g of ammonium dihydrogen phosphate, 174.11 g of titanium dioxide having a bet surface area of 27 m 2 /g, 101 g of water and A 5% by weight dispersion of a vinyl acetate/ethylene copolymer (for example, the vinnapas® family of products from Air Products) and a 2000 g suspension of water coated 2 〇〇〇g in a size of 8 χ 6 X 5 claws a block of talc in the form of a hollow round crucible. The active material is applied in a thin layer. After the generation of the individual catalysts, 65 cm of catalyst D, 6 cm of catalyst C, 160 cm of catalyst B and 35 cmi of catalyst a are sequentially poured. In a 450 cm long reaction tube, in order to regulate the temperature, the reaction tube is embedded in a heated bed in the form of a liquid salt bath which can be heated up to a temperature of up to 450 ° C. A 3 mm protective tube with a suitable thermocouple is located in the catalyst charge. Through the heat 25 201132614 galvanic display Catalyst temperature in all catalyst combinations. To determine the catalytic performance data, cesium up to 85 g/:Nm3 of o-xylene (purity 99.9%) was passed through 4.0 Nm3 of air per hour through this catalyst combination in ABCD order and The reaction gas passes through a condenser after leaving the reaction tube, and all organic components of the reaction gas are precipitated and precipitated in the condenser except for carbon monoxide and carbon dioxide. The crude product is precipitated by superheated steam, collected, and then weighed. The four-layer catalyst system was calcined as follows: heated from room temperature to 23 ° C under a stream of air of 0.5 Nm 3 /h, wherein the pilot air flow was passed from the bottom to the top through the reactor, followed by a flow of 4 Nm 3 /h from 230 ° C Heating to 300 t, wherein the air flow was directed through the reactor from top to bottom, and the target temperature was maintained for 12 h, then heated from 30 (TC to 41 〇 under a flow of 4 Nm 3 /h. 〇 and kept at 41 〇. After 72 hours, the salt bath temperature was lowered to 39 〇 <> c. The four-layer catalyst system according to the specific example of the present invention was started in accordance with the present invention. After starting the catalyst system, 4 〇Nm3 of air per hour is applied in an amount of 20-40 g per Nm3 of air, 99.9 wt% of o-diphenylbenzene, from top to bottom through the tube (step b)), wherein the adjacent two are gradually increased. The load is low and the salt bath temperature is lowered. Once the hot spot has moved from the fourth layer (the last layer visible in the flow direction) to the second layer, it reaches between the benefit and the (10) (from the gas inlet side). Position, ie reduce the amount of air at the same load: 3. 使其 and pass it through the reactor for 24 hours ((4) 〇). After these 24 hours, the amount of air was adjusted to the amount of the desired process (3 to 4 26 201132614 (step e)) and the load was increased to 8 〇g/Nm3 within 2 days (step f)). Comparative Example In a comparative example, in order to start a four-layer catalyst system, 3.3 Nm3 of air having a loading of 9-40 g/Nm of 99.2 wt0/xylene xylene was passed through the tube from top to bottom and continued for 2 per hour. Hour. Then gradually adjust the amount of air from the second volume to the target process (up to 4Nm3/h). The load is increased to 80g/Nm3 within 2 days. Oxidation of o-xylene to phthalic anhydride after startup An amount of 4.ONm3 of air having a loading of 99 to 9 wt% o-xylene of 30 to 80 g/Nm3 was passed through the tube from top to bottom per hour. The results are summarized in the table (the results are obtained under 8 gram g of o-diphenylbenzene per Nm3 of air ("pA yield" means phthalic anhydride obtained in weight percent relative to 1% o-xylene) The crude yield was determined as follows: Maximum crude PA yield [wt%] Crude PA weighed amount [g] χ 1〇〇/o-xylene influx [Fantasy X o-dimethyl stupid purity [%/1 QQ] Table 1 : Model tube results in the oxidation of o-xylene to phthalic anhydride, starting with two different ratios of space (3.3 and 4.0 NmVh) and 33 and 25 g of o-dimethyl/Nm3. 27 201132614 Table 1 Implementation Example Maximum loading amount Crude PA yield PA quality (benzoquinone value in the reaction gas) Hot spot temperature and layer 80 g/Nm3 according to the invention 115.8 wt% < 250 ppm 445 °C 5 0 cm (layer 2) Method according to Comparative Example 80 g/Nm3 114.6 750 ppm 440 C 8 0 cm (Layer 2) As can be seen from Table 1, the catalyst activated according to the present invention exhibited a significantly improved crude PA yield and pa quality. As early as in the second catalyst layer. The method of the present invention will be further explained below with the aid of the accompanying drawings. In the drawings, 'Figures 1 to 2 Shows the temperature characteristics of the reactor inside the position. Position 0 is related to the gas inlet side of the reactor. As can be seen, the initial 25 g/Nm3 ortho-diphenyl loading and 4 Nm /h air pass in Figure 1. In the embodiment carried out in the amount, the hot spot has a temperature of about 45 〇〇c at the start of the measurement in about 1 7.5 hours, and the position at the position of 8 〇〇 mm travels as far as 2,35 〇mm. Position where the hot spot temperature drops to approximately 430 ° C (step c)). The salt bath temperature is a constant value of 39 (Γ(:, its load I first increases slightly and decreases slightly near the end. In Figure 2, the initial loading of 34 g/Nm3 dimethyl benzene is shown at 3.3 Nm / h) Example of operation under air flux. The salt bath temperature was maintained at a constant temperature of 390 ° C. Within 36 h, a hot spot having an initial temperature of about 434 t traveled forward from a position of 2,850 mm to a position of 25 mm ( Figure 3), where the temperature drops slightly to 43 Gt. The loading increases from the initial amount to a total of 37 g/Nm3 o-xylene.

S 28 201132614 [Simple description of the diagram] [Main component symbol description

Claims (1)

201132614 VII. Patent Application Range: 1. A method for vapor phase oxidation of aromatic hydrocarbons using a catalyst charge, wherein the catalyst charge is placed in a heated bed and wherein the method comprises the following: a) setting the heated bed The temperature is from 365 °C to 395. b) The hydrocarbon loading is 10 to 5 5Nm1 2 3/h of air per Nm3 of air. The air is fed through the catalyst, c) at the end of the catalysis (four) U)% to 25% of the length formed in the direction of flow of the air, the temperature is 40 (rc, preferably 4i〇t, to 47〇 °c below the hot spot. Z · : «〇甲说辱利六付Proudly in step a2), an amount of air of 0.5 to 5 NmVh is charged through the catalyst until the temperature of the heated bed has dropped by 5 ° c to 1 Torr. In the method of the method of claim 2, the amount of air is 3.7 to 4.3 Nm 4 /h. 4. The method of claim 3, wherein the amount of air in the range of 3*5 to Nm3/h is used in step 32. 30 1 _ as claimed in any of items 1 to 4 of the patent application range... the method characterized by the item in step b), which is 10 to 60 g/Nm3 秋2 in the autumn. In the method of item 5, the hydrocarbon loading is 20 to 50 g/Nm3. The characteristic is that the step b) 3 7. The hydrocarbon loading in the aspect of claim 6 is characterized by the step b) that the monthly weight is 20 to 40 g/Nm3. 4 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 The position at the place is reduced. 9. The method of claim 8, wherein the amount of air in step d) is reduced to 2.8 to 3.3 Nm3/h. 10. The method of claim 9, wherein the amount of air in the step is reduced to 2.9 to 3.1 Nm3/h. The method of any one of claims 8 to 1 wherein the step d) is continued until a temperature of 410 is formed in the first 7% to 30% of the length of the catalyst charge. Hot spots up to 47 〇t, preferably 43 至 to 470 °C. 12. The method of claim n, wherein the temperature is 41 Torr, preferably 43 Å, in the first 7% to 30% of the length of the catalyst charge. . To 470. . After the hot spot below, the amount of air is increased to the amount of target air in the step 〇.曰 13. The method of claim 12, wherein the target air amount is between 2.8 and 4.0 Nm3/h. 14. If the patent application is in the 12th or 13th π <RTI ID=0.0>>>>"""""" 15. The use of any of the π < 10,000 methods of the aforementioned patent application for the production of succinic acid, maleic anhydride, o-benzene-undecauline anhydride, isobenzoic acid, terephthalic acid , pyromellitic anhydride, naphthalic anhydride or nicotinic acid. 31