TWI320722B - Multizone catalyst for preparing phthalic anhydride - Google Patents

Description

1320722 . (1) EMBODIMENT DESCRIPTION OF THE INVENTION [Technical Field to Which the Invention Is Ascribed] The present invention relates to a multi-strip catalyst (i.e., a catalyst having three or more different bands (layers)) for The phthalic anhydride is prepared by gaseous oxidation of xylene and/or naphthalene, and its active composition content is decreased from the first catalyst zone disposed toward the gas population to the third catalyst zone disposed toward the gas outlet side. [Prior Art] Industrial grade preparation of phthalic anhydride is accomplished by catalytic gaseous oxidation of o-xylene and/or naphthalene. For this purpose, a catalyst suitable for this reaction is fed into the reactor, preferably a conventional tube-and-column reactor in which multiple tubes are arranged in parallel with a mixture of hydrocarbons and oxygen (for example, air) from the top thereof. Or flow through at the bottom. Because these oxidation reactions generate intense heat, it is necessary for the heat transfer medium to flow around the reaction tube to avoid the hotspots and remove the heat generated. This energy can be used to make steam. The heat transfer medium used is usually a salt melt, which is preferably a eutectic mixture of NaN02 and KN〇3. To suppress unwanted hot spots, similarly, it is also feasible to feed a structured catalyst (which can produce, for example, two or three catalytic strips containing different constituent catalysts). Such systems are known from EP 1 082 317 B1 or EP 1 084 115 B1. The layered arrangement of the catalyst also has undesirable by-products in the crude PA product (i.e., in the possible reactor 5--(2) 1320722· in the preparation of phthalic anhydride from o-xylene and/or naphthalene, The compound before the actual product) is as low as possible. These undesirable by-products mainly include o-tolualdehyde and anhydrides. Further reaction of these compounds into phthalic anhydride will additionally increase the selectivity to the actual product. In addition to the above oxidation reaction, excessive oxidation products are also produced in the reaction. These include maleic anhydride, citraconic anhydride, benzoic acid and carbon dioxide. Selective inhibition inhibits the formation of these undesirable by-products to facilitate product formation and further enhances the catalyst production and practical viability requirements. • EP 1 084 1 1 5 discloses a process for the preparation of phthalic anhydride by catalytic gaseous oxidation of a gas of xylene and/or naphthalene with an oxygen-containing molecule, in a fixed bed, at high temperature, using at least three coating catalysts The layer (which is layered on top of the other layer and coated with a layer of catalytically active metal oxide on the core of the carrier) is reacted, wherein the catalytically active gas inlet side to the gas outlet side are layer by layer, and the catalyst of each layer The activity is adjusted as follows: 'The least active catalyst has a lower active composition content and, if appropriate, other alkali metals selected from potassium, riveted and planed (charged as dopant) More, and subsequently more active catalysts having the same amount of active composition with a smaller amount of alkali metal dopant or having a greater amount of active composition and, if appropriate, less than the base of the second layer of catalyst Metal dopants, provided that the prerequisites are: a) that the less active catalyst on the non-microporous support has from 5 to 9% by weight of the active composition of the total weight of the catalyst, the active composition comprising 3-8 Amount %V205, 0-3_5 wt% Sb203, 0-0.3 wt% P, 0.1-0.5 wt% base (calculated as alkali metal) and the remaining anatase form of titanium dioxide (with a BET surface area of 18-22 m2/ g ), (3) (3) 1320722 · b) The second active agent (the other components are the same as the catalyst (a)) has a higher active composition content of 1 - 5 wt% (absolute 値) And a lower alkali content of 0-0.25 wt% (absolute 値) and c) the most active catalyst (other components are the same as the catalyst (a)) having greater than (a) catalyst 1-5 wt% (absolute 値The higher active composition content and less than (a) the lower content of the catalyst 0-0.25 wt% (absolute 値) 8 The disadvantage of the inventive catalyst shown in this case is that although the catalyst of such structure is used, There is still an extremely high ratio of unwanted phenylhydrazine by-products in the crude PA product. It is obvious to those skilled in the art that the evaporation separation of these two products is only feasible if the valuable product is lost. In addition to this, there is a need to improve the PA yield. For this reason, we have been in urgent need of improved multi-belt (multilayer) catalysts for the preparation of phthalic anhydride. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved catalyst for the preparation of phthalic anhydride by gaseous oxidation of o-xylene and/or naphthalene which not only avoids the disadvantages of the prior art and in particular It is highly selective and active even after prolonged operation. This purpose is achieved by the catalyst of the first item of the patent application. The ideal system is shown in the subsidiary of the scope of the patent application. Therefore, we have surprisingly found that the most favorable catalyst system is composed of at least three different catalyst belts, and the active composition content is from the first catalyst belt disposed on the gas inlet side to the configuration. It is produced when the catalyst band toward the gas outlet side (4) 1320722 is decremented. It has been found that substantially the active constituent content of the first catalyst band is between about 7 and 12% by weight, in particular between about 8 and 1% by weight, and the active composition content of the second catalytic band is Between about m wt%, especially between about 7-1 wt%, and the third catalyst strip has an active composition content of between about 5-10 wt%, especially between about 6 Between -9 wt%. • [Embodiment] The first catalyst strip, the second catalyst strip and the third catalyst strip used in the present invention are defined as follows. The first catalyst strip refers to a catalyst disposed on the gas inlet side. There are two other catalyst strips of the present invention with the 'facing gas exit side', which are referred to as a second catalyst strip and a third catalyst strip, respectively. The third catalyst strip is closer to the gas outlet side than the second catalyst strip. In the preferred system of the invention, the catalyst of the invention has three catalytic strips. In this case, the third catalyst band is located on the gas outlet side. However, it is not necessary to exclude the presence of other catalytic strips downstream of the first catalyst zone in the gas stream. For example, in the system of the present invention, there may be a fourth catalyst band (having an active composition content equal to or lower than the third catalyst band) downstream of the third catalyst band as defined herein. According to the present invention, the active composition content may be decreased between the first catalyst band and the second catalyst band and/or decreased between the second catalyst band and the third catalyst band. The active composition content is decreased between the second catalyst band and the third catalyst band. Undoubtedly, the active composition contains -8-(5) 1320722. It is impossible to increase the catalytic band from the catalyst inlet side of the gas inlet side to the gas outlet side in order, at most, the content is equal. It is assumed by us (but the invention is not limited thereto) that the layer thickness of the catalytically active composition is preferably from the first catalyst to the layer due to the different layer thicknesses in each of the catalytic strips (associated with different active composition contents). The third catalyst band is decremented, first causing o-xylene to react to the first catalyst band and, if appropriate, to the PA in the second catalyst band, in addition to having a thinner layer of active composition In the third catalyst zone, the remaining oxidized product is then oxidized (e.g., oxidized from benzoquinone to PA), but the non-oxidized PA becomes an excessive oxidation product (e.g., COx). As a result, under this fully structured package, the highest yield and lowest ratio of unwanted by-products of o-xylene oxidation to P A can be obtained. In a preferred embodiment of the invention, the BET surface area is increased from a first catalyst strip disposed toward the gas inlet side to a third catalyst strip disposed toward the gas outlet side. The result is surprisingly possible to achieve a particularly good catalyst performance # " BET surface area is preferably 15-25m2 / g (first catalyst band), 15-2 5m2 / g (second catalyst band) And 25-45 m2/g (third catalytic band) 〇 - In general, according to the present invention, it is desirable that the first catalyst band bet. The surface area is smaller than the bet surface area of the third catalyst band. A particularly advantageous catalyst can also be obtained when the BET surface area of the first catalyst strip is equal to the BET surface area of the second catalyst strip and the BET surface area of the third catalyst strip is greater than the lower. When there are more than three catalytic strips, in a preferred system of the invention, the BET surface area of the last catalyst strip toward the gas outlet side is greater than the BET surface area of the catalyst strip near the gas inlet side of (6) 1320722. Advantageously, in another system, all catalyst strips except the last catalyst strip towards the gas outlet side may have the same BET surface area. In a preferred embodiment of the invention, the activity of the catalyst toward the gas inlet side is lower than the activity of the catalyst toward the gas outlet side. It has also been surprisingly found that the multiple tape or multilayer catalyst of the present invention, wherein the amount of active composition contained therein is degraded, is particularly advantageous for the preparation of phthalic anhydride when the catalyst bands are present at a certain length ratio to each other. Thus, in a particularly desirable system of the invention, the first catalyst strip disposed towards the gas inlet side has a length fraction of at least 40%, especially at least 45%, more preferably at least 50%, of the total length of the catalyst bed. It is particularly desirable that the first catalyst band accounts for 40 to 70% of the total length of the catalyst bed, especially 40-55 %, and more preferably 40.52% of the length fraction. The second catalyst band should comprise from about 10% to about 40% of the total length of the catalyst bed, especially a length fraction of from about 10% to about 0%. We have also been surprised to find that the ratio of the length of the third catalyst to the length of the second catalyst is between about 1 and 2, especially between 1.2 and 1.7, more preferably between 1.3 and 1.7. Between 1.6, the economic benefits (such as raw material use efficiency and catalyst production) can provide the best results. We have found that the aforementioned choices due to the length fraction of each catalyst band (especially in combination with the above-mentioned decreasing active composition content) enable the positioning of the hot spots (especially the hot spots in the first zone) and the excellent temperature control. Avoid excessive hot spot temperatures (even in the case of extended catalyst operation time). Therefore, the yield can be improved, especially in terms of the life of the catalyst. Ugly-10- (7) 1320722 (but the invention is not limited thereto), the relative length ratios of the aforementioned catalyst strips to each other cause the xylene used to be substantially completely converted in the second catalyst strip, thus having The third catalyst zone, which has the advantages described above, results in the well-known "product polishing", i.e., the removal of unwanted by-products by oxidation of the product of the valuable oxime to clean the reaction gases. In addition, those skilled in the art know that after a certain period of operation, the aforementioned catalyst will be activated in the hot spot (usually in the first zone). This deactivation causes the φ reaction to move to the second, more active band, resulting in extremely high hot spot temperatures and problems associated with selectivity and plant safety. Due to the respective belt length ratios selected by the catalyst of the present invention (especially the first belt), it is possible to ensure that the hot spot resides in the first belt for the longest time and achieves the known advantages, the second belt and the third belt of the present invention. The length also ensures that the lowest ratio of undesired products is produced while at the same time yielding the highest yield of the valuable hydrazine product. It has also been found that the ratio of lengths of the bands defined herein is also advantageous for other multiple catalysts (i.e., those having no reduced active composition of the invention). In addition to the catalyst for the preparation of phthalic anhydride by gaseous oxidation of o-xylene and/or naphthalene, this is generally the case for other multiple catalysts for gaseous oxidation of hydrocarbons. The temperature control of the gaseous oxidation of o-xylene to phthalic anhydride is well known to those skilled in the art, and reference is made, for example, to DE 1 00 40 827 Α1. In a more desirable system, the active composition of the catalyst of the present invention (catalytically active composition) comprises titanium dioxide having a specific BET surface area and a specific pore radius distribution. We have surprisingly found that at least 25%, especially at least about 4%, more preferably at least about 50%, most preferably at least about 60% of the total volume of '-11-(8) 1320722 micropores in the titanium dioxide used. A particularly advantageous catalyst is obtained by the formation of micropores having a radius between 60 and 400 nm. In another preferred embodiment, the primary crystal size (first order particle size) is greater than about 22 A, preferably greater than about 25 A. More preferably, it is at least 27 A, especially at least about 30 A of TiO 2 . Therefore, it has been found that Ti(R) 2-grade crystals having the above (minimum 値) size can produce a particularly advantageous catalyst. A • The size of the crystal should be less than 80A, especially less than 50A. The above-mentioned primary crystal size is remarkably promoted to form a titanium oxide which is not excessively tight and relatively open-microporous structure is formed in the catalyst (the present invention is not limited to this assumption). The method for determining the size of the primary crystal is described in detail in the following method section. In another preferred embodiment, TiO2 having a bulk density of less than 1.0 g/ml, especially less than 〇8 g/ml, more preferably less than about 0.6 g/ml, is used. Most preferably, the bulk density is not more than about 〇.55 g/ml of TiO 2 . The method of measuring bulk density is detailed in the following method paragraphs. Therefore, it has been found that titanium dioxide having a density as defined above can produce a particularly high performance catalyst. We assume (the invention is not limited to this hypothesis) that this bulk density is a measure of the most advantageous structure of the Ti02 surface in the catalyst, and a loose but not overly compact structure provides a particularly favorable reaction space and The reaction products provide an access channel and a detachment channel, respectively. It is assumed by us (but not limiting to the present invention) that the use of titanium dioxide having the properties described herein in the catalyst provides a particularly advantageous reaction space for the desired reaction, especially within the microporous structure. At the same time, when the Ti〇2 substrate of the present invention is used, a channel for facilitating the reaction site to the reaction site on the surface of the Ti〇2 substrate-12-(9) 1320722 can be provided, which also provides a channel for the reaction product to detach. When the catalyst of the present invention is used to prepare phthalic anhydride, a mixture of a gas containing oxygen molecules (for example, air) and a starting material to be oxidized (particularly o-xylene and/or naphthalene) is passed through a fixed bed reaction. The reactor, in particular the tube cluster reactor (which may consist of a plurality of tubes arranged in parallel). In the reactor tube, the tube is in each case provided with a bed of at least one catalyst. It has been described above that a bed composed of a plurality of (different) catalyst strips is preferred. When the catalyst of the present invention is used to prepare phthalic anhydride by gaseous oxidation of o-xylene and/or naphthalene, it has been surprisingly found that it can attain very high PA yields and very low levels of benzoquinone. In a preferred embodiment of the invention, the butyl ruthenium 02 used has a BET surface area of at least 15 m2/g, preferably between 15 and 60 m2/g, especially between about 15 and 45 m2/g. More preferably, it is between 15-30 m2/g. # More desirably, the total micropore volume of Ti02 is up to 80%, preferably up to 75%, especially up to 70% formed by micropores having a radius between 60 and 400 nm. The micropore volume and fraction referred to herein are measured using a mercury porosimetry (DIN 66133) unless otherwise indicated. The total volume of micropores mentioned in each of the examples in the present invention is based on the total pore volume of the micropore size measured by a mercury porosimeter between 75 00 and 3 · 7 nm. In the total volume of micropores of titanium dioxide used, the micro-13-(10) 1320722 pores having a radius greater than 4 〇〇 nm are preferably less than about 30% 'especially less than about 2 2%', more preferably less than 20% °. It is desirable that 'about 50% to 75%, especially about 50% to 70%' of the total pore volume of the titanium dioxide used is more preferably about 50-65% formed by micropores having a radius of 60-400 nm, and micropores. Approximately 15-25% of the total volume is preferably formed by micropores having a radius greater than 4 〇〇 nm2. With respect to the smaller micropore radius, it is desirable that less than 30% of the total pore volume of the titanium dioxide used, especially less than 20%, is formed by micropores having a radius of 3.7 · φ 60 nm. For this micropore size, a particularly desirable range herein is about 10-30% of the total volume of the micropores 'especially' 2-20%. In a better system of the invention, the titanium dioxide used has the following Particle size distribution: Dio is preferably 〇·5μχη or smaller; D5〇値 (that is, in each case, half of the particles have larger or smaller particle diameter) is preferably 1.5μπι or less; D90値It should be 4μηη or smaller. The D90 of the cerium oxide used is preferably between about 5 μm and 20 μm, especially between about μm to ΙΟμηι, more preferably between about 2 μm and 5 μm. In the electron micrograph, the Ti02 used in the present invention preferably has a sponge-like open microporous structure. The primary crystals are preferably combined to form a preferred open microporous agglomerate to a degree greater than 30%, especially greater than 50%. This particular structure of titanium dioxide used in the hypothesis (but not limiting to the present invention), which is reflected in the micropore radius distribution, provides a particularly advantageous reaction condition for the gaseous oxidation reaction. Depending on the intended use of the catalyst of the present invention, in addition to the titanium dioxide used in the present invention, conventional ingredients known to those skilled in the art may also be present in the active composition of the -14-(11) 1320722 catalyst. The shape of the catalyst and its uniformity or non-uniformity are not limited in principle to the content of the present invention and may include any system that is familiar with the art and is apparently suitable for this particular field of use. In the preparation of phthalic anhydride, it has been found that a particularly useful catalyst is a medium for the use of these catalysts under the reaction conditions, such as quartz (Si〇2), china clay, magnesium oxide, tin dioxide, carbonization.矽, stone, clay (Al2〇3), aluminum citrate, magnesium citrate, chromium citrate or strontium, or a mixture of the foregoing. The carrier can be, for example, a sphere, a shell or a hollow cylinder. A thin layer of shell-like catalytically active composition is applied to the support. It is also possible to coat a plurality of catalytically active compositions having the same or different compositions. Regarding other components in the catalytically active composition of the catalyst of the present invention, in addition to titanium dioxide, it is possible in principle to refer to the compositions and ingredients well known in the related art. These are mainly catalyst systems which contain vanadium oxide in addition to titanium dioxide. The foregoing is described, for example, in EP 0 964 744 B1, which is incorporated herein by reference. In particular, the prior art describes a series of catalysts that enhance catalyst production, and the same can be used in the catalyst of the present invention. These accelerators are a mixture of an alkali metal and an alkaline earth metal, lanthanum, cerium, phosphorus, iron, lanthanum, cobalt, molybdenum, tungsten, tin, lead, and/or cerium, and two or more of the foregoing. For example, DE 2 1 59 44 1 A describes a catalyst consisting of from 1 to 30% by weight of pentoxide and cerium oxide in addition to anatase-modified titanium dioxide. It is possible to influence the contact of the catalyst structure by different promoters, and the ring shape of the ruthenium ruthenate is equivalent to two or (except and in addition to the mediation, including the silver's compound except for the vanadium -15- (12) 1320722 Sex and selectivity, in particular by increasing or decreasing activity. Promoters that increase selectivity include, for example, alkali metal oxides, while phosphorus oxides, especially phosphorus pentoxide, increase the catalyst at sacrificial selectivity. For the preparation method of the catalyst of the present invention, the prior art describes various suitable methods, and therefore, it is not necessary to elaborate in detail herein. For the preparation method of the coated catalyst, for example, DE-A- A method as described in the above-mentioned method, in which a component or a precursor compound of the catalytically active composition comprises a solution or suspension of an aqueous or organic solvent (which is often It is referred to as "slurry" in a heated coating drum and is sprayed onto the carrier material at elevated temperatures until the desired catalytically active composition content (based on the total weight of the catalyst) is reached. According to DE 21 06 796 It is also possible to carry out the coating of the catalytically active composition in a fluidized bed coater. It is preferred to prepare a coated catalyst by coating a thin layer of 50.500 μηι of the active ingredient on an emotional carrier (for example, US 2, 03 5,606). It has been found that useful carriers are in particular spherical or hollow cylindrical shapes. These shaped bodies produce high enthalpy charge at low pressure drop of Φ and reduce the formation of charge defects when the catalyst is fed into the reaction tube. The risk of melting and sintering of the shaped body must be heat resistant in the temperature range in which the reaction is carried out. As detailed above, the possible materials are, for example, tantalum carbide, talc, quartz, kaolin, Si〇. 2, Al2〇3 or clay. The advantage of the coating of the carrier body in the fluidized bed is the high uniformity of the layer thickness, which plays a very important role in the catalytic performance of the catalyst. The particularly uniform coating is sprayed. A solution or suspension of the active ingredient is obtained by heating onto a heated carrier at 80 to 200 ° C in a fluidized bed (for example, according to D Ε 1 2 8 0 -16- (13) 1320722 7 5 6, DE 1 9 8 2 8 5 83 or DE 1 97 09 5 8 9 ). In the foregoing In the fluidized bed method, contrary to the coating in the coating drum, when a hollow cylinder is used as the carrier, it is possible to uniformly coat the inside of the hollow cylinder. In the aforementioned fluidized bed method, DE 1 97 09 5 89 The method is particularly advantageous because the main horizontal cyclic action of the carrier not only results in a uniform coating, but also a low friction of the device parts. For the coating operation, the active ingredient and the organic binder (preferably ethyl acetate) An aqueous solution or suspension of vinyl laurate, a copolymer of vinyl acetate/ethylene or styrene/acrylate, is sprayed onto the heated fluidized support via one or more nozzles. It is particularly advantageous to introduce a spray liquid at the highest product speed point which can result in a uniform distribution of the spray material within the bed. Continuous spraying until the suspension is used up or the required amount of active ingredient has been applied to the carrier. In a particularly desirable system of the invention, the catalytically active composition of the catalyst of the invention is in the moving bed with the aid of a suitable binder. The Φ is coated in the fluidized bed to obtain a coated catalyst. Suitable binders include organic binders well known to those skilled in the art, preferably vinyl acetate/vinyl laurate, vinyl acetate/acrylate, styrene/acrylate, vinyl acetate/maleate and acetic acid. The copolymer of vinyl ester/ethylene is preferably in the form of an aqueous dispersion. It is desirable to use an organic polymer or copolymer adhesive (especially an ethylene acetate copolymer adhesive) as a binder. The binder used is added in a conventional amount to catalyze the active composition, for example, from about 10% to about 20% by weight based on the solids content of the catalytically active composition. For example, refer to EP 744 2 ] 4 . When the catalytically active composition is added at a high temperature of about 150 ° C, as is conventionally known from the art, -17-(14) 1320722, it is also possible to apply directly to the support without the need for a binder. When the foregoing bonding agent is used, the coating temperature which can be used is, for example, between about 50 and 450 ° C according to DE 2 106796. When the feed reactor begins to operate, the binder used is burned out in a short period of time during which the catalyst is dried. The binder is mainly used to enhance the adhesion of the catalytically active composition to the carrier and to reduce the loss during catalyst transfer and feed. Other possible methods for preparing coated catalysts for the conversion of aromatic hydrocarbons to carboxylic acids and / φ or carboxylic anhydrides by catalytic gaseous oxidation are disclosed, for example, in WO 98/00778 and EP-A 7 1 4700. According to these, from the solution and/or the suspension of the catalytically active metal oxide and/or its precursor compound, any powder in the presence of a catalyst for the preparation of the catalyst, the powder is prepared first, and accordingly, in order to prepare the carrier The medium, optionally after conditioning and optionally after heat treatment to produce a catalytically active metal oxide, is coated in a coating form, and the carrier coated in this manner is further heat treated to produce a catalytically active metal oxide or treated to remove Volatile ingredients. # Suitable for the reaction conditions for the preparation of phthalic anhydride from o-xylene and/or naphthalene

It is also known to those skilled in the art from the prior art. In particular, reference is made to K. Towae, W. Enke, R. Jackh, N. Bhargana “Phthalic Acid and Derivatives” in Ullmann's Encyclopedia of Industrial Chemistry Vol. A. 20,1 992, 1 8 1 and its reference to the case . For example, the boundary conditions known from the aforementioned references (WO-A98/3 7 9 67 or WO 99/6 1 433) can be selected for stable operation of the oxidation reaction. For this purpose, the catalyst is first fed to the reactor. The reaction tube (which is subjected to a constant temperature treatment of the outer-18-(15) 1320722 to the reaction temperature, for example, using a salt melt). The reaction gas is usually at a temperature of from 300 to 450 ° C, preferably from 320 to 420 ° C, more preferably from 340 to 400 ° C, and usually from 0.] to 2.5 bar, preferably from 0.3 to 1.5 bar. The catalyst thus obtained is passed at a space rate of usually 750-500011. The reaction gas fed into the catalyst is usually a gas mixed with oxygen-containing molecules (which may contain, in addition to oxygen, a suitable reaction modifier and/or diluent • 'such as 'vapor, carbon dioxide and/or nitrogen) and will be Oxidized aromatic hydrocarbons, the gas containing oxygen molecules may generally contain 1-10 〇m 〇 1%, preferably 2-50 mol%, more preferably 10-30 mol% of oxygen, 〇-30 mol%, preferably 0. - 10 mol% of steam, and 0-50 mol%, preferably 〇-l mol% of carbon dioxide, the balance being nitrogen. To produce the reaction gas, the oxygen-containing gas is usually fed together with 30"50 g/m3 (STP) of the oxidized aromatic hydrocarbon gas. In the particularly desirable system of the present invention, the catalytic activity of the catalyst of the present invention The composition of φ is between about 7% and about 2% by weight, especially between 8 and 10% by weight. The active composition (catalytically active composition) comprises 5-15% by weight of V2〇5' 〇-4. % by weight Sb203, 〇_2-0.75 wt% Cs, 0-3 wt% Nb2〇5 and the balance being Ti02. The catalyst of the present invention is advantageous in, for example, a double catalytic belt or a multi-catalyst belt. The first catalyst strip disposed toward the gas inlet side. In a particularly desirable system of the invention, the BET surface area of the catalyst is between 15 and about 25 m 2 /g. More desirably - the first - catalyst band occupies about 40-60% of the total length of the catalytic band (the total length of the catalytic bed) - 19 - (16) 1320722 length fraction. In another ideal system of the invention, The catalytically active composition content of the inventive catalyst is between about 6-1% by weight, especially between 7 and 9% by weight, active The composition comprises 5-15% by weight of V205, 〇-4% by weight 81 > 203, 0.05-0.3% by weight of 5'0-2% by weight] <[152 05 and the remainder is Ding 102. This inventive catalyst It is advantageous to be used, for example, as a second catalyst strip, that is, downstream of the first catalyst strip disposed toward the gas inlet side (see above). φ Preferably, the BET surface area of the catalyst is between about 1 More preferably, the second catalyst band accounts for about 10-30% of the total length of the catalyst band. In another ideal system of the present invention, The active composition of the inventive catalyst is present in an amount between about 5 and 10% by weight, in particular between 6 and 8% by weight, and the active composition (catalytically active composition) comprises from 5 to 15% by weight of V205, 〇 -4% by weight of Sb203, 0-0.1% by weight of Cs' 0-1% by weight of Nb205 and the remainder of Ti 〇2. The catalyst of the present invention is advantageously used, for example, to be disposed downstream of the second catalyst zone of Shangxin The third catalyst band. Preferably, the BET surface area of the catalyst is slightly higher than the BET surface area of the layer disposed closer to the gas inlet side, especially between about 2 In the range of 5 to about 45 m 2 /g, it is more desirable that the third catalyst band accounts for about 10-50% of the total length of the total length of the catalytic band. According to another preferred embodiment of the present invention When the catalyst of the present invention is used in a multi-belt catalyst bed, the alkali metal content in the catalyst strip decreases from the gas inlet side to the gas outlet side. In principle, the catalyst of the present invention may also be used differently from the above. The -20-(17) 1320722 characteristics (i.e., 'different BET surface area, porosity and/or particle size distribution) are different from titanium dioxide. However, it is particularly preferred in accordance with the invention that at least 50% 'especially at least 75%, more preferably all of the 1 丨〇2 used have a BET surface area and porosity as defined herein, and desirably also have said Particle size distribution. It is also possible to use blends of different Ti 2 Ο 2 materials. It has also been found that in a preferred system of the present invention, the catalytically active composition does not contain any phosphorus and the catalyst used for the T i Ο 2 依 used in the present invention has exceptional activity and is also extremely high. Selectivity. More desirably, at least 0.05% by weight of the catalytically active composition is formed from at least an alkali metal (calculated as an alkali metal). The alkali metal used is more preferably planed. Further, according to the results of the present inventors, in a system, it is preferred that the catalyst of the present invention contains 0.01 to 2% by weight, particularly 5% to 1% by weight, based on the catalytically active composition. The catalyst of the present invention is usually heat treated or calcined (conditioned) prior to use. It has been found that the catalyst is calcined in an oxygen-containing gas, especially in air, for at least 24 hours at a temperature of at least 390 Torr, especially at & 400. (: calcination 2 4 - 7 2 hours is advantageous. This temperature must not exceed 500 ° C, especially about 470 ° C. However, other suitable calcination conditions familiar to this art are in principle In another aspect, the invention relates to a process for the preparation of the aforementioned catalyst comprising the steps of: a. providing a catalytically active composition as defined herein; b. providing an inert carrier, especially inert forming a carrier; c. applying the catalytically active composition to an inert support, especially in a stream of -21 - (18) 1320722 or moving bed. In another aspect, the invention also relates to o-xylene and / or a gaseous oxidation reaction of naphthalene to produce phthalic anhydride, which uses a three or more layer of a catalyst as defined herein. In another aspect, the invention also relates to the use of a catalyst as defined above, Provided as a catalyst for the oxidative reaction of o-xylene and/or naphthalene to phthalic anhydride. Method For determining the parameters of the catalyst of the invention, the following method is used: 1. BET surface area: This measurement is based on BET according to DIN 66131 method The publication of the BET method can also be found in J. Am. Chem. Soc 60, 309 (1938). φ 2. Micropore radius distribution: Micropore radius distribution and micropore volume of titanium dioxide used DIN 6 6 1 3 1 Mercury porosity measured; maximum pressure: 2 〇〇〇 bar, porosimeter 4000 (por〇tec from Germany), according to the manufacturer's instructions. 3 · -Grade crystal size: primary crystal size (first-order particle size) It is determined by powder X-ray diffraction. The analysis is carried out according to the instructions of Rruker 'Germany : BRUKER AXS -D 4 E ndeav 〇r. The obtained X-ray diffraction pattern is based on -22-(19) (19)1320722 The manufacturer's instructions for the "DiffracPlus D4 Measurrement" software component record, while the 1%% refraction of the half-height width is evaluated using the "DiffracPlus Evalution" software, according to the Debye-Scherrer formula of the manufacturer's instructions to determine the primary crystal size. Dimensions: Particle size is measured by laser diffraction using the Fritsch Particle Sizer Analysette 22 Economy (from Fritsch, Germany), according to the manufacturer's instructions. Pretreatment of the test sample: The sample was homogenized in deionized water without the addition of adjuvant and treated with ultrasonic for 5 minutes. 5 · Bulk density: The bulk density was used to prepare the catalyst titanium dioxide (at 50 ° C, It was measured with the aid of drying under reduced pressure without calcination. The average enthalpy of three measurements was obtained. The bulk density was measured by introducing 100 g of titanium dioxide into a 1000 ml container and shaking it for about 30 seconds (if necessary, several batches were simultaneously carried out). Weigh the measuring cylinder (the volume is exactly 100ml) and the empty weight is 10mg. The splint holder and clip secure the powder funnel to the opening of the cylinder. When the stopwatch starts timing, the titanium dioxide is fed into the graduated cylinder within 15 seconds. The supply fixed with a spatula is more than enough to allow the cylinder to be slightly overfilled. After 2 minutes, use the scraping clock to produce! I In addition to excessive cooking, care must be taken to avoid pressing the material into the cylinder.塡 ^ ® The tube is brushed and weighed. The bulk density is expressed in g/nil. -23- (20) 1320722 BET surface area, micropore radius distribution and micropore volume, as well as body size and primary particle size distribution for the determination of titanium dioxide, in the case of materials measured at 150 ° C and reduced pressure . The BET surface area of the catalyst or catalyst zone in this specification is related to the BET surface area of the titanium dioxide used in each case (dry calcination at 150 ° C and reduced pressure, see above). While the addition of other catalytically active components does have an effect on the extent of the BET surface area, the BET surface area of the catalyst is typically measured using the BET surface area of the titanium used. This is well known to those skilled in the art. In each case, the active composition content (excluding the binder active composition content) is the catalytic activity in the total weight of the catalyst, which is included in the specific carrier. The composition content (% by weight) phase was measured after adjusting for 4 hours at 400 °C. The invention will now be further described with reference to the following non-limiting examples:

Example 1: Preparation of Catalyst A For the preparation of an active composition content of 8% by weight and 7.5 bismuth dioxide 3% 3% by weight of antimony trioxide, 〇.4 〇 wt% planing (calculation), 〇·2 weight % phosphorus (calculated as phosphorus) and the remaining catalyst A' 260 〇g in a hollow cylindrical (8 x 6 x 5 mm) block fluidized bed coater, 70. (:, with 17.9g vanadium pentoxide, 7. bismuth,] 3g sulfuric acid planing,] 9g ammonium dihydrogen phosphate, 2] l.] g two first crystal each data is also dry, not Catalytic catalyst band associated with a certain amount of oxidation 3. The amount of detail is 5% by weight of titanium talc in 6g of titanyl oxide-24- (21) 1320722 (BET surface area is 21 m2/g), 130.5g Adhesive (consisting of water and ethyl acetate/ethylene copolymer (Vinnapas® EP 6.5 W from Wacker) in a 5 % dispersion) and 2 〇〇〇g water suspension. The active composition is Coating in the form of a film. Example 2: Preparation of catalyst b For the preparation of 8% by weight of active composition and 7.5% by weight of five φ vanadium oxide, 3.2% by weight of antimony trioxide, c. 20% by weight ) 2% by weight of phosphorus (calculated as phosphorus) and the rest of the catalyst B of titanium dioxide, 2200g of hollow cylindrical (8x6x5mm) block talc in a fluidized bed coater at 70 ° C, with 15.4 g vanadium pentoxide, 6.6g antimony trioxide '0.5g carbonic acid' 1.5g diammonium phosphate, I82.9g titanium dioxide (BET surface 21 m2/g), 110.7 g of binder (composed of water and 50% dispersion of acetonitrile/ethylene copolymer (Vinnapas® EP 65 W from Wacker)) and 2000 g of water suspension φ. The active composition is applied as a film.

Example 3: Preparation of Catalyst C For the preparation of 8% by weight of active composition and 7.5 wt% vanadium pentoxide, 3-2 wt% antimony trioxide" 0.2 wt% phosphorus (calculated as phosphorus) and the balance being titanium dioxide Catalyst C of the composition, 2000 g of hollow _ cylindrical (8 x 6 x 5 mm) talc in a fluidized bed coater, at 70 ° C, with 13.35 g of vanadium pentoxide '5.7 g of antimony trioxide, 1.34 g of phosphoric acid Dihydrogen, 158_65g titanium dioxide (BET surface area 21m2/g), l〇9.4g binder-25- (22) 1320722 (from water and vinyl acetate/ethylene copolymer (Vinnapas® EP 65 W ' from Wacker) The composition of 50% dispersion was coated with 2000 g of a suspension of water. The active composition is applied as a film.

Example 4: Preparation of Catalyst D For the preparation of 9% by weight of active composition and 7.5% by weight of vanadium pentoxide, 3.2% by weight of antimony trioxide, 0.40% by weight of planer (calculated as φ), 0.2% by weight Phosphorus (calculated as phosphorus) and the remaining catalyst D of titanium dioxide composition, 2000 g of hollow cylindrical (8 x 6 x 5 mm) talc in a fluid bed coater, 70 ° C, with 17.0 g of vanadium pentoxide, 7.0 g antimony trioxide, l.lg sulfuric acid planer, 1.65g ammonium dihydrogen phosphate, 194.9g titanium dioxide (BET surface area 21m2 / g), l〇2.1g binder (from water and vinyl acetate / ethylene copolymer (Vinnapas ® EP 65 W, consisting of 50% dispersion of Wacker) coated with 2000 g of water suspension. The active composition is applied as a film.

Example 5: Preparation of Catalyst E For the preparation of 8% by weight of active composition and 8% by weight of vanadium pentoxide, 3.2% by weight of antimony trioxide, 0.20% by weight of planer (calculated by planing), 〇. 2% by weight Phosphorus (calculated as phosphorus) and the remaining catalyst E of the composition of titanium dioxide, 2000 g hollow cylindrical (8 x 6 x 5 mn talc in a fluid bed coater, at 70 ° C, with 5.1 g vanadium pentoxide, 6.3 g of antimony trioxide, 0.53 g of sulfuric acid planer, 1.47 g of ammonium dihydrogen phosphate, I73.7 g of titanium dioxide (BET surface area of 2] m2/g),] 〇lg binder (from water and ethyl acetate-26- (23 1320722 Ethyl ester/ethylene copolymer (composed of 5 〇% dispersion of Vinnapas® EP 65 W from Wacker) was coated with a suspension of 200 g of water. The active composition was applied as a film.

Example 6: Preparation of Catalyst F For the preparation of 8% by weight of active composition and 7.5% by weight of vanadium pentoxide, 3.2% by weight of antimony trioxide, 0.2% by weight of phosphorus (calculated as phosphorus) and the balance being titanium dioxide Catalyst F of the composition, 2000 g of hollow cylindrical (8 x 6 x 5 mm) talc in a fluidized bed coater, at 70 ° C, with 15.1 g of vanadium pentoxide, 6.25 g of antimony trioxide, 1.47 g of phosphoric acid Dihydrogen ammonium, 174.11g titanium dioxide (BET surface area 27m2/g), 101g binder (composed of water and vinyl acetate/ethylene copolymer (Vinnapas® EP 65 W, from Wacker) 50% dispersion) and 2000g Water suspension coating. The active composition is applied as a film.

#Example 7: Preparation of Catalyst G For the preparation of 8% by weight of active composition and 7.5% by weight of vanadium pentoxide, 3-2% by weight of antimony trioxide '0.2% by weight of phosphorus (calculated as phosphorus) and the balance being titanium dioxide The catalyst G of the composition except for the use of titanium dioxide having a surface area of 2 1 m 2 /g was the same as the preparation of the catalyst F as in the above Example 6. Example 8: Catalytic performance parameter in the oxidation reaction of o-xylene to phthalic anhydride (Comparative Example 1) -27- (24) 1320722 450 cm long reaction tube was sequentially fed with a catalyst C of length l〇〇cm , 60cm long catalyst B and 13 Ocm long catalyst A. The reaction tube is placed in a liquid salt melt which can be heated to a temperature of up to 45 °C. A 3 mm guard tube is disposed in the catalytic bed, the tube having a catalytic element that can be used to display the temperature of the catalyst in the complete catalyst combination. In order to determine the catalytic performance parameters, o-xylene (purity 99.9%) of 0-maximum 70 g/ni3 (STP) was passed through the catalyst combination series ABC at a rate of 3.6 m3 (STP) air/hour, and the reaction gas downstream of the outlet of the reaction tube φ Through the condenser, in addition to carbon monoxide and carbon dioxide, the organic components of all the reaction gases are deposited in the condenser. The deposited crude product is melted by superheated steam, collected and then weighed. The crude yield was determined as follows: Maximum PA crude yield 丨% by weight] = PA coarse weight 丨 g] xlOO/o-xylene feed amount [g]> (o-xylene purity 丨%/100J Test results are listed in Table 1 Example 9: Catalytic performance parameter in the oxidation reaction of o-xylene to phthalic anhydride (Inventive Example 1) A catalyst of 90 cm length is fed in a 45 〇cm long reaction tube, and the length is 60 cm. Catalyst E and 140 cm long catalyst D. Other procedures are as described in Example 8. The test results are listed in the table. Example 1 〇: Oxidation of ortho-xylene to catalytic performance parameters in phthalic anhydride (Comparative Example 2) -28- (25) 1320722 450 cm long reaction tube was sequentially fed with 130 cm long catalyst C, 60 cm long catalyst B and I 00 cm long catalyst A. Other programs are as in the examples The test results are listed in Table 1. Example] 1: Catalytic performance parameter in the oxidation reaction of o-xylene to phthalic anhydride (Inventive Example 2) sequentially feeding in a 450 cm long reaction tube 90 cm long catalyst G, 60 cm long φ catalyst E and 140 cm long catalyst D. Other procedures are as described in Example 8. The test results are shown in Table 1. Table 1 Example 'Maximum loaded PA crude yield PA quality (benzoquinone in the reaction gas) Hot spot temperature and position Example 8: Catalyst combination A (130 cm) B (60 cm) C (100 cm) 50 g/m\STP 112.4 Weight ° / 〇 > 2000 ppm 450 〇 C ] 50 cm (second belt) Example 9: Catalyst combination D (140 cm) E (60 cm) F (90 cm) 57 g / m 3 (STP) 113.8 Weight 〇 / 〇 &lt 500 ppm 440 〇C 50 cm (first zone) Example ίο: Catalyst combination A (100 cm) B (60 cm) C (130 cm) 45 g/m3 (STP) 106.7 Weight °/. >10000ppm 450〇C 150cm (second zone) Implementation 働1: Catalyst combination D (140cm) E (60cm) G (90cm) 58g/m3 (STP) 113.6 Military halo% <800ppm 440〇C 50cm ( A belt) It can be seen from Table 1 that the catalyst of the present invention according to Examples 9 and 0 has the highest PA yield and PA quality. The hotspot is extremely advantageous for positioning in the first catalyst band. Inventive Example 9 (wherein the BET surface area is increased from the first catalyst band to the third catalyst band, in this case: the third catalyst band is higher than the first catalyst band and the second contact -29- (26) (26) 1320722 Media tape) The quality of the PA is even higher than in the embodiment 1 of the invention (wherein the BET surface area does not increase from the first catalyst band to the third catalyst band).

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Claims (1)

1320722 m (more) 正细丨10, the scope of application for patents Annex 3: Patent application No. 94117557 The scope of patent application for Chinese application is replaced by November 18, 1998. 1. By o-xylene and/or naphthalene The gaseous oxidation reaction prepares a catalyst for phthalic anhydride, which comprises a first catalyst strip φ′ disposed on the gas inlet side and a second catalyst strip disposed closer to the gas outlet side and disposed closer to or on the gas outlet side. a third catalyst strip having different compositions and each having an active composition containing TiO 2 , and the active composition content is decreased from the first catalyst strip to the third catalyst strip, except that the prerequisite is (a) The first catalyst band has an active composition content of about 7-12% by weight, (b) the second catalyst band has an active composition content of 6-11% by weight, and the active composition of the second catalyst band The content of the active ingredient is less than or equal to the active composition of the first contact medium, and (c) the third catalytic band has an active composition content of 5-10% by weight, and the active composition content of the third catalytic band Less than or equal to the activity of the second catalyst band Into the content. 2. The catalyst of claim 1, wherein the first catalyst band has an active composition content of between about 8 and 11% by weight. 3. For the catalyst of claim 1 or 2, wherein the second catalyst strip has an active composition content of between about 7 and 10% by weight » 4. The touch of claim 1 or 2 The medium, wherein the third 1320722 catalyst belt has an active composition content of between about 6 and 9 wt%. 5. The catalyst according to claim 1 or 2, wherein the catalytic activity of the catalytic belt toward the gas inlet side is lower than the catalytic activity of the catalytic belt toward the gas outlet side. 6. The catalyst of claim 1 or 2 wherein the BET surface area of the first catalyst band is lower than the BET surface area of the third catalyst band. 7. The catalyst of claim 6, wherein the first catalyst strip has a BET surface area equal to the BET surface area of the second catalyst strip, and the third catalyst strip has a larger BET surface area than the lower. 8. The catalyst of claim 6, wherein the BET surface area of the first catalyst strip and the BET surface area of the second catalyst strip are each between about 15 and 25 m2/g, and the third catalyst strip The BET surface area is between about 25 and 45 m2/g. 9. The catalyst of claim 1 or 2, wherein the first catalyst strip disposed toward the gas inlet side occupies at least 40% of the total length of the catalyst bed. 10. The catalyst of claim 9, wherein the ratio of the first catalyst band to the total length of the catalyst bed is between 40% and 70%. 11. For the catalyst of claim 1 or 2, wherein the ratio of the second catalyst zone to the total length of the catalyst bed is between about 10% and 4〇%2. 12. The catalyst according to claim 1 or 2, wherein the ratio of the length of the third catalyst band to the length of the second catalyst band is between about 1 and 2 of stomach +/- 1320722 1 3 . At least about 40% of the total pore volume of the catalyst Ti02 of claim 1 or 2 is formed by the micropores of the radius. 14. Up to 75 % of the total pore volume of the catalyst Ti02 as claimed in claim 1 or 2 is formed by the micropores of the radius. 15. The catalyst Φ active composition as claimed in claim 1 or 2 is applied to a moving bed or fluidized bed. 16. Less than about 30% of the total pore volume of the catalyst Ti02 as claimed in claim 1 or 2 is formed by a large radius micropore. 17. Approximately 17-27% of the total pore volume of the catalyst 'Ti02 as claimed in claim 16 is formed by a radius larger than the pores. 18. Approximately 50-75% of the total volume of the micropores of the catalyst '#Ti02" as claimed in item 14 of the patent application is formed by a radius between the micropores. 19. Less than 30% of the total pore volume of the catalyst Ti02 as claimed in claim 1 or 2 is formed by a radius of micropores. 20. Approximately 10-30% of the total pore volume of the catalyst Ti02 as claimed in claim 1 or 2 is formed by a radius of micropores. 21. The catalyst of claim 1 or 2, wherein is used for 60-400 nm, wherein, for 60-400 nm, wherein catalysis, wherein 400 nm is used, 400 nm of which is used, Among the 60-400 nm used, among the 3.7-60 nm used, among the 3.7-60 nm used, the D9Q lanthanum of the -3- 1320722 Ti〇2 used is between about 0.5 and 20 μm. 2 2. As claimed in the patent application The catalyst of item 1 or 2, wherein less than 10% of the total pore volume of Ti〇2 used is present in micropores having a pore radius of less than 3.7 nm. 23. The catalyst according to claim 1 or 2, wherein vanadium (calculated as vanadium pentoxide) is present in an amount of 8 wt% or more of the catalytically active composition. 24. The catalyst of claim 1 or 2 wherein at least 5% by weight of the catalytically active composition is formed from at least one alkali metal (calculated as alkali metal). 25. The catalyst according to claim 1 or 2, wherein the adhesive used for the catalytically active composition is an organic polymer or copolymer. 26. The catalyst of claim 1 or 2 wherein the catalyst is calcined or conditioned at greater than 390 ° C for at least 24 hours in an oxygen-containing gas. 27. The catalyst of claim 1 or 2 wherein the copper content is from 0.1 to 2% by weight of the catalytically active composition. 28_Case as claimed in claim 1 or 2, wherein only one Ti〇2 source is used. 'All used Ti02 has a BET surface area as defined in claim 8 or as defined in claim 13 The pore radius distribution. 29_ The catalyst of claim 1 or 2 wherein the active composition does not contain phosphorus. 3 0. — a gaseous oxidation reaction of o-xylene and/or naphthalene to produce 1320722' A method of producing phthalic anhydride, which uses the catalyst according to any one of claims 1 to 29. 31. Use of a catalyst according to any one of claims 1 to 29 for the gaseous oxidation of o-xylene and/or naphthalene to produce phthalic anhydride. -5-