Abstract: An intelligent agent system comprising terminal devices and, a control method are disclosed. The control method for the intelligent agent system comprises the steps of: transmitting, by a first terminal device, data including context information of a user to a server; storing, by the server, the received data in a user profile; receiving, by the second terminal device, the data including the context information of the recognized user from a server, when a second terminal device recognizes the user; and detecting, by the second terminal device, current context information of the user and recommending a service to the user on the basis of the detected current context information of the user, the received context information, and the characteristics of the second terminal device.

Abstract: The invention relates to a process of the oxidative dehydrogenation of a C2-6 alkane, comprising subjecting a stream comprising methane and the C2-6 alkane, in which stream the volume ratio of methane to the C2-6 alkane is of from 0.005:1 to 100:1, to oxydehydrogenation conditions resulting in a stream comprising methane, a C2-6 alkene and optionally a C2-6 carboxylic acid.

Abstract: A catalytic converter arrangement for producing phthalic anhydride by means of a gas phase oxidation of aromatic hydrocarbons, comprising a reactor with a gas inlet side for a reactant gas, a gas outlet side for a product gas, a first catalytic converter layer made of catalytic converter elements, and at least one second catalytic converter layer made of catalytic converter elements. The first catalytic converter layer is arranged on the gas inlet side, and the second catalytic converter layer is arranged downstream of the first catalytic converter layer in the gas flow direction. The catalytic converter elements have an outer layer of an active compound. The invention is characterized in that the active compound content in the first catalytic converter layer and/or in the second catalytic converter layer is below 7 wt.

Abstract: The invention relates to a catalyst arrangement for preparing phthalic anhydride by gas-phase oxidation of aromatic hydrocarbons, which comprises a reactor having a gas inlet end for a feed gas and a gas outlet end for a product gas and also a first catalyst zone made up of catalyst bodies and at least one second catalyst zone made up of catalyst bodies, where the first catalyst zone is arranged at the gas inlet end and the second catalyst zone is arranged downstream of the first catalyst zone in the gas flow direction and the length of the first catalyst zone in the gas flow direction is less than the length of the second catalyst zone in the gas flow direction, characterized in that the first catalyst zone has a higher gap content compared to the second catalyst zone.

Abstract: The present invention relates to a catalyst system for oxidation of o-xylene and/or naphthalene to phthalic anhydride (PA), comprising a plurality of catalyst zones arranged in succession in the reaction tube, which have been produced using antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm. The present invention further relates to a process for gas phase oxidation, in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst system which comprises a plurality of catalyst zones arranged in succession in the reaction tube and which has been produced using an antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm.

Abstract: A process for preparing carboxylic acids and/or carboxylic anhydrides by gas phase oxidation of aromatic hydrocarbons, in which a gas stream comprising at least one aromatic hydrocarbon and molecular oxygen is passed continuously over a catalyst thermostatted by a heat carrier medium, which comprises keeping the temperature of the heat carrier medium constant during the startup of the reactor for at least 24 hours, during which neither the loading of the gas stream with hydrocarbons nor the gas stream volume is increased by more than 3%.

Abstract: The present invention relates to a catalyst for preparing carboxylic acids and/or carboxylic anhydrides, which has a plurality of catalyst zones arranged in series and has been produced using a vanadium antimonate having a maximum content of crystalline valentinite of 5% by weight. The present invention further relates to a process for gas-phase oxidation in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst which has a plurality of catalyst zones arranged in series and has been produced using a vanadium antimonate having a maximum content of crystalline valentinite of 5% by weight.

Abstract: In a process for controlling a gas phase oxidation reactor for preparation of phthalic anhydride, by passing a gas stream which comprises an aromatic hydrocarbon and molecular oxygen through a multitude of reaction tubes arranged in the gas phase oxidation reactor, each of which comprises a bed of at least one catalyst and the temperature of which can be controlled by means of a heat transfer medium, at least one control parameter is measured and correcting interventions for control of the control parameter are determined, the at least one control parameter comprising the phthalic anhydride yield and the correcting parameter used being the temperature of the heat carrier medium. Over at least 90% of the lifetime of the catalyst, the change in the correcting parameter is limited to a maximum of 0.5 K within a period of 30 days. In this way, the cumulated phthalic anhydride yield over the lifetime of the catalyst is maximized.

Abstract: The present invention relates to a multilayer catalyst for preparing phthalic anhydride which has a plurality of catalyst layers arranged in succession in the reaction tube, with the individual catalyst layers having alkali metal contents which decrease in the flow direction. The present invention further relates to a process for the oxidation of naphthalene or o-xylene/naphthalene mixtures over such a multilayer catalyst and the use of such multilayer catalysts for the oxidation of naphthalene or o-xylene/naphthalene mixtures to phthalic anhydride.

Abstract: The invention relates to the use of monoliths as particle filters for limiting the deactivation of catalysts during catalytic reactions in multi-tubular reactors. The invention is particularly well-suited for catalytic oxidation reactions in the gaseous phase. The invention also relates to multi-tubular reactors including monoliths as particle filters.

Abstract: A method for producing phthalic anhydride by catalytic gas-phase oxidation of o-xylene and/or naphthalene, carried out by means of a catalyst arrangement which has a first catalyst layer at the gas inlet side and at least one second catalyst layer after the first catalyst layer in the gas flow direction with different catalytic activity, wherein when the gas-phase oxidation is being carried out a lower maximum temperature is formed in the first catalyst layer than in the second catalyst layer. Furthermore, a method for producing the catalyst arrangement, as well as the catalyst arrangement itself.

Abstract: The present invention relates to a catalyst system for preparing carboxylic acids and/or carboxylic anhydrides, which system comprises a plurality of superposed catalyst layers arranged in a reaction tube, where vanadium antimonate is introduced into the active material in at least one of the catalyst layers. The present invention further relates to a process for gas-phase oxidation, in which a gaseous stream comprising at least one hydrocarbon and molecular oxygen is passed through a plurality of catalyst layers and the maximum hot spot temperature is below 425° C.

Abstract: Disclosed is an improved process for the production of phthalic anhydride wherein the spent catalyst is removed from the oxidation reactor tubes more effectively by vacuuming from the top and using a vacuum hose having a tip with an increased impact strength and with a maximum hardness. As a result, the new catalyst loading can be made more uniform and the process may be operated with improved stability at higher organics loadings in the reactor feed. Process stability may be further improved by varying the outlet temperature of the phthalic anhydride precondenser over time.

Abstract: In the production of phthalic anhydride by the oxidation of ortho-xylene with air, the ortho-xylene loading is increased without increasing the likelihood of explosion by insulating the system to avoid cold spots to keep the ortho-xylene at a temperature above its dew point; in addition the system may be electrically interconnected and grounded to reduce the risk of spark initiated explosions or deflagrations.

Abstract: A chemical reactor including: a plurality of heat exchange plates which between them define reaction compartments, in which reactor each heat exchange plate includes two walls between them defining at least one heat exchange space, the respective walls being fixed together by joining regions, and the reactor also comprises at least one injection device for injecting substance into the reaction compartments, said substance-injection device passing through the heat-exchange plates in respective joining regions thereof. Also, a chemical reaction process that can be carried out in this reactor.

Abstract: The present invention relates to a catalyst for preparing carboxylic acids and/or carboxylic anhydrides, which has a plurality of catalyst zones arranged in series and has been produced using a vanadium antimonate having a maximum content of crystalline valentinite of 5% by weight. The present invention further relates to a process for gas-phase oxidation in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst which has a plurality of catalyst zones arranged in series and has been produced using a vanadium antimonate having a maximum content of crystalline valentinite of 5% by weight.

Abstract: What is described is a process for starting up a gas phase oxidation reactor for oxidation of o-xylene to phthalic anhydride, said reactor comprising at least one catalyst layer and being temperature-controllable by means of a heat carrier medium, wherein a) the catalyst layer is interrupted by a moderator layer which is less catalytically active than the catalyst layer or is catalytically inactive, b) a gas stream is passed through the reactor with an initial loading of o-xylene and at an initial temperature of the heat transfer medium, c) the loading of the gas stream is increased to a target loading and, in parallel, the temperature of the heat transfer medium is lowered to an operating temperature. The introduction of the moderator layer allows the loading to be increased more rapidly and the startup time to be shortened.

Abstract: Disclosed is an improved process for the production of phthalic anhydride wherein the spent catalyst is removed from the oxidation reactor tubes more effectively by vacuuming from the top and using a vacuum hose having a tip with an increased impact strength and with a maximum hardness. As a result, the new catalyst loading can be made more uniform and the process may be operated with improved stability at higher organics loadings in the reactor feed. Process stability may be further improved by varying the outlet temperature of the phthalic anhydride precondenser over time.

Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene, in, in a main reactor, a gaseous mixture of o-xylene and an oxygenous gas is passed through at least two reaction zones whose temperature can be controlled independently, and converted to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, and the intermediate reaction product is introduced into a postreactor, wherein the temperature of the reaction zones in the main reactor is regulated in such a way that the concentration of unconverted o-xylene in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality.

Abstract: The invention relates to a catalyst for partially oxidizing hydrocarbons in the gas phase, containing a multi-metal oxide of the general formula (I), AgaMObVcMdOe.f H2O (I), wherein M stands for at least one element selected from among Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Si, Sn, Pb, P, Sb, Bi, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Au, Zn, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and U, a has a value of 0.5 to 1.5, b has a value of 0.5 to 1.5, c has a value of 0.5 to 1.5, a+b+c has the value 3, d has a value of less than 1, e means a number that is determined by the valence and frequency of the elements other than oxygen in the formula (I), f has a value of 0 to 20, which multi-metal oxide exists in a crystal structure, the X-ray powder diffractogram of which is characterized by diffraction reflections at a minimum of 5 lattice distances selected from among d=4.53, 3.38, 3.32, 3.23, 2.88, 2.57, 2.39, 2.26, 1.83, 1.77 AA (+?0.

Abstract: The present invention relates to a catalyst for the oxidation of o-xylene and/or naphthalene to phthalic anhydride, which has a plurality of catalyst zones which are arranged in series in the reaction tube and have been produced using an antimony trioxide which comprises a significant proportion of valentinite. The present invention further relates to a process for gas-phase oxidation, in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst produced using an antimony trioxide which comprises a significant proportion of valentinite.

Abstract: A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene, in which a gaseous mixture of o-xylene and an oxygenous gas is converted in a main reactor to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, the heat of reaction which arises in the main reactor being removed at least partly by indirect cooling with a heat carrier medium, and the intermediate reaction product being introduced into a postreactor. The concentration of unconverted o-xylene in the intermediate reaction product is at least 1% by weight, and the sum of the concentrations of phthalic anhydride underoxidation products in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality.

Abstract: The present invention relates to a catalyst, in particular for the preparation of phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, having an inert support and at least one layer which has been applied thereto and has a catalytically active composition comprising TiO2, characterized in that at least a portion of the TiO2 used has the following properties: (a) the BET surface area is more than 15 m2/g, (b) at least 25% of the total pore volume is formed by pores having a radius between 60 and 400 nm, and (c) the primary crystal size is more than 22 ångstrøm. Also described is a preferred process for preparing such a catalyst, and the preferred use of the titanium dioxide used in accordance with the invention.

Abstract: The present invention relates to a multilayer catalyst for preparing phthalic anhydride which has a plurality of catalyst layers arranged in succession in the reaction tube, with the individual catalyst layers having alkali metal contents which decrease in the flow direction. The present invention further relates to a process for the oxidation of naphthalene or o-xylene/naphthalene mixtures over such a multilayer catalyst and the use of such multilayer catalysts for the oxidation of naphthalene or o-xylene/naphthalene mixtures to phthalic anhydride.

Abstract: A process for gas phase oxidation in which a gaseous stream which comprises at least one aromatic hydrocarbon and molecular oxygen is passed through one or more catalyst layers, wherein a moderator layer is arranged between two catalyst layers arranged in succession in flow direction of the gaseous stream, the moderator layer being less catalytically active than the catalysts adjacent upstream and downstream or being catalytically inactive. The desired oxidation products are obtained in high yield over prolonged periods.

Abstract: In a process for controlling a gas phase oxidation reactor for preparation of phthalic anhydride, by passing a gas stream which comprises an aromatic hydrocarbon and molecular oxygen through a multitude of reaction tubes arranged in the gas phase oxidation reactor, each of which comprises a bed of at least one catalyst and the temperature of which can be controlled by means of a heat transfer medium, at least one control parameter is measured and correcting interventions for control of the control parameter are determined, the at least one control parameter comprising the phthalic anhydride yield and the correcting parameter used being the temperature of the heat carrier medium. Over at least 90% of the lifetime of the catalyst, the change in the correcting parameter is limited to a maximum of 0.5 K within a period of 30 days. In this way, the cumulated phthalic anhydride yield over the lifetime of the catalyst is maximized.

Abstract: A catalyst for gas phase oxidations comprises an inert support and a catalytically active material which comprises vanadium oxide and titanium dioxide and has been applied thereto. The titanium dioxide has a content of sulfur compounds, calculated as S, of less than 1000 ppm and a content of calcium compounds, calculated as Ca, of less than 150 ppm. The catalyst has a relatively high activity and/or selectivity and thus enables relatively high yields of the desired target product, for example phthalic anhydride. Also described is a process for preparing phthalic anhydride, wherein a gas stream which comprises molecular oxygen and o-xylene, naphthalene or mixtures thereof is contacted with the catalyst.

Abstract: In the production of phthalic anhydride by the oxidation of ortho-xylene with air, the ortho-xylene loading is increased without increasing the likelihood of explosion by insulating the system to avoid cold spots to keep the ortho-xylene at a temperature above its dew point; in addition the system may be electrically interconnected and grounded to reduce the risk of spark initiated explosions or deflagrations.

Abstract: A system for mixing ortho-xylene with an oxygen-containing gas such as air comprises an evaporator vessel fed with the gas and having a lance projecting into the gas. The lance is provided with a metal spray nozzle for injecting droplets of hot liquid ortho-xylene into the gas stream, concurrently with the direction of flow of the gas. The metal at the surface of the spray nozzle, that in use is in contact with the liquid ortho-xylene, has a high surface hardness to resist erosion, particularly by cavitation. The system is useful in the production of phthalic anhydride by the oxidation of ortho-xylene with air, whereby the risk for deflagrations is reduced. A soft metal seal is the preferred gasket between the spray nozzle and the lance.

Abstract: A multimetal oxide of the formula I Aga-bMbV2Ox*cH2O,??I where M is a metal selected from the group consisting of Li, Na, K, Rb, Cs, Tl, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, Al, Fe, Co, Ni and/or Mo, a is from 0.3 to 1.9 and b is from 0 to 0.5, with the proviso that the difference (a?b)?0.1 and c is from 0 to 20 and x is a number determined by the valence and amount of elements different from oxygen in the formula I, which has a crystal structure giving an X-ray powder diffraction pattern which displays reflections at the lattice spacings d of 15.23±0.6, 12.16±0.4, 10.68±0.3, 3.41±0.04, 3.09±0.04, 3.02±0.04, 2.36±0.04 and 1.80±0.04 ?. Precatalysts and catalysts produced therefrom for the partial oxidation of aromatic hydrocarbons are also provided.

Abstract: Method for the production of phthalic acid anhydride by catalytic gas phase oxidation of o-xylol with oxygen, in which the reaction is carried out in 5 to 60 serially arranged reaction zones under adiabatic conditions, and reactor system for carrying out the method.

Abstract: The present invention relates to a catalyst system for preparing carboxylic acids and/or carboxylic anhydrides, which system comprises a plurality of superposed catalyst layers arranged in a reaction tube, where vanadium antimonate is introduced into the active material in at least one of the catalyst layers. The present invention further relates to a process for gas-phase oxidation, in which a gaseous stream comprising at least one hydrocarbon and molecular oxygen is passed through a plurality of catalyst layers and the maximum hot spot temperature is below 425° C.

Abstract: What is described is a process for starting up a gas phase oxidation reactor for oxidation of o-xylene to phthalic anhydride, said reactor comprising at least one catalyst layer and being temperature-controllable by means of a heat carrier medium, wherein a) the catalyst layer is interrupted by a moderator layer which is less catalytically active than the catalyst layer or is catalytically inactive, b) a gas stream is passed through the reactor with an initial loading of o-xylene and at an initial temperature of the heat transfer medium, c) the loading of the gas stream is increased to a target loading and, in parallel, the temperature of the heat transfer medium is lowered to an operating temperature. The introduction of the moderator layer allows the loading to be increased more rapidly and the startup time to be shortened.

Abstract: Herein disclosed is a method, comprising: forming a dispersion under high shear comprising gas bubbles of an oxidant dispersed in a liquid phase, wherein the bubbles have a mean diameter of less than 1.5 micron; and contacting the dispersion with an oxidation catalyst to produce a product stream, wherein the product stream comprises a substance selected from the group consisting of dicarboxylic acid, benzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, and phthalic anhydride. In some cases, forming the dispersion under high shear comprises introducing the oxidant and the liquid phase into a high shear device comprising at least one rotor and at least one complementarily-shaped stator. Herein also disclosed is a system for producing a substance selected from the group consisting of dicarboxylic acid, benzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, and phthalic anhydride.

Abstract: The present invention provides: a fixed-bed shell-and-tube reactor, which can stably produce an aimed product for a long period when a solid particulate material such as a catalyst is packed and used for each substance; and its usage. The fixed-bed shell-and-tube reactor comprises a plurality of reaction tubes that are packed with a solid particulate material and arranged in parallel, wherein the solid particulate material is weighed so as to be uniform volume, and is packed in each reaction tube in a packing time of not shorter than 30 seconds per liter.

Abstract: In this disclosure, a system is described, comprising a shear device with at least one inlet and at least one outlet and a mixing vessel with at least one inlet and at least one outlet, wherein an inlet of the shear device is in fluid communication with an outlet of the mixing vessel. In certain embodiments, the shear device and the mixing vessel form a loop for fluid communication. Also disclosed herein is a method of high shear oxidation, comprising mixing an oxidant with a substrate to form a substrate-oxidant mixture and applying shear to the substrate-oxidant mixture to form a product. The product includes ethylene oxide, propylene oxide, terephthalic acid, phenol, acrylonitrile, maleic anhydride, phthalic anhydride, nitric acid, caprolactam, oxidized polyethylene, oxidized polypropylene, oxidized polyethylene copolymers, and oxidized polypropylene copolymers. Suitable oxidant includes air, oxygen, ozone, peroxide, organic peroxide, halogen, oxygen-containing gas, and halogen-containing gas.

Abstract: Catalyst systems for preparing phthalic anhydride by means of gas-phase oxidation of o-xylene and/or naphthalene, and a process for preparing phthalic anhydride using the catalyst systems

Abstract: A multimetal oxide of the formula I Aga-bMbV2Ox*cH2O,??I where M is a metal selected from the group consisting of Li, Na, K, Rb, Cs, Tl, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, Al, Fe, Co, Ni and/or Mo, a is from 0.3 to 1.9 and b is from 0 to 0.5, with the proviso that the difference (a-b) and c is from 0 to 20 and x is a number determined by the valence and amount of elements different from oxygen in the formula I, which has a crystal structure giving an X-ray powder diffraction pattern which displays reflections at the lattice spacings d of 15.23±0.6, 12.16±0.4, 10.68±0.3, 3.41±0.04, 3.09±0.04, 3.02±0.04, 2.36±0.04 and 1.80±0.04 ?. Precatalysts and catalysts produced therefrom for the partial oxidation of aromatic hydrocarbons are also provided.

Abstract: Processes comprising: (a) providing a reactant comprising a component selected from the group consisting of o-xylene, naphthalene and mixtures thereof, and a gas comprising oxygen; (b) reacting the reactant and the gas in a reaction system, in the presence of a catalyst, to form phthalic anhydride; wherein the reaction system comprises: (i) at least two reaction zones, each reaction zone cooled with a coolant; and (ii) an intermediate cooling zone disposed between a first of the at least two reaction zones and a second of the at least two reaction zones; and wherein the coolant entering the first of the at least two reaction zones has a temperature which is more than 20° C. higher than a temperature of the coolant entering the second of the at leas two reaction zones.

Abstract: The present invention relates to a catalyst for preparing phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, comprising at least three catalyst zones which have different compositions and, from the gas inlet side toward the gas outlet side, are referred to as first, second and third catalyst zone, the catalyst zones having in each case an active composition comprising TiO2, and the active composition content decreasing from the first catalyst zone disposed toward the gas inlet side to the third catalyst zone disposed toward the gas outlet side, with the proviso that (a) the first catalyst zone has an active composition content between about 7 and 12% by weight, (b) the second catalyst zone has an active composition content in the range between 6 and 11% by weight, the active composition content of the second catalyst zone being less than or equal to the active composition content of the first catalyst zone, and (c) the third catalyst zone has an active composition content in the rang

Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: Processes comprising: (a) providing a reactant comprising a component selected from the group consisting of o-xylene, naphthalene and mixtures thereof, and a gas comprising oxygen; (b) reacting the reactant and the gas in a reaction system, in the presence of a catalyst, to form phthalic anhydride; wherein the reaction system comprises: (i) at least two reaction zones, each reaction zone cooled with a coolant; and (ii) an intermediate cooling zone disposed between a first of the at least two reaction zones and a second of the at least two reaction zones; and wherein the coolant entering the first of the at least two reaction zones has a temperature which is more than 20° C. higher than a temperature of the coolant entering the second of the at leas two reaction zones.

Abstract: The present invention relates to a catalyst system for preparing carboxylic acids and/or carboxylic anhydrides which has at least three catalyst layers arranged one on top of the other in the reaction tube, with the proviso that the most inactive catalyst layer is preceded in the upstream direction by a more active catalyst layer. The invention further relates to a process for gas phase oxidation in which a gaseous stream which comprises one hydrocarbon and molecular oxygen is passed through a plurality of catalyst layers, the least active catalyst layer being upstream of a more active catalyst layer.

Abstract: The present invention relates to a catalyst, in particular for the preparation of phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, having an inert support and at least one layer which has been applied thereto and has a catalytically active composition comprising TiO2, characterized in that at least a portion of the TiO2 used has the following properties: (a) the BET surface area is more than 15 m2/g, (b) the primary crystal size is more than 210 ångstrøm. Also described is a preferred process for preparing such a catalyst, and the preferred use of the titanium dioxide used in accordance with the invention.

Abstract: The present invention relates to the use of a catalyst comprising at least one first catalyst zone located towards the gas inlet, a second catalyst zone located closer to the gas outlet and a third catalyst zone located even closer to or at the gas outlet for the preparation of phthalic anhydride by gas-phase oxidation of o-xylene and/or naphthalene, with the catalyst zones preferably each having an active composition comprising TiO2, characterized in that the catalyst activity of the first catalyst zone is higher than the catalyst activity of the second catalyst zone. Furthermore, a preferred process for the preparation of phthalic anhydride is described.

Abstract: The present invention relates to processes for improving or optimizing a catalyst for the preparation of phthalic anhydride by gas-phase oxidation of o-xylene and/or naphthalene, which comprises the following steps: a) provision of a starting catalyst (C) comprising at least one first catalyst zone located towards the gas inlet and a second catalyst zone located closer to the gas outlet, with the catalyst zones preferably each having an active composition comprising TiO2; b) replacement of part of the first catalyst zone by an upstream zone of a catalyst having a higher activity than the first catalyst zone in order to provide an improved catalyst. Furthermore, an improved catalyst obtainable by this process is described.

Abstract: A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene. In, in a main reactor, a gaseous mixture of o-xylene and an oxygenous gas is passed through at least two reaction zones whose temperature can be controlled independently, and converted to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, and the intermediate reaction product is introduced into a postreactor, wherein the temperature of the reaction zones in the main reactor is regulated in such a way that the concentration of unconverted o-xylene in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality.

Abstract: Multi-tubular reactors for fluid processing incorporate reactor tubes containing thermally conductive monolithic catalyst structures with relative dimensions and thermal expansion characteristics effective to establish both a non-interfering or slidably interfering fit between the monolith structures and the reactor tubes at selected monolith mounting temperatures, and geometries at reactor operating temperatures such that the operating gaps between tubes and monoliths under the conditions of reactor operation do not exceed about 250 ?m over tube sections where high heat flux to or from the monoliths is required.

Abstract: A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene, in which a gaseous mixture of o-xylene and an oxygenous gas is converted in a main reactor to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, the heat of reaction which arises in the main reactor being removed at least partly by indirect cooling with a heat carrier medium, and the intermediate reaction product being introduced into a postreactor. The concentration of unconverted o-xylene in the intermediate reaction product is at least 1% by weight, and the sum of the concentrations of phthalic anhydride underoxidation products in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality.