Abstract: A catalyst comprising palladium, a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina, the palladium content in the catalyst being in the range 0.01% to 2% by weight with respect to the total catalyst weight, at least 80% by weight of the palladium being distributed in a crust at the periphery of said support, the thickness of said crust being in the range 20 to 100 ?m, characterized in that said support is in the form of an extrudate and in that said support comprises a specific surface area in the range 165 to 250 m2/g.

Abstract: A promoted VPO catalyst for the oxidation of n-butane to maleic anhydride wherein the catalyst comprises the mixed oxides of vanadium and phosphorus, niobium and at least one of antimony and bismuth, wherein the catalyst may be produced in a process comprising impregnating a VPO catalyst with a metal source compound of niobium and a metal source compound of at least one of antimony and bismuth, to form a metal impregnated VPO catalyst, and then drying the metal impregnated VPO catalyst to form the promoted VPO catalyst.

Abstract: Apparatus for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a stream containing hydrocarbons having at least 4 carbon atoms per molecule, which includes a reactor with reaction tubes into which a solid-state catalyst over which the exothermic reaction of the stream with an oxygen-comprising gas stream takes place is introduced and one or more pumps and heat exchangers located outside the reactor and through which a heat transfer medium formed by a salt melt flows through the intermediate space in the reactor between the reaction tubes and takes up the heat of reaction, with the temperature of the melt being in the range from 350 to 480° C. The reaction tubes are made of a heat-resistant alloy steel which includes at least 0.5% by weight of chromium or at least 0.25% by weight of molybdenum or both.

Abstract: The invention relates to a catalyst molded body for preparing maleic anhydride by gas-phase oxidation of a hydrocarbon having at least four carbon atoms using a catalytically active composition contains vanadium, phosphorus and oxygen, where the shaped catalyst body has an essentially cylindrical body having a longitudinal axis, wherein the cylindrical body has at least two parallel internal holes which are essentially parallel to the cylinder axis of the body and go right through the body. The catalyst molded body has a large outer surface area, a lower pressure loss and sufficient mechanical stability.

Abstract: A catalyst for the gas phase oxidation of organic hydrocarbons comprises a multielement oxide which comprises at least one transition meal such as vanadium, wherein the catalyst has a charge transport activation energy Ec at a temperature of 375 to 425° C. of less than 0 kJ/mol. The catalyst serves for preparation of maleic anhydride.

Abstract: Embodiments of the present invention disclose improved micro-pore catalyst structures containing catalytic material comprised of mixed oxides of vanadium and phosphorus and using such improved micro-pore catalyst structures for the production of maleic anhydride.

Abstract: The invention relates to a shaped catalyst body for the catalytic conversion of organic and inorganic components in fixed-bed reactors, wherein the shaped catalyst body is formed as cylinder with a base, a cylinder surface, a cylinder axis and at least one continuous opening running parallel to the cylinder axis, and the base of the cylinder has at least four corners.

Abstract: A catalyst for the gas phase oxidation of organic hydrocarbons comprises a multielement oxide which comprises at least one transition meal such as vanadium, wherein the catalyst has a charge transport activation energy Ec at a temperature of 375 to 425° C. of less than 0 kJ/mol. The catalyst serves for preparation of maleic anhydride.

Abstract: An oxidation catalyst comprising vanadium, phosphorus, and oxygen having average vanadium valence less than about 4.10, and a method of preparing such catalyst, is provided. The catalyst has side crush strength of at least about 5 lbs. and improved yield of maleic anhydride from n-butane between about 1% and about 6% absolute. The catalyst is formed by exposing a conventional active VPO catalyst having average vanadium valence between about 4.10 and about 4.40 to an organic solvent having a dielectric constant between about 5 and about 55 under conditions that facilitate an oxidation-reduction reaction, reducing the valence of the vanadium below 4.10.

Abstract: A process for preparing a catalyst by selecting an active catalyst and contacting the active catalyst with one or more fluids containing an organic solvent or mixture of organic solvents. In one embodiment, each organic solvent has a dielectric constant within a range of about 5 to about 55 when measured at a temperature of 20° C. to 25° C. The catalyst thus prepared may be used in a process for preparing maleic anhydride.

Abstract: Embodiments of the present invention include improved shaped catalyst structures containing catalytic material comprised of mixed oxides of vanadium and phosphorus and using such shaped catalyst structures for the production of maleic anhydride.

Abstract: Embodiments of the present invention disclose improved micro-pore catalyst structures containing catalytic material comprised of mixed oxides of vanadium and phosphorus and using such improved micro-pore catalyst structures for the production of maleic 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: A process for preparing a catalyst by selecting an active catalyst and contacting the active catalyst with one or more fluids containing an organic solvent or mixture of organic solvents. In one embodiment, each organic solvent has a dielectric constant within a range of about 5 to about 55 when measured at a temperature of 20° C. to 25° C. The catalyst thus prepared may be used in a process for preparing maleic anhydride.

Abstract: A novel polynary metal oxide phosphate of the general formula I Ma(VO)(P2O7)b(PO4)c is described, in which M is one or more metals selected from V, Ti, Zr, Hf, Cr, Fe, Co, Ni, Ru, Rh, Pd, Cu, Zn, Cd, Hg, B, Be, Mg, Ca, Sr and Ba, a is from 1.5 to 2.5, b is from 0.5 to 1.5, c is from 0.5 to 1.5, having a crystal structure whose powder X-ray diffractogram is characterized by defined reflections. A preferred representative is Fe2VO(P2O7)(PO4). The metal oxide phosphates are suitable as gas phase oxidation catalysts, for example for preparing maleic anhydride from a hydrocarbon having at least four carbon atoms.

Abstract: A process is disclosed for the improvement of fluid bed vanadium phosphorus mixed oxide catalyst performance in the manufacture of maleic anhydride from butane, which process comprises impregnating the VPO catalyst powder with a phosphorus compound, such as an alkyl ester of orthophosphoric acid and then using this impregnated catalyst powder to provide phosphorus to the maleic anhydride producing catalyst.

Abstract: An improved process for the production of maleic anhydride by the catalytic oxidation of n-butane. Maleic anhydride is produced by reacting n-butane gas with oxygen gas or an oxygen-containing gas, in the presence of a vanadium phosphorus oxide catalyst. A trialkyl phosphite or trialkyl phosphate component is continuously added to the gases in an amount of from about 0.5 ppm to about 4 ppm by weight of elemental phosphorus in the trialkyl phosphate or trialkyl phosphite component. Heat is applied to the gases at a temperature of from about 400° C. to about 440° C. while maintaining a maximum temperature of gases present in the reaction of about 480° C. A simultaneous conversion of n-butane to maleic anhydride of about 84% or more and a conversion of n-butane to by-product acrylic acid of about 1.5% or less is achieved.

Abstract: An improved process for the production of maleic anhydride by the catalytic oxidation of n-butane. Maleic anhydride is produced by reacting n-butane gas with oxygen or an oxygen-containing gas, in the presence of a vanadium phosphorus oxide (VPO) catalyst. An improved yield and selectivity in the production of maleic anhydride is attained by the addition of a substantially pure carbon monoxide gas stream in the reactant feed stream. A process is given for the production of maleic anhydride by reacting a combination of gas streams in the presence of a VPO catalyst. The combination of gas streams comprises an n-butane gas stream, an oxygen or oxygen-containing gas stream, and a substantially pure carbon monoxide gas stream. The amount of carbon monoxide present in the combination of gas streams is from about 0.5 volume % to about 6 volume % based on the total volume of the combination of gas streams.

Abstract: The present invention relates to a process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon, which comprises feeding a hydrocarbon-comprising stream and a stream comprising oxygen or an oxygen source into a microchannel reactor and carrying out the reaction to form maleic anhydride in the explosive range in the microchannel reactor comprising the catalyst.

Abstract: An elongate, shaped particle having three protrusions each extending from and attached to a central position aligned along the central longitudinal axis of the particle, the cross-section of the particle occupying the area encompassed by the outer edges of six outer circles around a central circle minus the area occupied by three alternating outer circles, wherein each of the six outer circles is touching two neighbouring outer circles and wherein three alternating outer circles are equidistant to the central circle, have the same diameter, and may be attached to the central circle.

Abstract: A process for preparing a vanadium, phosphorus, and oxygen catalyst precursor for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon having at least four carbon atoms, which comprises (a) reacting vanadium pentoxide with from 102 to 110% strength phosphoric acid in the presence of a primary or secondary, noncyclic or cyclic, unbranched or branched, saturated alcohol having from 3 to 6 carbon atoms in a temperature range from 80 to 160° C.; (b) isolating the precipitate formed; (c) setting an organic carbon content of ?1.1% by weight in the isolated precipitate by heat treatment in a temperature range from 250 to 350° C., the heat-treated product, following the addition of 3.0% by weight of graphite, giving a powder X-ray diffraction diagram which in the 2? region features a ratio of the height of the peak of any pyrophosphate phase present at 28.5° to the height of the peak due to the graphite at 26.6° of ?0.

Abstract: A process for preparing a vanadium, phosphorus, and oxygen catalyst precursor for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon having at least four carbon atoms, by reacting vanadium pentoxide (I) in the presence of a primary or secondary, noncyclic or cyclic, unbranched or branched, saturated alcohol having from 3 to 6 carbon atoms (II) with a pentavalent or trivalent phosphorus compound (III) in a temperature range from 80 to 160° C. with stirring and subsequently filtering the resultant suspension, in which (a) the way in which the phosphorus compound (III) and the vanadium pentoxide (I) are combined in the presence of the alcohol (II), (b) the action of a stirring power of from 0.01 to 0.6 W/kg suspension, and/or (c) the filtration at a temperature from 65° C. to 160° C.

Abstract: Process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of hydrocarbons having at least four carbon atoms by means of oxygen-containing gases at from 350 to 500° C.

Abstract: Active vanadium/phosphorus mixed oxide catalyst for the conversion of non-aromatic hydrocarbons, e.g., n-butane, into maleic anhydride. The catalyst is prepared from the catalyst precursor, that is, prepared by the reaction of a source of vanadium in an organic medium in the presence of a phosphorus source. The organic medium is (a) isobutyl alcohol or a mixture of isobutyl alcohol and benzyl alcohol and (b) a polyol. The catalyst precurso is transformed into the active catalyst by an activation process that includes a heat treatment that includes applying a temperature of up to 600° C.

Abstract: In a process for purifying an organic solvent for the absorption of maleic anhydride from a gaseous mixture, in which the maleic anhydride is separated off from the solvent, a substream is taken from the solvent stream, this substream is distilled and returned to the solvent circuit, the proposed improvement comprises separating off a low-boiling fraction and a high-boiling fraction from the fraction consisting essentially of purified solvent and feeding the fraction consisting essentially of purified solvent back into the solvent stream.

Abstract: A process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of an n-butene-containing hydrocarbon stream by means of oxygen-containing gases in a shell-and-tube reactor having two successive reaction zones, where the first, feed-side reaction zone contains at least one catalyst which is suitable for the oxydehydrogenation of n-butenes to 1,3-butadiene and the second, product-side reaction zone contains at least one catalyst which is suitable for the oxidation of 1,3-butadiene to maleic anhydride, is carried out using a shell-and-tube reactor which has at least one heat transfer medium circuit in the region of the first, feed-side reaction zone and at least one further heat transfer medium circuit in the region of the second, product-side reaction zone.

Abstract: A catalyst used in a process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon having at least four carbon atoms by means of oxygen-containing gases comprises a catalytically active composition comprising vanadium, phosphorus and oxygen and has a essentially hollow cylindrical structure in which (a) the ratio of the height h to the diameter of the continuous hole d2 is not more than 1.5 and (b) the ratio of the geometric surface area Ageo to the geometric volume Vgeo is at least 2 mm−1.

Abstract: In a process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of hydrocarbons having at least four carbon atoms using oxygen-containing gases in the presence of a volatile phosphorus compound over a catalyst comprising vanadium, phosphorus and oxygen in a shell-and-tube reactor unit having at least two successive cooled reaction zones, the temperature of the first reaction zone is from 350 to 450° C. and the temperature of the second and further reaction zones is from 350 to 480° C. and the temperature difference between the hottest reaction zone and the coolest reaction zone is at least 2° C.

Abstract: A vanadium-, phosphorus- and oxygen-containing catalyst for the preparation of maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon of at least four carbon atoms has a phosphorus/vanadium ratio of from 0.9 to 1.5, comprises particles having a mean diameter of at least 2 mm and has a composition which, using CuK&agr; radiation (&lgr;=1.54·10−10 m), gives a powder X-ray diffraction pattern which, in the 2&thgr; range from 10° to 70°, has a signal/background ratio of ≦10 for all diffraction lines which are attributable to a vanadium- and phosphorus-containing phase. Said catalyst is prepared and is used for the preparation of maleic anhydride.

Abstract: A process for the preparation of maleic anhydride by heterogeneously catalyzed gas-phase oxidation in a reactor with feed for the reaction mixture at one end of the reactor and discharge of the product mixture at the opposite end of the reactor, and with devices for dissipating the heat of reaction which are arranged in the reactor interior and through which a heat-exchange medium flows and which are designed as heat-exchanger plates.

Abstract: Disclosed is a process for the production of maleic anhydride, which comprises: reacting a hydrocarbon with an oxygen-containing gas in the presence of a catalyst; recovering maleic anhydride from the reaction gas; recovering unreacted hydrocarbon from the remaining gas; and returning the hydrocarbon thus recovered to the reactor for re-use, wherein said reaction is effected under the conditions such that the hydrocarbon concentration X (vol %) and oxygen concentration Y (vol) in all the gases to be fed into the reactor, the hydrocarbon conversion Z (t) in the reactor and the oxygen concentration W (vol %) in all the effluent gases from the reactor satisfy the following relationships: Y≧20, X+Y≦70, 1≦Y/X≦5, and 20(Y−10)/X≦Z≦25Y/X or 2≦W≦10.

Abstract: This invention is directed towards an improved process for the selective gas phase oxidation of a organic reactant using a metal oxide redox catalyst, wherein the organic reactant and air feeds are at a substantially continuous level, the improvement comprising adding a fluctuating flow of oxygen at alternating relatively high and relatively low levels. The invention also teaches means by which a gas may be provided to a reaction process on a fluctuating basis.

Abstract: Disclosed herein are compositions comprising organic anhydrides having a reduced tendency to discolor with time, even when held at elevated temperatures for extended times. The compositions are produced by mixing at least one acid halide and various derivatives of hydroxy carboxylic acids with an anhydride to form a homogenous solution. Also disclosed is a process for preparing the compositions.

Abstract: A catalyst used in a process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of a hydrocarbon having at least four carbon atoms by means of oxygen-containing gases comprises a catalytically active composition comprising vanadium, phosphorus and oxygen and has a essentially hollow cylindrical structure in which (a) the ratio of the height h to the diameter of the continuous hole d2 is not more than 1.5 and (b) the ratio of the geometric surface area Ageo to the geometric volume Vgeo is at least 2 mm−1.

Abstract: In a process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of hydrocarbons having at least four carbon atoms using oxygen-containing gases in the presence of a volatile phosphorus compound over a catalyst comprising vanadium, phosphorus and oxygen in a shell-and-tube reactor unit having at least two successive cooled reaction zones, the temperature of the first reaction zone is from 350 to 450° C. and the temperature of the second and further reaction zones is from 350 to 480° C. and the temperature difference between the hottest reaction zone and the coolest reaction zone is at least 2° C.

Abstract: Disclosed is a process for the preparation of maleic anhydride which comprises subjecting an aliphatic hydrocarbon having four or more carbon atoms to gas phase oxidation reaction in the presence of a catalyst, wherein supposing that the function of reaction product gas composition is FL and the function of temperature and pressure of reaction product gas is FR, the safety index F satisfies the following relationship (1): F=FL−FR>0  (1) According to the present invention, it is possible that the loss of unreacted hydrocarbon and maleic anhydride as reaction product due to non-catalytic oxidation reaction is prevented while effecting the reaction in a stable manner, whereby the yield of maleic anhydride can be kept maximum while assuring safety.

Abstract: A process for selectively oxidizing an organic molecule by reacting said organic molecule and oxygen in the presence of a selective oxidation catalyst supported on a mesh-like structure.

Abstract: This invention relates to catalysts useful in the vapor phase oxidation of hydrocarbons, such as 1,3-butadiene to furan and maleic anhydride. The catalysts comprise vanadium oxides, vanadium phosphorus oxides or vanadium antimony oxides incorporated in a matrix comprising oxides or oxyhydroxides of silicon, titanium, tantalum and/or niobium derived using sol-gel chemistry, optionally in the presence of an organic directing agent, such as dodecylamine.

Abstract: Disclosed is a process for the production of maleic anhydride, which comprises: reacting a hydrocarbon with an oxygen-containing gas in the presence of a catalyst; recovering maleic anhydride from the reaction gas; recovering unreacted hydrocarbon from the remaining gas; and returning the hydrocarbon thus recovered to the reactor for re-use, wherein said reaction is effected under the conditions such that the hydrocarbon concentration X (vol %) and oxygen concentration Y (vol %) in all the gases to be fed into the reactor, the hydrocarbon conversion Z (%) in the reactor and the oxygen concentration W (vol %) in all the effluent gases from the reactor satisfy the following relationships: Y≧20, X+Y≦70, 1≦Y/X≦5, and 20(Y−10)/X≦Z≦25Y/X or 2≦W≦10.

Abstract: Improved methods and apparatus for the preparation of maleic anhydride by reacting a hydrocarbon having at least four carbon atoms in a straight chain with molecular oxygen in a catalytic reactor, the reactor comprising a fixed catalyst bed having active sites comprising a vanadium-phosphorus-oxygen catalyst for the catalytic oxidation of the hydrocarbon to maleic anhydride, said process further comprising the continuous or intermittent introduction of a phosphorus-containing agent to the reactor. The introduction of the phosphorus-containing agent into the maleic anhydride production system is controlled so to provide for a more uniform distribution of the phosphorus-containing agent throughout the reactor. The methods of the invention are effective to reduce deposits of the phosphorus-containing agent or decomposition products of the phosphorus-containing agent on reactor surfaces other than the catalytic bed thereby decreasing reactor maintenance and increasing reactor lifetime.

Abstract: An exothermic oxidation process wherein a rotating bed containing a variable oxidation state material is cycled through a succession of stages including an oxidative regeneration stage including a step wherein an oxidising fluid is passed through the bed, and a reaction stage wherein feedstock is passed through the bed, whereby said feedstock is oxidised to give products stream with the concurrent reduction of the convertible material to its lower oxidation state. The process can further include a stage wherein cooling fluid is passed through the bed.

Abstract: N-butane and molecular oxygen are reacted in a first reactor to form maleic anhydride, the produced maleic anhydride is scrubbed to separate maleic anhydride values, n-butane is added to the scrubber gases and these are reacted in a second reactor to form additional maleic anhydride.

Abstract: In the production of maleic anhydride by the contact of a raw material gas containing an aliphatic hydrocarbon of not less than 4 carbon atoms and molecular oxygen with a vanadium-phosphorus oxide catalyst, the raw material gas is caused to allow presence therein of nitrogen and an inert gas possessing a thermal conductivity of not less than 800 (10−4Wm−1K−1) at 700 K. The gas formed by the oxidation reaction is allowed to contact an absorbent to effect recovery of the produced maleic anhydride. Maleic anhydride is recovered from produced oxidation reaction gas separated from a remained oxidation reaction gas after recovering maleic anhydride, and the saparated inert gas is circulated to the reaction zone. The catalyst capable of producing maleic anhydride with a high yield can be obtained by activating the vanadium-phosphorus oxide catalyst with the gas composition containing an inert gas possessing a thermal conductivity of not less than 800 (10−4Wm−1K−1) at 700 K.

Abstract: A process for producing maleic anhydride is described, which comprises (i) reacting a hydrocarbon with oxygen in a vapor phase in the presence of a catalyst to yield a reaction mixture gas containing maleic anhydride, (ii) bringing the reaction mixture gas into contact with an organic solvent to collect the maleic anhydride in the organic solvent, (iii) separating at least part of the maleic anhydride from the organic solvent, (iv) washing with an aqueous alkali solution at least part of the organic solvent from which maleic anhydride has been separated, and (v) reusing the resultant washed organic solvent and the residual organic solvent for contact with the reaction mixture gas.

Abstract: There is a process for producing coated catalysts for the gas-phase oxidation of C.sub.4 hydrocarbons to maleic anhydride. A vanadyl phosphate catalyst precursor is prepared having a V/P ratio of from 1:0.5 to 1:2 and a mean vanadium oxidation state of from 3.9 to 4.5. The vanadyl phosphate precursor is then calcined by heating for a several hours at a temperature of from 200.degree. C. to 500.degree. C. before being applied, in an aqueous suspension to the support bodies. Furthermore, there is the use of these coated catalysts in processes for the gas-phase oxidation of saturated or unsaturated C.sub.4 -hydrocarbons to maleic anhydride.

Abstract: Improved methods and apparatus for manufacture of maleic anhydride by catalytic oxidation of n-butane or other hydrocarbon having four carbon atoms in a straight chain over a fixed catalyst bed comprising a phosphorus vanadium oxide catalyst. Movement of catalyst bodies with respect to each other and with respect to the walls of the reaction chamber is restrained so as to prevent the catalyst bodies from abrading against each other or the reactor chamber walls in a manner that would cause formation of catalyst fines. Methods and apparatus are also provided for removal of fines from a fixed catalyst bed. The methods of the invention are effective to prevent loss of catalyst from a tubular reactor, and to control degradation of solvent absorbent in a process in which maleic anhydride is separated from the reaction gas by absorption into such a solvent.

Abstract: An improved process for the manufacture of maleic anhydride by catalytic oxidation of a nonaromatic hydrocarbon having at least four carbon atoms in a straight chain, in which a gas containing oxygen and hydrocarbon is passed through a fixed catalyst bed in a tubular reactor. The activity of the catalyst bed is graded in such manner that the reactor can be operated at an initial (feed gas) hydrocarbon concentration of over 1.5% by volume, an integrated average temperature difference between gas and cooling fluid of at least about 15.degree. C. over that portion of the bed in which the gas temperature exceeds the cooling fluid temperature, and a productivity of at least about 5.0 lbs. maleic anhydride per hour, without the temperature difference between the gas and the cooling fluid exceeding 80.degree. C. at any point in the catalyst bed during the course of the reaction.

Abstract: Petrochemicals are produced by the vapor phase reaction of a hydrocarbon with air in the presence of a suitable catalyst. The petrochemical product is removed from the product gas stream, and part or all of the remaining gas stream is passed through a bed of hydrophobic adsorbent, which adsorbs mainly the unreacted hydrocarbon from the gas stream without adsorbing water vapor. The adsorbed hydrocarbon is purged from the bed with air, and the air-hydrocarbon mixture is recycled to the partial oxidation reactor.

Abstract: The invention relates to a heterogeneous vanadium-phosphorus oxide catalyst system for the selective oxidation of hydrocarbons, which may or may not be saturated, comprising a support based on one or more metal oxides, and vanadium-phosphorus oxide in an amount of from 0.01 to 45 wt. %, based on the weight of the catalyst and calculated as (VO).sub.2 P.sub.2 O.sub.7, to a process for the selective oxidation of an organic compound in the presence of a vanadium-phosphorus oxide catalyst, which process comprises an oxidation and a reduction phase, wherein a hydrocarbon is contacted with said catalyst in the reduction phase and in oxidized or non-oxidized form is adsorbed to the catalyst, whereafter the thus loaded catalyst is brought into the oxidation phase, the desired product is formed in the presence of gaseous oxygen and subsequently separated.

Abstract: A vanadium-phosphorus oxide having an X-ray diffraction spectrum (Cu--K.alpha.) showing main peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 18.5.degree., 23.0.degree., 28.4.degree., 29.9.degree., and 43.1.degree. and having the intensity ratio of the peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 23.0.degree. and 28.4.degree. in the following range0.3.ltoreq.I (23.0)/I (28.4).ltoreq.0.7wherein I (23.0) and I (28.4) respectively represent the intensities of the peaks of the diffraction angle 2.theta.(.+-.0.2.degree.) at 23.0.degree. and 28.4.degree., a method for the production of the oxide, a catalyst for use in a vapor phase oxidation formed of the oxide, and a method for the partial vapor phase oxidation of a hydrocarbon.