DE112009000404T5 - Phase-enriched MoVTeNb mixed oxide catalyst and process for its preparation - Google Patents

Abstract

A process for preparing a metal oxide catalyst material comprising a composite oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), said process comprising the steps of:
(i) subjecting a catalyst precursor mixture comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), a calcination treatment in an oxygen-containing atmosphere at a temperature of 150 to 400 ° C, whereby calcined catalyst material is produced,
(ii) subjecting the calcined catalyst material to a treatment at a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase, whereby a catalyst material comprising a mixed oxide comprising molybdenum (Mo), vanadium (V), Tellurium (Te) and niobium (Nb) is produced.

Description

Field of the invention

The The present invention relates to a metal oxide catalyst (a material) and process for the preparation thereof and its use in the oxidation of hydrocarbons. More specifically, the present invention comprises a catalyst (a material) comprising Oxides of Mo, V, Te and Nb, where the catalyst is strong in M1 phase enriched and its use in the oxidation of hydrocarbons z. As unsaturated carboxylic acids such as acrylic acid and methacrylic acid.

State of the art

Multimetal oxides based on molybdenum, vanadium, tellurium, and niobium with a nominal composition of about Mo ₁ V _0.3 Te _0.23 Nb _0.125 O _x are out US 5,380,933 are known and to achieve excellent performance as a catalyst in the oxidation of alkanes, especially in the conversion of propane to acrylic acid. Despite their considerable chemical complexity, such materials normally consist essentially of two orthorhombic phases, known as M1 and M2 [ T. Ushikubo, K. Oshima, A. Kayou and M. Hatano, Studies in Surface Science and Catalysis 112 (1997) 473 ]. Minority phases such as (Mo _0.93 V _0.07 ) ₅ O ₁₄ , MoO ₃ and TeMo ₅ O ₁₆ [ M. Baca, A. Pigamo, J.-L. Dubois and JMM Millet, Topics in Catalysis 23 (2003) 39, JM Lopez Nieto, P. Botella, B. Solsona and JM Oliver, Catalysis Today 81 (2003) 87 ] can also be formed depending on the manufacturing process and the activation method used. In the M1 phase (ICSD 55097 [Inorganic Crystal Structure Database, FIZ Karlsruhe, Germany]), corner-sharing MO ₆ (M = Mo, V) octahedra are arranged to form 6- and 7-membered rings, provide partial TeO units with space [ P. DeSanto, DJ Buttrey, RK Grasselli, CG Lugmair, AF Volpe, BH Toby and T. Vogt, Journal of Crystallography 219 (2004) 152 . JMM Millet, H. Roussel, A. Pigamo, JL Dubois and JC Jumas, Applied Catalysis A: General 232 (2002) 77 . H. Tsuji, K. Oshima and Y. Koyasu, Chemistry of Materials 15 (2003) 2112 . H. Murayama, D. Vitry, W. Ueda, G. Fuchs, M. Anne and JL Dubois, Applied Catalysis A: General 318 (2007) 137 ]. It has been postulated that niobium exists exclusively in the center of a pentagonal MO ₇ bipyramidal unit that forms edges with the surrounding octahedra [ P. DeSanto, et al. ibid .; H. Murayama, et al., Ibid. ]. The (001) planes are congruently stacked along the [001] direction, forming a bronze-like structure similar to the structure of Cs _0.7 (Nb _2.7 W _2.3 ) O ₁₄ (ICSD 67974 [Inorganic Crystal Structure Database, Fachinformationszentrum (FIZ) Karlsruhe, Germany; M. Lundberg and M. Sundberg, Ultramicroscopy 52 (1993) 429 ]). The M2 phase differs from the M1 in the absence of the pentagonal bipyramidal unit and the 7-membered ring [ DeSanto, et al., Ibid. ]. The formulas of the refined unit cells have been determined to be Mo _7.8 V _1.2 NbTe _0.937 O _28.9 for M1 and Mo _4.31 V _1.36 Te _1.81 Nb _0.33 O _19.81 for M2 [ DeSanto, et al., Ibid. ].

The selective oxidation of propane has been attributed to the presence of the M1 phase. The M2 phase alone does not activate propane but selectively oxidizes the propylene intermediate. Although correlations between phase composition and catalytic properties are still vividly debated, it is generally accepted that the high selectivity for acrylic acid is linked to the presence of the M1 phase [ M. Barca et al., Topics in Catalysis, and W. Ueda, D. Vitry and T. Katou, Catalysis Today 99 (2005) 43 ]. To investigate the mechanism underlying this activity, the synthesis of phase-pure M1 catalysts in large scale is a prerequisite.

Usually are two different manufacturing processes known as "slurry" processes or "hydrothermal treatment" has been used, to synthesize MoVTeNb mixed oxide catalysts.

According to the z. B. in the WO 2006/008177 Ammonium heptamolybdate, ammonium metavanadate and telluric acid are dissolved in water followed by the addition of ammonium niobium oxalate, thereby precipitating a slurry, which is then spray-dried. After a calcination step in air at about 275 ° C, the final activation of the catalyst is carried out essentially in the absence of oxygen at much higher temperatures of typically 600 to 650 ° C. This preparation process usually yields catalysts composed of several phases, including a mixture of M1 and M2 phases [ Beato, A. Blume, F. Girgsdies, RE Jentoft, R. Schlögl, O. Timpe, A. Trunschke, G. Weinberg, Q. Basher, FA Hamid, SBA Hamid, E. Omar and L. Mohd Salim, Applied Catalysis A: General 307 (2006) 137 and US 5,422,328 ]. Purification by aftertreatment with nitric acid [ H. Hibst, F. Rosowski and G. Cox, Catalysis Today 111 (2006) 234 ] or H ₂ O ₂ [ M. Baca and JMM Millet, Applied Catalysis A: General 279 (2005) 67 ] gives excess Pha sen-enriched M1 catalysts. However, these post-treatments are considered cumbersome and do not always result in a phase-pure material or change the chemical composition of the M1 phase.

The alternative hydrothermal synthesis route for MoVTeNb oxide catalysts is z. B. from W. Ueda, D. Vitry, T. Kato, N. Watanabe and Y. Endo, Research an Chemical Intermediates 32 (2006) 217 been described. According to Ueda, MoVTeNb oxide is hydrothermally synthesized by dissolving (NH ₄ ) ₆ Mo ₇ O ₂₄ and telluric acid in water and adding solutions of VoSO ₄ and niobium oxalate. The resulting slurry is stirred at 80 ° C before being placed in an autoclave which is heated at 175 ° C for 48 hours. After drying the obtained dark blue powder, the catalysts were calcined at 500 to 600 ° C for 2 hours before the catalytic tests under nitrogen flow. In particular, Ueda evaluates the catalytic properties of the orthorhombic Mo ₁ V _0.25 Te _0.11 Nb _0.12 O _x and finds low conversion and average selectivity values of 33% C ₃ H ₈ conversion and 62% acrylic acid selectivity, respectively.

In a second publication, Ueda [ W. Ueda, D. Vitry, Y. Morikawa and JL Dubois, Applied Catalysis A: General 251 (2003) 411 ] orthorhombic MoVTeNb mixed oxides also by using a synthesis temperature of 448K (175 ° C) and a 48 hour synthesis time. Several other authors performed hydrothermal synthesis under similar conditions in a Teflon-lined stainless steel autoclave using different metal-containing compounds and various metal stoichiometries [ P. Botella, B. Solsona, A. Martinez-Arias, JM López Nieto, Catalysis Letters 74 (2001) 149 ; P. Botella, JM López Nieto, B. Solsona, A. Mifsud and F. Márquez, Journal of Catalysis 209 (2002) 445 ; Botella, E. Garcia-González, J. López Nieto and Y. Moreno, Catalysis Today 99 (2005) 51 ; F. Ivars, P. Botella, A. Dejoz, JM López Nieto, P. Concepción and MI Vazquez, Topics in Catalysis 38 (2006) 59 ]. After heat treatment of the hydrothermally produced precursors for 2 hours at 600 ° C in nitrogen, they usually received M1 / M2 phase mixtures. From F. Ivars et al., Ibid. , it appears that M1 is a major phase with a nominal metal stoichiometry of Mo / V / Te / Nb = 1 / 0.2 / 0.17 / 0.17 and molar oxalate / molybdenum ratios ranging between 0.2 and 0.6 were obtained. The so-synthesized metal stoichiometry of materials that appeared to contain higher amounts of the M1 phase corresponded to Mo / V / Te / Nb = 1 / 0.20-0.27 / 0.19-0.22 / 0.19-0, 21st

The Literature published regarding hydrothermal synthesis was concerned with the production of rather small amounts of catalytic Material. Attempts by the present inventors to hydrothermal synthesis to ascend on amounts of catalyst greater than 5 g to suggest that this is having difficulties in particular in terms of the reproducibility of the results.

Other structurally related NoVNbTe oxide catalysts and their use in the production of acrylic acid from propane are disclosed in US Pat EP 0 608 838 A2 . US Pat. No. 6,432,870 B1 . US 6,734,136 B2 . US 6,610,639 B2 . EP 1 346 766 . US 6,060,419 . US Pat. No. 6,426,433 B1 and US 6,541,664 B1 ,

It It is an object of the present invention to provide a process for the preparation to provide a MoVTeNb mixed oxide catalyst, which in M1 phase is greatly enriched.

It Another object of the present invention is a method to provide for the production of MoVTeNb mixed oxide catalysts, the greater the sales and / or the larger one Selectivity in the oxidation of hydrocarbons, in particular the oxidation of propane to acrylic acid show.

It Another object of the present invention is a method to provide for the production of MoVTeNb mixed oxide catalysts, that the production of larger amounts of catalyst allowed and preferred for the production of industrially relevant Quantities is suitable.

It Another object of the present invention is to provide a stable MoVTeNb mixed oxide catalyst to provide a larger Turnover and / or greater selectivity in the oxidation of hydrocarbons, especially the oxidation from propane to acrylic acid, shows.

It Another object of the present invention is a method for the oxidation of hydrocarbons using such catalysts to provide, in particular for the oxidation of alkanes such as propane to unsaturated carboxylic acids or to ammoxidation from propane or propylene to acrylonitrile.

Summary of the invention

• (I) Ein Verfahren zur Herstellung eines Metalloxidkatalysatormaterials, umfassend ein Mischoxid, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), wobei das Verfahren folgende Schritte umfasst:
• (i) Unterwerfen einer Katalysator-Precursor-Mischung, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), einer Calcinierungsbehandlung in einer sauerstoffhaltigen Atmosphäre bei einer Temperatur von 150 bis 400°C, wodurch ein calciniertes Katalysatormaterial hergestellt wird,
• (ii) Unterwerfen des calcinierten Katalysatormaterials einer Behandlung bei einem Druck von mindestens 10 MPa und einer Temperatur von mindestens 400°C in Gegenwart einer inerten fluiden Phase, wodurch ein Katalysatormaterial, umfassend ein Mischoxid, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), hergestellt wird;
• (II).1) ein Metalloxidkatalysatormaterial, umfassend ein Mischmetalloxid, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), wobei das Metalloxidkatalysatormaterial einen Kristallinitätsgrad von mindestens 80 Gew.-% und einen Gehalt an M1-Phase in einer Menge von mindestens 85 Gew.-%, bezogen auf die Gesamtmenge an kristalliner Metalloxidphase, aufweist, und erhältlich ist durch das obige Verfahren und bevorzugt eine mittlere Zusammensetzung aufweist, die innerhalb der durch die allgemeine Formel (I) definierten Bereiche liegt: MoV_aTe_bNb_cZ_dO_x (I)worin a = 0,15–0,50, b = 0,02–0,45, insbesondere 0,05–0,40, c = 0,05–0,45, d ≤ 0,05 und x die molare Zahl von Sauerstoff ist, der an die Metallatome, die in diesem Mischmetalloxid vorliegen, gebunden ist, welche aus der relativen Menge und Valenz der Metallelemente folgt, und Z zumindest ein Element ist, ausgewählt aus Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pd und Bi, sowie
• 2) ein Metalloxidkatalysatormaterial, umfassend ein Mischoxid, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), wobei das Metalloxidkatalysatormaterial einen Kristallinitätsgrad von mindestens 80 Gew.-% aufweist und M1-Phase in einer Menge von mindestens 85 Gew.-% umfasst, bezogen auf die Gesamtmenge an kristalliner Metalloxidkatalysatorphase, und eine mittlere Zusammensetzung innerhalb der durch die folgende Formel (II) definierten Bereiche aufweist: MoV_aTe_bNb_cZ_dO_x (II)worin a = 0,28–0,40, bevorzugt 0,29–0,38, insbesondere 0,30–0,36, b = 0,03–0,30, insbesondere 0,05–0,25, c = 0,05–0,20 und d und x wie oben definiert sind;
• III. ein Verfahren zur Herstellung eines oxidierten Kohlenwasserstoffes aus einem Kohlenwasserstoff, welches umfasst: Unterwerfen des Kohlenwasserstoffs einer katalytischen Dampfphasenoxidationsreaktion in Gegenwart von Sauerstoff und eines Katalysators, umfassend ein Metalloxidkatalysatormaterial, wie oben definiert, bevorzugt ein Verfahren, worin der Kohlenwasserstoff ein Alkan ist und der oxidierte Kohlenwasserstoff eine ungesättigte Carbonsäure ist; und
• IV. ein Verfahren zur Erhöhung des Gehaltes an M1-Phase in einem calcinierten Metalloxidkatalysator, umfassend ein Mischoxid, umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb), das den folgenden Schritt umfasst: Unterwerfen des calcinierten Metalloxidkatalysators einer Behandlung bei einem Druck von mindestens 10 MPa und einer Temperatur von mindestens 400°C in Gegenwart einer inerten fluiden Phase, was vorteilhafterweise bei der Regeneration dieser calcinierten Katalysatoren engesetzt werden kann.

The present invention relates to:

• (I) A process for producing a metal oxide catalyst material comprising a composite oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), said process comprising the steps of:
• (i) subjecting a catalyst precursor mixture comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), a calcination treatment in an oxygen-containing atmosphere at a temperature of 150 to 400 ° C, whereby calcined catalyst material is produced,
• (ii) subjecting the calcined catalyst material to a treatment at a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase, whereby a catalyst material comprising a mixed oxide comprising molybdenum (Mo), vanadium (V), Tellurium (Te) and niobium (Nb);
• (II) .1) a metal oxide catalyst material comprising a mixed metal oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), the metal oxide catalyst material having a degree of crystallinity of at least 80% by weight and a content of M1 phase in an amount of at least 85% by weight, based on the total amount of crystalline metal oxide phase, obtainable by the above process and preferably having an average composition within the ranges defined by general formula (I) lies: MoV _a Te _b Nb _c Z _d O _x (I) where a = 0.15-0.50, b = 0.02-0.45, especially 0.05-0.40, c = 0.05-0.45, d ≤ 0.05, and x is the molar number of oxygen bound to the metal atoms present in this mixed metal oxide, which follows from the relative amount and valency of the metal elements, and Z is at least one element selected from Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pd and Bi such as
• 2) a metal oxide catalyst material comprising a mixed oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), wherein the metal oxide catalyst material has a degree of crystallinity of at least 80% by weight and M1 phase in an amount of at least 85% by weight, based on the total amount of crystalline metal oxide catalyst phase, and having an average composition within the ranges defined by the following formula (II): MoV _a Te _b Nb _c Z _d O _x (II) where a = 0.28-0.40, preferably 0.29-0.38, in particular 0.30-0.36, b = 0.03-0.30, in particular 0.05-0.25, c = 0.05-0.20 and d and x are as defined above;
• III. a process for producing an oxidized hydrocarbon from a hydrocarbon, which comprises subjecting the hydrocarbon to a vapor phase catalytic oxidation reaction in the presence of oxygen and a catalyst comprising a metal oxide catalyst material as defined above, preferably a process wherein the hydrocarbon is an alkane and the oxidized hydrocarbon an unsaturated carboxylic acid; and
• IV. A process for increasing the content of M1 phase in a calcined metal oxide catalyst comprising a composite oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), comprising the step of: subjecting calcined metal oxide catalyst of a treatment at a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase, which can be advantageously used in the regeneration of these calcined catalysts.

Description of the figures

1 Figure 5 shows a SEM image of a catalyst sample (MoVTeNbO _x ) treated at 500 ° C (773 K) in superheated water prior to a final activation treatment according to Example 1.

2 shows an SEM image of the catalyst sample according to 1 after the final activation treatment.

3 Figure 9 shows XRD diagrams [(a) to (c)] of samples taken at different stages of production of MoVTeNbO _x according to Example 1 and an M1 reference material [(d)].

Detailed description the invention

in the The following also includes the use of "comprising" more restrictive embodiments, in which "comprising" by "essentially consisting of "or" consisting of "replaced becomes. In addition, the explicit will be disclosed here below Disclosing a broader quantitative range of values (e.g. A-d) together with an included (preferred) narrower range (eg b-c) also the two possible ones Subareas that are located within the total area on one of the lying on both sides of the narrower area. Therefore, within this wider quantitative range of values (eg a-d) more Embodiments through all areas (eg a-b, a-c, b-d or c-d), which by combining any upper limit or lower limit thereof specially defined broader quantitative range with the lower limit or the upper limit of any explicitly defined and included (preferred) narrower range can be formed.

I. Catalyst Preparation Process

According to the becomes first step (i) of the claimed manufacturing process a catalyst precursor mixture comprising at least the four Elements molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb) and optionally other catalyst metal elements, as defined below Z (hereinafter also abbreviated to "catalyst metals"), a calcination treatment in an oxygen-containing atmosphere (Air or a synthetic oxygen-containing atmosphere) subjected to a temperature of 150 to 400 ° C, thereby a calcined catalyst precursor is prepared.

The Catalyst precursor mixture used in the first step of the claimed Method to be calcined, after each well-known Procedures are obtained.

Under "Source material" for the catalyst precursor mixture we mean chemical compounds, the catalyst metals include and in the calcination treatment can be converted into metal oxides or already contain such oxides (the term "can be converted "do not exclude that this transformation already at least partially at an earlier date takes place, for. B. during drying at higher Temperature). The starting material is preferably selected from salts of the catalyst metals, metal-containing acids, in particular oxo acids, organometallic compounds, organic Metal complexes and metal oxides. More preferably, it is selected from organic salts and (oxo) acids. It is possible, to prepare the catalyst precursor mixture by the combination from as many metal-containing starting materials as metals in should be included in the final catalyst, or by adding at least one starting material which is more than contains one of these metals.

• (a) Herstellen einer Lösung oder Dispersion aus Ausgangsmaterialien (z. B. Salzen und/oder Säuren), umfassend Molybdän (Mo), Vanadium (V), Tellur (Te) und Niob (Nb) und optional mindestens ein weiteres Metall, das zu dem Katalysator zugegeben werden soll, wie das unten definierte Element Z, in einem Lösungsmittel,
• (b) optionales Ausfällen gelöster Ausgangsmaterialien dieser Metalle,
• (c) Entfernen des Lösungsmittels aus der Lösung, Dispersion oder optional dem Niederschlag, wodurch eine feste Mischung gebildet wird, und
• (d) Trocknen dieser festen Mischung, wodurch eine Katalysator-Precursor-Mischung gebildet wird.

The catalyst precursor mixture is preferably prepared in a wet mixing process, which preferably comprises the following steps:

• (a) preparing a solution or dispersion of starting materials (eg, salts and / or acids) comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), and optionally at least one other metal to be added to the catalyst, such as element Z defined below, in a solvent,
• (b) optional precipitation of dissolved starting materials of these metals,
• (c) removing the solvent from the solution, dispersion or optionally the precipitate to form a solid mixture, and
• (d) drying this solid mixture to form a catalyst precursor mixture.

The Steps (b), (c) and (d) may be consecutively or simultaneously be performed as in a preferred embodiment of the present invention (spray-drying).

Around Solutions or dispersions containing the catalyst metals contain, are usually suitable Starting materials in predetermined proportions in a suitable Solvent dissolved or dispersed if necessary under heating, and combined.

The subsequent isolation of a dry catalyst precursor mixture can be effected in a usual way, e.g. B. by Filtration, evaporation to dryness (eg rotary evaporation), spray-drying, Freeze-drying, drying at room temperature and / or vacuum drying.

Solvents that can be used in the preparation of the catalyst precursor mixture are not particularly limited, and preferred solvents include water, alcohols, preferably Me ethanol, ethanol, propanol and butanol, diols such as ethylene glycol or propylene glycol, and other polar solvents. Water is more preferable. Further, any suitable mixture of the above solvents may be used.

Suitable starting materials (metal sources) for Mo, V, Te and Nb oxides are, for. For example, those in US 5,380,933 (Column 3, lines 27-57) and / or US 6,710,207 (Col. 8, lines 12-30) and include salts and acids (usually oxo acids) of the desired metal elements. The salts are selected so that after calcination only metal elements and oxygen remain in the calcined catalyst precursor since all other components are volatile or volatilized by decomposition or oxidation. For this reason, the use of ammonium salts of the metal elements (or the corresponding oxo acid), organic salts such as oxalates, alkoxides or acetylacetonates, organic metal complexes or organometallic compounds is preferred. Moreover, the selected salts and acids are preferably soluble or at least dispersible in the selected solvent, such as water. In one embodiment, the water solubility of the starting salt or the starting acid is at least 0.1 moles of metal per 1 liter of water at 373 K (100 ° C). Suitable starting salts and acids include, for. Ammonium para- or heptamolybdate, molybdenum oxalate, ammonium metavanadate, vanadium oxalate, telluric acid and ammonium niobium oxalate.

According to one Embodiment will be a solution of the V source (eg an aqueous ammonium metavanadate solution) and a solution of the Te source (eg, an aqueous Solution of telluric acid) to a solution of Mo source (eg, an aqueous solution of ammonium heptamolybdate) added, preferably after heating the Mo solution, followed by the addition of the solution of an Nb source (e.g. an aqueous solution of ammonium niobium oxalate).

According to one Another preferred embodiment is the dry one Catalyst precursor mixture prepared by spray drying a clear aqueous solution made from Molybdenum oxalate, telluric acid, vanadium oxalate and Ammonium niobium. If spray-drying is used, the drying temperatures are in the range of more than 100 to 250 ° C, z. B. 150 to 220 ° C, preferably, especially when the catalyst precursor mixture of aqueous solutions or dispersions was made.

It it is preferred that the drying process does not remove any remaining Moisture removed in the material to be calcined. typically, the drying process (eg spray drying) is terminated when no longer agglomerate the particles to be calcined. excessive Drying should be avoided to maintain residual moisture which is believed to be responsible for the transport phenomenon is cheap. Excessive drying occurs when the dried particles begin to dust.

• (a) Lösen oder Dispergieren von Ausgangsmaterialien, enthaltend die Katalysatormetalle, wenn erforderlich unter Erwärmen,
• (b) Kombinieren, optional unter Erwärmen, der resultierenden Lösungen) und/oder Dispersion(en) mit einer wässrigen Mischung, enthaltend die Katalysatormetalle in dem gewünschten Anteil für das Katalysatorendmaterial,
• (c) Erwärmen der wässrigen Mischung bei erhöhtem Druck, wodurch ein festes Material gebildet wird,
• (d) Sammeln und Trocknen des festen Materials, das in Schritt (c) gebildet wurde.

According to a further embodiment, the catalyst precursor mixture to be calcined is prepared under so-called "hydrothermal" conditions, ie in the presence of water under elevated temperature and pressure. The starting material for the hydrothermal production is preferably selected from the above-mentioned catalyst metal-containing compounds, more preferably from inorganic or organic salts and oxo acids. Suitable starting salts and acids include, for. Ammonium para- or heptamolybdate, molybdenum oxalate, ammonium metavanadate, vanadium oxalate, vanadyl sulfate (VOSO ₄ ) and hydrates thereof, telluric acid and ammonium niobium oxalate. Hydrothermal production involves the following steps:

• (a) dissolving or dispersing starting materials containing the catalyst metals, if necessary with heating,
• (b) combining, optionally with heating, the resulting solutions) and / or dispersion (s) with an aqueous mixture containing the catalyst metals in the desired proportion for the final catalyst material,
• (c) heating the aqueous mixture at elevated pressure to form a solid material,
• (d) collecting and drying the solid material formed in step (c).

Step (c) is preferably carried out at a temperature of above 100 ° C to 250 ° C, e.g. B. 120 to 200 ° C, preferably 130 to 180 ° C, at a pressure of more than 0.2 MPa (2 bar). There is no specific upper limit for the pressure (it is conceivable, for example, to work with a pressure of up to 9 MPa). For practical reasons, pressures of 0.3 to 2 MPa, such as 0.4 to 1 MPa, are normally used. Typically, the reaction is carried out in a sealed reactor, such as an autoclave, in which the autogenous pressure generated at elevated temperatures by the water present is utilized. Furthermore, the reaction time (at the target temperature) can be varied considerably and can, for. B. in the range of 24 to 144 hours, with 80 hours to 130 hours are preferred. It is not considered necessary It is preferable to operate under oxygen-free conditions, but it is preferable to exchange the air in the reactor with an inert gas. The reaction is preferably carried out in autoclaves of a suitable inert material (eg Hastelloy C276) or with a suitable inner lining (eg Teflon).

In Regarding further embodiments and conditions may Reference is made to the previous description, as far as this does not contradict the hydrothermal production process.

The Calcination and activation of a catalyst precursor mixture, hydrothermally under suitably selected conditions can be prepared to M1-rich catalyst materials, such as shown in Comparative Example 1 lead. The resulting However, catalyst materials show insufficient performance, in particular with regard to the conversion of propane to acrylic acid. High performance can only be achieved by a p / T intermediate treatment, d. H. Step (ii) of the claimed manufacturing process, such as explained in detail below.

The molar ratio of starting materials to the metal components is selected according to the desired final composition of the catalyst, taking into account possible changes, as discussed below. The final composition is a mixed metal oxide comprising the metal oxides Mo, V, Te and Nb and optionally oxides of other metal elements so long as they do not adversely affect the function of the resulting material as a catalyst in the oxidation reactions referred to herein. Preferably, the average final catalyst composition is within the ranges defined by general formula (I): MoV _a Te _b Nb _c Z _d O _x (I) where a = 0.15-0.50, b = 0.02-0.45, especially 0.05-0.40, c = 0.05-0.45, d ≤ 0.05, and x is the molar number of oxygen which binds to the metal atoms present in this mixed metal oxide, which follows from the relative amount and valency of the metal elements, and Z is at least one element selected from Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pb and Bi.

"Medium" composition means the composition as it can be determined by techniques such as XRF, particularly suitable for analyzing the elemental bulk composition. The EDX measurements used in the experimental part for determining the medium bulk compositions were performed, also gave reliable results.

According to one Embodiment of the present invention is d 0 in formula (I).

If in the compound of formula (I) the at least one optional element Z is present (i.e., d> 0) it prefers at least one element selected from Ru, Mn, Cr, Fe, Co, Ni, Zr, Rh, Pd, In, Sb, Ce, Ta, W, Pt and Bi are compounds of formula (I) wherein Z, when present, is at least one element selected from Cr and Ni. A Another preferred embodiment relates to the use of Ru, Cu, Rh, Re and / or Mn as Z element, where Ru, Mn and Cu, in particular Ru and Mn, are particularly preferred. If element Z is present, the lower limit of d is preferably 0.0005, in particular 0.001.

According to a more preferred embodiment, the average final catalyst composition is within the ranges defined by the general formula (II): MoV _a Te _b Nb _c Z _d O _x (II) where a = 0.28-0.40, preferably 0.29-0.38, in particular 0.30-0.36, b = 0.03-0.30, in particular 0.05-0.25, c = 0.05-0.20 and d and x are as defined above.

At the Select the ratio of the starting materials should be taken into account during the Calcination step and the subsequent treatment at higher pressure and higher temperature (below referred to as "p / T treatment") is the molar Ratio of the catalyst metals to a certain extent Can change degrees.

Since it appears that the V content is enriched in the final composition, the V content in the starting material may be lower than specified in formula (I) above, e.g. By 2-20%, 5-15% or 8-13% lower. Accordingly, in the starting material mixture, the variable "a" indicating the V content may be of the order of 0.15 to 0.30. As the volatility of Te often becomes a Te Ver Although the catalyst end composition tends to be more volatile than the starting material mixture, the Te content in the starting material mixture may be higher than specified in formula (I) above, although this is not preferred. Preferably, the Te content in the feedstock composition is as low as possible to effectively produce the M1 phase and process conditions are optimized to minimize Te loss.

In In one embodiment, the catalyst precursor mixture, which is to be calcined, and thus also the final catalyst material include a solid diluent. As a diluent Any inert material that meets the conditions of the Calcination of the p / T treatment and optionally the activation treatment That does not stand up to the other metal oxide catalyst material interacts so that its catalytic activity is impaired and not with the source materials, intermediates or End products of the oxidation reaction reacts.

The Presence of a solid diluent can be different Reasons to be favorable. First, are preferred Diluents characterized by a higher thermal conductivity as the catalytically active metal oxide material. This ensures a better heat transfer and prevents the formation of hotspots while using the catalyst, resulting in unwanted side reactions and reduction of Catalyst life could lead. Secondly the diluent has the function of a release agent for the catalytically active material and acts sintering processes contrary, between the grains of the catalyst material may occur. Furthermore, the diluent also improve the surface properties of the catalyst.

Suitable diluents may be selected from alumina, zirconia (zirconia), ceria (CeO ₂ ), SiC and silica. In one embodiment, the diluent is treated with a solution containing at least one metal defined in formula (I) prior to admixing it with the catalyst precursor material or a starting material thereof.

Prefers becomes the optionally pretreated and dried diluent subject to the same calcination method as used for the catalyst precursor material has been described before being used with the Catalyst starting material is combined. This will be optional pretreated diluents of this calcination are preferred twice, once before mixing with the catalyst starting material and a second time together with this catalyst precursor material.

Prefers is the weight ratio of the diluent not larger to the metal oxide catalyst material than 1.5: 1 and in particular not greater than 1: 1, z. B. not greater than 0.5: 1.

The Diluent can be added to the calcination procedure at any time be added, d. H. It can be mixed with the metal ones Catalyst starting materials in a dry or a wet Condition or it may, if the catalyst precursor mixture under Use of a solvent is prepared, to which Solvents are added, whereby the catalyst starting materials on the diluent during the procedure the preparation of the catalyst precursor mixture precipitated become.

Independently of which manufacturing process is chosen and whether a diluent in the resulting solid material (Catalyst precursor mixture) is present and / or this solid Material has been coated on a support (see please catalyst description in point II), the catalyst precursor mixture then a calcination in an oxygen-containing atmosphere subjected to (step i) at a temperature of 150-400 ° C, preferably 200-350 ° C, more preferably 250-300 ° C. This process is intended to remove the volatiles and convert the catalyst metal elements into their oxides.

Of the For simplicity, the calcination reaction becomes ordinary carried out at atmospheric pressure. Basically However, it is also possible to take this step under easy perform elevated or slightly reduced pressure, z. Within the range of an atmospheric pressure of ± 50% or ± 20% As an oxygenated atmosphere can Air or a synthetic oxygen-containing atmosphere be used. Depending on the other process conditions Oxygen is not normally contained in amounts of more than 50% by volume applied. Suitable oxygen volume ratios are z. B. 1 to 40 vol .-%, 5 to 35 vol .-% or 10 to 30 vol .-%. Of the The rest is nitrogen like in the air or any other inert gas like Ar or he.

In principle, any suitable reactor can be used to carry out the calcination. When organic metal salts are used as the starting material, it is particularly preferred to use in a ro calcining furnace, which apparently improves the complete removal of organic matter.

The Catalyst precursor mixture is heated gradually from the Starting temperature (normally room temperature, i.e. 20 ° C) to the final calcination temperature, preferably at a rate of 1 to 20 K / min, in particular 5 to 15 K / min. The calcination is then carried out at a final temperature of 150 to 400 ° C, preferably 200 to 350 ° C, more preferably 250 to 300 ° C, preferably over a period of 20 minutes to 20 hours, e.g. B. 30 min to 10 h, 1 h to 5 h or 1 h to 3 h.

While The calcination becomes the oxygen-containing atmosphere preferably continuously relative to the catalyst precursor mixture emotional. The term "moved" refers to Embodiments in which fresh oxygenated Atmosphere is fed to possibly spent and therefore oxygen depleted atmosphere again fill. Suitable delivery rates are z. B. in the order of 10 to 100 ml / min, in particular 30 to 70 ml / min, based on the weight of the catalyst mixture from 1-50 g.

According to the second step (ii) of the catalyst preparation process the calcined catalyst material of a high pressure treatment and high temperature (hereinafter also referred to as "p / T treatment") subjected to a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid Phase. The inventors have surprisingly found that this p / T treatment the formation of M1 phase in the final catalyst material is extraordinary increased, either during the p / t treatment itself or in a subsequent activation treatment.

It gives no special upper limit in terms of pressure and temperature, which should be used in this treatment. Accordingly is it z. B. possible, the treatment at pressures of up to 50 MPa or more and temperatures up to 700 ° C or more. Very high temperatures and pressures However, the material of the reactor put higher loads out. Therefore, it is preferred from an industrial point of view, the lowest possible Temperature and pressure values to be used in the formation of the M1 phase or increase their content sufficiently effective are. Further embodiments for the temperature range, which is to be used include 420 to 600 ° C, 440 up to 560 ° C and 460 to 540 ° C. According to others Embodiments may be the pressure within the range from 12 to 40 MPa, 14 to 35 MPa, 15 to 30 MPa and 16 to 25 MPa be set.

The p / T treatment of the present invention is performed in the presence of an inert fluid phase. It is believed that this treatment favors transport reactions, thereby Dissolution, phase reorganization and recrystallization methods which increases the formation of the M1 phase. The inert fluid phase may be under the conditions of p / T treatment be a vapor, a liquid, a critical or supercritical Phase. It is intended that the term "liquid" all Conditions of pressure and temperature in which the Phase is not in a vapor state and is a critical or supercritical State has not yet reached.

The Compound containing the inert fluid phase (hereinafter referred to as "phase-forming." Compound "denotes) should be under the conditions do not decompose the p / T treatment. Without wishing, on This mechanistic reasoning seems to be bound it that the phase-forming compound could be capable at least partially dissolve the calcined catalyst material, whereby transport and recrystallization processes are improved.

• • Die phasenbildende Verbindung ist ein kleines Molekül mit bevorzugt einem Molekulargewicht von weniger als 150, bevorzugter weniger als 100, insbesondere weniger als 80.
• • Die phasenbildende Verbindung besitzt mindestens eine polare Bindung zwischen zwei unterschiedlichen Atomen, wie C-O, C=O, O-H, S=O, während Verbindungen (Moleküle), die allein aus demselben Atomtyp bestehen, und Moleküle, die allein durch unpolare C-C-Bindungen und C-H-Bindungen aufgebaut sind, weniger bevorzugt sind.
• • Gemäß einer Ausführungsform besteht die phasenbildende Verbindung aus mindestens zwei unterschiedlichen chemischen Elementen, ausgewählt aus der Gruppe, bestehend aus C, S, O und H. Verbindungen, die Stickstoffatome enthalten, sind weniger bevorzugt.

In addition, it seems preferable if the following conditions are met:

• The phase-forming compound is a small molecule, preferably having a molecular weight of less than 150, more preferably less than 100, in particular less than 80.
• • The phase-forming compound has at least one polar bond between two different atoms, such as CO, C = O, OH, S = O, while compounds (molecules) composed solely of the same atomic type and molecules solely by nonpolar C-C bonds and CH bonds are less preferred.
• According to one embodiment, the phase-forming compound consists of at least two different chemical elements selected from the group consisting of C, S, O and H. Compounds containing nitrogen atoms are less preferred.

Three examples of suitable phase-forming compounds are water, CO ₂ and SO ₂ . Their critical data are Tc [K] = 647.35 and Pc [MPa] = 22.11 for water, Tc [K] = 304.15 and Pc [MPa] = 7.37 for CO ₂ and Tc [K] = 430.65 and Pc [MPa] = 7.88 for SO ₂ . It can be observed that within the required Conditions for the p / T treatment CO ₂ and SO _{2 are} always used at supercritical conditions, whereas water can equally be used as vapor or liquid (ie in a subcritical state) at the critical point or supercritical conditions.

The p / T treatment of the present invention can be carried out are used in any apparatus which has the required high temperature and pressure conditions. Typically, she will carried out in a sealed autoclave or Reactor. To make sure the pressure drop over the treatment duration is as small as possible, become special Sealing materials that have their sealing properties under the do not lose required pressure and temperature conditions, preferably used. Copper and silver seals provide z. B. such materials.

The p / T treatment of the present invention is preferably carried out over 0.5 to 30 h, z. B. 1 to 25 hours or 2 to 20 hours.

These p / T treatment is usually performed after the air present in the reactor (eg autoclave) through inert gas, such as nitrogen, argon or helium, was replaced from the addition of the phase-forming compound. It seems, however not to be necessary, under essentially oxygen-free Conditions to work, and it is believed that a smaller Content of oxygen, eg. B. less than 1 vol .-% or less than 0.5% by volume, based on the total amount of liquid media, does not adversely affect the p / T treatment.

The Metal oxide catalyst material obtained after the p / T treatment can already show a high M1 phase content, z. At least 85 wt .-%, at least 90 wt .-% or at least 95 wt .-%, and other properties later related to the claimed metal oxide catalyst can be explained. Then it is not necessary to increase the M1 phase content further, by subjecting the catalyst to the following "activation treatment" becomes.

In a preferred embodiment, if necessary, normally after an intermediate cooling step, this second thermal treatment (also referred to as "activation treatment") follows the p / T treatment to further increase the crystallinity (and thereby also the M1 content). The activation treatment proceeds in an inert atmosphere, preferably in nitrogen gas or argon gas, at a temperature of 350-700 ° C, preferably 550-680 ° C, more preferably 580-670 ° C, especially 590-670 ° C. During this activation treatment, it is particularly important to work in the absence of oxygen since the mixed metal oxide (like the M1 phase itself) obtained after the p / T treatment is not in a fully oxidized state (since it is at least partially molybdenum (Mo) in an oxidation state of less than + VI and at least partially vanadium (V) in an oxidation state of less than + V) and complete oxidation to MoO ₃ or V ₂ O _{5 is to} be avoided.

Out For practical reasons, this activation treatment becomes common carried out at atmospheric pressure. Basically However, it is also possible to treat under light perform elevated or slightly reduced pressure, z. Within the range of one atmospheric pressure of ± 50% or ± 20% The treatment time in this Step is also not specifically limited and is preferred 0.5-30 h, more preferably 1-20 h, and especially 1-10 h.

The Catalyst precursor mixture is heated gradually from the starting temperature (usually room temperature, d. H. 20 ° C) to the final activation temperature, preferably with a rate of 0.5 to 5 K / min, in particular 1 to 3 K / min.

II. Metal oxide catalyst and material

The The present invention also provides a novel and improved MoVTeNb mixed oxide catalyst material ready, excellent sales rates and / or selectivities in the oxidation of hydrocarbons, in particular to unsaturated Carboxylic acids shows. The catalyst material is preferred Essentially crystalline, which means that it is a preferred one Crystallinity level of at least 80 wt .-%, more preferably at least 85% by weight, more preferably at least 90% by weight, still more preferably at least 95% by weight, based on the total amount Metal oxide catalyst phase (note: natural neither the optional diluent nor the Carrier considered as part of this metal oxide catalyst phase). The crystallinity can be determined by XRD with a internal standard, as explained in the experimental part.

The claimed mixed oxide catalyst material is also characterized by a very high content of M1 phase of at least 85% by weight preferably at least 90% by weight, more preferably at least 95% by weight M1 phase, based on the total amount of crystalline metal oxide catalyst phase. The amount of M1 phase in wt% can be determined as in the experimental part described.

In the context of the present invention, the term "M1 phase" is to be understood as an orthorhombic phase which is characterized by the presence of (1) corner-linked MO ₆ (M = Mo, V) octahedra which form 6- and 7-membered rings and (2) NbO ₇ pentagonal bipyramidal units that share edges with the surrounding corner-sharing MO ₆ octahedra. It is assumed that these structural elements allow a clear distinction from the M2 phase. Of course, other structural features as set forth in the "prior art" can also be used to define the M1 phase.

About that In addition, the M1 phase shows a characteristic needle shape with medium Length values of typically 100 to 400 nm, e.g. 200 to 300 nm and average diameter values of 50 to 300 nm, z. 100 up to 250 or 100 to 200 nm. Activation at higher temperatures usually the formation of bigger ones seems to favor average diameters. morphology studies and shape analysis can be performed under Using a Scanning Electron Microscope (SEM). For SEM examinations were performed on a carbon band without the samples put every pretreatment. From the SEM images were size distributions the M1 needles by measuring the length and the diameter obtained from 300 randomly selected M1 needles.

According to one Embodiment of the claimed catalyst material ("First catalyst material") becomes a MoVTeNb mixed oxide catalyst material, comprising oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb) and optionally other catalyst metals, such as the one above defined element Z, provided that the M1 phase in one Amount of at least 85 wt .-%, based on the total amount of crystalline metal oxide catalyst phase, and that obtainable is through the manufacturing process explained above.

The average composition of this catalyst material is preferred within the ranges defined by the above general formula (I), in particular the above formula (II) are defined.

Surprised It has been found that such a catalyst material has improved Performance in terms of sales and / or selectivity comparable hydrothermally produced catalyst materials shows. The reason why the manufacturing process, in particular the p / t treatment, optional in combination with the subsequent Activation treatment, this positive influence on the catalyst performance is not yet fully investigated Service. However, it is believed that other manufacturing related Factors as the M1 phase content to this positive result contribute.

According to one further embodiment ("second catalyst material") the present invention provides a novel catalyst material, comprising oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb) and optionally other catalyst metals, such as the element Z, defined above, characterized is that it has an M1 phase content of at least 85% by weight and has a medium composition within the ranges which is defined for the above-mentioned formula (II) are.

These Embodiment includes catalyst compositions, which show improved performance, regardless of theirs Production method. However, it is preferable to have these M1-rich ones Catalyst material compositions according to the manufacture previously described, as adopted This will provide additional benefits in terms of catalyst performance results.

Both the first and second catalyst materials of the invention may optionally be further described by their specific surface area. The specific surface area of the catalyst material, measured according to the BET method with nitrogen described in the examples, is preferably greater than 5 m ² / g, in particular greater than 6 m ² / g, eg. B. 6 to 40 m ² / g, z. B. 7 to 20 m ² / g.

It In particular, it has been found that the first and second catalyst material The invention prefers a propane conversion of at least 40%, preferably at least 45%, and / or selectivity for Acrylic acid of at least 65%, preferably at least 70%, under the hydrocarbon oxidation conditions specified in the examples shows.

The catalyst material of the invention may be used as a catalyst obtained after the p / T treatment or, if necessary, after the activation treatment, which is a powder equivalent. In one embodiment, catalyst particles of a defined size are formed from the resulting powdered catalyst material (which may also contain a diluent).

It There are no special restrictions on size the catalyst materials to be used. The following however, structural features are preferred.

The macroscopic size (middle longest Diameter) of the individual catalyst particles is preferred in the range of 0.5 to 10 mm. Catalyst particles of this size can be obtained by methods which are in the state of Technics are known, for. B. by pressing a dried Catalyst starting material, re-crushing the compressed Material and performing a size-selective step, Like sieving, before performing the calcination step. Alternatively, the already calcined material is pressed again crushed and a size-selective step, like seven, subject. Instead of pressing can be an extrudate be formed.

pressing and extrusion can be done equally be with p / T-treated and optionally activated catalyst material.

According to one Another embodiment is the catalyst end material on a carrier according to techniques that are known in the art coated. This coating the corresponding precursor materials can be used equally be effected at an earlier state, z. B. before the calcination treatment, before the p / T treatment or before the optional activation treatment.

Of the Support, which is preferably inert, can be any shape and surface structure have. However, they are uniformly shaped mechanically stable bodies, such as spheres, rings, pipe sections, Half rings, triangular shapes, spirals or honeycomb carrier bodies or carrier bodies provided with channels are, such. As fiber mats or ceramic foams, preferably. The size and shape of the carrier body is determined z. B. by the dimensions, primarily the inner Diameter of the reaction tubes when the catalyst used in tube or shell and tube reactors. The diameter of the carrier body should then be between 1/2 and 1/10 be the inner diameter of the reactor. In the case of liquid bed reactors If the carrier diameter is determined z. B. by the liquid dynamics in the reactor. Suitable materials are for. Steatite, Duranit, Stoneware, porcelain, silicon dioxide, silicates, alumina, aluminates, Silicon carbide or mixtures of these substances. Pipe sections, Rings and balls are made of ceramic, silicon carbide or carbon preferably used.

The Ratio of the applied layer to the carrier is preferably 1 to 30 wt .-%, particularly preferably 2 to 20 wt .-%, based on the total mass of the catalyst material (exclusive of the optionally present diluent). The thickness of the Layer is preferably 5 to 300 μm, particularly preferred 5 to 10 μm.

In a preferred embodiment, the selected Carrier coated with an aqueous slurry from the starting materials for the catalyst precursor material or a suspension thereof in an organic solvent, such as Toluene, followed by the removal of water or the organic Solvent and followed by the process steps, which are described in point I (calcination, p / T treatment, optional Activation). If the carrier to a later When coated, the same techniques can be used be applied using an optional heat treatment after the removal of water or the organic solvent, to fix the catalyst material on the support.

III. Process for oxidizing a hydrocarbon

One Another aspect of the present invention relates to a method for oxidizing a hydrocarbon in the presence of oxygen and a catalyst as defined above.

According to one preferred embodiment, this method comprises a Step in which a hydrocarbon, in particular an alkane, a subjected to catalytic vapor phase oxidation reaction, whereby an unsaturated carboxylic acid is produced. This embodiment is preferably applied to C1 to C5 alkanes. If z. As propane or isobutane as starting alkanes used is acrylic acid or methacrylic acid obtained in good yields.

In this embodiment, the catalyst of the invention may be used under usual conditions to obtain Koh to convert hydrogens to unsaturated carboxylic acids. The reaction is preferably carried out in fixed bed reactors, e.g. B. fixed bed tube reactors. For the sake of simplicity, atmospheric pressure may be used while the reaction proceeds similarly at lower or higher pressures. An inert gas (eg nitrogen) and / or steam mixed with the hydrocarbon (eg propane) and oxygen are preferred. A standard feed composition is e.g. Alkane (eg propane) / oxygen / nitrogen / steam of 1 / 2-2.2 / 18-17.8 / 9 (molar ratio). Preferred reaction temperatures are in the range of 350 to 450 ° C. The molar amount of steam (H ₂ O) based on the total molar amount of hydrocarbon, O ₂ , inert gas (e.g., N ₂ ), and steam (H ₂ O) can be varied significantly with the catalyst of the invention. Suitable results are achieved with molar amounts of preferably 5-65%, z. B. 10-50%.

The Present inventors have found that M1-rich catalyst samples under conditions of use, as described in Example 4, surprisingly are stable. After 50 hours, there was essentially no loss observed the catalytic activity. A phase analysis the catalyst samples used over this period of time were also left no apparent reduction in the Detect M1 phase content. This makes the catalyst of the present Invention to a particularly attractive choice for industrial Process for the oxidation of hydrocarbons, such as described hereinbefore wherein the same catalyst batch is over a few months, eg At least 3 months, at least 6 months or even at least 1 year was used.

According to one Another embodiment is a saturated or unsaturated hydrocarbon, such as C3 to C7 alkane or alkene oxidizes ("ammoxidation") in the presence of oxygen, ammonia and the catalyst of the invention to the corresponding nitrile. Acrylonitrile or methacrylonitrile can produced in this way from propane, propylene, isobutane or isobutene become. This embodiment is performed under in this field ordinary conditions, what z. Legs Reaction temperature of 350 to 500 ° C, z. B. 400 to 500 ° C. and atmospheric pressure up to 3 atm. As an oxygen source usually air is used.

IV. Procedure for increasing the M1 content of the calcined metal oxide catalyst

The Concept underlying the present invention is equally applicable to the M1 phase content of the calcined MoVTeNb oxide catalyst (Material), which has a different history than in the claimed Manufacturing process defined to increase. To this Way it is possible the performance of an already calcined Catalyst (material), the z. B. undesirably high levels at the amorphous phase or M2 phase has to increase.

Accordingly another aspect of the present invention relates to a method to increase the content of M1 phase in a calcined Metal oxide catalyst material comprising oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb) and optionally at least another catalyst metal element, such as the Z defined above, which comprises the step of the calcined metal oxide catalyst a treatment at a pressure of at least 10 MPa and a Temperature of at least 400 ° C in the presence of an inert is subjected to fluid phase. This treatment can be done be under the same conditions as in point I for the p / T treatment, as the second step of the claimed manufacturing process was presented.

According to one preferred embodiment of the present method becomes the p / T-treated catalyst of an activation treatment in an inert gas atmosphere at a temperature of 350 to 700 ° C, in particular 580 to 670 ° C, subjected. For details and embodiments of this activation treatment Reference is also made to the manufacturing process of Invention (see point I).

The present method is preferably applied to catalysts with a medium composition, as described in points I and II has been described, for. B. for catalyst materials of Formula (I) or (II) and embodiments thereof.

The Method can be applied to the M1 phase content by z. B. at least 10% by weight, at least 20% by weight, at least 30% by weight, at least 40% by weight, at least 50% by weight, at least 60% by weight, to increase at least 70% by weight or at least 80% by weight, depending on the M1 content of the calcined catalyst material, that should be treated and the target value.

According to one embodiment, the calcined metal oxide catalyst material before treatment has a content of less than 70 wt .-%, z. Less than 60% by weight, less than 50% by weight or less as 40 wt .-% M1 phase on and after the treatment at least 85 wt .-% M1 phase, preferably at least 90 wt .-% M1 phase, more preferably at least 95 wt .-% M1 phase, each based on the Total amount of crystalline metal oxide catalyst phase.

This Method for increasing the M1 content may be advantageous be used in the regeneration of catalysts that never showed a higher content of M1 phase or at least partially their original M1 phase content during lost the application. In this preferred embodiment is the treated calcined catalyst material from a (usually continuous) method of preparation an unsaturated carboxylic acid containing the step includes that an alkane of a vapor phase catalytic oxidation reaction in the presence of oxygen and the calcined catalyst (such as in point III) is removed, and at least partially attributed to the process, after the process for increasing the content of M1 phase has been carried out.

The The present invention will now be explained in more detail by the following examples of the invention and Comparative examples and their use in a representative Hydrocarbon oxidation reaction.

Examples

The The following analytical techniques were used for the assessment the catalysts of the present invention and comparative catalysts.

X-ray powder diffraction (XRD)

Determination of M1 phase content (wt.%) and crystallinity (% by weight)

The phase composition of the catalysts, determined by X-ray diffraction, performed on laboratory diffractometers, either a STOE STADI P transmission diffractometer, equipped with a focusing primary Ge (111) -monochromator and a position-sensitive detector using Cu-Kα ₁ radiation, or a Bruker AXS D8 Advance Bragg Brentano diffractometer equipped with a secondary graphite monochromator and scintillation counter using Cu-K _{α + 2} radiation.

Of the M1 phase content in (wt%) was determined by fitting calculated diffraction diagrams of the experimental X-ray diffraction data using the Rietveld method (quantitative Rietveld analysis), where the "TOPAS" software was used (v.3, Bruker AXS). In its basic form, this analysis gives the mass fractions (Wt .-%) of such crystalline phases in a phase mixture, the have a known crystal structure whose sum is defined as 100% becomes. Accordingly, the content of amorphous material can only be like to be determined later explained.

To the knowledge of the present inventors, catalysts having a chemical composition as contemplated in the present invention form as main phases only M1 and M2 and occasionally one or more of five minority crystalline phases, ie (Mo, V, Nb) ₅ O ₁₄ and V _0.95 Mo _0.97 O ₅ , MoO ₂ , MoO ₃ and TeMo ₅ O ₁₆ .

The crystal structures of M1 and M2, published by DeSanto et al. [ Z. Kristallogr. (2004) 219, 152-165 ] (ICSD entries 55097 and 55098, ICSD = Inorganic Crystal Structure Database, copyright 2007 by Fachinformationszentrum (FIZ) Karlsruhe, Germany) are used to calculate the theoretical diffraction patterns of these phases. The M1: M2 ratio is defined as the ratio of the corresponding mass fractions found.

If necessary, the theoretical diffraction patterns of minority phases are considered, based on the structure information for Mo ₅ O ₁₄ (ICSD-27202) and V _0.95 Mo _0.97 O ₅ (ICSD-39386), MoO ₂ (ICSD-80830), MoO ₃ (ICSD-35076) and TeMo ₅ O ₁₆ (ICSD-69063). If optional catalyst elements such as Z (in formulas I and II) are present (d ≤ 0.05, based on Mo ₁ ), they do not alter the diffraction pattern of the crystalline phases such that this must be considered within the accuracy of the determination. In the very unlikely event that the crystalline metal oxide phase would contain an unknown crystalline material in larger quantities, crystallographic analysis allows the consideration of its diffraction pattern in determining the M1 content.

According to an alternative description of a metal oxide catalyst material with very high M1 Pha The XRD plot shows only diffraction signals that can be attributed to the M1 phase and is essentially free of other well-defined diffraction peaks. The term "well defined diffraction peak" is understood to refer to a diffraction signal having a FWHM (half width), ie, the width of the peak at 50% of its height above the baseline, of at most 3 ° in 2 theta.

The amount of (X-ray) amorphous material can be quantified by extending the above method, if the sample is analyzed in a known ratio with an internal diffraction standard of known crystallinity and suitable linear attenuation, e.g. NIST SRM 674b TiO ₂ (μ = 536 cm ^-1 for Cu-Kα radiation), which is commercially available from the National Institute of Standards and Technology (NIST), USA. Now, the sum of the crystalline phases is not more than 100%, but the fitting results are scaled back according to the known mass fraction (wt%) of the internal standard. The difference between the sum of the recalculated mass fractions of the crystalline phase and 100% is then attributed to the amorphous material. Finally, all mass fractions determined in this way are re-scaled back to values that correspond to the original sample (ie, prior to mixing with the standard). In this way the degree of crystallinity of the sample (in% by weight) can be determined.

REM and EDX

morphology studies and shape analysis can be performed using from scanning electron microscopy (SEM). For SEM examinations Samples were placed on a carbon tape without pretreatment. A Hitachi S-5200 with a PGT spirit EDX system and a Hitachi S-4800 with an EDAX genesis EDX detector were used. EDX studies in the SEMs were performed with an acceleration voltage of 10 kV while SEM images were taken at 2 kV to optimize the surface resolution. The dry sample was minced using a mortar and pestles. The crushed powder was in dry form a carbon-coated copper net finely distributed. To the Bulk composition of a given compound via EDX To calculate some measurements must be combined and averaged due to the fact that the area considered by EDX is relative is small. A meaningful value can be obtained by averaging the values obtained from 50 EDX measurements.

Physisorption of nitrogen

The measurement of nitrogen adsorption at -196 ° C was performed using an Autosorb-1 instrument (Quantachrome). The Brunauer-Emmett-Teller (BET) method was used to determine the surface area of solid materials. The instrument measures the amount of nitrogen adsorbed on the catalyst surface by the static volumetric method at equilibrium vapor pressure. The surface area is calculated from the amount of adsorbed nitrogen that forms a monolayer, assuming that the molecular cross-sectional area of nitrogen is 16.2 Å ² . Prior to adsorption, the samples must be vacuum treated for several hours at temperatures between 80 to 300 ° C to remove molecules adsorbed from the environment. The catalyst of the invention was evacuated for 4 hours at 80 ° C. Thereafter, known amounts of N _{2 are left} in a sample cell which holds the catalyst at -196 ° C. The BET analysis requires a linear plot of the amount of adsorbed nitrogen at a relative pressure p / p ₀ (p is the measured equilibrium vapor pressure, p ₀ is the equilibrium vapor pressure of liquid nitrogen), which is limited to a limited range of the adsorption isotherm, usually in the p / p ₀ range of 0.05 to 0.3. Complete adsorption / desorption isotherms in the p / p ₀ range of 0.001 to 1 were recorded. The Quantachrome AUTOSORB software was used to determine the BET surface area of the catalyst of the invention taking into account 5 data points in the linear relative pressure range of the adsorption isotherm (p / p ₀ pressure range 0.05 to 0.3). The amount of the sample is about 0.1 g.

X-ray fluorescence measurements (XRF)

XRF measurements were performed on a Sequence X-ray Fluorescence Spectrometer System S4 PIONEER, available from Bruker AXS GmbH, Germany. To further increase the precision of the process, standard samples can be prepared which are adapted to the sample to be analyzed, such as MoO ₃ , V ₂ O ₅ , Te (OH) ₆ and Nb ₂ O ₅ . If necessary, other suitable standards known in the art can be used.

Example 1 (treatment with water)

raw materials

Molybdenum (VI) oxide (MoO ₃ , 99.5% Fluka), telluric acid (Te (OH) ₆ ), 97.5-102.5% Aldrich), vanadium (V) oxide (V ₂ O ₅ , 99.5 % Riedelde Haën), ammonium niobate (V) oxalate hydrate (NH ₄ [NbO (C ₂ O ₄ ) ₂ ] xH ₂ O, 99.99% HC Starck) and oxalic acid dihydrate (C ₂ H ₂ O ₄ .2H ₂ O, 99 , 5% ROTH) were used as received. Distilled water was also used for the preparation of the aqueous solutions.

Preparation of Mo-V-Te-Nb-O Complex Oxide Catalysts

First were the molybdenum (VI) oxide (130 mmol) and oxalic acid dihydrate (158 mmol) in distilled water (300 ml) with vigorous stirring dissolved at 80 ° C for 30 minutes. Next became the Te-containing solution consisting of telluric acid (30 mmol) dissolved in distilled water (30 ml) under continuous Stirring at 40 ° C for 15 minutes was added to the molybdenum-containing solution. The V-containing solution was added by carefully adding Oxalic acid dihydrate (56 mmol) to a suspension of the Vanadium (V) oxide (19.5 mmol) in distilled water (50 ml) under continuous stirring at 65 ° C for Made for 30 minutes. Then this solution became the added from Mo / Te. Thereafter, the Nb-containing solution consisting from ammonium niobate (V) oxalate hydrate (16 mmol) dissolved in distilled water (30 ml), with continuous stirring at 40 ° C for 15 minutes to the Mo / V / Te Solution added. Eventually it became out of it originating homogeneous complex solution with a nominal molar ratio of Mo / V / Te / Nb of 1 / 0.3 / 0.23 / 0.123 stirred at 40 ° C for a further 30 minutes.

Around to get a powder from this complex solution was the spray-drying process carried out in one Büchi 191 Mini Spray Dryer, with an inlet temperature of 150 ° C, an outlet temperature of about 110 ° C, Suction and pump levels of 100% and 10% and an air flow rate of ~ 600 ml / min works. The resulting powdery product was quickly collected and immediately undergone treatment at a moderate Temperature in an atmosphere of air flow (100 ml / min) subjected. The treatment included a 25-minute Heat up to 275 ° C and hold at this level for 1 hour. The resulting powder was ground thoroughly in an agate mortar and pestle.

The complex Mo-V-Te-Nb-O-oxide catalyst material was prepared by p / T treatment of the resulting precursor in superheated steam followed by activation in argon. Typically, 1.6 g of the precursor powder and 2.65 ml of distilled water were mixed in a stainless steel kettle (volume - 48 cm ³ ), the kettle was then sealed with a stainless steel cover (copper seals were placed between the kettle and the seal) and into a stainless steel bomb posed. The bomb was sealed and kept at 500 ° C for 2 hours. The superheated steam treatment product collected with the spatula was then air dried at 110 ° C for 2 hours. The p / T treated catalyst sample showed a sponge-like morphology, as in 1 shown. Their p / T surface value was 18 m ² / g.

The resulting powder was carefully ground in an agate mortar and pestle and subjected to an activation treatment with heating in an atmosphere of argon flow (100 ml / min). This treatment included heating to 600 ° C for 40 minutes and holding at this level for 2 hours. The catalyst material thus synthesized was carefully ground in an agate mortar and pestle and stored in a moisture-free desiccator. The recrystallization that occurred during this activation treatment resulted in the formation of a virtually phase-pure material containing 95 wt% M1, 2 wt% M2, and 3 wt% V _0.95 Mo _0.97 O ₅ , as by XRD determined. The activated material showed the usual acicular morphology of the M1 phase, as in 2 shown.

The average bulk composition of the resulting catalyst material was determined by EDX as Mo / V / Te / Nb = 1 / 0.34 / 0.078 / 0.14.

If the composition of the catalyst end material is compared with the molar ratio of the starting materials to note that the vanadium content increased slightly, whereas the tellurium content was significantly reduced. The latter due the volatility of tellurium under the conditions of manufacture. It is believed that this Te depletion is not a big one Has an influence on the properties of the catalyst end material, as long as the tellurium content is within certain ranges, as in specified in the present application.

• a) das calcinierte Katalysatormaterial vor der p/T-Behandlung in Anwesenheit von Wasser, und
• b) nach dieser Behandlung; und
• c) das Katalysatorendmaterial nach der Aktivierungsbehandlung in Ar bei 600°C.
• d) Das oberste XRD-Muster stammt von einem M1-Referenzmaterial.

XRD plots of samples taken at various stages of fabrication are in 3 juxtaposed. These XRD diagrams concern

• a) the calcined catalyst material before the p / T treatment in the presence of water, and
• b) after this treatment; and
• c) the catalyst end material after the activation treatment in Ar at 600 ° C.
• d) The topmost XRD pattern is from an M1 reference material.

3 confirms that the initially amorphous calcined catalyst material ( 3a ) undergoes substantial structural rearrangements in the high pressure / temperature (p / T) treatment of the present invention. It appears that, under these conditions, structural units predominantly align along the crystallographic c-axis, resulting in nanocrystalline M1, as shown by nonisotropic line broadening analysis of the simulated M1 diagrams ( PD Santo, DJ Buttrey, RK Grasseli, CG Lugmair, AF Volpe, BH Toby, T. Vogt, Cristallogr magazine. 219 (2004) 152 ). However, the material is still X-ray amorphous (see 3b ). Crystallinity can be achieved in the final activation treatment ( 3c ).

Example 2 (treatment with carbon dioxide) Example 1 was repeated except that 2.65 g of H ₂ O was replaced by 6.57 g of solid CO ₂ (dry ice) and the treatment was carried out at high pressure and temperature for 15 hours. The resulting catalyst material had almost the same chemical composition as that of Example 1 and very similar properties.

Comparative Example 1 (hydrothermal production without subsequent p / T treatment)

Ammonium heptamolybdate (NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O (Merck), vanadyl sulfate VoSO ₄ .5H ₂ O (Riedel-de Häen), telluric acid (Te (OH) ₆ (Aldrich) and ammonium niobium oxalate (NH ₄ ) [NbO (C ₂ O ₄ ) ₂ (H ₂ O) ₂ ] .3H ₂ O (Aldrich) were used as starting materials to prepare the starting suspension containing the catalyst metals in a molar ratio of Mo / V / Te / Nb = 1/0 For this purpose, ammonium molybdate in an amount corresponding to 52 mmol of Mo was added to 100 ml of H ₂ O at 353 K (80 ° C), followed by the addition of vanadyl sulfate (m.p. 13 mmol V) and telluric acid (12 mmol Te) The resulting aqueous mixture was cooled to 313 K (40 ° C) and added to a second solution prepared by dissolving ammonium niobium oxalate in an amount corresponding to 6.5 mmol Nb. in 50 ml of H ₂ O at 313 K (40 ° C.) After replacing residual air with nitrogen, hydrothermal synthesis was carried out in an autoclave made by Hastelloy at 448K ( 175 ° C) for 48 hours, producing an autogenous pressure of about 0.9 MPa. The resulting suspension was centrifuged for 20 minutes and the precipitate was washed with 100 ml of distilled water for 10 minutes and filtered under vacuum. Finally, the solid material was air dried in a muffle furnace at 353K (80 ° C) for 16 hours to yield a catalyst precursor material.

3 g of the precursor were heated in a rotating oven in synthetic air (100 ml / min) to 598 K (325 ° C) at a heating rate of 10 K / min and calcined at this temperature for 1 h. The calcined catalyst precursor material was then subjected to a final activation treatment in a rotating oven under an inert gas stream (nitrogen, 100 ml / min) for 2 h at 923 K (650 ° C). The resulting catalyst material had a BET surface area of 1 m ² / g and a metal composition (EDX analysis) of Mo / V / Te / Nb = 1 / 0.22 / 0.186 / 0.29. The M1 phase content was more than 95% by weight.

Example 3 (oxidation test)

The Performance of the catalyst according to Example 1 and Comparative Example 1 was in the following oxidation process assessed.

Partial oxidation of propane was carried out in a parallel catalytic testing reactor with twelve fixed bed quartz tube reactors (id 4 mm, length 225 mm) operating at atmospheric pressure. The catalyst material was compacted in a hydraulic press (8 tons force on a round surface of about 3 cm diameter), ground and screened manually for particle sizes between 0.24 and 0.45 mm. The feed rate was fixed at a space velocity (GHSV) of 4800 h ^-1 (at STP: standard temperature pressure conditions) with a catalytic bed volume of 0.5 ml and a corresponding bed height.

• Umsatz (%) = mol an verbrauchtem Propan/mol an zugeführtem Propans
• Selektivität (%) = mol an gebildeter Acrylsäure/mol an verbrauchtem Propan × 100
• Ausbeute (%) = mol an geformter Acrylsäure/mol an zugeführtem Propan × 100

The feed composition was 2.8 vol% propane, 6.3 vol% oxygen, 50.9 vol% nitrogen and 40 vol% steam. The reaction was carried out at 673 K (400 ° C). The products were analyzed by two online gas chromatograph systems. At the reactor outlet, the gases produced were analyzed calculated by two GCs and the conversion of propane, the selectivity of acrylic acid and the acrylic acid yield. The first GC was configured with a molecular sieve and Porapak columns coupled with a thermal conductivity detector for analysis of inorganic gases and hydrocarbons (C1-C3). The second GC was configured with a capillary column (HP-FFAP) coupled with a flame ionization detector for analysis of oxidized products.

• Turnover (%) = moles of propane used / mole of propane delivered
• Selectivity (%) = mol of acrylic acid produced / mol of propane used × 100
• Yield (%) = mol of molded acrylic acid / mol of propane fed × 100

The results are shown in the following Table 1. Table 1 Catalytic Performance catalyst Preparation BET [m ² / g) C ₃ H ₈ conversion [%] Selectivity for acrylic acid [%] Acrylic acid yield example 1 7 49 73 36 Comparative Example 1 1 5 100 5

SUMMARY

Phase-enriched MoVTeNb mixed oxide catalyst and method for its production

The The present invention provides a process for the preparation of a Metal oxide catalyst material comprising oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), the process being as follows Steps comprises: (i) subjecting a catalyst precursor mixture to comprising molybdenum (Mo), vanadium (V), tellurium (Te) and Niobium (Nb) a calcination treatment in an oxygen-containing Atmosphere at a temperature of 150 to 400 ° C, whereby a calcined catalyst material is produced, and (ii) subjecting the calcined catalyst material to treatment at a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase, whereby a catalyst material is prepared, the oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb). This method gives catalyst materials with very high levels of crystallographic M1 phase and excellent propane conversion, rates and selectivities for acrylic acid in the oxidation of propane.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

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Claims (24)

Process for the preparation of a metal oxide catalyst material, comprising a mixed oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), the process being the steps includes: (i) subjecting a catalyst precursor mixture to comprising molybdenum (Mo), vanadium (V), tellurium (Te) and Niobium (Nb), a calcination treatment in an oxygen-containing Atmosphere at a temperature of 150 to 400 ° C, whereby a calcined catalyst material is produced, (Ii) Subjecting the calcined catalyst material to treatment at a pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase, whereby a catalyst material comprising a mixed oxide comprising molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb). A method according to claim 1, wherein the catalyst material obtained in step (ii) of an activation treatment in an inert gas atmosphere at a temperature of 350 is subjected to 700 ° C. A method according to claim 1 or 2, wherein the catalyst precursor mixture of salts and acids, comprising molybdenum (Mo), vanadium (V), tellurium (Te) and Niobium (Nb) is produced. A method according to claim 1 or 2, wherein the catalyst precursor mixture is prepared in a method comprising the steps of preparing a solution or dispersion of salts and acids, comprising at least Molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb) in a solvent, optional precipitation of dissolved salts and acids of these metals, removing of the solvent from the solution, dispersion or optionally the precipitate, thereby forming a solid mixture and drying this solid mixture, thereby forming a catalyst precursor mixture is formed. A method according to claim 1 or 2, wherein the calcination treatment at 200 to 350 ° C. is carried out. A method according to claim 1 or 2, wherein the treatment according to step (ii) is performed is at a temperature of at least 460 ° C and a Pressure of at least 16 MPa. A method according to claim 1 or 2, wherein the fluid phase is formed by at least one compound, which has a molecular weight of less than 150 and at least two different elements selected from the group, consisting of C, S, O and H exists. A method according to claim 7, wherein The compound is selected from carbon dioxide, water and sulfur dioxide. A method according to claim 2, wherein the activation treatment was carried out at 580 to 670 ° C becomes. A process according to claim 1 or 2, wherein the average composition of the metal oxide catalyst material is within the ranges defined by the following formula (I): MoV _a Te _b Nb _c Z _d O _x (I) where a = 0.15-0.50, b = 0.02-0.45, especially 0.05-0.40, c = 0.05-0.45, d ≤ 0.05, and x is the molar number of oxygen which binds to the metal atoms present in this mixed metal oxide, which follows from the relative amount and valence of the metal elements, and Z is at least one element selected from Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pb and Bi, and preferably within the Ranges defined by the following formula (II): MoV _a Te _b Nb _c Z _d O _x (II) where a = 0.28-0.40, preferably 0.29-0.38, in particular 0.30-0.36, b = 0.03-0.30, in particular 0.05-0.25, c = 0.05-0.20 and Z, d and x are as defined above. A method according to claim 1 or 2, wherein the metal oxide catalyst material has a degree of crystallinity of at least 80% by weight and a content of M1 phase in an amount of at least 85% by weight, preferably at least 90% by weight, more preferably at least 95% by weight, based on the total amount crystalline metal oxide catalyst phase. Metal oxide catalyst material comprising a mixed metal oxide, comprising molybdenum (Mo), vanadium (V), tellurium (Te) and Niobium (Nb), wherein the metal oxide catalyst material a degree of crystallinity of at least 80% by weight and a content of M1 phase in an amount of at least 85% by weight, based on the total amount crystalline metal oxide phase and is available through a method as defined in any one of claims 1 to 10 is. The metal oxide catalyst material according to claim 12, wherein the average composition of the metal oxide catalyst material is within the ranges defined by the following formula (I): MoV _a Te _b Nb _c Z _d O _x (I) where a = 0.15-0.50, b = 0.02-0.45, especially 0.05-0.40, c = 0.05-0.45, d ≤ 0.05, and x is the molar number of oxygen which binds to the metal atoms present in this mixed metal oxide, which follows from the relative amount and valency of the metal elements, and Z is at least one element selected from Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pb and Bi, and preferably within the Ranges defined by the following formula (II): MoV _a Te _b Nb _c Z _d O _x (II) where a = 0.28-0.40, preferably 0.29-0.38, in particular 0.30-0.36, b = 0.03-0.30, in particular 0.05-0.25, c = 0.05-0.20 and Z, d and x are as defined above. A metal oxide catalyst material comprising a composite oxide comprising molydbene (Mo), vanadium (V), tellurium (Te) and niobium (Nb), wherein the metal oxide catalyst material has a degree of crystallinity of at least 80% by weight and M1 phase in an amount of at least 85 Wt .-%, based on the total amount of the crystalline metal oxide catalyst phase and the average composition of the material is within the ranges defined by the following formula (II): MoV _a Te _b Nb _c Z _d O _x (II) where a = 0.28-0.40, preferably 0.29-0.38, in particular 0.30-0.36, b = 0.03-0.30, in particular 0.05-0.25, c = 0.05-0.20 and d ≤ 0.05 and x is the molar number of oxygen that binds to the metal atoms present in this mixed metal oxide, which follows from the relative amount and valency of the metal elements, and Z is at least one element selected from Ru, Mn, Sc, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Rh, Pd, In, Sb, Ce, Pr, Nd, Te, Sm, Tb, Ta, W, Re, Ir, Pt, Au, Pb and Bi. Metal oxide catalyst material according to claim 12, 13 or 14, wherein the M1 phase content is at least 90% by weight, in particular at least 95% by weight. Metal oxide catalyst material according to claim 12, 13 or 14, the catalyst being in the oxidation from propane to acrylic acid is used, a propane conversion rate of at least 40% and selectivity to acrylic acid of at least 65% shows. Process for the preparation of an oxidized hydrocarbon from a hydrocarbon that includes the hydrocarbon a catalytic vapor phase oxidation reaction in the presence of oxygen and a catalyst comprising a metal oxide catalyst material, as defined in any one of claims 12 to 16 becomes. A method according to claim 17, wherein the hydrocarbon is an alkane and the oxidized hydrocarbon is an unsaturated carboxylic acid. The method of claim 18, wherein the alkane is propane and the unsaturated carboxylic acid Acrylic acid is. A method according to claim 17, wherein the hydrocarbon is an alkane or an alkene, the reaction in The presence of ammonia is carried out and the oxidized Hydrocarbon is a nitrile. A process for increasing the content of M1 phase in a calcined metal oxide catalyst comprising oxides of molybdenum (Mo), vanadium (V), tellurium (Te) and niobium (Nb), comprising the step of: subjecting a calcined metal oxide catalyst to treatment at one Pressure of at least 10 MPa and a temperature of at least 400 ° C in the presence of an inert fluid phase. The method of claim 21, wherein the treated calcined catalyst of an activation treatment in an inert gas atmosphere at a temperature of 350 to 700 ° C, in particular 580 to 670 ° C, subjected becomes. A method according to claim 21 or 22, wherein the calcined metal oxide catalyst prior to treatment a Content of less than 70 wt .-% M1 phase and after the Treatment more than 85 wt .-% M1 phase, in each case based on the Total amount of crystalline catalytic metal oxide phase. A method according to claim 21, 22 or 23, wherein the calcined catalyst to be treated is: (I) is removed from a continuous process for production an unsaturated carboxylic acid containing the step includes an alkane in the presence of oxygen and the calcined Catalyst subjected to a catalytic vapor phase oxidation reaction becomes, (ii) at least partially for the process again is used after the process of increasing the content on M1 phase has been carried out.