JP2020508208A - Catalytic material for oxidation of hydrocarbons with titanium dioxide doped with antimony - Google Patents

Abstract

The present invention uses a catalytic material for the oxidation of hydrocarbons with gaseous oxygen, including TiO ₂ material doped with V and Sb, and gaseous oxygen, of a TiO ₂ material doped with Sb. It relates to the use as a support material in catalytic materials for the oxidation of hydrocarbons. The invention furthermore relates to a process for the oxidation of hydrocarbons with gaseous oxygen, characterized in that the hydrocarbons to be oxidized and oxygen are brought into contact with the catalytic material according to the invention. The present invention further provides a catalyst molded body comprising an inert carrier, wherein the catalyst material of the present invention is provided on the carrier, and the catalyst material of the present invention comprising the following steps: On how to:
a) producing a mixture of TiO ₂ and Sb ₂ O ₃ ;
b) firing a mixture of TiO ₂ and Sb ₂ O ₃ to obtain a Sb-doped TiO ₂ material, and c) impregnating the Sb-doped TiO ₂ material with a V-containing compound.

Description

The present invention relates to a catalytic material for oxidation of hydrocarbons using gaseous oxygen, comprising V and an Sb-doped TiO ₂ material. The catalyst material is particularly suitable for use in a catalyst for the oxidation of ortho-xylene and / or naphthalene to phthalic anhydride.

The industrial production of phthalic anhydride from ortho-xylene or naphthalene is carried out by selective gas-phase oxidation in a shell-and-tube reactor, in which four to five different catalyst layers are formed in the axial direction of the reactor. In order. The individual catalyst layers consist of a loose deposit made of a catalyst compact, usually consisting of an inert carrier ring coated with a catalytically active material. The active material usually consists of a mixture of V ₂ O ₅ , Sb ₂ O ₃ , anatase-modified TiO ₂ and further cocatalysts. Such systems are described, for example, in WO2006092304A1 (Patent Document 1), WO2008077979A1 (Patent Document 2), EP0985648A1 (Patent Document 3) or WO2011061132A1 (Patent Document 4).

WO2006093041A1 comprises at least one first catalyst layer located on the gas inlet side, a second catalyst layer located closer to the gas outlet side and a third catalyst layer located closer to or on the outlet side of the gas outlet Wherein the catalyst layer is preferably a catalyst having an active material comprising TiO ₂ , respectively, for the production of phthalic anhydride by gas-phase oxidation of ortho-xylene and / or naphthalene. The use is described wherein the catalytic activity of the first catalyst layer is higher than the catalytic activity of the second catalyst layer. The activity of the first catalyst layer can be adjusted by all means known to those skilled in the art such that it is higher than the activity of the subsequent second catalyst layer. According to a preferred embodiment, the increased activity in the first catalyst layer is increased, for example, by increasing the bulk density in the first catalyst layer, for example by using another (ring) shape of the inert compact used. This can be achieved by:

  WO2008077971A1 describes a method for gas-phase oxidation in which a gaseous stream containing aromatic hydrocarbons and molecular oxygen is passed through two or more catalyst layers. Furthermore, this publication relates to a catalyst system for a gas phase reaction using a front layer. The product or volume of the diameter and height of the front inert-and / or catalyst-ring is smaller than at least one subsequent catalyst layer, or the volume / volume of the front inert-and / or catalyst-ring The percentage of surface area is greater than at least one subsequent catalyst layer.

  EP 0 965 648 A1 relates to the gas-phase oxidation of hydrocarbons, in which a gaseous mixture containing a molecular oxygen-containing gas and a hydrocarbon optionally having substituents is passed through a fixed catalyst bed. Provided is a method for gas phase oxidation carried out by flowing through a fixed catalyst bed, wherein the cavity of the catalyst layer is increased in one or more steps in the direction of flow along the flow of the gaseous mixture of crude material. .

  WO2011061132A1 is a catalyst system for the production of carboxylic acids and / or carboxylic anhydrides, comprising a plurality of catalyst layers arranged one above the other in a reaction tube, wherein at least one of the catalyst layers has vanadium antimonate active. It relates to the catalyst system introduced into the material. Further, the present invention provides a method for gas-phase oxidation in which a plurality of catalyst layers are passed through a gas stream containing at least one kind of hydrocarbon and molecular oxygen, wherein a maximum temperature of a hot spot is less than 425 ° C. About the method.

  The active material further comprises a binder that allows the active material to adhere to the inert support and imparts mechanical stability to the shaped catalyst body. Such binders are described, for example, in DE 198 24 532 A1.

  DE 198 24 532 A1 consists of a catalytically active metal oxide coated in a carrier core and a shell on it, on a hot carrier material at 50 to 450 ° C., at a higher temperature, an aqueous active material comprising the active oxide. A process for the preparation of a shell catalyst for the catalytic gas-phase oxidation of aromatic carboxylic acids and / or carboxylic anhydrides, obtained by spraying the suspension, wherein the aqueous active material suspension is It comprises from 1 to 10% by weight, based on the solids content of the active material suspension, of a binder, wherein the binder comprises: A) an ethylenically unsaturated anhydride or an ethylenically unsaturated dicarboxylic acid whose carboxyl group has an anhydride. A radical monomer comprising from 5 to 100% by weight of a monomer (a) which can be formed) and from 0 to 95% by weight of a monoethylenically unsaturated monomer (b). (Provided that monomers (a) and (b) have on average at most 6 carbon atoms not functionalized with oxygen-containing groups) and B) at least 2 OH A alkanolamine having at most 2 nitrogen atoms and at most 8 C atoms, wherein the weight ratio A: B is from 1: 0.05 to 1: 1.

  After providing the catalyst layers to the reactor, the catalytic activators that form each layer must be activated. It is a heat treatment of the shaped catalyst body, which is thought to decompose the organic binder present and form an oxide-like vanadium-containing active material. The activation of the shaped catalyst bodies takes place in situ, that is to say in the reaction tube, by the so-called “Anfahren”. Here, a mixture of air and the hydrocarbon to be oxidized (starting material gas) is burned, and a region of maximum temperature ("hot spot") forms in the first two catalyst layers, but the temperature rises in the reactor. It decreases continuously from the location of the hot spot to the end of the reactor in the axial direction. To enable activation of the catalyst layer following the hot spot, the flow rate of the starting material gas can be temporarily increased and the hot spot moved (in the direction of flow) to a subsequent layer. However, in this case it is disadvantageous that only a relatively low hot spot temperature is achieved, since the starting material gas partially reacts in the front layer. According to this start-up method, the subsequent catalyst layer is in some cases only poorly activated in situ, since only a short and relatively small temperature rise occurs in the catalyst bed. . However, the insufficient activation of the subsequent catalyst layer increases the proportion of undesirable underoxidation products, which adversely affects, for example, the quality of the phthalic anhydride product.

WO200609304A1 WO2008077971A1 EP0985648A1 WO2011061132A1 DE 198 24 532 A1

  The present invention is therefore based on the task of finding a catalyst which is rapidly activated and has a high activity while at the same time being highly selective.

This problem is solved by a catalytic material for oxidizing hydrocarbons using gaseous oxygen, comprising V and a TiO ₂ material doped with Sb.

  The catalyst material according to the invention can be, for example, an active material applied on an inert support to form a shaped catalyst body. Catalyst shaped bodies for the oxidation of ortho-xylene and / or naphthalene to phthalic anhydride are preferred. Preferably, said inert carrier is a steatite ring.

The Sb-doped TiO ₂ material is preferably present in powder form and can be present in any modification, but is preferably present in the anatase modification. The phrase Sb doping is understood in the sense of the present application to be present in that Sb is at least partially incorporated into the TiO ₂ material. Here, Sb may be present in the crystal lattice of the TiO ₂ material, isomorphically replacing the Ti atoms, or otherwise. Here, Sb may not necessarily be present in the TiO ₂ material in a uniformly dispersed state, but may be separated, for example, at the surface of the doped TiO ₂ material or at a near-surface region.

TiO ₂ material doped said, based on the total weight of the catalyst material of the present invention, preferably 0.01 to 5.0 wt% of Sb, and even more preferably 0.1 to 3.0 wt% of Sb Having.

The catalyst material of the present invention can have any BET surface area, but preferably it is in the range of 15-25 m < ² > / g, more preferably in the range of 17-23 m < ² > / g.

The present invention further relates to a method for producing the catalyst material of the present invention, comprising the following steps:
a) producing a mixture made of TiO ₂ and a Sb-containing compound;
b) firing a mixture made of TiO ₂ and a Sb-containing compound to obtain a Sb-doped TiO ₂ material;
c) impregnating the TiO ₂ material doped with Sb with a V-containing compound.

The TiO ₂ used as a starting material can be any TiO ₂ (preferably in powder form) and can be present in any modification, but is preferably present in the anatase modification. Wherein the Sb-containing compounds used as starting material, preferably antimony oxide, for example, Sb ₂ O ₃ or Sb 2 _O 5 or nitrate _antimony, wherein degree of hydration may vary. The starting materials should be intimately mixed in order for Sb to allow a solid state reaction to dope TiO.

Calcination of the mixture made of TiO ₂ and Sb-containing compound (step b)) is preferably 1 to 10 hours, more preferably 3 to 8 hours, in air, 300 ° C. greater than the temperature, preferably 400 ° C. ~ It is carried out at a temperature in the range of 700C, more preferably in the range of 450C to 600C.

It may be advantageous to treat the TiO ₂ from step b) with an acid in order to remove excess Sb not incorporated into the TiO ₂ material (eg in the form of Sb ₂ O ₃ or Sb ₂ O ₅ ). . For this purpose, cheap inorganic acids are preferably used, for example HCl, H ₂ SO ₄ or HNO ₃ . After the acid treatment, the doped TiO ₂ material is preferably washed with water and subsequently dried to remove acid residues.

Impregnation with V-containing compounds of the TiO ₂ material doped with Sb is preferably carried out by generating an aqueous suspension containing Sb-doped TiO ₂ material and V-containing compounds. The aqueous suspension can also include further compounds such as P-containing compounds, Sb, Cs or Na-containing compounds, and can further include a binder. Next, the aqueous suspension is preferably applied to an inert carrier, for example, a cyclic (ring-shaped) carrier to produce a shaped catalyst. The application of the suspension on the carrier is effected, for example, using a fluidized-bed apparatus (eg as described in DE 197 09 589 A1). Preferably, V-containing compound in the aqueous suspension is _V 2 _{O 5.}

The invention further relates to the use of the Sb-doped TiO ₂ material as a support material for a catalyst for the oxidation of hydrocarbons using gaseous oxygen. Preferably, the hydrocarbon is ortho-xylene or naphthalene or a mixture of both, and the oxidation product is at least partially phthalic anhydride.

  The invention further relates to a process for the oxidation of hydrocarbons with gaseous oxygen, characterized in that the hydrocarbon (s) to be oxidized and oxygen are contacted with the catalyst according to the invention. Typically, the hydrocarbon (s) to be oxidized and oxygen are contacted with the catalyst of the invention at elevated temperature in the reactor. The reaction temperature in the reactor is preferably above 200C, more preferably in the range of 350C to 500C. The reactor is preferably a tube in a shell-and-tube reactor temperature controlled by a salt bath.

  Preferably, the catalyst material is applied on an inert carrier to form a shaped catalyst body. As multiple catalyst bodies are introduced into one reaction tube, they form one catalyst layer, ie a loose deposit of catalyst bodies, in the reaction tube. A plurality of such catalyst layers comprising different shaped catalyst bodies form a catalytic device in the sense of the present invention. The reaction gas is passed axially through a reactor, which is typically tubular, in which the starting material gas is introduced at the gas inlet side of the reactor and the resulting product gas leaves the reactor at the gas outlet side. Is discharged.

  The above-described catalyst device includes the shaped catalyst article of the present invention including the catalyst material of the present invention. Here, the catalyst molded body of the catalyst layer closest to the gas outlet side preferably contains the catalyst material of the present invention.

  In the following experimental runs, the manufactured shaped catalyst bodies are also referred to simply as catalysts.

Method The determination of the ratio of the binder is performed by calcining the coated catalyst molded body at 450 ° C. for 7 hours to completely thermally decompose the organic binder. Following the firing, the proportion of binder is Gl. Determined according to 1:
Gl. 1:

_AB = proportion of binder M _E = weighed amount of catalyst before calcining M _A = weighed amount of catalyst after calcining Physicochemical property analysis (BET, XRF) of the active material This is done by mechanical separation from the carrier ring using a sieve. The remaining portion of the active material still attached to the carrier ring is completely removed by sonication. Finally, the washed carrier ring is dried at 120 ° C. in a drying cabinet and weighed. Following firing, the proportion of active material is determined by the Gl. Determined according to 2:
Gl. 2:

A _A = proportion of active material M _A = weighed amount of catalyst after calcination M _T = weighed amount of carrier ring The measurement of the specific surface area of the active material is carried out by the BET method according to DIN 66131; J. Am. Chem. Soc. 60, 309 (1938). The sample to be measured is dried in a quartz tube at 350 ° C. under reduced pressure (F = 50 ml (min) 1.5 hours). The quartz tube is then cooled to room temperature, evacuated and immersed in a dewar containing liquid nitrogen. Nitrogen adsorption is carried out at 77 K using RXM 100 solution system (Advanced Scientific Design, Inc.).

  For the determination of the chemical composition by X-ray fluorescence analysis (XRF), 14 g of the active material are mixed vigorously with 3.5 g of wax (Hoechst Wachs C Mikropulver) using a stirring mill and subsequently pressed (17 t compression). (1 min compression time) to obtain three discs. The compact is then analyzed on a multi-element X-ray fluorescence spectrometer (S4 Pioneer, Bruker) without standardlos. The measurements are averaged per active material (3 compacts, 3 individual measurements per compact) and the composition of the elements detected totals 100% by weight of their oxides.

  For the analysis of the catalytic properties of the catalyst, each 25 g of the shaped catalyst body are uniformly diluted with 540 g of inert material (steatite ring O 3 mm), have a 25 mm inner diameter and 1 m length and are cooled in a salt bath. Fill the tubes to be filled. For in situ calcination, the catalyst in the tubes is passed with at least 30 NL / h of air at a salt bath temperature of 410 ° C. for at least 48 hours. In the tube, a 3 mm thermosensor with a withdrawal element (Zugeelement) is centrally located for temperature measurement.

To carry out the measurement of the catalyst, 330 NL (standard liters) of air were continuously pumped above the tube at a total pressure of about 1200 mbar at a load of 60 g ortho-xylene / Nm ³ air (ortho-xylene purity> 98%). From below. Each measurement is performed at a salt bath temperature of 410 ° C.

To examine each of the active constants A ^* and product selectivity S _P output catalysts, after the initial metering of the starting materials flow (flow time TOS = 0h), the product stream with respect to its composition, at regular intervals Gasukuroma The analysis is carried out using a chromatography (GC6890N, Agilent) and a non-dispersive IR analyzer (EL3020, ABB).

Gl. 4 using the conversion U determined according to Gl. According to 3, the active material-based activity constant A * of the catalyst can be calculated:
Gl. 3:

Here it means:
A *: Active constant of active material based on active material [L / (h * g)];
Q: Total volume flow [L / h] under reaction conditions
m _Aktivmass : amount of active material introduced into the reactor [g];
U: Conversion of starting material (where U is calculated according to GI.4).
Gl. 4:

_Mrein : flow rate [mol / s] of the starting material ortho-xylene supplied to the catalyst packing;
M _ras : flow rate of the starting material ortho-xylene leaving the catalyst charge [mol / s]
Product selectivity _{S P} is, Gl. Calculated according to 5:
Gl. 5:

_Mrein : flow rate [mol / s] of the starting material ortho-xylene supplied to the catalyst packing;
M _ras : flow rate of the starting material ortho-xylene leaving the catalyst charge [mol / s]
_MPA : flow rate of product phthalic anhydride leaving catalyst packing [mol / s]
M _TA : flow rate of product tolualdehyde leaving catalyst charge [mol / s]
M _TAc : flow rate of product toluic acid leaving catalyst packing [mol / s]
M _PD : Flow rate of product phthalide leaving catalyst packing [mol / s]

  The results of the catalytic characterization of the example according to the invention (see Example 1) and the comparative examples not according to the invention (see Comparatives 1-4) are shown in FIGS. 1 and 2, respectively.

Example 1
194.3 g of anatase-modified TiO ₂ (Titandioxide DT20, Cristal Global) was mixed vigorously with 7.72 g of Sb ₂ O ₃ (Antimontrioxide reinst, Merck) using a drum hoop mixer and then in air at 500 ° C. for 6 hours. Baking. In order to dissolve the unbound Sb ₂ O ₃ , the powder obtained is suspended a total of three times at room temperature with 500 ml of 6 molar hydrochloric acid, and after one hour is filtered through a white band filter (Weissbandfilter). The resulting powder is finally washed a total of four times with 300 mL of deionized water without chloride, filtered using a white band filter and dried overnight at 80 ° C. in air. The resulting antimony-doped titanium dioxide support has an antimony content of 1.5% by weight.

For the production of shaped catalyst bodies, 131.9 g of antimony-doped TiO ₂ , 10.9 g of V ₂ O ₅ (Vanadiumpentoxide purum, Treibacher Industry AG) and 0.779 g of Cs ₂ SO ₄ (700 mL of deionized water) A suspension of Caesiumsulfat, Rockwood Lithium GmbH) is prepared. A further 121.6 g of binder (vinyl acetate / ethylene copolymer) are added to the suspension. As inert carrier, a 2500 g steatite ring having the following dimensions is used: 6 (height) x 5 (outer diameter) x 4 (inner diameter) mm. The suspension is applied to the ceramic support in a fluidized-bed process at 70 ° C. using a fluidized-bed apparatus (for example, the apparatus described in DE 197 09 589 A1). The final properties of the produced catalyst are summarized in Table 1.

Comparison 1
194.3 g of anatase-modified TiO ₂ (Titandioxide DT20, Crystal Global) was mixed vigorously with 16.47 g of V ₂ O ₅ (Vanadium pentoxid purum, Treibacher Industrie AG) using a drum hoop mixer and then for 6 hours in air using a drum hoop mixer. Bake at 500 ° C.

For the production of shaped catalyst bodies, 140.5 g of vanadium-doped TiO ₂ , 2.15 g of Sb ₂ O ₃ (Antimontrioxide reinst, Merck) and 0.779 g of Cs ₂ SO ₄ (Caesium sulfate) in 700 mL of deionized water , Rockwood Lithium GmbH). A further 121.6 g of binder (vinyl acetate / ethylene copolymer) are added to the suspension. As inert carrier, a 2500 g steatite ring having the following dimensions is used: 6 (height) x 5 (outer diameter) x 4 (inner diameter) mm. The suspension is applied to the ceramic support in a fluidized-bed process at 70 ° C. using a fluidized-bed apparatus (for example, the apparatus described in DE 197 09 589 A1). The final properties of the produced catalyst are summarized in Table 1.

Comparison 2
For the production of shaped catalyst bodies, 129.1 g of anatase-modified TiO ₂ (Titandioxide DT20, Cristal Global) in 1700 g of deionized water, 10.9 g of V ₂ O ₅ (Vanadiumpentoxide purum, Treibacher Industrie AG, 2) _Sb 2 _O 3 of .15g (Antimontrioxid reinst, Merck) and 0.779g of _{Cs 2 SO 4 (Caesiumsulfat, Rockwood} Lithium GmbH) preparing a suspension of. A further 121.6 g of binder (vinyl acetate / ethylene copolymer) are added to the suspension. As inert carrier, a 2500 g steatite ring having the following dimensions is used: 6 (height) x 5 (outer diameter) x 4 (inner diameter) mm. The suspension is applied to the ceramic support in a fluidized-bed process at 70 ° C. using a fluidized-bed apparatus (for example, the apparatus described in DE 197 09 589 A1). The final properties of the produced catalyst are summarized in Table 1.

Comparison 3
21.9 g of V ₂ O ₅ (Vanadium pentoxide purum, Treibacher Industrie AG) is mixed vigorously with 4.78 g of Sb ₂ O ₃ (Antimontrioxide reinst, Merck) using a drum hoop mixer and then at 500 ° C. for 6 hours in air. Baking. The antimony vanadate powder so produced was finally homogenized in a mortar.

For the production of shaped catalyst bodies, 13.3 g of antimony vanadate powder in 700 mL of deionized water, 129.1 g of anatase-modified TiO ₂ (Titandioxide DT20, Cristal Global) and 0.779 g of Cs ₂ SO ₄ ( A suspension of Caesiumsulfat, Rockwood Lithium GmbH) is prepared. A further 121.6 g of binder (vinyl acetate / ethylene copolymer) are added to the suspension. As inert carrier, a 2500 g steatite ring having the following dimensions is used: 6 (height) x 5 (outer diameter) x 4 (inner diameter) mm. The suspension is applied to the ceramic support in a fluidized-bed process at 70 ° C. using a fluidized-bed apparatus (for example, the apparatus described in DE 197 09 589 A1). The final properties of the produced catalyst are summarized in Table 1.

Claims (14)

The catalyst material containing hydrocarbons to oxidized with gaseous oxygen, and V, and the TiO ₂ material is doped with Sb. TiO ₂ material and having an anatase modification, the catalyst material of claim 1. _{3. The} catalyst material according to claim 1, wherein the TiO ₂ material contains 0.01 to 5.0% by weight of Sb based on the mass of the catalyst material. 4. The catalyst material according to TiO ₂ material, characterized in that V is a carrier material which is present in oxide form on the surface, any one of claims 1 to 3. It characterized by having a BET surface area in the range between 15~25m ² / g, the catalytic material according to any one of claims 1 to 4. Of a hydrocarbon as a carrier material in the catalyst material for the oxidation with gaseous oxygen, the use of the doped TiO ₂ material Sb.   A method for oxidizing hydrocarbons using gaseous oxygen, comprising contacting the hydrocarbons to be oxidized and oxygen with the catalyst material according to claim 1.   A shaped catalyst body containing an inert carrier, wherein the shaped catalyst material according to claim 1 is applied on the carrier.   A catalyst layer in the reactor, wherein the catalyst layer is made of the shaped catalyst article according to claim 8.   A reactor with a gas inlet side for the starting material gas and a gas outlet side for the product gas and a first catalyst layer made of shaped catalyst and at least one second catalyst layer made of shaped catalyst. A catalyst device for hydrocarbon oxidation, wherein one of the catalyst layers comprises the catalyst material of claim 1.   The catalyst device according to claim 10, wherein the catalyst layer located closest to the gas outlet side includes a catalyst molded body containing the catalyst material according to claim 1. A method for producing a catalyst material according to any one of claims 1 to 5, comprising the following steps:
a) producing a mixture of TiO ₂ and Sb ₂ O ₃ ;
b) firing a mixture of TiO ₂ and Sb ₂ O ₃ to obtain a Sb-doped TiO ₂ material;
c) impregnating the Sb-doped TiO ₂ material with a V-containing compound. Characterized by treating the doped TiO ₂ material with acid in Sb from step b), The method of claim 12. Wherein the V-containing compounds of the is a V ₂ O _5, The method of claim 12 or 13.