EP0264747A1
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EP
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Process for preparation of an oxidation catalyst
Assignee: Polynt SpA
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Filing: 1987-10-09
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Granted: —
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Expires: 2007-10-09
Abstract
Abstract An oxidation catalyst formed from V₂0₅ and TiO₂ of rutile structure is obtained by a process which comprises the following stages: a) preparation of a solution of Ti(IV) by dissolution (partial hydrolysis) of TiCl₄ in an aqueous solution at a final pH below 1.0, b) preparation of a solution of V(IV) by heating, in order to dissolve it, solid V₂0₅ suspended in an aqueous oxalic acid solution, c) precipitation of metatitanic acid from the Ti(IV) solution at a pH not higher than 1.3, d) precipitation of vanadium oxide from the said V(IV) solution in the presence of the metatitanic acid obtained in (c), and e) separation of the precipitate, drying and calcination thereof at elevated temperature. This gives a catalyst formed from V₂0₅ and TiO₂ of rutile structure, which has a specific surface area of the order of 10-60 m²/g, is highly active, selective and stable under conditions of catalytic oxidation, especially under the conditions of the oxidation of o-xylene to phthalic anhydride.
Inventors
- 👤 Alfredo Riva
- 👤 Fabrizio Cavani
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 16:17
CPC Classifications
B; B01; B01J; B01J21/00; B01J21/06; B01J21/063; B01J23/00; B01J23/16; B01J23/20; B01J23/22; B01J27/00; B01J27/14; B01J27/186; B01J27/195; B01J27/198; B01J37/00; B01J37/02; B01J37/03; C; C01; C01G; C01G23/00; C01G23/04; C01G23/047; C01G23/053; C01G23/0536; C01G31/00; C07; C07C; C07C51/00; C07C51/16; C07C51/21; C07C51/255; C07C51/265; B01J35/00; B01J35/60; B01J35/61; B01J35/613; C01P; C01P2006/00; C01P2006/12
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
36 words
An oxidation catalyst, which comprises vanadium pentoxide and titanium dioxide of rutile structure, the said catalyst containing 1-50% by weight of vanadium pentoxide and having a surface area in the range from 10 to 60 m²/g.
Claim 2
Dependent Claim
36 words
An oxidation catalyst, which comprises vanadium pentoxide and titanium dioxide of rutile structure, the said catalyst containing 1-50% by weight of vanadium pentoxide and having a surface area in the range from 10 to 60 m²/g.
Claim 3
Dependent Claim
15 words
A catalyst as claimed in claim 1, which contains 10-20% by weight of vanadium pentoxide.
Claim 4
Dependent Claim
32 words
A catalyst as claimed in claim 1 or 2, which also contains at least one oxidation promoter selected from the group comprising potassium, rubidium , cesium, antimony, boron, phosphorus and mixtures thereof.
Claim 5
Dependent Claim
127 words
A process for preparing an oxidation catalyst as claimed in any one of claims 1 to 3, which comprises the following stages: a) preparation of a solution of Ti(IV) by partial hydrolysis of TiCl₄ in an aqueous solution at a temperature below 50°C and a final pH below 1.0, b) preparation of a solution of V(IV) by dissolving, by means of heating, solid V₂0₅ suspended in an aqueous oxalic acid solution, c) precipitation of metatitanic acid from the said Ti(IV) solution, while maintaining the pH at no higher than 1.3, d) precipitation of vanadium oxide from the said V(IV) solution in the presence of the metatitanic acid obtained in (c), and e) separation of the precipitate obtained in (d), drying and calcination thereof at temperatures above 300°C.
Claim 6
Dependent Claim
28 words
The process as claimed in claim 4, wherein the partial hydrolysis stage (a) is carried out in an aqueous hydrochloric acid solution to a final pH of 0.
Claim 7
Dependent Claim
24 words
The process as claimed in claim 4, wherein the partial hydrolysis stage (a) is carried out in water in the absence of added acid.
Claim 8
Dependent Claim
28 words
The process as claimed in any one of claims 4 to 6, wherein the molar oxalic acid/vanadium ratio varying from 0.5/1 to 2/1 is used in stage (b).
Claim 9
Dependent Claim
25 words
The process as claimed in any one of claims 4 to 7, wherein stage (b) is carried out at a temperature from 40 to 70°C.
Claim 10
Dependent Claim
54 words
The process as claimed in any one of claims 4 to 8, wherein the metatitanic acid precipitation stage (c) is carried out by introducing an alkalizing agent into the Ti(IV) solution until a pH no higher than 1.3 is reached, the solution being stirred at a temperature in the range from 20 to 90°C.
Claim 11
Dependent Claim
14 words
The process as claimed in claim 9, wherein the said alkalizing agent is ammonia.
Claim 12
Dependent Claim
39 words
The process as claimed in any one of claims 4 to 8, wherein stage (c) is carried out in the absence of an alkalizing agent at a pH below 1 and at a temperature in the range from 55-95°C.
Claim 13
Dependent Claim
71 words
The process according to any one of claims 4 to 11, which comprises, before the said stage (c), a stage of mixing the said Ti(IV) and V(IV) solutions, prepared in stages (a) and (b) respectively, in such a ratio that a Ti/V atomic ratio from 1 to 100 is obtained in the resulting mixture, the said stage (c) carried out on this mixture leading to a selective precipitation of metatitanic acid.
Claim 14
Dependent Claim
62 words
The process as claimed in any one of claims 4 to 12, wherein the said stage (d) is carried out by introducing an alkalizing agent into a mixture of the said V(IV) solution and the metatitanic acid precipitated in (c), until a pH of about 5 is reached, the mixture being stirred at a temperature in the range from 20 to 90°C.
Claim 15
Dependent Claim
14 words
The process as claimed in claim 13, wherein the said alkalizing agent is ammonia.
Claim 16
Dependent Claim
50 words
The process as claimed in any one of claims 4 to 12, wherein the said stage (d) is carried out by subjecting a mixture of the said V(IV) solution and the metatitanic acid precipitated in (c) to evaporation under a pressure which varies from atmospheric pressure to a reduced pressure.
Claim 17
Dependent Claim
57 words
The process as claimed in any one of claims 4 to 15, which also comprises the addition, in one of stages (a), (b) or the mixing of the Ti(IV) and V(IV) solutions before stage (c), of an oxidation promoter selected from the group comprising potassium, rubidium, cesium, antimony, boron, phosphorus, molybdenum, tungsten, their precursors and their mixtures.
Claim 18
Dependent Claim
160 words
A process for preparing an oxidation catalyst containing 1-50% by weight of V₂0₅, the remainder being TiO₂ of rutile structure, and having a surface area of 10-60 m²/g, which comprises the following stages: a) preparation of a solution of Ti(IV) by partial hydrolysis of TiCl₄ in an aqueous solution at a temperature below 50°C and a final pH below 1.0, b) preparation of a solution of V(IV) by dissolving, by means of heating, solid V₂0₅ suspended in an aqueous oxalic acid solution, i) mixing of the said solutions prepared in (a) and (b) to obtain a mixture containing a Ti/V atomic ratio in the range from 1 to 100, c) selective precipitation of metatitanic acid from the said mixture, while maintaining the pH at no higher than 1.3, d) precipitation of vanadium oxide on the metatitanic acid from the solution obtained in (c), and e) separation of the coprecipitate obtained in (d), drying and calcination thereof at temperatures above 300°C.
Claim 19
Dependent Claim
160 words
A process for preparing an oxidation catalyst containing 1-50% by weight of V₂0₅, the remainder being TiO₂ of rutile structure, and having a surface area of 10-60 m²/g, which comprises the following stages: a) preparation of a solution of Ti(IV) by partial hydrolysis of TiCl₄ in an aqueous solution at a temperature below 50°C and a final pH below 1.0, b) preparation of a solution of V(IV) by dissolving, by means of heating, solid V₂0₅ suspended in an aqueous oxalic acid solution, i) mixing of the said solutions prepared in (a) and (b) to obtain a mixture containing a Ti/V atomic ratio in the range from 1 to 100, c) selective precipitation of metatitanic acid from the said mixture, while maintaining the pH at no higher than 1.3, d) precipitation of vanadium oxide on the metatitanic acid from the solution obtained in (c), and e) separation of the coprecipitate obtained in (d), drying and calcination thereof at temperatures above 300°C.
Claim 20
Dependent Claim
148 words
A process for preparing an oxidation catalyst containing 1-50% by weight of V₂0₅, the remainder being TiO₂ of rutile structure, and having a surface area of 10-60 m²/g, which comprises the following stages: a) preparation of a solution of Ti(IV) by partial hydrolysis of TiCl₄ in an aqueous solution at a temperature below 50°C and a final pH below 1.0, b) preparation of a solution of V(IV) by dissolving, by means of heating, solid V₂0₅ suspended in an aqueous oxalic acid solution, c) precipitation of metatitanic acid from the said Ti(IV) solution, while maintaining the pH at no higher than 1.3, ii) mixing of the product obtained in (c) with the V(IV) solution obtained in (b), d) precipitation of vanadium oxide on the metatitanic acid from the mixture obtained in (ii), and e) separation of the coprecipitate obtained in (d), drying and calcination thereof at temperatures above 300°C.
Claim 21
Dependent Claim
148 words
A process for preparing an oxidation catalyst containing 1-50% by weight of V₂0₅, the remainder being TiO₂ of rutile structure, and having a surface area of 10-60 m²/g, which comprises the following stages: a) preparation of a solution of Ti(IV) by partial hydrolysis of TiCl₄ in an aqueous solution at a temperature below 50°C and a final pH below 1.0, b) preparation of a solution of V(IV) by dissolving, by means of heating, solid V₂0₅ suspended in an aqueous oxalic acid solution, c) precipitation of metatitanic acid from the said Ti(IV) solution, while maintaining the pH at no higher than 1.3, ii) mixing of the product obtained in (c) with the V(IV) solution obtained in (b), d) precipitation of vanadium oxide on the metatitanic acid from the mixture obtained in (ii), and e) separation of the coprecipitate obtained in (d), drying and calcination thereof at temperatures above 300°C.
Claim 22
Dependent Claim
19 words
An oxidation process, which comprises using an oxidation catalyst as claimed in any one of claims 1 to 3.
Claim 23
Dependent Claim
24 words
A process for oxidizing o-xylene to phthalic anhydride, which comprises using an oxidation catalyst as claimed in any one of claims 1 to 3.
Claim 24
Dependent Claim
28 words
A process for oxidizing o-xylene to phthalic anhydride, which comprises using an oxidation catalyst prepared by a process as claimed in any one of claims 4 to 18.
References Cited (Backward Citations)
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