JPH024525B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel substituted solid solution crystalline oxide useful as a precursor of a gas phase oxidation catalyst, particularly a catalyst for producing maleic anhydride from _C4 hydrocarbons. As a catalyst for producing maleic anhydride by gas phase oxidation of _C4 hydrocarbons, V-P-O complex oxides (JP-A No. 48-63982, No. 51-95990, No. 52-156193,
53-146992, Special Publication No. 53-39037, etc.), or
Multi-component oxide catalysts containing vanadium, phosphorus, and iron or chromium as a third component (Japanese Patent Publications No. 53-43928, No. 53-43929, No. 53-60391,
53-61587, USP3, 156, 705, etc.) are known. Among these known oxide catalysts, the former is a crystalline oxide, and the latter is amorphous. As a result of various studies on the suitability of multi-component oxidation catalysts for gas phase oxidation reactions, the present inventor found that catalysts made by simply adding a third component such as cobalt or nickel to a crystalline vanadium-phosphorus oxide were not known in the art. Compared to the crystalline vanadium-phosphorus oxide of
Although the activity and selectivity in gas-phase oxidation reactions are lower, new substituted solids obtained by substituting cobalt, nickel, titanium, etc. for a part of vanadium without destroying the crystal structure of crystalline vanadium-phosphorus oxides. The present invention was achieved by discovering that a dissolved crystalline oxide can serve as a precursor for a gas-phase oxidation catalyst with high activity and excellent selectivity. The present invention will be explained in detail below. The substituted solid solution crystalline oxide of the present invention consists of vanadium, phosphorus, oxygen, hydrogen and titanium, or further includes manganese, cobalt, nickel, iron,
It is a crystalline oxide that also contains an element selected from chromium and aluminum, and is a blue crystal in which a part of the vanadium forming the crystal is replaced with a metal other than the vanadium. The composition of the substituted solid solution crystalline oxide excluding oxygen, hydrogen, and water of crystallization is the following formula [] V _1.0-abc Ti _a X _b Y _c P _1.0 ... [] (However, Y represents at least one selected from Fe, Cr, and Al.
represents at least one type selected from 0<a≦
0.4, preferably 0.001≦a≦0.4, more preferably 0.005≦a≦0.25, 0≦b≦0.4, preferably
0.001≦b≦0.4, more preferably 0.005≦b≦
0.25, 0<a+b≦0.4 preferably 0.001≦a+b
≦0.4, more preferably 0.005≦a+b≦0.25,
0≦c≦0.4, preferably 0≦c≦0.2, 0<a+
b+c≦0.4, preferably 0.001≦a+b+c≦
0.4, more preferably 0.005≦a+b+c≦0.25
It is. ). The substituted solid solution type crystalline oxide of the present invention is disclosed in Japanese Unexamined Patent Publication No. 51
It shows an X-ray diffraction pattern that almost matches that of the vanadium-phosphorus crystalline oxide described in the specification of 95990, and the diffraction angle and intensity of the diffraction peak are as follows:
As shown in Table 1 below,

[Table] As the degree of vanadium substitution increases, the diffraction angle tends to shift very slightly. Raw materials for producing the substituted solid solution crystalline oxide of the present invention include pentavalent vanadium compounds such as vanadium pentoxide, metavanadic acid, pyrovanadic acid, vanadium oxytrichloride, and tetravalent vanadium compounds such as vanadium oxydichloride. vanadium compounds, pentavalent phosphorus compounds such as phosphorus pentoxide, orthophosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, phosphorus oxytrichloride, halides such as chlorides of manganese, cobalt, and nickel, organic acid salts such as acetates, hydroxides, carbonates or nitrates, chlorides or sulfates of titanium,
Halide oxyacids or acetates of iron, chromium, and aluminum are used. When a pentavalent vanadium compound is used as a raw material, a reducing agent such as hydrazine, hydroxylamine, or their hydrohalides or hydrogen halides is used in combination to reduce the oxyacid of tetravalent vanadium or pentavalent phosphorus. The substituted solid solution type crystalline oxide of the present invention can be obtained by preparing a homogeneous aqueous solution containing halogen ions, other metal components, and halogen ions, and performing techniques such as concentration and evaporation to dryness. Furthermore, by adding a hydrogen halide scavenger such as ethylene oxide or ethylene carbonate prior to concentrating the aqueous solution, it is possible to increase the purity of the crystals and obtain crystals with a high specific surface area. Alternatively, the purity of the crystals can be increased by evaporating to dryness to remove most of the hydrogen halide, followed by adding water and washing by boiling to remove soluble substances. The usage ratio of each raw material is preferably 0.8 to 1.25, especially 1.00 to 1.10 in atomic ratio of phosphorus to the total of vanadium and metal components other than vanadium, and The atomic ratio of the metal components is preferably adjusted to the ratio shown in the above formula []. Also, the initial concentration of phosphoric acid in the aqueous solution is 5~
It is adjusted to 50% by weight, preferably 10 to 35% by weight. The substituted solid solution type crystalline oxide of the present invention is prepared by supporting it on a carrier or molding it by a conventional method,
By calcining at °C, the gas phase oxidation catalyst, especially
It can be used as a catalyst for producing maleic anhydride from _C4 hydrocarbons. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Example 1 An aqueous solution of 2.378 g of hydrazine dihydrochloride dissolved in 50 ml of water was added to 40 ml of a 2.52 M aqueous orthophosphoric acid solution, and vanadium pentoxide was added in a flask equipped with a reflux condenser while stirring on a water bath at 75°C. 8.2379g was added in portions. For about 30 minutes, gases such as nitrogen were generated as the reduction of vanadium progressed, but after almost no bubbling was observed, the temperature was kept at about 100℃ for 30 minutes.
The reduction was completed by boiling and refluxing. After cooling, add 0.573 g of titanium tetrachloride and 1.676 g of cobalt chloride to 10 ml of water.
Add the dissolved solution to 100 ml for 1 hour again.
Boiling and refluxing was carried out at °C. Next, the inner solution was transferred to an evaporating dish, and the inner solution was dried in a constant temperature bath at 130° C. while stirring until the odor of hydrochloric acid was no longer observed. Approximately 100 ml of water was added to the precipitate and the mixture was boiled, filtered, washed with water, and dried to obtain blue crystals. Obtained crystal Co/Ti atomic ratio 7/3, (Co+Ti)
(V+Co+Ti) atomic ratio 0.1, P/(V+Co+Ti)
The atomic ratio was 1.0, and as a result of analysis using an X-ray diffraction spectrum (anticathode; Cu-Kα), an X-ray diffraction pattern almost identical to that described in Table 1 was obtained. [X-ray spectrum diagram (Anticathode: Cu-Kα)
is shown in Figure 1. ] Also, 2θ≒27.0 and 2θ≒
Table 2 shows the results of precisely measuring the interplanar spacing of the 24.2° diffraction peak using an α-alumina internal standard (λ = 1.54050 Å) and the yield. Comparative Example 1 11.529 g of 85% by weight orthophosphoric acid was added to 60 ml of water, and 2.625 g of hydrazine dihydrochloride was added to 30 ml of water.
An aqueous solution obtained by dissolving the mixture was added. This aqueous solution was heated to 80°C on a water bath, and 9.095% vanadium pentoxide was added.
g was added little by little with stirring, stirring was continued for 30 minutes, and boiling and refluxing was carried out at approximately 100° C. for another 30 minutes to obtain a blue aqueous solution. The resulting aqueous solution was evaporated to dryness in a constant temperature bath at 130°C in the same manner as in Example 1 to obtain pale blue crystals. The P/V ratio of the obtained crystal was 1.0, and the X-ray diffraction pattern matched that shown in Table 1. In addition, Table 2 shows the results of precision measurement of interplanar spacing and yield for the diffraction peaks at 2θ≒27.0° and 2θ≒24.2°.

[Table] Example 2 Titanium tetrachloride 0.573g and iron trichloride (FeCl ₃ 6H ₂ O) instead of titanium tetrachloride and cobalt chloride
A substituted solid solution crystalline oxide was prepared in the same manner as in Example 1 using 1.892 g, and the Fe/Ti atomic ratio was 7/3.
(Fe+Ti)/(V+Fe+Ti) atomic ratio 0.1, P/
A yield of 14.2 g of blue crystals with a (V+Fe+Ti) atomic ratio of 1.0 was obtained. Reaction usage example Substituted solid solution type crystalline oxide produced in Examples 1 and 2, V-P- produced in Comparative Example 1
O-based crystalline oxide and 7.74 g of the crystalline oxide produced in Comparative Example 1 and nickel phosphate (Ni ₃
(PO ₄ ) ₂ ) 1.647g mixture (composition; V _1.0 N _i0.1 P _1.07 )
Each was baked at 550℃ for 2 hours under a nitrogen stream,
Formed into tablets of 7 mmφ x 3 mm and then crushed into 14 to 24
A catalyst with particle size of mesh (JIS standard) was obtained. 0.5ml of the above catalyst was packed into a glass microreactor with an inner diameter of 6mm, and air containing 1.5% by volume of n-butane was passed through it at a GHSV of 500hr ^-1 or 2000hr ^-1 . A gas phase oxidation reaction was performed. The reaction product gas was directly introduced into a gas chromatograph through a heat-insulated gas sampler, and analyzed and quantified. Table 3 shows the GHSV, optimum reaction temperature, n-butane conversion rate, and maleic anhydride yield for each catalyst.

【table】 [Brief explanation of drawings]

Figure 1 shows the crystalline oxide X obtained in Example 1.
This is a line diffraction spectrum.

Claims (1)

[Claims] 1 Consists of vanadium, phosphorus, oxygen, hydrogen and titanium, or further contains manganese, cobalt,
A crystalline oxide also containing an element selected from nickel, iron, chromium and aluminum,
In line diffraction spectrum (anticathode; Cu-Kα)
A crystalline oxide having the same crystal form as a crystalline oxide composed of vanadium, phosphorus, and oxygen having peaks at diffraction angles (2θ) of 15.7°, 19.8°, 24.4°, 27.3°, 30.6°, and 40.6°. 1. A substituted solid solution type crystalline oxide, characterized in that - part of vanadium is substituted with a metal other than vanadium.