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Method for producing phthallic anhydride

A technology of phthalic anhydride and ortho-xylene, which is applied in the field of gas-phase catalytic oxidation reaction for preparing phthalic anhydride, can solve the problems of decreased phthalic anhydride yield, increased content of irritating gas, and high content of ortho-xylene, and can reduce the The content of main impurity phthalide, the effect of overcoming irritation and improving product quality

Active Publication Date: 2008-02-27
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Even by improving the catalyst composition and increasing the amount of o-xylene, it is difficult to ensure that the catalyst has good phthalic anhydride selectivity and product quality
Especially in the high load state of o-xylene, for example, when the o-xylene concentration reaches 80g / m 3 When above, the conversion rate of o-xylene decreases, and the content of o-xylene in the reaction gas is high, and phthalide, benzoic acid, benzaldehyde, methylbenzoic acid, methylbenzaldehyde and citrafuric anhydride, etc. also have a significant increase, making the phthalic anhydride yield The rate of decline will affect the quality of phthalic anhydride products, and due to the increase of intermediate products, the content of irritating gases in the tail gas will increase, which will bring serious environmental protection problems. Therefore, the performance of the catalyst needs to be further improved and improved, especially to improve the thermal stability and selection of the catalyst. sex

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] It is a two-stage bed, and catalyst I and catalyst III are used to form a catalytic reaction system. In a reaction tube with an inner diameter of 25mm and a tube length of 4000mm, the upper bed is filled with catalyst I, and the filling height is 1700mm, and the lower bed is filled with catalyst III. The filling height is 1500mm. The reaction heat is removed by forcing the molten salt in the outer jacket of the reaction tube to flow, and the reaction temperature is measured by a multi-point thermocouple in the reaction tube.

[0054] At an air flow rate of 4Nm 3 / h, the concentration of o-xylene is 83g / Nm 3 , when the salt bath temperature was 357°C, the yield of phthalic anhydride was 113%. The hot spot temperature of the catalyst is 430°C-440°C, and the hot spot position is located within the catalyst bed at a distance of 500mm-600mm from top to bottom. Through sampling analysis, the content of phthalide in the reaction gas was 0.05%.

Embodiment 2

[0056] It is a two-stage bed layer, and catalyst II and catalyst IV are used to form a catalytic reaction system, and the reaction device is the same as in Example 1. The upper bed is filled with catalyst I with a packing height of 1700 mm, and the lower bed is filled with catalyst III with a packing height of 1500 mm. At an air flow rate of 4Nm 3 / h, the concentration of o-xylene is 81g / Nm 3 , when the salt bath temperature was 356°C, the yield of phthalic anhydride was 113%. The hot spot temperature of the catalyst is 430°C-445°C, and the hot spot position is located within the catalyst bed at a distance of 500mm-600mm from top to bottom. In the reaction gas, the content of phthalide is 0.05%.

Embodiment 3

[0058]It is a three-stage bed, and catalyst I, catalyst II, and catalyst III are used to form a catalytic system, and the reaction device is the same as in Example 1. The upper bed is filled with catalyst I with a packing height of 1300 mm, the middle bed is filled with catalyst II with a packing height of 800 mm, and the lower bed is filled with catalyst III with a packing height of 1300 mm. At an air flow rate of 4Nm 3 / h, the concentration of o-xylene is 85g / Nm 3 , when the salt bath temperature was 355°C, the yield of phthalic anhydride was 114%. The hot spot temperature of the catalyst is 440-450°C, and the hot spot position is located within the catalyst bed at a distance of 500-600mm from top to bottom. In the reaction gas, the content of phthalide is 0.05%.

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Abstract

The invention discloses a preparing method of ortho-phthalic anhydride, which is characterized by the following: choosing ortho-xylene and naphthalene as raw material; proceeding gas phase catalytic oxidation reaction; adopting two-phase, three-phase bed or four-phase bed V-Ti type accelerant; setting the accelerant as carrier material; coating catalytic activity matter with vanadic oxide and titanium oxide on the carrier; choosing compound from free alkali metal, Sb, P and Nb; adding as catalyst promoter. This invention can modify composite of the reacting rear gas, which can be used to organic chemical industry domain.

Description

technical field [0001] The invention relates to a method for preparing phthalic anhydride, in particular to a method for preparing phthalic anhydride by gas-phase catalytic oxidation reaction using o-xylene and naphthalene as raw materials. Background technique [0002] To produce phthalic anhydride (phthalic anhydride) by fixed-bed catalytic oxidation of o-xylene and / or naphthalene as raw material, V-Ti type catalyst is generally used, that is, V 2 o 5 and TiO 2 It is a catalytically active substance, and at least one compound selected from the group consisting of alkali metals, Sb, P, Nb, Ag, Zr, W, Au, Sn, Bi, etc. is added as a cocatalyst, and a non-porous inert carrier material is used. The catalyst is prepared by coating the catalytically active material on an inert, non-porous carrier in the form of a thin layer, usually 0.02 to 2 mm. [0003] However, the catalysts in the prior art are not satisfactory in terms of catalytic activity, suppression of by-product form...

Claims

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Application Information

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IPC IPC(8): C07D307/89
Inventor 盛丁杰吴保军卢灏罗国庆张晓锋赵彦霞胡英花王刚
Owner CHINA PETROLEUM & CHEM CORP
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