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Method for production of hydroxylammonium phosphate in the synthesis of caprolactam

A technology of caprolactam and oxygen, which is applied to the preparation of lactam, oxime preparation, chemical instruments and methods, etc., can solve the problems of increased production capacity, large capital investment, etc., and achieve the effect of reducing residence time

Inactive Publication Date: 2004-06-30
PRAXAIR TECH INC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the increase in production capacity of such equipment requires a large amount of capital investment

Method used

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  • Method for production of hydroxylammonium phosphate in the synthesis of caprolactam
  • Method for production of hydroxylammonium phosphate in the synthesis of caprolactam
  • Method for production of hydroxylammonium phosphate in the synthesis of caprolactam

Examples

Experimental program
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Effect test

Embodiment

[0060] The process of the present invention is used to retrofit an existing caprolactam production plant using the DSM-HPO process, where the upper part of the absorption tower has been damaged. This in turn reduces the reoxidation of NO to NO by the absorber 2 and the ability to absorb nitrate ions. As a result, production is limited and nitrogen oxide emissions increase.

[0061] test

[0062] Therefore, in these tests, about 50-100% of the secondary air stream was diverted from the deaerator to the converter. Oxygen is added at a rate of 3.2-3.8 moles per mole of ammonia added. Oxygen addition removes dissolved NO from nitrate-rich stream 2 , thereby helping to increase NO to NO 2 oxidation and an increase in hydroxylammonium phosphate production of up to 9.8%. Furthermore, said increase in the production of hydroxylammonium phosphate is obtained without an increase in the nitrogen oxide content of the exhaust gas.

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Abstract

A method for production of caprolactam involves: reacting air with ammonia gas in an ammonia conversion zone to produce nitric oxide; oxidizing at least a portion of the nitric oxide to nitrogen dioxide to produce an NOx-rich process gas stream; reactively absorbing the NOx-rich gas stream with phosphoric acid containing solution in an absorption zone to form nitrate ions; contacting the nitrate ions with air in a degassing zone to produce a nitrate-rich aqueous process stream; reducing the nitrate-rich aqueous stream with hydrogen in the presence of phosphoric acid to produce hydroxylammonium phosphate; oximating the hydroxylammonium phosphate with cyclohexanone to produce cyclohexanone oxime; and converting the cyclohexanone oxime to caprolactam. Supplemental oxygen is added downstream of the ammonia conversion zone to increase the quantity and rate of formation of nitrogen dioxide in the NOx-rich process gas stream.

Description

technical field [0001] The present invention provides improvements to the Dutch State Mines-hydroxyammonium phosphate-oxime process for the preparation of caprolactam. Background technique [0002] Caprolactam can be produced from three hydrocarbon feedstocks: cyclohexane, phenol and toluene. About 68% of the world's caprolactam is produced from cyclohexane, while 31% comes from phenol and 1% from toluene. All production based on cyclohexane and phenol takes place through the formation of cyclohexanone oxime. In 94% of caprolactam production based on cyclohexane and phenol, the formation of this oxime requires an ammoxidation step. [0003] In processes involving an ammoxidation step, the preparation of caprolactam with cyclohexane or phenol can be divided into the following steps: [0004] Oxidation of cyclohexane or hydrogenation of phenol to synthesize cyclohexanone; [0005] Oxidation of ammonia to nitric oxide, followed by various reaction steps to form hydroxylamin...

Claims

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Application Information

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IPC IPC(8): C07D201/06C07D201/10
CPCC07D201/06C07D201/10C01B21/1418C07C249/08C07C2601/14C07C251/44C07D227/087
Inventor D·F·埃切加赖A·A·M·维洛索M·L·瓦格纳
Owner PRAXAIR TECH INC
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