Method for improving sulfonation process of naphthalene-based water reducer

Abstract

The invention relates to a method for improving the sulfonation process of a naphthalene-based water reducer, characterized by cascading a heat exchanger and a vacuum-pumping device to the cover of a reaction vessel, sulfonating the naphthalene-based water reducer for 0.5-1h, then generating negative pressure by extracting the gas of the reaction vessel every 0.5 h to bring out the moisture generated by the reaction; simultaneously letting in steam to the air inlet of the heat exchanger while extracting to let the industrial naphthalene volatilized and crystallized in the extracting process melt and relux to the sulfonation system and circulate continuously to be sulfonated, after finishing the sulfonation reaction, conducting hydrolysis, condensation and neutralization to obtain a powder product. According to the invention, the content of the toxic raw material industrial naphthalene in the water reducer is reduced, the production cost is reduced, the pollution of the materials to the environment is eliminated, and the method is easy to operate, and the operation is convenient.

Description

technical field [0001] The invention relates to a naphthalene-based water-reducer used in concrete, in particular to a method for improving the sulfonation process of the naphthalene-based water-reducer. Background technique [0002] Due to the needs of industrial development, people have put forward higher and higher requirements for the performance of concrete, and a necessary condition for realizing high-performance concrete is the use of high-efficiency water reducing agent, which can not only improve construction conditions, but also increase the compressive strength of concrete , but also can enhance the performance of concrete such as frost resistance and impermeability, and is considered to be the fifth component necessary for concrete. At present, most of the high-efficiency water reducers used in China are naphthalene-based water reducers, accounting for more than 60% of the market. [0003] The production method of naphthalene-based water reducer is relatively ma...

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Problems solved by technology

However, this method has serious defects. During the sulfonation reaction of naphthalene-based water reducers, at a temperature of 160-165°C, the molar ratio of naphthalene to concentrated sulfuric acid is 1:1.3-1.45. After 2.5-4h of sulfonation, industrial naphthalene is Sulfonation into naphthalenesulfonic acid and water mainly composed of β-naphthalenesulfonic acid and supplemented by α-naphthalenesulfonic acid. Due to the reversibility of the reaction, water is formed in the reaction. The existence of water will affect the deviation of the chemical balance, so that The reaction balance shifts in the opposite direction, so that the sulfonation reaction cannot continue, resulting in a low sulfonation rate. At the same time, the free naphthalene without sulfonation after sulfonation of industrial naphthalene directly enters the condensation stage, and the final neutralization discharge is mixed into the water reducer , not only wasting energy, but also absorbing a small amount of water reducing agent, which affects the performance of the product. The most important thing is that free naphthalene itself has certain toxicity, which is not conducive to the protection of the environment.

To solve this problem, in the prior art, steam is passed into the material being sulfonated to blow out industrial naphthalene, but even so, it still needs to go through collection, separation and post-processing procedures, the process is complicated and the waste is serious

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