Crystallization method of high-purity antioxidant BHT (butylated hydroxytoluene)

Abstract

The invention discloses a crystallization method of high-purity antioxidant BHT (butylated hydroxytoluene). The method comprises the following steps: adding paracresol and isobutanol as raw materials, and adding concentrated sulfuric acid as a catalyst; conducting an alkylation reaction by controlling the temperature and time, wherein the reaction comprises two stages, in the first stage, the alkylation reaction is conducted in vacuum and a constant-temperature mode is adopted for crystallization, and in the second stage, the alkylation reaction is conducted under micro-positive pressure and a direct freezing mode is adopted for crystallization; finally reacting in the presence of the catalyst to obtain an alkylated mixed solution based on antioxidant BHT. According to the method, the yield of the alkylation reaction, the output quantity and the finished product content are increased, and crystal scales or crystal scars formed on the wall of a kettle are reduced; a product is uniform in crystal particles, high in purity, good in glossiness and long in quality guarantee period.

Description

technical field [0001] The invention belongs to the technical field of antioxidant crystallization, and in particular relates to a high-purity antioxidant BHT crystallization method. Background technique [0002] The traditional crystallization method of the antioxidant BHT is to establish the supersaturation in the metastable region under the condition of maintaining a suitable supersaturation. The traditional method is to precipitate crystals by cooling and crystallizing. And the antioxidant BHT is first realized through the alkylation reaction, but the traditional alkylation reaction is two ways of normal pressure reaction and high pressure reaction. And the most critical problem is that it is difficult to control the metastable region of supersaturation in the process of cooling and cooling, resulting in uneven grains in the crystal grains obtained by crystallization (polarization of thickness, all grains are too large, and crystal grains are generally finer. )The phen...

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Problems solved by technology

[0003] The purpose of the embodiments of the present invention is to provide a high-purity antioxidant BHT crystallization method, aiming to solve the problem in the existing technology that it is difficult to control the metastable region of supersaturation in the process of cooling and cooling, resulting in crystallization. The grains of the crystal particles will be uneven, so that the obtained product cannot be fully guaranteed, and the product purity is generally low

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