Decomposition method of CTF in light component in production process of trimethylolpropane by calcium method

Abstract

The invention discloses a method for decomposing CTF in a light component in a calcium-process trimethylolpropane production process, which comprises the following steps: 1) adding the light component separated from a separation tower into a decomposition kettle, adding 85% formic acid accounting for 0.2% of the weight of the light component at the temperature of 140 DEG C, and adding 99% methanesulfonic acid accounting for 0.05% of the weight of the light component; 2) the temperature is 180 DEG C, and the retention time is 2 hours; and 3) separating the trimethylolpropane product from the liquid obtained after the reaction in the decomposition kettle in a negative pressure flash evaporation manner. In the process of producing trimethylolpropane through a disproportionation method, a large amount of CTF is contained in light components, O-C cyclic chemical bonds exist in the chemical structure of the CTF, specific catalysts formic acid and methanesulfonic acid are selected for reaction according to the properties of the light components, and the CTF is converted into the trimethylolpropane, so that the yield of the trimethylolpropane is increased, loss of valuable substances is avoided, and the yield of the trimethylolpropane is increased. Further, the economic benefit of trimethylolpropane production is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of the calcium method for the production of trimethylolpropane, and particularly relates to a method for decomposing CTF in light components during the production process of trimethylolpropane by the calcium method. Background Art

[0002] The chemical name of trimethylolpropane is 2-ethyl-2-hydroxymethyl-1,3-propanediol, abbreviated as trimethylol (TMP). Trimethylol is a polyol containing a neopentyl structure with an α-methyl group. Currently, the industrial production methods are mainly divided into two types: the Cannizzaro disproportionation method and the hydrogenation reduction method. The hydrogenation reduction method is to use a supported catalyst (Pd / C or Pd / Al 2 O 3 ) to carry out hydrogenation reduction of the intermediate after the condensation reaction of formaldehyde and n-butyraldehyde to synthesize trimethylolpropane. The hydrogenation reduction method can obtain a relatively high yield of trimethylolpropane, but it needs to be operated under high temperature and high pressure conditions, and has high requirements for hydrogenation equipment and catalysts. The Cannizzaro disproportionation method uses formaldehyde and n-butyraldehyde as raw materials and inorganic or organic bases as catalysts to produce trimethylolpropane through base-catalyzed condensation reaction and disproportionation reaction. Due to the significant advantages of the traditional Cannizzaro disproportionation method such as mature process, easy operation, and low equipment requirements, it occupies an important position in the industrial production of trimethylolpropane.

[0003] A large amount of trimethylolpropane cyclic formal (abbreviated as CTF) and other low-boiling impurities are produced as side reactions in the Cannizzaro disproportionation method. These low-boiling impurities are enriched in the light components. The valuable CTF contained in the light components is sold together with other low-boiling impurities at a lower price, resulting in a waste of a large amount of valuable substances and reducing the production income of trimethylolpropane.

[0004] Therefore, there is an urgent need in the prior art for a method for decomposing CTF in light components during the production process of trimethylolpropane by the calcium method to avoid the loss of valuable substances, increase the yield of trimethylolpropane, and thus improve the economic benefits of trimethylolpropane production. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies existing in the prior art and provide a method for decomposing CTF in light components during the production process of trimethylolpropane by the calcium method to avoid the loss of valuable substances, increase the yield of trimethylolpropane, and thus improve the economic benefits of trimethylolpropane production.

[0006] The purpose of the present invention is achieved by the following technical solutions: A method for decomposing CTF in light components during the production process of trimethylolpropane by the calcium method, characterized by comprising the following steps: 1) Add the light components separated from the self-separation tower into the decomposition kettle. At a temperature of 140°C, add formic acid with a mass concentration of 85% accounting for 0.2% of the weight of the light components, and add methanesulfonic acid with a mass concentration of 99% accounting for 0.05% of the weight of the light components. 2) The temperature is 180°C and the residence time is 2 hours. 3) The liquid after the reaction in the decomposition kettle is separated by negative pressure flash evaporation to obtain trimethylolpropane products.

[0007] The negative pressure flash evaporation is as follows: The liquid after the reaction in the decomposition kettle enters the vacuum flash evaporation tank. The reaction temperature is 180°C. The low-boiling light components are vaporized and discharged from the top, and are collected after being cooled to 80°C; the high-boiling trimethylolpropane is liquefied and collected from the bottom of the flash evaporation tank to obtain trimethylolpropane products.

[0008] The beneficial effects of the present invention are as follows: During the production of trimethylolpropane by the disproportionation method, a large amount of CTF is contained in the light components. There is an O-C cyclic chemical bond in the chemical structure of CTF. According to its properties, specific catalysts formic acid and methanesulfonic acid are selected for the reaction to convert CTF into trimethylolpropane, so as to increase the yield of trimethylolpropane, avoid the loss of valuable substances, and further improve the economic benefits of trimethylolpropane production. Detailed implementation mode

[0009] The following is a detailed description of the present invention. Example 1

[0010] A method for decomposing CTF in light components during the production of trimethylolpropane by the calcium method, which is characterized by including the following steps: 1) Add the light components separated from the self-separation tower into the decomposition kettle. At a temperature of 140°C, add formic acid with a mass concentration of 85% accounting for 0.2% of the weight of the light components, and add methanesulfonic acid with a mass concentration of 99% accounting for 0.05% of the weight of the light components. 2) The temperature is 175°C and the residence time is 2 hours. 3) The liquid after the reaction in the decomposition kettle is separated by negative pressure flash evaporation to obtain trimethylolpropane products; The negative pressure flash evaporation is as follows: The liquid after the reaction in the decomposition kettle enters the vacuum flash evaporation tank. The reaction temperature is 180°C. The low-boiling light components are vaporized and discharged from the top, and are collected after being cooled to 80°C; the high-boiling trimethylolpropane is liquefied and collected from the bottom of the flash evaporation tank to obtain trimethylolpropane products.

[0011] After being processed by the above steps, the CTF content (mass fraction) in the light components is reduced from 35% to 2.6%. Example 2

[0012] A method for decomposing CTF in light components during the production of trimethylolpropane by the calcium method, which is characterized by including the following steps: 1) Add the light components separated by the self-separation tower into the decomposition kettle. At a temperature of 140°C, add formic acid with a mass concentration of 85% accounting for 0.2% of the weight of the light components, and add methanesulfonic acid with a mass concentration of 99% accounting for 0.05% of the weight of the light components. 2) At a temperature of 180°C, with a residence time of 2 hours. 3) For the liquid after the reaction in the decomposition kettle, separate the trimethylolpropane product through negative pressure flashing. Negative pressure flashing: The liquid after the reaction in the decomposition kettle enters the vacuum flashing tank. The reaction temperature is 180°C. The low-boiling light components are vaporized and discharged from the top, and are collected after being cooled to 80°C; the high-boiling trimethylolpropane is liquefied and collected from the bottom of the flashing tank to obtain the trimethylolpropane product.

[0013] After being processed through the above steps, the CTF content (mass fraction) in the light components is reduced from 35% to 1.8%.

[0014] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement made by those of ordinary skill in the art to the technical solution of the present invention shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for decomposing CTF in light components of a calcium process for producing trimethylolpropane, characterized in that The steps include: 1) Add the light component separated from the separation tower into the decomposition kettle, add 0.2% of the weight of the light component with a mass concentration of 85% formic acid, and add 0.05% of the weight of the light component with a mass concentration of 99% methanesulfonic acid at a temperature of 140°C; 2) Temperature 175-180°C, residence time 2 hours; 3) The liquid after the reaction in the decomposition kettle is subjected to negative pressure flash evaporation to separate the trimethylolpropane product.

2. The method for decomposing CTF in light components of the calcium process for producing trimethylolpropane according to claim 1, characterized in that: The negative pressure flash evaporation is as follows: the liquid after the reaction in the decomposition kettle enters the vacuum flash tank, the reaction temperature is 180°C, the light components with low boiling points are gasified and discharged from the top, and then taken out after being cooled at 80°C; the trimethylolpropane with high boiling points is liquefied and taken out from the bottom of the flash tank to obtain the trimethylolpropane product.