Method for preparing trimethylolpropane by efficient condensation with calcium

Abstract

The application discloses a method for efficiently preparing trimethylolpropane by calcium method, which comprises the following steps: filling nitrogen into a reaction kettle; adding process water into a condensation reaction kettle, and adding 3.6 molar ratio of formaldehyde steam into the bottom of the reaction kettle; controlling the mass concentration of formaldehyde in the condensation kettle to be 16%, and cooling the formaldehyde to below 15 DEG C by using ice water, and controlling the formaldehyde adding time to be 2 hours; diluting 0.58 molar ratio of calcium hydroxide into a suspension solution with a concentration of 30% by adding water, controlling the condensation reaction kettle reaction time to be 2 hours, and ensuring that the reaction pH value is 11.5; adding 1 molar ratio of n-butyl aldehyde into the bottom of the condensation kettle, and controlling the adding time to be 2 hours; controlling the reaction termination temperature to be less than 45 DEG C after 2 hours by using ice water; keeping the termination temperature constant for 30 minutes; adding hydrogen peroxide; adding formic acid, and controlling the condensation liquid termination pH value to be 6.8. The application reduces the generation of impurities, improves the trimethylolpropane yield, and reduces the consumption of calcium hydroxide and n-butyl aldehyde.

Description

Technical Field

[0001] This invention relates to a method for preparing trimethylolpropane, specifically a calcium-based method for the efficient condensation preparation of trimethylolpropane. Background Technology

[0002] In existing technologies, the preparation methods of trimethylolpropane typically include the "sodium method" and the "calcium method". Since the raw material calcium hydroxide of the "calcium method" is inexpensive, while the product calcium formate is expensive, it has an economic advantage over the "sodium method".

[0003] The calcium condensation process is affected by various factors, with numerous side reactions leading to a higher concentration of impurities. This increases the difficulty of separating trimethylolpropane (TMP), increases the load on the equipment, reduces operational stability, and affects the overall efficiency and product quality. Furthermore, the calcium condensation process results in low TMP yield and high raw material consumption.

[0004] Therefore, how to reduce impurity generation, increase the yield of trimethylolpropane, and reduce raw material consumption has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a calcium-based method for the efficient condensation preparation of trimethylolpropane, so as to reduce the generation of impurities, increase the yield of trimethylolpropane, and reduce the consumption of raw materials.

[0006] The objective of this invention is achieved through the following technical solution: a highly efficient condensation preparation method for trimethylolpropane using the calcium method, comprising the following steps:

[0007] 1) Introduce nitrogen gas into the reactor and control the pressure in the condensation vessel to 0.2 MPa;

[0008] 2) Add process water to the condensation reactor, add formaldehyde vapor with a molar ratio of 3.6 to the bottom of the reactor, control the formaldehyde mass concentration in the condensation reactor to 16%, cool it down to below 15°C using ice water, and control the formaldehyde addition time to 2 hours.

[0009] 3) Dilute 0.58 molar calcium hydroxide with water to a 30% suspension solution, control the reaction time in the condensation reactor to 2 hours, and ensure the reaction pH is 11.5;

[0010] 4) Add 1 molar ratio of n-butyraldehyde to the bottom of the condensation vessel, and control the addition time to 2 hours;

[0011] 5) When calcium hydroxide is added, the condensation kettle will heat up rapidly. Use ice water to control the heating rate and control the reaction termination temperature to be less than 45°C after 2 hours.

[0012] 6) After the n-butyraldehyde is completely added, maintain the temperature at the termination temperature for 30 minutes to ensure the reaction is complete;

[0013] 7) Add hydrogen peroxide to the condensation solution after it has been kept at a constant temperature to remove unreacted formaldehyde;

[0014] 8) Add formic acid to control the final pH of the condensation solution to 6.8.

[0015] The beneficial effects of this invention are as follows: By controlling the concentration of the catalyst, the forward reaction is ensured, and the generation of impurities is reduced. By controlling the addition of calcium hydroxide, formaldehyde, and n-butyraldehyde, the reaction rate is controlled, ensuring the complete reaction of n-butyraldehyde. The condensation solution obtained by this invention contains more than 87% trimethylolpropane. The consumption of calcium hydroxide required for the production of trimethylolpropane is reduced to 0.43 t / t, and the consumption of n-butyraldehyde is reduced to 0.63 t / t. Detailed Implementation

[0016] The present invention will now be described in detail. Example 1

[0017] A method for the efficient condensation preparation of trimethylolpropane using a calcium method includes the following steps:

[0018] 1) Introduce nitrogen gas into the reactor and control the pressure in the condensation vessel to 0.2 MPa;

[0019] 2) Add process water to the condensation reactor, add 3.6 moles of formaldehyde vapor to the bottom of the reactor, control the formaldehyde mass concentration in the condensation reactor to 16%, cool it down to below 15°C using ice water, and control the formaldehyde addition time to 2 hours.

[0020] 3) Dilute 0.58 mol of calcium hydroxide with water to form a 30% suspension solution, control the reaction time in the condensation reactor to 2 hours, and ensure that the reaction pH is 11.5;

[0021] 4) Add 1 mole of n-butyraldehyde to the bottom of the condensation vessel, and control the addition time to be 2 hours;

[0022] 5) When calcium hydroxide is added, the condensation vessel will heat up rapidly. Use ice water to control the heating rate and control the reaction termination temperature to be less than 45°C after 2 hours.

[0023] 6) After the n-butyraldehyde is completely added, maintain the temperature at the termination temperature for 30 minutes to ensure the reaction is complete;

[0024] 7) Add hydrogen peroxide to the condensation solution after it has been kept at a constant temperature to remove unreacted formaldehyde;

[0025] 8) Add formic acid to control the final pH of the condensation solution to 6.8.

[0026] The trimethylolpropane condensation reaction is significantly affected by catalyst concentration. High concentrations result in rapid reactions, but excessively rapid local heating can lead to other side reactions. Conversely, low concentrations result in poor catalytic performance and may trigger other aldol condensation reactions. Therefore, controlling the catalyst concentration ensures the forward reaction proceeds and reduces impurity generation. Meanwhile, n-butyraldehyde is volatile and easily oxidized. Its oxidation to n-butyric acid reduces the effectiveness of the catalyst base, leading to other side reactions and decreasing the conversion rate of n-butyraldehyde. This invention controls the reaction rate by regulating the addition of calcium hydroxide, formaldehyde, and n-butyraldehyde, ensuring complete n-butyraldehyde reaction. The resulting condensation solution contains 87.2% trimethylolpropane, reducing the calcium hydroxide consumption for trimethylolpropane production to 0.43 t / t and the n-butyraldehyde consumption to 0.63 t / t.

[0027] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for the efficient condensation of trimethylolpropane by the calcium method, characterized in that The method comprises the following steps: 1) nitrogen is filled into the reaction kettle, and the pressure of the condensation kettle is controlled to 0.2 Mpa; 2) process water is added into the condensation reaction kettle, 3.6 moles of formaldehyde steam are added into the bottom of the reaction kettle, the formaldehyde mass concentration of the condensation kettle is controlled to be 16%, ice water is used for cooling to below 15 DEG C, and the formaldehyde adding time is controlled to be 2 hours; 3) 0.58 moles of calcium hydroxide are diluted into a suspension solution with a concentration of 30% by adding water, the condensation reaction kettle reaction time is controlled to be 2 hours, and the reaction pH value is ensured to be 11.5; 4) 1 mole of n-butyl aldehyde is added into the bottom of the condensation kettle, and the adding time is controlled to be 2 hours; 5) after the calcium hydroxide is added, the condensation kettle is rapidly warmed, the ice water is used for controlling the warming speed, and the reaction termination temperature is controlled to be less than 45 DEG C after 2 hours; 6) after the n-butyl aldehyde is added, the constant temperature is maintained for 30 minutes according to the termination temperature, and the reaction is ensured to be complete; 7) hydrogen peroxide is added into the constant-temperature condensation liquid, and the unreacted formaldehyde is removed; 8) formic acid is added, and the condensation liquid termination pH value is controlled to be 6.8.