Method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane

A technology of paraformaldehyde and dioxane, applied in the direction of sustainable manufacturing/processing, organic chemistry, climate sustainability, etc., can solve the problems of corrosive equipment and pipelines, rectification column equipment pipeline blockage, large pollution, etc.

Active Publication Date: 2020-10-30
CHINA CHEM TECH RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current process generally adopts the method of crystallization or extraction to carry out preliminary separation of the synthetic product, plus the refining of rectification, but it is still unable to obtain paraformaldehyde with ultra-purity or close to 100% purity. At the same time, the extraction process introduces new solvents, resulting in The separation system is more complicated, resulting in energy consumption and dilute aldehyde recovery difficulties, and often requires a separate dilute aldehyde recovery unit for recovery
[0014] Second, in the existing and above-mentioned paraformaldehyde preparation process, there are difficulties of large amount of dilute aldehyde and high recovery energy consumption. For example, every ton of paraformaldehyde produced will produce about 4 tons of 15% dilute formaldehyde
Therefore, the dehydration of formaldehyde solution is a complicated physical and chemical process, which leads to the extremely high energy consumption of rectification and recovery of dilute aldehyde
[0016] Third, dioxane can form an azeotrope with water, with an azeotropic point of 70-73°C and a water content of 6.7%, making separation difficult. At the same time, due to the presence of formaldehyde, the local concentration in the separation unit is too high, and formaldehyde polymers are easily formed , resulting in clogging of the pipes of the distillation tower equipment, and the presence of formic acid, which easily corrodes the equipment and pipes
Low efficiency, high difficulty, high energy consumption and high pollution

Method used

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  • Method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane
  • Method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane

Examples

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Effect test

Embodiment 1

[0071] A method for preparing polyoxymethylene by co-production of paraformaldehyde and dioxane, comprising the following steps:

[0072] Step 1: the 37% formaldehyde solution produced by the Ag method is concentrated to obtain 58% formaldehyde solution stream 1 and the paraformaldehyde enrichment tower (T1101) tower kettle recycle stream 3 mixes and enters the paraformaldehyde that molecular sieve catalyst is housed in advance In the reactor (R1101), the molecular sieve catalyst filling mass is 5% of the reaction solution, the reaction temperature is 100°C, and the reaction pressure is -0.05MPa. The aqueous solution stream 2 of paraformaldehyde and formaldehyde is recovered in the gas phase at the outlet of the reactor, and its composition is: 39% of formaldehyde, 20% of paraformaldehyde and 41% of water.

[0073] Stream 2 is fed from the 8th tray in the middle of the tower, and enters the paraformaldehyde concentration tower (T1101), the number of trays is 20, the temperatur...

Embodiment 2

[0080] A method for preparing polyoxymethylene by co-production of paraformaldehyde and dioxane, comprising the following steps:

[0081] Step 1: enter the paraformaldehyde reactor (R1101) that the resin catalyst is pre-installed after the 60% formaldehyde aqueous solution stream 1 that iron molybdenum is produced is mixed with the paraformaldehyde enrichment tower (T1101) tower bottom recycle stream 3, and the resin catalyst The filling mass is 15% of the reaction solution, the reaction temperature is 102° C., and the reaction pressure is normal pressure. The aqueous solution stream 2 of paraformaldehyde and formaldehyde is recovered in the gas phase at the outlet of the reactor, and its composition is: 41% of formaldehyde, 16% of paraformaldehyde and 43% of water.

[0082] Stream 2 is fed from the 10th tray in the middle of the tower, and enters the paraformaldehyde concentration tower (T1101), the number of trays is 22, the temperature of the tower bottom is 73°C, the tempe...

Embodiment 3

[0090] A device for preparing polyoxymethylene by co-producing paraformaldehyde and dioxane, comprising three units: a paraformaldehyde monomer preparation unit, a dioxane monomer preparation unit and a polyoxymethylene preparation unit.

[0091] The paraformaldehyde monomer preparation unit comprises a paraformaldehyde reactor (R1101), a paraformaldehyde concentration tower (T1101), a paraformaldehyde dealdehyde tower (T1102) and a paraformaldehyde membrane dehydration device (M1101); The dioxane monomer preparation unit includes a low water content hemiacetal membrane dehydration device (M2201), a dioxane reactive distillation tower (R1201) and a dioxane membrane dehydration device (M1202); the polyoxymethylene preparation unit Consists of polyoxymethylene reactor (R2301).

[0092] (1) Paraformaldehyde monomer preparation unit

[0093] The 60% formaldehyde aqueous solution stream 1 that iron molybdenum produces enters the paraformaldehyde reactor (R1101) that the resin cata...

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Abstract

The invention relates to a method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane. The method comprises the following steps of: synthesizing ethylene glycol and formaldehyde in a trioxymethylene crude product into hemiacetal, performing separation, and synthesizing dioxolane, thereby simplifying the subsequent separation and refining process of the dealdehydedtrioxymethylene crude product. According to the process, the amount of dilute aldehyde in the polyformaldehyde monomer preparation process is reduced, the energy consumption of the preparation process is reduced, and the product quality of the polyformaldehyde monomer is improved.

Description

technical field [0001] The disclosure relates to a process for preparing polyoxymethylene through the joint production of paraformaldehyde and dioxane, and specifically relates to the production field of polyoxymethylene. Utilize ethylene glycol and formaldehyde in the crude paraformaldehyde to synthesize hemiacetal, which is used to synthesize dioxane after separation, and the subsequent separation and purification process of the dealdehydeized crude paraformaldehyde is simplified. Background technique [0002] Polyoxymethylene is one of the five major engineering plastics in the world. my country has become the largest producer and consumer of polyoxymethylene in the world. At the same time, polyoxymethylene is an important branch of C1 chemistry in the coal chemical industry. Advantages of mass production. However, the current situation of the domestic POM production industry is "big but not strong", the production equipment technology is backward, the product structure i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G2/24C07D317/12
CPCC08G2/24C07D317/12Y02P20/10
Inventor 张小明陈洪林邓聪迩雷蔚鑫雷骞李克景
Owner CHINA CHEM TECH RES INST
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