Polytetramethylene ether glycol (PTMEG) depolymerization process

Abstract

The invention belongs to the technical field of chemical industry, and in particular relates to a polytetramethylene ether glycol (PTMEG) depolymerization process. The process comprises the followingsteps: S1, adding steam condensate or desalted water into a reactor; S2, preheating PTMEG and then adding the preheated PTMEG into the reactor; S3, carrying out circulating reflux on PTMEG defective in the reactor by using a reboiler; S4, adding 98% concentrated sulfuric acid into the reactor, depolymerizing the PTMEG defective into tetrahydrofuran in the reactor, separating the tetrahydrofuran from sulfuric acid in a separation tower, and enabling the tetrahydrofuran to enter a condensate tank after passing through a condenser; S5, enabling part of the tetrahydrofuran at an outlet of the condensate tank to flow back to the separation tower, and enabling the other part of tetrahydrofuran at the outlet of the condensate tank to flow into a mixer through a discharge pipe; adding water for production and 20-30%(m / v) sodium hydroxide solution into the mixer, adjusting the pH value of the tetrahydrofuran to be 6-10, and adjusting the concentration of the tetrahydrofuran to be 70-80%. The PTMEG depolymerization process remarkably increases the depolymerization load and the yield of the tetrahydrofuran, obviously reduces the switching and cleaning frequency of the reboiler, reduces the discharge amount of tar and lowers the depolymerization cost.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a PTMEG depolymerization process. Background technique [0002] Polytetramethylene ether glycol (PTMEG), also known as polytetramethylene ether glycol, tetrahydrofuran homopolyether, etc., its English name is Polytetramethylene Ether Glycol, referred to as PTMEG. Its molecular formula is HO[CH 2 CH 2 CH 2 CH 2 O] n H, is a homopolymer obtained by cationic ring-opening polymerization of monomer tetrahydrofuran (THF) in the presence of a catalyst. It is a linear polyether diol with a primary hydroxyl end group. It is a white waxy solid at room temperature. When the temperature exceeds room temperature, it melts into a transparent, colorless liquid, easily soluble in alcohols, esters, ketones, aromatic hydrocarbons and chlorinated hydrocarbons, insoluble in aliphatic hydrocarbons and water. PTMEG is mainly used in the production of polyurethane elastomers...

AI Technical Summary

Problems solved by technology

The depolymerization process of PTMEG defective products is a unique operation mode in the production process of INVISTA in the United States. Other PTMEG production process technologies cannot complete depolymerization production on the basis of the original equipment. However, among several manufacturers using the production process of INVISTA in the United States, depolymerization The load and efficiency are also very different. It is common that the maximum load is less than 50% during depolymerization, and the tar concentration rises rapidly, resulting in frequent cleaning and switching of the reboiler, frequent pumping of the circulating pump, and the need to clean the filter at the pump inlet, resulting in The cost of depolymerization is high, and the output of depolymerization is also unstable

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