Process for producing cellulose ether by directly separating and recovering diluent

Abstract

The invention discloses a process for producing cellulose ether by directly separating and recovering diluent, which comprises the following steps: adding sodium hydroxide and refined cottons into a mixed diluent system to carry out alkalization reaction; then adding etherifying agent into the obtained mixture to carry out etherification reaction, after the etherification reaction is completed, obtaining a mixed slurry of cellulose ether and organic diluent; and then recycling the organic diluent, and washing and refining the separated cellulose ether so as to obtain a finished product. The process is characterized in that the mixed slurry obtained in the step of etherification reaction is pumped to a centrifugal machine to carry out solid-liquid separation directly; then the obtained liquid mainly comprising the diluent enters into a settling tank to carry out gravity settling, and the obtained liquid subjected to gravity settling is directly used as diluent for recycling; and the obtained solid enters into a recover kettle and then neutralized with acid, and a small amount of diluent contained in the solid is recycled by way of steam heating and distillation. The invention not only greatly reduces the energy consumption in the process of diluent evaporation and recycling, but also recycles the alkali which is not consumed in the reaction, thereby reducing the consumption of acid used in alkali neutralization, saving energy and reducing consumption, and improving the utilization rate of raw materials.

Description

technical field [0001] The invention belongs to the technical field of cellulose preparation, and relates to a method for producing cellulose ether. Background technique [0002] The current traditional cellulose ether preparation process is to add sodium hydroxide and refined cotton to the mixed diluent system in a certain ratio for alkalization, and then add etherification agent to it, depending on the type of cellulose ether , the etherification agent may be one or both of methyl chloride, ethyl chloride, propylene oxide, and ethylene oxide. After etherification, after neutralization, the steam is heated to recover the diluent, and then washed and dried And crushing and other processes to get finished products. In this process, the diluent system generally adopts a mixed system of toluene, isopropanol and water, and its composition mass ratio is: toluene: isopropanol: water=1: 0.1~0.5: 0.2~1. After the etherification reaction is completed, the organic diluent must be re...

AI Technical Summary

Problems solved by technology

This process is now mature, but there are major shortcomings in this process. First, in the reaction process itself, part of the catalytic sodium hydroxide is consumed in large quantities; second, in the solvent recovery process, heat energy is used to evaporate first. , and then carry out condensation, which involves the liquid-gas phase conversion process, so there are always disadvantages such as high energy consumption and slow speed.