CN1583988A

CN1583988A - Preparing method for pure glycerine

Info

Publication number: CN1583988A
Application number: CN 03135620
Authority: CN
Inventors: 杨宏
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-08-19
Filing date: 2003-08-19
Publication date: 2005-02-23
Anticipated expiration: 2023-08-19
Also published as: CN1236032C

Abstract

This invention is a producing method of pure glycerol. It improve the existing method of continuous distillation. First remove the gas from coarse glycerol and dry it circularly and then insert soluble oxalate. Secondly, mix them statically and then filter it. Thirdly, distill them under certain temperature and pressure. Finally, deodorize it circular and decolor it continuous. The invention solves the problem that the existing method to produce pure glycerol involves by-reaction, and it avoids contaminant such as hydronitrogen, volatile grease, and acrolein. Additionally, the pureness of the glycerol can be up to 99.5%, and moreover, it has no peculliar smell and meets the demand of food and medicine.

Description

Production method of pure glycerol

Technical Field

The invention belongs to the technical field of oil chemical industry, and particularly relates to a method for producing pure glycerol with the purity of more than 99.5 percent by further refining the glycerol after coarse refining.

Background

The method comprises the following steps of refining the crude glycerol into the glycerol with the purity of 99 percent, wherein the prior art comprises two production processes of a continuous distillation method and a gap distillation method, and the continuous method has the advantages of stable product quality and easily controlled production process parameters compared with the gap method. ③ at high temperatures, acrolein is formed, which is a very difficult to eliminate odorous contaminant the products of these reactions become impurities in the glycerol, reducing the quality of the finished glycerol。

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for producing pure glycerol by reducing side reactions in the distillation process as much as possible, so that the purity of the produced glycerol reaches more than 99.5 percent, no peculiar smell exists, the color is water white, the quality is excellent, and the requirements of food and medicines are met.

The scheme of the invention is as follows: the production process of pure glycerin includes the following steps and conditions:

a. circularly degassing and drying crude glycerol;

b. adding soluble oxalate into glycerol, statically mixing, and filtering, wherein the addition amount of the oxalate is 0.2-0.4 per mill;

c. the distillation is carried out, the absolute pressure of the distillation is controlled at 100-450Pa, and the liquid phase temperature is controlled at 130-138 ℃.

d. After condensation, the product is circularly deodorized and continuously decolorized.

The invention utilizes the reducibility of oxalate to reduce the oxidative decomposition of glycerol, and the alkalescence of the oxalate can inhibit the reactions of ② and ③ in the prior art, controls the absolute pressure of distillation at 100-450pa and the temperature at 130-138 ℃, so that the impurities generated by the reactions of ① and ③ in the prior art are reduced, thereby achieving the purpose of improving the quality of the glycerol, producing the glycerol with the purity of more than 99.5 percent and meeting the requirements of food and medical use.

Detailed description of the preferred embodiments

The invention can be further illustrated by means of examples.

Example 1: after the crude glycerin is circularly degassed and dried, adding sodium oxalate, wherein the adding amount of the sodium oxalate is 0.2 per mill of the glycerin, fully mixing, filtering, and then entering a distillation kettle, wherein the absolute pressure of the distillation kettle is controlled to be 280-340Pa, the liquid phase temperature is controlled to be 136-138 ℃, and the product is obtained through the working procedures of circular deodorization and continuous decolorization after the glycerin is condensed. The purity of the finished glycerol is 99.73%, and the specific gravity (d)₂₀ ²⁰) In the order of 1.2636, is,no peculiar smell, chroma (Hazen) 5.

Example 2: degassing and drying crude glycerol, adding potassium oxalate, wherein the adding amount of the potassium oxalate is 0.22 per mill, fully mixing, filtering, and then feeding into a distillation kettle, controlling the absolute pressure of the distillation kettle at 150 plus 220Pa, controlling the liquid phase temperature at 131-134 ℃, condensing the glycerol, then performing cyclic deodorization, and continuously decoloring to obtain the product. The glycerol purity of the finished glycerol is 99.62%, and the specific gravity (d)₂₀ ²⁰) 1.2632 showed no off-flavor and a color number of (Hazen) 5.

Claims

1. The production method of pure glycerol is characterized in that the production process is realized according to the following steps:

a. circularly degassing and drying crude glycerol;

b. adding soluble oxalate into glycerol, statically mixing, and filtering, wherein the addition amount of the oxalate is 0.1-0.3 per mill;

c. the distillation is carried out, the absolute pressure of the distillation is controlled at 100-450Pa, and the temperature is controlled at 130-138 ℃.

2. The method according to claim 1, wherein the soluble salt added to the glycerin is sodium oxalate.

3. The method according to claim 1, wherein the soluble oxalate added to the glycerol is potassium oxalate.

4. The method for producing pure glycerol according to claim 2, wherein the amount of sodium oxalate added is 0.2 ‰, the absolute pressure of the distillation still during distillation is controlled at 280340 pa, and the liquid phase temperature is controlled at 136-138 ℃.

5. The method for producing pure glycerol according to claim 3, wherein the amount of potassium oxalate added is 0.22% o, and the absolute pressure of the distillation kettle during distillation is controlled at 150-220 Pa. The temperature of the liquid phase is controlled between 131 ℃ and 134 ℃.