The object of the present invention is to provide a production method for purifying and purifying high-purity undecenoic acid that can overcome the shortcomings of the prior art.
The present invention uses castor oil as a raw material to separate and purify the crude Undecenoic obtained by alcohol exchange, thermal cracking, addition, saponification and acidification by a three-stage molecular distillation method to obtain high-purity Undecenoic products.
The specific production steps are as follows:
(1) first-stage thin-film distillation: the Undecenoic crude product is directly put into the molecular distillation equipment feed tank, and is input into the first-stage thin-film distiller through the feeding pump, and is controlled at vacuum tightness-0.085～-0. 095MPa, 50～80 ℃ of temperature, feed rate are to carry out dehydration, degassing under 15～30kg/h operating conditions;
(2) second-stage molecular distillation: the Undecenoic crude product through step (1) dehydration, degassing is directly input into the second-stage molecular distiller through feed pump, controlled at vacuum tightness 100Pa～-0.1MPa, Separating and removing low-boiling aldehydes, alcohols, hydrocarbons, neutral aliphatic impurities under temperature 50～70 ℃ of operating conditions, obtains the undecylenic acid crude product that removes low-boiling impurities;
(3) third-stage molecular distillation: directly input the undecylenic acid crude product through the removal of low-boiling impurity into the third-stage molecular distiller through feed pump, and operating conditions are controlled at vacuum tightness 100½～-0.1MPa, temperature 80 ~95 DEG C, isolate high boiler and obtain colorless or slightly yellow high-purity undecylenic acid fine product.
The equipment involved in the step (1) is a thin film evaporator; the equipment involved in the steps (2) and (3) is a molecular distillation secondary molecular still. Steps (1), (2), (3) are coordinated with each other, and continuous feeding and continuous discharging are adopted.
Described steps (1), (2), (3) three-stage molecular distiller system, involved material conveying pipeline and discharge pipeline are sandwich pipe and pass into 30～40 ℃ of hot water for insulation.
The molecular distillation equipment includes a molecular evaporator, a degassing and dehydration system, a feeding system, a heating system, a material conveying pipeline insulation system, a cooling vacuum system and a control system. Wiped-Film Style, which adopts Smith-type 45° diagonal chute scraper, the feed liquid flows through a heated vacuum chamber for evaporation; the material conveying pipeline and the discharging pipeline are heated by hot water There is a separator in the lower part of the molecular evaporator, the first stage separates water, the second stage separates high and low boiling point impurities, and the third stage separates high boiling point substances.
The vacuum chamber of the scraper type molecular distillation equipment is a cylindrical vacuum chamber. After the feed liquid flows through the heated cylindrical vacuum chamber, the scraping action of the feed liquid film is used to remove the volatile components from the non-volatile ones. The ingredients are still out.
This process is characterized by: short residence time of the feed liquid, sufficient cooling due to high vacuum performance, optimum mixing efficiency, and optimum mass and heat transfer. The result of this highly efficient thermal separation technology: minimal product degradation and highest product quality. The feed liquid (crude undecylenic acid) is exposed to the heated wall for a very short time (only a few seconds to a dozen seconds), which is partly due to the slotted scraper design, which forces the liquid to move downward and retains Time, film thickness, and flow characteristics are all tightly controlled, making them ideal for separation applications of heat-sensitive substances. In addition, this chute scraper does not throw material off the walls of the distiller, contaminating the separated light components. Compared with traditional column distillation equipment, falling film distillation equipment, rotary evaporator and other separation equipment, scraped surface molecular distillation equipment is recognized as much better.