SU445261A1 - The method of obtaining primary synthetic fatty alcohols - Google Patents

Description

The invention relates to a process for the preparation of primary synthetic fatty alcohols, which are used in the manufacture of surfactants. Methods are known for preparing fatty alcohols by catalytic direct hydrogenation of fatty acids of the Ciu-Cis fraction on a copper-chromium stationary and suspended catalyst at elevated temperature and pressure. The method on a stationary catalyst is characterized by a high consumption of catalyst per 1 ton of alcohols, low productivity of the hydrogenation reactor, low yield of alcohols. The technology of the known method of hydrogenation of fatty acids on a suspended copper-chromium catalyst in industry involves the addition to the reaction mass of alcohols obtained by hydrogenation of fatty acids. The feed is introduced into the reactor in three streams: the first is the original fatty acids, the second is hydrogen, the third is alcohols with a catalyst in the form of a suspension. However, according to a known method, continuously introduced into the reactor alcohols are completely sterilized with a large excess of acids, the recovery rate of the resulting high molecular weight esters is significantly lower than the acid recovery rate. As a consequence, the residence time of the feedstock in the reactor is 2.5 hours, for which the total acid conversion is about 99% by weight. % The performance of the reactor is low. The hydrogenation product — hydrogenate — includes up to 7% of high molecular weight esters, indicating that the acid is not efficiently consumed. Acids fed to the reactor at a temperature of 200 ° C are partially oxidized, polymerized, which affects the quality of the resulting product, crude alcohols. There is also known a method for producing fatty alcohols by hydrogenating synthetic polar acids without adding alcohols to the reaction mass. The copper-chromium catalyst is mixed with acids and pumped through the reactor as a paste. The process is carried out at 340 ° C, a pressure of 300 at1 and a bulk feed rate of 0.64. Hydrogenate has the following characteristic: Hydroxyl number 260 Content of hydrocarbons,% 4.8 Acid number 0.5-2 The disadvantage of this method is the insufficient high quality of hydrogenate, not corresponding to the requirement of GOST 1393-67 for alcohols fraction Syu-Cig.

In order to improve the quality of the alcohols obtained and increase the productivity of the reactor, the hydrogenation process is proposed to be carried out initially at 150–180 ° C to the degree of conversion of acids to alcohols 25–40% followed by, and: m hydrogenating the resulting reaction mixture at a temperature of 300–320 ° C.

For this, according to the proposed method, the input of raw materials into the hydrogenation reactor is dried, in two streams: the first is circulating hydrogen heated to 450 ° C, the second is catalyst slurry in acids, hydrogenated at 160-180 ° C to the degree of conversion of acids to alcohols 25-40%. Both streams flow through the tubes down the reactor. From the upper part of the reactor hydrogenate and excess hydrogen enters the system of separation, condensation, filtration from the catalyst. The catalyst is circulating in the system with the addition of fresh.

Example. The hydrogenation reactor of 1X18H9T steel has a volume of 2 liters, a length of 1200 mm, an internal diameter of 45 mm. Suspension from catalyst in acids 5-7 wt. % are prepared separately in containers with agitators and circulation pumps for intensive mixing at a temperature of 40-50 ° C. The suspension thus prepared is mixed with a stream of fresh hydrogen heated to 180-200 ° C, l is fed in the presence of hydrogen into the hydrogenation reactor in the presence of hydrogen.

Circulating hydrogen heated to 450 ° C enters the upper part of the reactor through a tube placed along the height of the reactor. From the top of the reactor, the product enters the separation, condensation, and catalyst filtration system. Hydrogenation mode: pressure 300 MPa, temperature 300-320 ° C, volumetric rate for acids 0.6-1.0 hour; molar ratio of acids and hydrogen 1: 100.

: leave

acid conversion form

9E, 6 wt. % Degree of conversion into

99.3 alcohol is 98-99 wt. % Catalyst consumption is 1 wt. % on acid. Characterization of the original fatty acids fraction Su-Cis.

Acid number, mg KOH / g

261 Essential number, mg KOH / g 2.5 Carbonyl number, mg KOH / g 8.9 9.0 iodine number, g / 100 g Contents unwashed, weight.

o L5 Fractional composition, weight. % to Xu

5.9 Syu-Ci8 83.1 above Ci8 11.0

The crude alcohols obtained during filtration are characterized by the following indicators:

Acid number, mg KOH / g

0.1 Ester number, mg KOH / g

1J

267.0 Hydroxyl Number Carbonyl Number

About iodine number

ABOUT

Hydrocarbon content, wt. %

1.5

Fo rumula invention Method of obtaining

primary synthetic fatty snakes by hydrogenating a preliminarily prepared suspension of synthetic fatty acids and a copper-chromium catalyst at elevated temperature and pressure, followed by isolating the target products by known techniques, characterized in that, in order to improve the process performance and improve the quality of snaps, hydrogenation is first carried out at a temperature of 150-180 ° C to a degree of conversion of acids to alcohols 25-40% and the resulting reaction mass is hydrogenated at a temperature of 300-320 ° C.