Preparation method and application of catalyst for carbonylation of ethanol to propionic acid

Abstract

The invention relates to a preparation method of a catalyst used in synthesizing of propionic acid by carbonylating ethyl alcohol and applications of the catalyst. The preparation method of the catalyst comprises the following steps: weighing dipropylenetriamine, dissolving the dipropylenetriamine in 20-25 times of mole amount of ethyl alcohol based on the amount of the dipropylenetriamine, stirring for 5-15 minutes, adding 0.5 time of mole amount of dichloro tetracarbonyl dirhodium based on the amount of the dipropylenetriamine, continuously stirring and reacting for 10 minutes, precipitating by using excessive diethyl ether, fully precipitating reactants, filtering and separating sediment, washing the sediment by using the diethyl ether, drying the sediment in vacuum at the room temperature until the final weight is constant to obtain dipropylenetriamine / carbonylrhodium catalyst (DPTA-Rh). Under the existence of the catalyst, the ethyl alcohol is capable of being catalyzed and carbonylatd with the high selectivity to react to obtain the propionic acid under the relative mild conditions.

Description

technical field [0001] The invention belongs to the field of preparing propionic acid by carbonylation reaction of ethanol, and in particular relates to a catalyst and a preparation method thereof. Background technique [0002] Propionic acid is an important basic chemical raw material, mainly used as food additive, feed and grain preservative. Propionic acid derivatives are widely used in the fields of pesticides, spices, cosmetics and pharmaceutical intermediates. [0003] The main processes for the industrial production of propionic acid are the Rapa method, the oxidation of propionaldehyde and the oxidation of light hydrocarbons. The Rapa method uses ethylene, carbon monoxide and water as raw materials to synthesize propionic acid. The method has simple process flow, high conversion rate and high selectivity (up to 95%), but propionic acid is highly corrosive under high temperature and high pressure, and a reactor with silver-lined inner wall is required. Propionaldeh...

AI Technical Summary

Problems solved by technology

Although theoretically speaking, the gas phase reaction device is simple, convenient for product separation, and less corrosive to equipment, but for the reaction of ethanol carbonylation of propionic acid, there are considerable limitations: (1) loss of active species of the catalyst , surface carbon of this type of strong exothermic reaction catalyst, etc., all directly affect the service life and service performance of the catalyst; (2) the dew point problem of the product propionic acid in the reaction system, according to literature reports, the reaction pressure and temperature can meet the requirements of ethanol and Ethyl iodide exists and reacts in a gaseous state during the reaction, but the product propionic acid is not in a gaseous state, that is, the generated propionic acid flows out of the fixed-bed reactor in liquid form, which will inevitably cause erosion and dissolution loss of the surface active species of the catalyst

In 1962, N.V.Katepov et al first used H 3 PO 4 , Fe, Ni, Co complexes as catalysts; carbonylation of ethanol to propionic acid, resulting in very low yield