You are currently viewing Direct Hydration Process of Ethylene to Produce Synthetic Ethanol | Ethanol Production via Direct Hydration of Ethylene

Direct Hydration Process of Ethylene to Produce Synthetic Ethanol | Ethanol Production via Direct Hydration of Ethylene

Ethanol Production

Ethanol production by direct hydration of ethylene:

Synthetic ethanol which is produced by the hydration of ethylene has a purity of 95-96%, this method is followed by all modern industries having a yield of about 95-97% of ethanol, this is a catalytic gaseous reaction where approximately about 5-6 kg of phosphoric acid is used. Commonly kieselguhr or diatomaceous earth is selected as support for phosphoric acid deposition on their surface. 

Process description:

Ethylene and water are pumped from the spheres and storage tanks respectively to the stream of the recycling pipeline which is fed to the effluent pre-heater shell side and then heated to 300oC in the furnace which uses the gas as fuel along with natural gas, the pressure about 6.8 MPa is maintained by the feed pumps which is controlled by the reactor outlet control valve, a reactor is packed bed and converts reactant to a product with a conversion of 4-25% and a side reaction will produce byproduct acetaldehyde which is sold or hydrogenated to produced ethanol.

Main reaction:

CH2=CH2 + H2O β†’H3PO4β†’ C2H5OH at 300oC and 6.8MPa

The outlet vapour mixture of the reactor is separated into products and unreacted reactants in the high-pressure separator, before passing through the effluent preheater tube side which is used to heat the feed mixture as the reaction is exothermic one mole of ethylene and water will produce 45.6KJ of energy after complete conversion into ethanol. Unreacted reactants present in the separator top outlet are scrubbed with water to dissolve the ethanol carried over into the recycle stream. The vapours are recycled having 80-85% concentration of ethylene in such a way that the molar ratio of water to ethylene is 0.6:1 and is maintained. The bottom of the separator and scrubber is fed to Hydrogenator to convert acetaldehyde to ethanol on the nickel-packed catalyst by adding hydrogen to acetaldehyde.

Side reaction:

CH3CHO + H2Oβ†’ C2H5OH

Reacted vapour is fed to the acetaldehyde reduction column to separate Unreacted acetaldehyde and recycle to the reactor are some parts can be sold as by-products based on market demand, the bottom stream is fed to the light and heavy (purifier) column to distil out ethanol and increase it concentration.

Other methods used for the production of ethanol are:
Ethanol production from molasses fermentation

Related topic – click here

Aanchal Gupta

Welcome to my website! I'm Aanchal Gupta, an expert in Electrical Technology, and I'm excited to share my knowledge and insights with you. With a strong educational background and practical experience, I aim to provide valuable information and solutions related to the field of electrical engineering. I hold a Bachelor of Engineering (BE) degree in Electrical Engineering, which has equipped me with a solid foundation in the principles and applications of electrical technology. Throughout my academic journey, I focused on developing a deep understanding of various electrical systems, circuits, and power distribution networks.

Leave a Reply