One of the oldest methods to produce acetaldehyde is by oxidation of ethylene; two-stage technique is used initially during the development of the process later one stage method was commercialized. Palladium catalyst along with cupric chloride used to conduct the reaction at temperatures 130 oC and pressure around 150psig.
Process equipments involved in the acetaldehyde production by ethylene oxidation two stage process are:
- Packed bed reactor – I stage.
- Oxidizer – II stage.
- Flash regenerator.
Process description: Two reactors perform two-stage operation since one of the reactor handle reaction (packed bed reactor) and other oxidation (oxidizer). Ethylene is fed to reaction system at the bottom of the packed bed reactor and contacts with palladium chloride and water. Metallic palladium, hydrochloric acid and acetaldehyde are generated. Acetaldehyde is recovered from top of flash regenerator and the bottom cuprous salt stream is sent to oxidizer. Air is passed in to the oxidizer to convert cuprous chloride to cupric chloride. Metallic palladium reacts with formed cupric chloride to regenerate palladium chloride which is required in first stage. A continuous alteration of oxidation and reduction are done between the reactor and oxidizer. Nitrogen from oxidizer is vented out periodically. Acetaldehyde from flash regenerator is fed to degasifier and then to stripper to attain 99% purity.