Acetaldehyde Production from Ethylene (Single-Step Process)

The process under analysis comprises two major sections: (1) Reaction; (2) Recovery and Purification.

Reaction. In the first section, ethylene and oxygen are fed independently to a vertical ceramic-lined reactor, and ethylene is oxidized to Acetaldehyde in the presence of an aqueous solution of PdCl2 and CuCl2, used as a catalyst. The reaction is conducted at 130 °C, and about 3-4 bar. A solution containing the catalyst and Acetaldehyde formed is partially vaporized in the reactor itself and then routed to a separator, in which the Acetaldehyde-water vapor mixture is separated overhead and directed to distillation steps downstream. The catalyst solution withdrawn from the separator bottom, is returned to the reactor, after part of the catalyst being regenerated.

Recovery and Purification. The Acetaldehyde-water vapor mixture from the separator is cooled and scrubbed with process water for the condensation and recovery of Acetaldehyde at the bottom. A large part of the gas leaving the Scrubbing System is recycled to the reactor, but a small part needs to be purged. The purged gas is led to a burner for energy generation. Crude Acetaldehyde recovered at the bottom has a low concentration and needs to be directed to the Purification System, where, after passing through two distillation columns, high-purity Acetaldehyde is obtained. In the first column, low-boiling substances are stripped off and burned for energy generation, while the Acetaldehyde stream obtained as column’s bottom is fed to the second column. In this column, water and higher-boiling by-products are removed. High-purity Acetaldehyde is drawn from the column overhead, condensed, and obtained as the main product.