Acetaldehyde

Introduction

Acetaldehyde, first prepared in 1774 by Carl Wilhelm Scheele, is a colorless liquid at room temperature with a pungent odor. It is used in a range of applications including: the manufacture of pentaerythritol, pyridine bases, perfumes, resins, explosives, as well as fire retardants. While it was once used for the manufacture of acetic acid and acetic anhydride this use has largely been superseded by newer processes.

In many plant configurations acetaldehyde is produced by oxidizing ethylene. This is typically done by oxidizing ethylene in the liquid phase in the presence of a palladium (II) chloride catalyst. Almost complete conversion of the ethylene occurs in this reaction. Upon exiting the reactor, the stream is flashed to separate the acetaldehyde and non-condensable gases from the catalyst containing solution. Catalyst is regenerated before being returned to the reactor. The non-condensable gases are scrubbed of any residual acetaldehyde before being vented. The crude acetaldehyde solution is sent to a final distillation column to remove water and other impurities in the stream.

Figure 1: Acetaldehyde Plant

Applied Analytics’ OMA-300 can help manufacturers monitor their reactor’s conversion efficiency by enabling acetaldehyde measurements in real time. It’s no nonsense construction and solid-state design ensures continued operation and drastically reduces maintenance compared to other technologies. It’s fiber-optic based design enables process measurements to be isolated from analyzer electronics. This is particularly helpful as entrained catalyst-containing liquids in this process are corrosive. Keeping the corrosive chemicals away from analyzer electronics enables a “belt and suspender” approach that ensures the analyzer remains protected from harsh chemicals.

The OMA-300 can also help to keep costs low by monitoring the separation efficiency of the final acetaldehyde distillation. The heat duties for operating a distillation column can be quite large. Process disruptions or issues inside the column can have a significant impact on operating costs. Monitoring the column helps to identify issues as they occur in real time and eliminate unnecessary costs.

Further Reading