Fifty years of propionic acid manufacturing at BASF

Propionic acid, which also occurs naturally, is valued as a preservative for feedgrain and as a building block for synthesis, for example in the production of pharmaceuticals, crop protection products and plastics. BASF has to date produced about 2.4 million metric tons of propionic acid.

Process efficiency enhanced
In 1941, Professor Walter Reppe, a BASF chemist always keen on experimenting, managed to synthesize propionic acid from ethylene. Ten years later, BASF built a pilot plant, and the production started just another year later. Designed for 1,200 tons per annum, the plant was soon unable to meet the constantly rising demand. So in 1960 a new large-scale plant was built that continues to make propionic acid today. “The synthesis is still based on the principle developed by Reppe, but over the years we have optimized and expanded the plant so that production is now much more efficient,” explained Dr. Bernd Bartenbach, who is responsible for the production of propionic acid at the Ludwigshafen site.

Eco-efficient propionic acid has advantages
The importance of propionic acid is quite different now from what it used to be in Reppe’s time. In those days, nearly 70 percent of the total volume was used to make vinyl propionate. Processed into polymer dispersions, the acid was ultimately used as a protective exterior paint for buildings. Today, the acid’s main field of application is in preserving feedgrain. Propionic acid keeps feeds fresh for a long time because it prevents molding. Feedgrain preservation based on propionic acid offers clear economic and ecological benefits over other methods, as an  coefficiency analysis confirms. This study shows that using this acid to preserve feedgrain is much more eco-efficient than feedgrain preservation by means of drying or storage in air-tight silos.

BASF markets preservatives based on propionic acid under the trade names Lupro-Grain® and Luprosil®.

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