| abstract |
Hydroxycarboxylic acids, e.g., 3-hydroxypropionic acid, and/or their ammonium salts are dehydrated to their corresponding unsaturated carboxylic acids, e.g., acrylic acid, by a process that uses a catalyst comprising ammonium bisulfate. The use of ammonium bisulfate reduces or eliminates the problems associated with processes that use sulfuric acid as a dehydrating catalyst, e.g, excess sulfuric acid consumption and/or recovery. |