Method Of Making Acrylic Acid From Hydroxypropionic Acid

A method of making acrylic acid, acrylic acid derivatives, or mixtures thereof comprising contacting a gas feed stream comprising water vapor and hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof with a catalyst in a bi-layer reactor at a temperature, a water partial pressure, a GHSV, and a WHSV to dehydrate said hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof, resulting in the production of acrylic acid, acrylic acid derivatives, or mixtures thereof;

• wherein said catalyst comprises a phosphate salt comprising a cation and an anion represented by the empirical formula:
• [H2(1−x)PO(4−x)]−
• wherein x is any real number greater than or equal to 0 and less than or equal to 1;
• wherein said water partial pressure is equal to or greater than about 0.4 bar;
• wherein said bi-layer reactor comprises an outer layer, an inner layer, an outer surface, an inner surface, and an interface between said outer layer and said inner layer;
• wherein said outer layer is made from an outer layer material, has an outer layer thickness, and extends from said interface to said outer surface;
• wherein said inner layer is made from an inner layer material, has an inner layer thickness, and extends from said inner surface to said interface;
• wherein said inner layer material is selected from the group consisting of aluminum, silicon, copper, silver, gold, titanium, tantalum, tungsten, molybdenum, platinum, palladium, zirconium, and mixtures thereof;
• wherein said inner surface is in contact with said catalyst;
• and wherein said bi-layer reactor has a corrosion rate lower than about 1.3 mm/y during said dehydration.