This article discusses acrylic acids and acrylates, the processes currently used for their production, the drawbacks of such processes, and the feasibility of the sustainable production of these compounds.
What are Acrylic Acid and Acrylates?
Acrylic acid is an unsaturated carboxylic acid composed of a vinyl group that is directly connected to a carboxylic acid terminus. The organic compound is a colorless liquid with a characteristic tart or acrid odor at room temperature and is miscible with chloroform, ethers, alcohol, and water. The flash, boiling, and freezing points of acrylic acid are 130 oF, 286 oF, and 53 oF, respectively.
Esters, conjugate bases, and salts of acrylic acid are known as acrylates. Materials based on acrylic acid or acrylates possess good transparency, adhesion, stability, and flexibility. Acrylic acid is used extensively in the production of textiles, polishes, paint formulations, elastomers, adhesives, coatings, plastics, wastewater treatment chemicals, and detergents. Acrylates are utilized in cosmetics, diapers, orthopedics, bone cement, and contact lenses.
Currently Used Acrylic Acid and Acrylate Production Processes
Acrylic acid is primarily produced through the vapor phase oxidation of propylene, a gaseous by-product obtained during petroleum refining. The process involves two reactors in series using two catalysts. In this process, the first reactor converts propylene to acrolein while the second reactor converts acrolein to acrylic acid, the final product.
Acrylates are prepared industrially by treating an acrylic acid with the corresponding alcohol using a catalyst. The reaction with lower alcohols such as ethanol and methanol occurs at 100–120 °C using acidic heterogeneous catalysts. In comparison, the reaction with higher alcohols, such as n-butanol, is catalyzed in a homogenous phase using sulfuric acid.