Thermodynamics of Methacrylate Synthesis from Methanol and a Propionate

Methacrylate monomers can be formed by the reaction of methanol and a propionate, e.g., propionic acid, propionic anhydride, or methyl propionate. Formaldehyde, a necessary reaction intermediate, can be produced from methanol via either dehydrogenation or partial oxidation. The equilibrium compositions for several variations of this chemistry were calculated as a function of temperature, total pressure, and inlet composition using a free-energy minimization technique. The thermodynamic analysis revealed that the methanol dehydrogenation route gave higher propionate conversion and selectivity than the partial oxidation alternative. For the dehydrogenation route, both conversion and selectivity were favored by high temperature and high methanol/propionate feed ratio. The calculations also showed that a methyl propionate feed produces the least amount of water and diethyl ketone, two byproducts which can complicate any process design for this chemistry.