New Process for Manufacturing MMA
Excellent Yields, Low Energy Requirements
Evonik industries AG, Essen, Germany, is currently working on the development of a unique process for producing methyl methacrylate (MMA), an important precursor for Plexiglas and for specialty applications such as contact lenses and adhesives. The process is currently being tested at a pilot plant in Darmstadt, Germany. Initial results have already shown the quality of MMA to be excellent.
Evonik engineers have named the technology LiMA, an acronym that reflects their ambitions: LiMA stands for Leading in Methacrylates. To create LiMA, Evonik combined individual established process steps with newly developed process designs, resulting in an overall new production route. Intelligent process set-up and control and a highly efficient new catalyst result in final product yields exceeding 90 %. Because it uses considerably less energy, the process also reduces carbon dioxide emissions by up to 40 percent. The overall favorable process design as well as moderate reaction conditions minimize wastewater streams, engineering work, and maintenance needs. According to Evonik, another advantage of the technology is its use of petrochemical raw materials, which are readily available throughout the world.
New Catalyst System
LiMA begins with ethylene and methanol. These then undergo multiple reaction steps to produce methacrolein. The key to the new process is the conversion of methacrolein to methyl methacrylate in a single step. Evonik achieved this by developing a brand-new catalyst system. The method is carried out entirely in the liquid phase and under moderate conditions, with temperatures generally well below 100°C.
The new catalyst system is remarkably robust and highly efficient. In other catalysts, individual components of the catalyst are gradually lost from the carrier with reaction time, but this phenomenon − known as bleeding − hardly occurs with LiMA catalysts. A unique combination of metal oxides and a special preparation procedure gives the catalyst its unusual stability. By-products and catalyst poisons are efficiently removed during preliminary process stages.