Evonik is currently working on the development of a new process for producing methyl methacrylate (MMA), an important precursor for Plexiglas and for specialty applications such as contact lenses and adhesives.
Darmstadt/Germany — The new technology is called Lima and is currently being tested at a pilot plant in Darmstadt.
The production of 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. The company achieved this by developing a 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 product can be used for optical applications without limitations — and that’s traditionally one of the most demanding applications for engineering-grade plastics,” explains Steffen Krill, the head of Methacrylates Innovation Management at Evonik.
The manufacturer 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 new catalyst result in final product yields exceeding 90 %, claims the company, adding that because it would use less energy, the process also reduces carbon dioxide emissions by up to 40 %.
In other catalysts, individual components of the catalyst are gradually lost from the carrier with reaction time. According to the company, 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.
At its production sites on three continents, Evonik is capable of manufacturing roughly 600,000 metric tons of methacrylate monomers. In the industry, MMA is currently made in a variety of processes depending on the region and the availability of raw materials. What is known as the C3 technology is the most widely used process. The raw material used here is acetone, and its three carbon atoms are what give the technology its name. Isobutene, which has four carbon atoms, is the basis for the C4 process. Its use of ethylene as a starting material makes LiMA a C2-based technology.
Typical applications of MMA include Plexiglas engineering-grade plastic, as well as finishes, floor coatings, adhesives, and dental products.