Comment Processing & Handling

A new C2-based production route to MMA

By Gerald Ondrey |

Chemists and engineers from the Performance Materials Segment of Evonik Industries AG (Essen, Germany; have developed a new process for making methyl methacrylate (MMA). With a yield of over 90%, the so-called Leading in Methacrylates (LiMA) process can be considered the most efficient MMA production process, says Steffen Krill, head of Innovation Management in the Methacrylates Business Line.

Today, MMA production is dominated by routes that start with acetone (C3) or — mainly in Asia — isobutene (C4), with only 10% of global production based on ethylene (C2). The C2 Alpha route that was first developed by Lucite International UK Ltd. (Wilton, U.K.;, which is now part of Mitsubishi Chemical Corp., was the winner of the 2009 Kirkpatrick Chemical Engineering Achievement Award (see Chem. Eng., December 2009, pp. 17–21;

production route for MMA

Similar to the C2 Alpha process, the LiMA process (diagram) uses ethylene, synthesis gas (syngas) and methanol as feedstocks, explains Krill. In the first step, ethylene and syngas are hydroformylated into propionaldehyde. In the next step, propionaldehyde and formalin undergo a Mannich condensation to form methacrolein. This intermediate is then directly esterified by methanol in a highly selective, single-step process into MMA. The high yield (over 90%) is due to the new patent-pending process setup in combination with a unique catalyst, which enables the reaction to take place in liquid phase at temperatures below 100°C. The lower temperature also increases the lifetime of the catalyst, which normally has to be replaced yearly in gas-phase routes operating at temperatures of 350°C, says Krill.

In fact, all reaction steps of the LiMA process take place in the liquid phase at temperatures far below that required by gas-phase routes, says Krill. As a result, CO2-equivalent per ton of MMA produced is reduced by up to 30–40%. Also, the raw materials and reaction products serve as the primary solvents themselves, thereby eliminating the need for dilutions or solvents. As a result, LiMA generates one-eighth to one-tenth the intermediary water streams compared to C3 and C4 routes. The milder reaction conditions and absence of corrosive media are also expected to significantly reduce maintenance requirements, while allowing for less expensive materials of construction, he adds.

The LiMA process has operated for over 8,000 hours in a pilot plant in Darmstadt.

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