(603d) Novel Catalysts for the Environmentally Friendly Synthesis of Methyl Methacrylate
Although many chemicals have been produced in large volumes for decades, practitioners in the industry continues to seek innovative ways to produce classic chemicals more sustainably using less energy intense processes. Methyl methacrylate (MMA) can be produced in diverse ways based on C2-C4 hydrocarbon feedstocks. Methyl methacrylate is a specialty monomer to produce polymethylmethacrylate (PMMA) where increasing demand has motivated the industry to develop clean technologies based on leveraging abundant ethylene from inexpensive shale gas feedstock. The dominant commercial process utilizes acetone and hydrogen cyanide to produce MMA (ACH route) however hydrogen cyanide and the acetone cyanohydrin intermediate are highly toxic and present a number of operational and other challanges. The processes based on C2 carbonylation are commercially attractive technologies for MMA manufacture. In particular, efforts are underway to develop platforms for producing propionate intermediates through hydroxy- and methoxy-carbonylation. These, intermediates, in turn, can be used to produce methyl methacrylate monomers through condensation process with formaldehyde. The development of a process from ethyelene can alleviate the operational challanges associated with the current ACH commercial MMA process. While the literature on catalytic systems for hydroxy- and methoxy-carbonylation focuses mainly on homogeneous catalysis, we instead focus on heterogeneous catalytic pathways that facilitate separation. We will discuss the synthesis and characterization of novel heterogeneous catalytic systems for ethylene hydroxy- and methoxy-carbonylation and the relationships between catalyst properties and catalyst performance. Remarkable catalysts were studied that facilitated significant steps forward in both the advancement of catalysis science and establishing the basis for new technologies. An emblematic example is represented by Mo(CO)6 on solid acid support for hydroxy-carbonylation and metal sulfide catalysts for methoxy-carbonylation process.