Mitsubishi Rayon acrylamide process

The biocatalytic acrylamide process is run by the Nitto Chemical Corp., now part of the Mitsubishi Rayon Corp., in Tokyo Bay on a scale of 30 000 tpy, in fed-batch mode up to 25-40% acrylamide at 0-10°C to complete conversion and with product yields > 99.9%, conditions under which a significant cost differential can be assumed with respect to the conventional chemical process. 

Another example in which a biocatalytic transformation has replaced a chemo-catalytic one, in a very simple reaction, is the Mitsubishi Rayon process for the production of acrylamide by hydration of acrylonitrile (Fig. 1.42). Whole cells of Rhodococcus rhodocrous, containing a nitrile hydratase, produced acrylamide in >99.9% purity at >99.9% conversion, and in high volumetric and space time yields [121]. The process (Fig. 1.42) currently accounts for more than 100000 tons annual production of acrylamide and replaced an existing process which employed a copper catalyst. A major advantage of the biocatalytic process is the high product purity, which is important for the main application of acrylamide as a specialty monomer. 

Rhodococcus sp. N-774 and Pseudomonas chlororaphis B23 resting cells have been used at industrial scale (as first- and second-generation biocatalysts) for the biological production of acrylamide from acrylonitrile since the 1980s [21]. Currently Rhodococcus rhodochrous J1 is being adopted as a third-generation biocatalyst (Mitsubishi Rayon Co.). The industrial production of nicotinamide from 3-cyanopyridine is also operated with this strain (Lonza AG). However, despite the enormous potentiality of nitrile-hydrolyzing biocatalysts for industrial applications, only a few commercial processes have been realized [22]. 

Mitsubishi Rayon produces acrylamide from acrylonitrile with the help of an immobilized bacterial enzyme, nitrile hydratase (see Fig. 9.20). This acrylamide is then polymerized to the conventional plastic polyacrylamide. This process was one of the first large-scale applications of enzymes in the bulk chemical industry and replaced the conventional process that used sulfuric acid and inorganic catalysts. The enzymatic process has several advantages over the chemical process. The efficiency of the enzymatic process is 100%, while that of the previous chemical process was only 30-45%. The energy consumption is only 0.4MJ/kg product, compared to 1.9MJ/kg product for the chemical route. The process generates less waste. The CO2 production is only 0.3 kg/kg monomer, while the previous process produced 1.5 kg/kg. The reaction is carried out at 15°C, which is milder than the original chemical route. About 100,000 tons of acrylamide are produced yearly now via this approach in Japan and other countries. 

Various nitrile hydratases are continued to be developed and compared to the existing wdld-type whole-cell catalysts (R. rhodochrous Jl) presently used in the commercial production of acrylamide from acrylonitrile. Mitsubishi Rayon has produced mutant enzymes of R. rhodochrous Jl with significantly improved thermal stabilities and ca ytic activities at 50-70°C [233,234]. Saint-Etierme France has licensed and commercialized the mamrfacture of acrylamide using Mitsubishi Rayon s immobilized R. rhodochrous ]l [235] and has independently developed a Rhodococcus pyridinovorans whole cell catalyst for this process [236]. 

---