engleski

Chemical engineering methodology in process development: a case study of MenD-catalyzed 1, 4-addition of α-ketoglutaric acid to acrylonitrile

Kinetics of the MenD-catalyzed 1, 4-addition of α-ketoglutaric acid to acrylonitrile were investigated in detail and based on the results a mathematical model of the process was developed and experimentally validated. The reaction kinetics were described by the double substrate Michaelis–Menten kinetics where the reaction rate linearly depends on acrylonitrile concentration. Non-competitive enzyme inhibition by p-methoxyphenol, i.e. acrylonitrile stabilizer, was also included in the model. Spontaneous reactivity of acrylonitrile towards polymerization was noted. Based on the experimental results, as well as model simulations, a fed-batch reactor was selected as the best reactor mode to carry out the reaction due to shortened reaction time compared to the repetitive batch reactor mode, and the ability to obtain maximum yield on the product, i.e. 6-cyano-4-oxohexanoic acid. Additionally, the fed-batch reactor method enables to set up the feeding strategy of acrylonitrile necessary to keep its concentrations below the level which significantly affects enzyme operational stability. The mathematical model was used for process optimization and as an assessment tool for the economic evaluation. Results have shown that in the investigated variable range all the requirements for the industrial implementation can be achieved ; i.e. product concentration of 70 g L–1, volume productivity of 58 g L–1 d–1, product yield of 96%, and biocatalyst yield of 28.9 gP gMenD–1. Based on the optimized production procedure, economic analysis was performed to determine the breakeven point of the process. In addition, influence of uncertainties in estimation of input variables on overall economic performance was assessed using sensitivity analysis. Project CARBAZYMES- This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 635595.

MenD, process modeling, proces economics

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