The simple transfer of established chemical production processes from batch to flow chemistry does not automatically result in more sustainable ones. Detailed process understanding and the motivation to scrutinize known process conditions are necessary factors for success. Although the focus is usually "only" on intensifying transport phenomena to operate under intrinsic kinetics, there is also a large intensification potential in chemistry under harsh conditions and in the specific design of flow processes. Such an understanding and proposed processes are required at an early stage of process design because decisions on the best-suited tools and parameters required to convert green engineering concepts into practice-typically with little chance of substantial changes later-are made during this period. Herein, we present a holistic and interdisciplinary process design approach that combines the concept of novel process windows with process modeling, simulation, and simplified cost and lifecycle assessment for the deliberate development of a cost-competitive and environmentally sustainable alternative to an existing production process for epoxidized soybean oil.
The Kolbe-Schmitt synthesis from resorcinol was exemplarily investigated to figure out the process intensification potential of continuous processing in the milli and micro scale, alone and combined with additional intensification means like alternative solvents, new reagents and an advanced reactor design. The oil bathheated synthesis was investigated for capillary reactors of different dimensions, using aqueous solutions of KHCO 3 and reactive ionic liquids. Already the first case led to space-time yields (STY) of 15,500 kg/(m 3 h) at 37 % yield. Synthesis with different CO 2 -donating salts showed that KHCO 3 has the highest activity and that hydrogen carbonates are better than carbonates. The replacement of KHCO 3 by reactive ionic liquids led to a substantial increase, both in yield (58 %) and STY (69,900 kg/(m 3 h)). The application of scCO 2 did not significantly increase the yield despite an even more substantial change of the reaction medium. Using an electrically heated microstructured reactor resulted in a tenfold higher productivity (0.75 t/a) compared to the capillary reactor and does much better ensure scalability of the reaction.
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