Design and operation of a cost-effective reactor for large protic ionic liquid synthesis

Over the past three decades, researchers have been establishing the possibility of ionic liquids as green alternatives to conventional solvents for industrial applications, such as the delignification of biomass. Protic ionic liquids (PILs), in particular, have gained significant attention due to their cost-effectiveness and straightforward synthesis. The next step towards industrialization is to address the challenges associated with the large-scale production of these novel solvents. PILs are synthesized through the neutralization of an acid and a base, which inherently involves highly exothermic reactions that are corrosive and reactive towards metals. Therefore, a comprehensive design study should be conducted around the careful selection of materials while maximizing reactor throughput. The current study focuses on the design and operation of a semi-batch reactor that exhibits flexibility, allowing it to be easily switched to a continuous-flow reactor. The reactor has been successfully commissioned to produce 0.8 kg h^-1 of 80 w/w % triethylamine hydrogen sulfate ([TEA][HSO₄]_{80 %}). The scale-up analysis showed that a reactor, which was scaled up by a factor of 15 in dimensions based on a constant power per unit volume, resulted in a design production capacity of 105 kg h^-1 [TEA][HSO₄]_{80 %}. To date, we have produced ca. 800 kg 80 w/w % of N,N-dimtheylbutyl ammonium hydrogen sulfate ([DMBA][HSO₄]_{80 %}), and [TEA][HSO₄]_{80 %} combined.