Supercritical CO2-applied equipment for chemical synthesis and transformation: Current status and perspectives

Due to the fascinating properties of low viscosity, zero surface tension, high gas-like diffusivity and high liquid-like density, as well as the characteristics of nontoxic, nonflammable and noncorrosive, supercritical carbon dioxide (SCCO2) has been widely used in green, sustainable and effective technologies, especially in the field of chemical engineering for chemical synthesis and transformation. SCCO2-based technologies have attracted the increasing attention of researchers, but the high sensitivity of SCCO2 to the change of parameters during the chemical reaction process limits the practical applications of SCCO2-based technologies. The key to transferring these technologies into practical applications is the reasonable design and construction of SCCO2-applied equipments, and different SCCO2-based applications usually require to be implemented with specific equipment. Herein, different from most of the reviews that focused on SCCO2 application itself, this review takes a unique perspective of systematically and comprehensively summarizing the current researches about various SCCO2-applied equipments, including their design principles, components constitution, operation mechanisms and applied fields, according to different applications in the field of chemical engineering for chemical synthesis and transformation, and analyzed the commonalities and specificities among the equipments. Furtherly, forward directions to explore and commercialization challenges to overcome are proposed for more in-depth and extensive development of SCCO2-applied equipments. This review aims to provide the thoughts for the target design of SCCO2-applied equipments, and offer the technical guidance for their optimization and improvement, as well as provide the inspiration for developing new applications of SCCO2-based technologies in the field of chemical engineering for chemical synthesis and transformation, thus supplying a reliable and valuable reference for the development and industrial applications of SCCO2-based technologies.