Supercritical reaction refers to a process where reactants are in a supercritical state or the reaction occurs in a supercritical medium. The basic principle of supercritical reaction is to control pressure and temperature to dissolve reactants in a supercritical fluid medium or to bring them into a supercritical state, converting reactants into low-viscosity fluids or liquid organic substances, causing “turbulence”. The molecules of the reactants become more active than in the normal state, more likely to interact with each other, more easily absorb and release energy, and mix more thoroughly with catalysts, making it easier to form new products. During the reaction, the solubility of supercritical fluids is utilized to transform heterogeneous reactions into homogeneous reactions, increasing the mass transfer rate, thereby accelerating the reaction speed, improving reaction efficiency, and simplifying the separation process of the final product and excess solvent by utilizing the easy phase transition characteristics of supercritical fluids. 

Technical Features

In the supercritical state, pressure has a strong influence on the reaction rate constant, with slight pressure changes causing several orders of magnitude changes in the reaction rate constant. Conducting chemical reactions in the supercritical state can transform traditional multiphase reactions into homogeneous reactions, that is, dissolving reactants and even catalysts in supercritical fluids, helping to eliminate diffusion limitations between reactants and catalysts, thereby increasing the reaction rate. Utilizing the sensitivity of the solubility of supercritical fluids to temperature and pressure, products that are insoluble in the supercritical reaction phase can be promptly removed by selecting appropriate temperature and pressure conditions. Alternatively, by gradually adjusting the system's temperature and pressure, products and reactants can be sequentially removed from the supercritical fluid, thus easily completing the separation between products, reactants, catalysts, and by-products. 

Technical Advantages

Using supercritical reaction technology can effectively lower the reaction temperature, inhibit or mitigate the common carbon deposition phenomenon in pyrolysis reactions, increase reaction speed and efficiency, simplify the separation of final products, and significantly improve product selectivity and yield. It can greatly enhance the stability of catalysts or gradually restore the catalytic activity of deactivated catalysts. Supercritical reactions are short, efficient, low-energy, easy to control, and do not produce harmful by-products, making them environmentally friendly, safer, and more sustainable in product production processes. 

Application Areas

In recent years, research on supercritical reactions has developed rapidly, with common research types including selective oxidation, hydrogenation, hydroformylation, alkylation, polymerization, esterification, transesterification, and enzymatic reactions. These are widely applied in food, chemical, pharmaceutical, and agricultural fields.