Supercritical Chemical Reaction
Supercritical CO2 fluid chemical reaction equipment
Supercritical chemical reaction refers to a process in which the reactants are in a supercritical state or the reaction is carried out in a supercritical medium.
The medium of the supercritical reaction should be non-corrosive to the device, the critical temperature should be close to the reaction operating temperature, the critical pressure should be low, and the medium with high selectivity and solubility for the reactant components. Since supercritical fluid has both liquid and gas properties, the solubility of the medium can be changed in a relatively large range through pressure adjustment. Therefore, the solubility of supercritical fluids is often used in chemical reactions to convert heterogeneous reactions into homogeneous reactions, increase the mass transfer rate, thereby increase the reaction rate and simplify product separation.
Characteristics of supercritical chemical reaction technology:
- In the supercritical state, pressure has a strong influence on the reaction rate constant. A slight pressure change can change the reaction rate constant by several orders of magnitude;
- Carrying out a chemical reaction in a supercritical state can turn a traditional heterogeneous reaction into a homogeneous reaction, that is, dissolving the reactants and even the catalyst in the supercritical fluid, which is beneficial to eliminate the diffusion restriction between the reactant and the catalyst, thereby increasing Increased reaction speed;
- Carrying out chemical reactions in a supercritical state can reduce the reaction temperature to a certain extent, inhibit or reduce the common carbon deposition phenomenon in pyrolysis reactions, and can also significantly improve product selectivity and yield.
- Taking advantage of the sensitivity of the solubility of supercritical fluids to temperature and pressure, products that are insoluble in the supercritical reaction phase can be removed in time by selecting appropriate temperature and pressure conditions, or by gradually adjusting the system The method of temperature and pressure, the product and reactant are removed from the supercritical fluid in turn, so as to easily complete the separation between product, reactant, catalyst and by-product;
- The supercritical fluid can dissolve certain substances that cause the deactivation of the solid catalyst, so that the supercritical fluid-solid catalytic reaction may maintain the activity of the catalyst for a long time. At the same time, by adjusting the temperature and pressure, the reaction mixture is in a supercritical state, thereby The deactivated catalyst gradually restores its catalytic activity.
CO2 has the characteristics of chemical inertness and easy realization of the critical state, so in recent years, the research on supercritical CO2 has developed rapidly. At present, the common research types mainly include selective oxidation, hydrogenation, hydroformylation, alkylation, polymerization, esterification, transesterification, and enzymatic reaction.
Due to the advantages of effectively reducing the reaction temperature, increasing the conversion rate of reactants and product selectivity, increasing the reaction speed, and greatly improving the stability of the catalyst, in recent years, supercritical CO2</sub >Chemical reactions are gradually receiving extensive attention, and related applied research and industrialization achievements are also rapidly increasing year by year.