A microwave chemical reactor is a high frequency electromagnetic wave that does not generate heat by itself. Natural microwaves cannot be used as an energy source because they are not concentrated. The magnetron used can convert electrical energy into microwaves and penetrate the medium at an oscillation frequency of 2450 MHz per second. When the medium has a suitable dielectric constant and medium. When it is worn out, high-frequency oscillation occurs in the electromagnetic field, and energy is accumulated inside the medium. For chemical reactions, both thermal and non-thermal effects can be produced.
Non-polar materials such as tetrafluoroethylene, but will be reflected on the metal surface. The power output of the microwave oven of the household microwave oven is basically fixed, and the smaller power is realized by changing the on/off time (occupying the space) of the current. The on/off of the current used by the microcomputer can be strictly controlled, and the same working conditions can be selected to obtain repeated chemical reaction conditions.
How microwave chemical reactors work
First, the sealing experiment: From the safety of the microwave oven and the operator, we must pay attention to the following points:
It is known that a gas reaction is generated, and the sealing tube test cannot be performed. The sealing tube must be made of pressure-resistant 95 material glass; the amount of the reaction material must be strictly controlled, such as a small amount of reactant without stirring, and a 50 ml or 100 ml flask can be used. The polytetraethylene tray is placed in the center of the bottom of the furnace, and the direct tube is inserted into the flask from the furnace through the cut-off waveguide, and a suitable reflux device is arranged above the top of the furnace. There is a magnetic stirrer at the bottom, which rotates clockwise from low to high. If the amount of reaction is large or a stirrer needs to be inserted (note: the stirrer must be made of glass or tetrafluoroethylene, metal products are not available), use a 50ml-250ml flask. The straight tube is passed through the top of the furnace through the cut-off waveguide to the neck of the flask, and is provided with a U-shaped or three-shaped connecting tube, and then a stirrer, a reflux device and a dropping funnel are arranged.
Second, solid phase chemical reaction: flexible arrangement of reactor and working mode according to reaction needs, but the following principles must be followed;
Gas-generating reactions, particularly corrosive, irritating gases, can easily damage circuits and computer boards. A reflow device should be installed and pumped out of the furnace through the conduit. The dielectric constant and dielectric loss of the reactants and products are different. The microwave absorption in the microwave field will be different. The local temperature difference often occurs during the reaction period. Therefore, in the process of the process, it is often necessary to turn over and shake in the middle of the process. Choose a lower power stage to make the reaction as uniform as possible. Any chemical reaction in the microwave reactor is not allowed to be placed in an open container, and it is not allowed to be placed in a closed container. Because the former can cause splashing and polluting the cavity; the latter is in danger of exploding.