The catalytic method of converting compounds into other compounds uses a chemical catalyst to increase the rate of a reaction. The catalyst is chemically unchanged after the reaction has occurred and can be recovered from the reaction mixture. Thirty of the top fifty commodity chemicals are created directly by catalysis.
In the fluidized bed reactor-regenerator (FBRR) a fluid is passed through the catalyst at high enough velocities to suspend the solid and cause it to behave as though it were a fluid. Measurement in the reactor vessel must contend with severe process conditions. Finished product and, in some configurations, spent catalyst, is on level control.