Impedance Measurements in Adsorption Reactors

Dielectric measurements also can be performed in capacitors placed inside adsorption columns. Here they provide a means to detect adsorption processes on site , i. e. to observe changes in the electric capacitance of the capacitor due to gas adsorption or desorption processes on the sorbent material in the capacitor. In this way not only breakthrough curves but also periodic loading and unloading curves of sorptive gases in laboratory or industrial adsorption reactors can be observed. 

In this section we will describe this method by presenting the experimental installation necessary for these measurements and also by giving several examples of sorption processes monitored by changes of the permittivity of the sorbent material due to gas ad- and desorption [6.10, 6.15]. 

3 Pressure/temp. gauge 5 Thermocouples 7 Impedance analyzer 

The adsorption column should be supplied with a number of thermocouples to observe heat effects during sorption. Also a supply system for sorptive gases and a carrier gas (He, Ar, N2) should be provided including well calibrated flow meters to set up mass balances. 

The TCD at the (upper level) end of the column registers the end of the desorption process after ca. 120 s, the last remnant molecules of CO leaving the TCD after 200 s. This clearly demonstates that the actual state of a porous sorbent during an ad- or desorption process easily can be checked and monitored by impedance measurements. For more details and other examples 

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