Dispersion Laboratory reactor types

In upflow bubble operation the consumption of the gas phase by reaction must also be considered in the model if the reactor operates under lower pressure (<20 bar) and if the reactor length is of technical dimensions (L>2 m) additionally gas phase dispersion (radial and axial) may have an influence on conversion [65]. As this reactor type is also used in waste water treatment as well as in fermentation processes, the possible non-Newtonian behavior of the liquid phase as well as the coalescence behavior of the system must be taken into account. Finally, it should be remembered that - comparable to fluidized bed reactors - results from laboratory reactors with small column diameter and/or particle sizes smaller than 0.2 cm usually cannot be regarded as representative for technical upflow units, because capillary force as well as lare scale circulation in the liquid phase may be significantly different. 

Potential pitfalls exist in ranking catalysts based solely on correlations of laboratory tests (MAT or FFB) to riser performance when catalysts decay at significantly different rates. Weekman first pointed out the erroneous conversion ranking of decaying catalysts in fixed bed and moving bed isothermal reactors (1-3). Phenomena such as axial dispersion in the FFB reactor, the nonisothermal nature of the MAT test, and feedstock differences further complicate the catalyst characterization. In addition, differences between REY, USY and RE-USY catalyst types exist due to differences in coke deactivation rates, heats of reaction, activation energies and intrinsic activities. 

Unlike X-rays, which can be produced in a laboratory, neutrons are only available in sufficient quantities at large facilities. Two main types of such facilities must be distinguished, reactor sources and spallation sources, because they have completely different characteristics in high-pressure experiments. The principle of reactor sources need not be described since they are by far the most common sources and have been used for several decades for solid-state studies. The flux from a reactor is usually continuous— the pulsed DUBNA source is an exception—and reactor fluxes are used mainly in the monochromatic angle dispersive mode (as ADXD) for X-ray diffraction. 

---