Advantages, Possibilities, and Limitations of Small-Scale Testing of Catalysts for Fixed-Bed Processes

A Pilot-Plant Simulation of the Influence of the H2/H2S Ratio on the Efficiency of a Commercial Hydrodesulfurization Plant

“…The axial diffusion criterion is calculated by the ratio of the inner reactor diameter and the effective particle diameter as D /dp = 36.5. It proves that there is no implication of axial dispersion since the value is higher than 25, which is the limit required for the presence of a three-phase system …”

“…13 The ratio between the bed length and the effective particle diameter, L/dp ) 305, was calculated assuming a firstorder reaction and a very high conversion of 97%. Since this ratio does not satisfy the required minimal value for a threephase system, 14 the catalyst bed had to be diluted with an inert material. Therefore, crushed R-alumina particles of size less than 0.2 mm were mixed with the catalyst in the ratio 1/1, resulting in a total volume of the catalyst and inert of approximately 150 cm 3 .…”

“…It proves that there is no implication of axial dispersion since the value is higher than 25, which is the limit required for the presence of a three-phase system. 14 The wetting criterion was checked by means of the equation where η L , F L , and u L are the dynamic viscosity, density, and linear velocity, all related to the liquid phase, g is the gravity constant, and W is a dimensionless number comparing flowing friction forces and the gravity force. Good catalyst bed wetting with an appropriate reconstruction of the liquid film at the top of the catalyst surface is guaranteed by the range of the calculated wetting criterion as W ) (1.9-2.6) × 10 -5 obtained for the extremes of linear velocity.…”

“…Good catalyst bed wetting with an appropriate reconstruction of the liquid film at the top of the catalyst surface is guaranteed by the range of the calculated wetting criterion as W ) (1.9-2.6) × 10 -5 obtained for the extremes of linear velocity. 14 The catalyst was activated in a flow of H 2 S/H 2 mixture very rich in H 2 . The amount of S added was calculated to be 3-4 wt %, the same as in the commercial unit.…”

Single Pellet String Reactor for Intensification of Catalyst Testing in Gas/Liquid/Solid Configuration

“…Reducing a reactor size brings up new challenges regarding its design, as discussed previously, and chemical engineering technology innovations are the only way forward. For example, in the 90s, the introduction of inert, small-sized (100 μm) particles in between the catalyst made it possible to test in 10-20-mm diameter reactors [4,5].…”