Studies on the Performance of a Microscale Trickle Bed Reactor Using Different Sizes of Diluent

Abstract

The microscale trickle bed reactor can be used for testing commercial size catalyst, if its inherent limitations, such as channeling, wall effect, and backmixing, are overcome by diluting the catalyst bed with a nonporous inert particles of suitable size. The effect of diluent size on the performance of a microscale trickle bed reactor, catalyst bed height, as well as on operating liquid holdup at different liquid hourly space velocities, has been studied in the present investigation. The proper size of diluent, which may be used for testing as low as 5 mL of commercial catalyst in a microreactor, has been identified experimentally. The results on the hydrodesulfurization of atmospheric gas oil obtained in the microreactor, using the suitable size of diluent were compared with the data generated in a bench scale unit. The activation energy calculated from both microreactor and bench-scale reactor rate data was 21 and 25 kcal/mol, respectively.

Dispersion and Holdup in Multiphase Packed Bed Microreactors

“…Such high values are not even obtained in upflow beds with large particles, e.g., Iliuta and coworkers [21] found static holdup in upflow packed beds of about 0.03 and reported dynamic holdup values in the range 0.10-0.25. In a separate study, Bej et al [22] found that reactor performance kept increasing for smaller particles, with optimal results only MS Figure 7. Effect of molecular diffusivity D M on residence time distribution and Pe p .…”

Microfluidics in Planar Microchannels: Synthesis of Chemical Compounds On-Chip

“…The control over parameters like diluents/catalyst ratio and dimensions was reported to be more determinant than the choice of operation liquid velocities below 0.1 mm/s for diluents size smaller than 200 μm (Bej et al 2000(Bej et al , 2001) that was considered an important requirement before van Herk's experiments. However, the introduction of solids in MCs limits fluid flow, influence mass and energy transports, and render continuous reactors inoperable (Hartman 2012).…”

Fluid Flow Characteristics of String Reactors Packed with Spherical Particles

“…However, the demands for safer operation, reduction of experimental cost, and minimization of experimental time have prompted many investigators to use small-scale reactors with total catalytic mass less than 10 g [4,5]. These reactors appear to be a very promising and useful tool for future applications, but their successful use will ultimately depend on their effective operation [5].…”

“…Many investigators use the dilution technique to avoid problems related to wall effects, low catalyst utilization, incomplete wetting, and axial backmixing for downflow or upflow operation in bench or microreactors [4,5,10], using small-diameter inert fines to fill the voids among the catalyst extrudates. The improved performance of the diluted beds operating in downflow mode is attributed to restricted liquid axial dispersion and the much higher liquid holdup [10] that mainly leads to improved wetting and utilization of catalyst particles.…”