Direct Comparison of a Trickle Bed and a Monolith for Hydrogenation of Pyrolysis Gasoline

Abstract

The applicability of a monolith system to a retrofit application for the hydrogenation of pyrolysis gasoline (Pygas) is evaluated. A direct comparison between a trickle bed (extruded trilobe) and a washcoated monolith is made using a simulated model Pygas mixture. Comparable nickel impregnated onto alumina catalysts (trilobe and monolith) are evaluated in a laboratory recycle reactor operating under the same industrially relevant conditions of temperature, pressure, and liquid/gas flow rate. The inferred flow rates are an order of magnitude lower than those used in many monolith studies. The volumetric rate of reaction over the monolith is approximately twice that of the trickle bed. The trickle bed, operated in both the trickle-flow and transition regimes, is mass-transfer-limited. Monoliths appear to give a rate benefit by virtue of mass-transfer enhancement. The rate of hydrogenation at two different flow velocities gave almost identical results for all components. However, these rate enhancements may not be as significant as previously claimed when considering operation at equivalent superficial velocities. No significant changes in selectivity are observed between the trickle bed and monolith operation.

Effect of phase maldistribution on performance of two‐phase catalytic monolith reactor and its comparison with trickle bed reactor

“…For an industrial‐scale deployment of monolith reactors, the performance of the monolith reactor and its comparison with TBR performance should be known. Such comparative studies have been reported by various authors . It should be noted that compared to monolith reactors, TBR have been well studied.…”

Step Up: Gas–Liquid Mass-Transfer Characterization at Plant Scale Using the Pressure Step Method

“…This is confirmed when the trial data are analyzed, with the results shown in Table 2. It can be seen that the solubility of the gas RDT k L a = 0.0171 × (N/1000) 6.05 e 0.38 × 10 −6 P + 0.00525…”

“…This often manifests as an apparent zero order kinetics with respect to time or conversion of other reactants, while at constant pressure. If C H 2 varies between reactors, for example, because of higher k L a in the laboratory than on plants, then both homogeneous concentration and heterogeneous catalyst surface coverage can also vary, potentially leading to alternate reaction pathways and selectivity to the wrong product. − For most processes, this would be highly problematic; for the pharmaceutical industry, it can be disastrous and could have a lasting impact on human health.…”

Moving from Batch to Continuous Operation for the Liquid Phase Dehydrogenation of Tetrahydrocarbazole

“…The TBR was operated either under semibatch mode where all the liquid flow was circulated back into the reactor by the metering pump while the gas was vented or in continuous mode, where a portion of the liquid feed was removed from the reactor while 99.75% of the liquid was recycled. This protocol has been described by the groups of Hickman 20 and Pollington 21 to ensure complete wetting of the catalyst bed and minimisation of external mass transfer, thereby allowing reliable measurement of a rate of reaction. The inlet and outlet flow of the liquid feed were both set to 1 mL min −1 .…”