Modeling of monolithic and trickle-bed reactors for the hydrogenation of styrene

Abstract

A kinetic study into the styrene hydrogenation over a palladium on alumina catalyst has been made. Styrene was used as a model component for pyrolysis gasoline. A kinetic rate expression has been derived and the inhibiting e ect of sulfur components has been included. Using this kinetics and mass-transfer models compiled from literature, the performance of two types of reactors for the styrene (pyrolysis gasoline) hydrogenation has been evaluated. A structured reactor such as a monolith has large advantages over a conventional trickle-bed reactor. For the monolithic reactor a more than 3 times higher volumetric productivity is obtained with much less catalyst. The modeling results indicate that deactivation by gum formation should be signiÿcantly less due to much better hydrogen mass transfer in the reactor. ?

Microchannel Reactor System Design & Demonstration For On-Site H2O2 Production by Controlled H2/O2 Reaction

“…This was done by calculating a concentration profile that did not take into account the difference in reaction rates between the gas and the liquid phases. The mass transfer rate of hydrogen into the liquid phase, determined by the parameter k gl a gl , is strongly affected by the lengths of gas and liquid slugs (Nijhuis et al, 2003., Kreutzer et al, 2001. However, the assumption of a pseudo singlephase model enabled us to calculate k gl a gl without the knowledge of slug lengths, as shown in the model equations below.…”

“…However, the assumption of a pseudo singlephase model enabled us to calculate k gl a gl without the knowledge of slug lengths, as shown in the model equations below. 5) The liquid-solid mass transfer parameter k ls a ls was estimated, using the correlations for monolith reactors (Nijhuis et al, 2003., Kreutzer et al, 2001, to be approximately one order of magnitude greater than the gas-liquid mass transfer parameter. This was expected since gas-liquid-solid reactions are usually not limited by liquid-solid mass transfer.…”

MORE ACTIVE AND SULFUR RESISTANT BIMETALLIC Pd-NI CATALYSTS

“…Both Pd and Ni catalysts are used for styrene hydrogenation. 3,4 The main problem of the PyGas streams is that they contain high amount of sulfided compounds, usually between 300 and 2000 ppm 1,3,5 that poison the catalysts. Thiophene is one of the main sulfided compounds causing deactivation of the catalysts by poisoning.…”

Modeling Styrene Hydrogenation Kinetics Using Palladium Catalysts

“…Styrene, mono and diolefins are also present in PYGAS in appreciable proportions. The high octane number of PYGAS is responsible for its insertion in the gasoline pool (Nijhuis et al, 2003).…”

“…Styrene was selected as a model molecule regarding PYGAS since it is one of the less reactive of its components (Cheng et al, 1986;Nijhuis et al, 2003;Gaspar et al, 2008).…”