Design of Membranal Dehydrogenation Reactors: The Fast Reaction Asymptote

Moshe Sheintuch*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


This study presents a systematic analysis of certain design aspects of a packed-bed catalytic membrane reactor for simple and fast dehydrogenation reactions. For sufficiently fast reactions, local chemical equilibrium can be assumed everywhere and conversion is transport limited. Under these assumptions, in a plug-flow isothermal reactor with a permselective membrane, analytical results can be derived showing the conversion dependence on reactor length and equilibrium coefficient. These results suggest that significant conversions should be expected in such a reactor with a reasonable membrane area-to-feed flow rate ratio (e.g., at 450°C during butane dehydrogenation, with membrane flux of 1 cm2/cm3/min). High pressures lead to lower equilibrium conversions and to higher diffusive fluxes, resulting in a marginal change in overall conversion. Shell-side hydrogen partial pressure affects the conversion significantly, and the shell-to-tube flow rate ratio should be sufficiently large (10 to 100). Catalyst loading should be optimized to decrease length and improve selectivity. Ceramic Knudsen-selective membranes yield poor conversions. A preliminary analysis of an adiabatic reactor in which the diffusing hydrogen is combusted to supply the dehydrogenation enthalpy is also presented. These conclusions are contrasted with experimental observations obtained during isobutane dehydrogenation in a Pd membrane reactor.

Original languageEnglish
Pages (from-to)807-814
Number of pages8
JournalIndustrial and Engineering Chemistry Research
Issue number3
StatePublished - Mar 1998
Externally publishedYes


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