Dehydrogenation of isobutane to isobutene in a palladium membrane reactor

Abstract

The dehydrogenation of isobutane to isobutene was conducted in a comparatively low-temperature range (from 623 to 723 K) using a hydrogen-permeable membrane reactor. An Al 2O 3-supported platinum catalyst exhibited high activity compared with a commercial Cr 2O 3-Al 2O 3 catalyst in a conventional flow reactor. In the membrane reactor, however, the platinum catalyst gave a lower yield of isobutene than the Cr 2O 3-Al 2O 3 catalyst, although the isobutene yields on both of these catalysts were high compared with thermodynamic equilibrium values attained in a conventional reactor. The platinum catalyst deteriorated more rapidly in the membrane reactor, due to deposition of carbonaceous material. On the other hand, undesirable side reactions such as hydroisomerization and hydrogenolysis were suppressed in the membrane reactor due to the removal of hydrogen produced from the reaction side, leading to high selectivity for isobutene. The yield of isobutene in the membrane reactor increased by the addition of tin to Pt/Al 2O 3, due to the suppression of coke formation.