Dynamic and catalytic studies of H-ferrierites made by hydrothermal and dry state syntheses

Abstract

The activity and selectivity of skeletal isomerization of 1-butene and disproportionation of ethylbenzene on H-ferrierite catalysts prepared by dry state recrystallization of magadiite and conventional hydrothermal synthesis from an alkaline SiO 2/Al 2O 3 gel are compared. The isobutene yields of the samples were found to be similar even though the ferrierite crystals had quite different morphologies. Significant differences were observed in the isobutene selectivities which can be correlated with processes occurring inside the crystals. Ammonia, acetylene, methane and propane sorption and intracrystalline diffusion rate-spectra are reported using the frequency-response technique. The sorption properties of the acid sites and the diffusional resistances of the morphologically different ferrierite crystals are compared. It was found that by the dry state synthesis the quality of the ferrierite framework was similar to that obtained by the conventional hydrothermal synthesis. The channels of ferrierite recrystallized from magadiite, however, seem to have fewer barriers and, thus, show better kinetic properties, e.g., faster diffusion of propane and higher selectivity to the formation of isobutene.