Johannes Petrus Verduijn

Zeolite L preparation

Binderless zeolite L particles are prepared by a method in which particles are formed from silica and from 0 to 95 wt % preformed zeolite L crystallites, and the particles are thereafter reacted with an alkaline solution comprising a source of alumina to convert the silica binder to zeolite L. These particles may comprise cylindrical zeolite L crystallites with a mean diameter of at least 0.05 micron in a zeolite L matrix and may be used as catalyst. Also acyclic hydrocarbons are dehydrocyclized and/or isomerized by contacting them at a temperature of from 370° C. to 600° C. with this catalyst incorporating at least one Group VIII metal having dehydrogenating activity to convert at least part of the acyclic hydrocarbons into aromatic hydrocarbons.

Cation site energies in dehydrated hexagonal faujaste (EMT)

Abstract The Na-ion distribution in dehydrated EMT-type zeolites was used as a probe for the characterization of the site-energy differences at the two different hexagonal-prism types using the combination of an (exact) statistical thermodynamical model and an X-ray powder diffraction study (Rietveld refinement). Compared to FAU-type zeolites, regions with a higher AI content most probably exist, coinciding with the twin planes, while the more FAU-like hexagonal prisms show a cation occupancy more typical for a high-Si material. An extensive materials characterization showed that the sample prepared in a crown-ether medium still contained about 25% FAU domains.

The development of an environmental friendly catalytic system for the conversion of olefins

Abstract An elegant method is described for the synthesis of ZSM-22. By controlled addition of seeds and applying stirring during the crystallization, the phase purity and the crystal size can be controlled. The H-ZSM-22 is tested in the dense phase oligomerization of propene at 180–250°C and 70 bar. It is found that adding small amounts of water significantly increases the activity and decreases the deactivation of the catalyst. Secondly, it is shown that catalyst activity is higher after calcination at 400°C versus 550°C and that smaller crystal sizes positively affect the catalyst activity. Both observations are ascribed to the presence of active sites located near the zeolite outer surface accounting for a major part of the catalytic activity.