Studies on post-synthetic treatments of micro- and mesoporous zeolites: Impact on their physicochemical and catalytic properties

Zeolites have a very wide application range, including the use as catalysts. Actually, zeolites constitute a large portion of the solid catalysts used to date in industry. The major challenge nowadays is the fine-tuning of these materials to a specific application, either by direct synthesis or by a combination with post-synthesis treatments. A well-known post synthesis treatment method is calcination, typically used to remove the organic template and/or to introduce Brønsted acid sites in the zeolite framework. However, calcination has some major drawbacks, such as a (partly) collapse of the structure and a reduction of the OH groups on the surface. In this thesis, the use of milder post-treatment techniques is described, with an emphasis on Fenton detemplation. The suitability of this methodology was determined for a number of relevant micro- and meso-porous zeolites and quantitative template removal was observed in most cases. Relevant material properties were determined and it was shown that the structure of the zeolite after the mild detemplation procedure resembles that of the zeolite after synthesis. The catalytic cracking of low-density polyethylene (LDPE) was used as model reaction to test performance of the various detemplated zeolites. It was shown that zeolites prepared using the mild Fenton approach were more active than those prepared using the conventional calcination technique.