Template-controlled acidity and catalytic activity of ferrierite crystals

A synthesis strategy to tailor the acid sites location in ferrierite crystals has been developed. The zeolite catalysts were synthesised in fluoride medium using different combinations of organic structure directing agents (SDAs) in the absence of inorganic cations. Therefore, the negative charge associated to the incorporation of aluminium to the framework was compensated exclusively by the positive charge of the organic SDAs. In this way, Al sitting in the zeolite framework was driven by the specific location of the different SDA molecules within the zeolite void volume. Following this synthesis strategy, it has been found that the distribution of strongly acidic hydroxyl groups in the proton form of the zeolites obtained after removal of the organic templates was dependent on the combination of organic molecules used as SDAs. Moreover, the catalytic activity of the zeolites in m-xylene and 1-butene isomerisation increased as the relative population of strong Brönsted acid groups in sterically constrained sites inside the ferrierite cavity decreased.

Al sitting in ferrierite crystals has been controlled by carrying out the zeolite synthesis with selected combinations of organic directing agents in fluoride medium. The catalytic activity for the isomerisation of linear butenes and m-xylene increased as the relative population of strong Brönsted acid groups in sterically constrained sites inside the ferrierite cavity decreased.Figure optionsDownload high-quality image (77 K)Download as PowerPoint slide