Mesoporous ZSM-5 catalysts: Preparation, characterisation and catalytic properties. Part I: Comparison of different synthesis routes

In an attempt to improve mass-transport limitations, mesopores were created in a series of ZSM-5 catalysts by the carbon-templating procedure. A successful low-cost dry gel synthesis route was developed which almost entirely removed the need for the organic structure-directing agent (TPA/SiO2 = 0.0033). Both an aqueous colloidal graphite sol and a pyrogenic (carbon black) material were investigated, at addition levels of 16.5–100 wt.%. No major differences were observed between the two carbon sources. The addition of carbon to the synthesis composition retarded the crystallisation rate and modified the crystal morphology. The products were characterised by a variety of physical techniques. Additional post-synthesis treatment (alkaline leaching) extended the mesopore system but also tended to reduce crystallinity and micropore volume.