Robust Zeolites and Related Nanoporous Materials for Catalytic Processes in Condensed Phases
Introducing microporous materials, such as zeolites, to the field of condensed phase reactions, showed their promising nature. Especially in the field of catalytic transformation of biomass and its derived compounds, zeolites present an astonishing performance. However, the ubiquitous amounts of water in the feedstock have a detrimental effect on the zeolite stability. We have recently proposed a mechanism for the selective hydrolysis of the zeolite framework in hot liquid water. The role of defects, found to be the cause for the zeolite’s susceptibility to water, was eliminated by our established stabilization approach involving the healing of defect nests deep within the crystal lattice using a reactive silane. While the defect concentration plays a significant role in pure water environments, in catalytically more relevant conditions, the intraporous water concentration, determined by the material’s intrinsic hydrophobicity, was found to be the most crucial factor in prolonging the zeolite’s lifetime. Ways to increase the hydrophobicity and in turn reduce the intraporous water concentration involved the healing of defect and deposition of hydrophobic moieties in the crystal, reducing the overall framework Al concentration by design, and synthesis in fluoride media.
In the second part the design, preparation and full characterization of a system composed of protozeolitic nanoparticles (below 10 nm in size) assembled into a highly porous, layered material will be presented. The main advantage of this new material is a considerably higher accessibility of active sites making it suitable for application as an effective catalyst for reactions carried out in a liquid organic phase. The results of catalytic performance (terpene hydrocarbon isomerization, synthesis of methylenedianiline (MDA)) of the materials will be presented and compared to that of standard (micron size) zeolite.