The growing demand for isobutane as a vital petrochemical feedstock and chemical intermediate has for many decades surpassed industrial outputs that can be supplied through liquified petroleum gases. Alternative methods to resource the isobutane market have been explored, primarily the isomerization of linear n-butane to the substituted isobutane. To date the isobutane market is valued at over 20 billion US dollars, enticing researchers to seek unique and novel catalytic materials to improve on current commercial practices. Two main classes of catalysts have dominated the butane isomerization literature in the last few decades; namely microporous zeolites and sulfated zirconia. Both have been widely researched for butane isomerization, to the point where key catalytic descriptors such as acidity, framework topology and metal doping are becoming well understood. While this provides new researchers with a roadmap for developing new materials, it is has also begun developing into an invaluable tool for diagnosing and understanding the effect of these individual descriptors on catalytic properties. In this review we explore the different factors that influence the active site behavior of particularly zeolites and sulfated zirconia catalysts towards understanding the use of butane isomerization as a diagnostic tool for solid-acid catalysts.
Novel in situ synchrotron total scattering measurements probe the assembly of primary building units into templated hierarchically porous aluminophosphate catalysts, providing unique insights to understanding crystallisation kinetics.
Hierarchically porous (HP) zeotype materials (possessing both micropores and mesopores) offer improved diffusional access to intra-framework active sites, analogous to mesoporous materials, yet retain the high selectivity of the microporous (MP) bulk. We have recently designed crystalline hierarchically porous silicoaluminophosphates (SAPOs) with enhanced mass-transport characteristics, which can lead to significant improvement in catalytic activity and catalyst lifetime. In this study, we have prepared PdAu bimetallic nanostructures supported on HP-SAPO frameworks by an incipient impregnation of metal precursors followed by H2 reduction at 300 °C, for the aerobic oxidation of benzyl alcohol to benzaldehyde. PdAu NPs supported on HP framework displayed significantly enhanced catalytic activities, when compared with their MP analogues, clearly highlighting the benefits of introducing hierarchical porosity in the SAPO support matrix.
The use of solar energy to activate chemical pathways in a sustainable manner drives the development in photocatalysis. While catalyst optimisation is a major theme in this pursuit, the development of novel photocatalytic reactors to enhance productivity is also imperative. In this work we combine, for the first time, microstructured optical fibre technology with photocatalysis, creating a photocatalytic microreactor coated with TiO2, decorated with palladium nanoparticles. In doing so, we create a system capable of effectively combining photons, liquids and gases within a monolithic, highly confined, transparent silica geometry. We utilise a range of characterisation techniques to selectively focus on the photocatalyst, that resides exclusively within the internal capillaries of this system. In doing so we validate our design approach, and demonstrate the ability to simultaneously control both nanoparticle size and metal content. Further, we justify our unique design, showing its activity in photocatalytic hydrogen generation from water. In doing so highlighting the importance in developing light propagation properties from optical fibres, and the significant potential of this technology in the expansive photocatalysis landscape.
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