Four different types of shaped catalysts with controlled deposition of platinum and the same composition were prepared by extrusion of beta zeolite agglomerated with bentonite as an aluminosilicate clay binder. The catalysts were characterized using mechanical strength tests; scanning electron microscopy for morphology; transmission electron microscopy for porosity and periodicity; nitrogen physisorption for surface area, pore volume, and pore size distribution; and Fourier transform infrared spectroscopy using pyridine as a probe molecule to elucidate the presence, strength, and amount of Brønsted and Lewis acid sites. Elemental analysis was carried out using energydispersive X-ray microanalysis. Activity and selectivity of catalysts in the isomerization of n-hexane were evaluated using a fixed bed reactor at 200−350 °C. At low temperature, the performance of metal/acid bifunctional shaped catalysis was strongly affected by the metal-to-acid site ratio. This ratio and the total acidity were strongly influenced by the preparation method of the shaped catalysts, while the textural properties were comparable. The highest conversion of n-hexane and selectivity to C 6 isomers (comprising all branched isomers, such as methyl pentane and dimethylbutane) was obtained with extrudates prepared via in situ synthesis with platinum located on the zeolite. The extrudates prepared in this way have the highest metal-to-acid site ratio and their closest proximity, albeit the lowest mechanical strength.

Plasma-assisted dry reforming of methane (DRM) is considered as a potential way to convert natural gas into fuels and chemicals under near ambient temperature and pressure; particularly for distributed processes based on renewable energy. Both catalytic and photocatalytic technologies have been applied for DRM to investigate the CH4 conversion and the energy efficiency of the process. For conventional catalysis; metaldoped Ni-based catalysts are proposed as a leading vector for further development. However; coke deposition leads to fast deactivation of catalysts which limits the catalyst lifetime. Photocatalysis in combination with non-thermal plasma (NTP), on the other hand; is an enabling technology to convert CH4 to more reactive intermediates. Placing the catalyst directly in the plasma zone or using post-plasma photocatalysis could generate a synergistic effect to increase the formation of the desired products. In this review; the recent progress in the area of NTP-(photo)catalysis applications for DRM has been described; with an in-depth discussion of novel plasma reactor types and operational conditions including employment of ferroelectric materials and nanosecond-pulse discharges. Finally, recent developments in the area of optical diagnostic tools for NTP, such as optical emission spectroscopy (OES), in-situ FTIR, and tunable diode laser absorption spectroscopy (TDLAS), are reviewed.

No abstract

BACKGROUND The metal–acid bifunctional catalysts are widely used in many industrially significant chemical processes, including hydroisomerization of n‐hexane. Deactivation and regeneration of metal–acid bifunctional extrudates was investigated in continuous n‐hexane hydroisomerization in a fixed‐bed reactor. Four Pt/H‐Beta‐25 catalysts containing 30% Bindzil binder were prepared with the same composition and controlled metal deposition. RESULTS Different preparation steps led to differences in the mechanical strength, Pt particle size, acidity and strength, metal‐to‐acid site (cPt/cAS) ratio and proximity between two types of active sites. A very slow deactivation and high selectivity to C6 isomers was obtained when Pt was deposited on H‐Beta‐25 zeolite. CONCLUSION Initial selectivity to the desired products was correlated with the physicochemical properties of the catalysts. Location of the metal has a larger influence on catalyst deactivation of the bifunctional catalysts rather than the metal‐to‐acid site ratio or site proximity. Decline of n‐hexane conversion and selectivity to C6 isomers were correlated with changes in the textural properties and acidity of the deactivated catalyst, respectively. © 2021 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

No abstract