Among the unconventional approaches of supporting catalyst nanoparticles, the layer-by-layer assembly of polyelectrolyte multilayers for nanoparticle adsorption represents an easy and convenient method. It enables the deposition of singularly adsorbed nanoparticles and prevents them from aggregating. In this work, polydopamine was grafted on the internal surface of a Teflon AF-2400 tubular membrane, known for its excellent permeability to light gases and inertness to chemicals.Poly(acrylic acid) and poly(allylamine hydrochloride) were sequentially adsorbed on the modified surface of the membrane. Ex situ synthesised spherical, cubical, truncated octahedral palladium and dendritic platinum-palladium nanoparticles were then incorporated. The catalytic membranes were assembled in a tube-in-tube configuration and tested for 6 h of continuous nitrobenzene hydrogenation with molecular hydrogen. Stable conversion was observed for the truncated octahedral and dendritic nanoparticles, while a progressive deactivation was observed for the other nanoparticles. Due to their small size, the 3.7 nm spherical nanoparticles exhibited the highest reaction rate, 629 mol reactant /(mol catalyst h), while the cubical nanoparticles showed the highest turnover frequency, 3000 h -1 . The reactor concept developed in this work demonstrates how such a tool can serve as platform for conducting continuous multiphase catalytic reactions in flow using singularly adsorbed and finely tuned nanoparticles. The small volume of pressurised gas present in the tube-intube reactor offers improved process safety compared to batch, while the Teflon AF-2400 membrane provides control over the gas permeation during reaction.

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A slurry loop reactor was designed for the aerobic oxidation of benzyl alcohol. • A tubular membrane was incorporated for safe and controlled oxygen delivery. • Similar oxidation rate was achieved to that of a conventional autoclave reactor. • The addition of a crossflow filter inside the loop allowed for continuous operation.

A novel microreactor for operando XAS and DRIFTS studies of catalytic reactions is reported, exhibiting plug-flow, isothermal behaviour and absence of mass transfer resistances and dead volume, enabling time- and spatially-resolved experiments.

A catalytic membrane reactor with a Au-Pd catalyst, impregnated at the inner side of the membrane, was studied in the catalytic oxidation of benzyl alcohol in flow. The reactor comprised of four concentric sections. The liquid substrate flowed in the annulus created by an inner tube and the membrane. The membrane consisted of 3 layers of α-alumina and a titania top layer with 5 nm average pore size. Oxygen was fed on the outer side of the membrane, and its use allowed the controlled contact of the liquid and the gas phase. Experiments revealed excellent stability of the impregnated membrane and selectivities to benzaldehyde were on average > 95%. Increasing the pressure of the gas phase and decreasing liquid flowrates and benzyl alcohol concentration resulted in an increased conversion, while selectivities to benzaldehyde remained constant and in excess of 95%.