Catalytic Teflon AF-2400 membrane reactor with adsorbed ex situ synthesized Pd-based nanoparticles for nitrobenzene hydrogenation

Abstract

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.

Concurrent Oxidation–Reduction Reactions in a Single System Using a Low-Plasma Phenomenon: Excellent Catalytic Performance and Stability in the Hydrogenation Reaction

“…Hence, this catalyst exhibited remarkable recyclability and catalytic activity compared to those reported previously (Tables and S3). − Moreover, in our case, it was easy to separate Cu-TiO 2 @SiO 2 from the reaction medium. Conversely, most reported catalysts require sophisticated methods for their removal from the reaction solution, such as centrifugation.…”

Toward Continuous‐Flow Hyperpolarisation of Metabolites via Heterogenous Catalysis, Side‐Arm‐Hydrogenation, and Membrane Dissolution of Parahydrogen

“…The high permeability of H 2 in AF2400 means that it quickly diffuses through and dissolves into the liquid. Similar designs have since been used in organic synthesis for both heterogeneous and homogeneous catalysis [15–18] . Recently, Tijssen et al .…”

“…Similar designs have since been used in organic synthesis for both heterogeneous and homogeneous catalysis. [15][16][17][18] Recently, Tijssen et al adapted the tube-in-tube set-up for use with a microfluidic NMR probe. [19] Using the membrane dissolution device, they monitored the hydrogenation of various compounds using palladium microencapsulated in polyurea as a heterogeneous catalyst in continuous flow.…”

Application of reactor engineering concepts in continuous flow chemistry: a review

“…Several more papers have since been published demonstrating this technology. 12,126,[128][129][130][131][132] Uniqsis Ltd. and Vapourtec Ltd. have also adapted this technology for commercial tube-in-tube reactors.…”