Marc Pera-Titus

Cardiff University, UK

Title: Catalysis on Particle-Stabilized Bubbles

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Biography

Marc Pera-Titus is Professor & Chair of Sustainable Catalytic Chemistry at Cardiff University (Wales, UK). Marc received a double MSc degree in Chemical Engineering (2001) and Physical Chemistry (2002), and a PhD (2006) from University of Barcelona (Catalonia, Spain). In 2007, he joined Ircelyon/CNRS (France) as postdoc and was further appointed CNRS fellow in 2008. From 2011-2020, Marc was project leader, expert and deputy director at the E2P2L CNRS-Solvay joint laboratory in Shanghai (China), merging industrial and academic research. Marc is author of 125 papers and inventor of 16 patents in the fields of membranes, adsorption, catalysis and process eco-design. Marc has received numerous awards, including the Rhone-Alpes Foundation Award (2007), the Elsevier Award for highly cited author in Catalysis (2009), the Silver and Gold Medals from the Chinese Academy of Inventions (2016, 2017), the DivCat award from the French Society of Chemistry (2017) and a ERC consolidator grant (2018). Since 2021, he is elected fellow of the Royal Society of Chemistry.

Abstract

Gas-liquid-solid (G/L/S) reactions are ubiquitous in chemical, petrochemical and environmental catalytic processes. Conventional G/L/S reactors comprise packed beds, stirred tanks and bubble column slurry reactors. These technologies usually suffer from mass/heat transfer limitations due to low G/L and L/S specific interface areas and poor gas solubility. As a way out, herein we developed particle-stabilized foams and bubbles in water and organic solvents as efficient G/L/S microreactors for conducting diffusion-free catalytic reactions at low gas pressures.

First, we prepared oil foams stabilized by surface-active silica particles bearing fluorinated chains and Pd nanoparticles. Foamability increased with both the particle concentration and stirring rate. High foam stability was achieved in benzyl alcohol / xylene mixtures at very low particle concentration (<1 wt%) for contact angles in the range 41-73°. The catalytic performance was strongly affected by the foaming properties, with 8-times activity increase in pure O₂ compared to non-foam systems. Particles were conveniently recycled with high foamability and catalytic efficiency maintained for at least 7 consecutive runs. Besides xylene, other solvents with surface tension lower than that of the substrate could tune the particle wettability, enhancing the foamability and catalytic performance in the aerobic oxidation reactions of a panel of alcohols.

In a next step, we engineered an on-purpose microfluidic tool to generate and test monodisperse bubbles in solvents stabilized by fluorinated silica particles. Bubble trapping and particle adsorption/desorption dynamics was studied using fluorescent particles adsorbed at the air/oil interface. Accumulation of particles at the back of bubbles was observed. When the confined bubbles left to the wider channel, the interface relaxed and became circular with redistribution of adsorbed particles. We compared the catalytic performance of particle-stabilized bubbles using amphiphilic catalysts able to adsorb at the G/L interface in model oxidation reactions, showing promising credentials compared to stirred tank G/L/S reactors.