First International Conference on
Unconventional Catalysis, Reactors and Applications

Zaragoza-Spain, 16-18 October 2019
09:30   Unconventional catalytic reactors 2
Chair: Pedro Castaño
20 mins

Oxidative cleavage of fatty acids/esters/nitriles to bi-functional bio-sourced monomers under ultrasounds
Ana Luisa Soutelo Maria, Jean-Luc Couturier, Jean-Luc Dubois, Giancarlo Cravotto (presenter: Ana Soutelo Maria)
Abstract: Oxidation of fatty acids to obtain high value monomers with hydrogen peroxide in a solvent-free conditions has been proved as a practical process applied industrially by Matrica S.p.A. In this case the oxidative cleavage of oleic acid to obtain azelaic acid and pelargonic acid have significant differences by batch and continuous processes. The bifunctional molecules obtained can be used in the polymer industry through polycondensation reactions. Among several catalysts described in the literature, catalytic species from the dissolution of tungsten-based catalysts in hydrogen peroxide proved to be the right choice to achieve the desirable monomers. Hydrogen peroxide is user-friendly, but the kinetics of the catalyzed reaction are still slow. In addition, selectivity issues caused by side-reactions leading to shortened cleavage products, highly affects the quality of the final products. Ultrasounds can be an essential key to overcome the mass transfer issues associated to biphasic system as described in several studies [1-4]. The aim of our work was to exploit sonochemical methods to overcome mass transfer and time limitation of conventional oxidative cleavage reaction in unsaturated fatty acids and derivatives. Significant results were obtained with an ultrasonic horn, working at frequency of 25 kHz with 100W of input power. With this system we were not only able to reduce 1) the reaction time from 24h to 5h, 2) the concentration of H2O2 from 70% to 35%, 3) reduce the working temperature from 90°C to 60°C but also 4) to achieve the desirable monomers in the absence of an emulsifier. Besides the safer alternative of using lower concentration of oxidant and no need of emulsifier, with this new technology, the monomers can be obtained in higher quality at shorter reaction time.
20 mins

Alberto Rodriguez Gomez, Ana Raquel de La Osa, Antonio de Lucas Consuegra, Paula Sánchez, Jose Luis Valverde (presenter: Alberto Rodríguez Gómez)
Abstract: In recent years bioethanol has become one of the most promising alternatives to traditional fossils fuels. However, the overproduction on both global (biodiesel crisis) and national scale (industrial waste of alcohol) has required the search of different strategies for the valorization of this compound. In this research work, the electrochemical reforming process is proposed as an alternative, which present some advantages (less deactivation and selectivity limitations) compared to conventional catalytic processes. Using a polymer membrane electrochemical reactor (PEM cell), in the anodic compartment the oxidation of ethanol takes place, producing protons and organic compounds of industrial interest (acetaldehyde, ethyl acetate, acetic acid. Reduction reaction takes place in the cathodic compartment, generating high purity hydrogen. In this scenario, the ethanol oxidation reaction was studied and a reaction mechanism was proposed (Fig 1.). For this, the reaction pathways for chemicals production (including possible competitive reactions) were checked by feeding the PEM reactor with different aqueous solution compositions of ethanol, acetaldehyde or acid acetic. Moreover, in order to prove the driving force of each reaction (catalytic or electro-catalytic nature), the electroreforming process was carried out at mild conditions (1 atm, 30ºC – 80ºC) under open circuit potential or under a fixed applied current.
20 mins

Bianca Trifan, Miriam Tovar, Raquel Raso, Javier Esteras, Javier Lasobras, Javier Herguido, Izumi Kumakiri, Miguel Menendez (presenter: Miguel Menendez)
Abstract: Methanol synthesis by CO2 hydrogenation transforms a green-house gas into a basic chemical that can be used as a fuel too. This research line opens a path to reduce the use of fossil fuels and the CO2 emissions. The reaction could be carried out with H2 obtained from renewable energy sources, thus making the reaction more eco-friendly. Nowadays, this reaction (CO2 + 3 H2  CH3OH + H2O) uses a moderate temperature (~220ºC), in order to avoid the secondary reactions, and high-pressure (~50 bar). A membrane reactor, where the membrane removes selectively the reaction products, has been proposed to provide higher yield or to allow lower operating pressures [1]. The challenge is to get a catalyst with a high selectivity to methanol and a membrane with a good separation factor. For this reason, this study is focused on modifications over the conventional catalyst Cu/ZnO/Al2O3 and on finding a suitable zeolite membrane. Modifications in the catalyst are aimed to improve methanol yield. These modifications include other metals like Ga or Pd, and changes in the synthesis time or the pH in the co-precipitation method. The membranes tested were selected taking in account different parameters: thermal resistance, hydrophilicity or selectivity to methanol and water. Zeolite membranes are very promising at these respects. Some of the membranes tested were: LTA, T or MOR.
20 mins

Baldassarre Venezia, Luca Panariello, Spyridon Damilos, Asterios Gavriilidis (presenter: Baldassarre Venezia)
Abstract: A Teflon AF-2400 tubular membrane (0.8 mm ID, 1.0 mm OD, 15 cm length) was modified on its inner surface using the polydopamine/poly(acrylic acid)/poly(allylamine hydrochloride) layer-by-layer assembly method. Ex-situ prepared gold-palladium nanoparticles were adsorbed on the modified membrane surface and employed in the hydrogenation of nitrobenzene. The nanoparticles were synthesized via reduction of palladium chloride with ascorbic acid over gold seeds produced via the Turkevich method. The membrane reactor was used in a tube-in-tube configuration, where 15 µL/min of 50 mM nitrobenzene solution in ethanol flowed in the membrane bore at a pressure of 5 barg and hydrogen was stagnant and pressurized in the annulus at 4 barg. The reaction was carried out at room temperature and the liquid residence time was 5 min. Nitrobenzene conversion was stable at around 70% for over 5 h of continuous operation. This unconventional catalytic reactor design offers the capability of adsorbing size-tuned ex-situ prepared catalytic nanoparticles by flowing them inside the modified membrane and employing it for gas-liquid catalytic reactions without mixing the gas and liquid phases.
20 mins

Melissa Lopez-Viveros, Montserrat Gomez, Isabelle Favier, Jean-Christophe Remigy, Jean-Francois Lahitte (presenter: Jean-Francois Lahitte)
Abstract: Metallic nanoparticles have high catalytic activity for a large number of chemical reactions. However, their high surface energy leads to an aggregation and then to a loss of reactivity. The immobilization of catalytic nanoparticles (Pd, Au) in a polymeric matrix permits to maintain them in a well-dispersed way while retaining their reactivity. We have developed catalytic membranes based on metallic nanoparticles trapped in a polymeric gel grafted on the surface of a polymeric filtration membrane. We have demonstrated that the structure of the gel (charge, porosity, swelling) controls the characteristics of the catalysts and its efficiency (conversion, selectivity) for catalytic reactions (nitroaromatic reduction, Suzuki-Miyaura coupling, Hydrogenation). The high local concentration of nanoparticles, 1000 time the usable concentrations in solution, permit to increase the kinetics of reaction, ensuring a total conversion in less than 10 seconds of residence time of the reagents in the membrane. The reaction and the separation of products from reactants was made in one-step. No leaching of nanoparticles or metal was detected. The modelling of this system demonstrated the ability of these compact reactors to meet the needs of the fine-chemicals industry production (100 ton/years).