Novel continuous process for methacrolein production in numerous droplet reactors

Abstract

A continuous process for methacrolein production was constructed by filling w/o Pickering emulsions in a column reactor. Ionic liquid (IL‐[HDEA]Ac) with secondary amine was designed to catalyze propionaldehyde condensation with formaldehyde through the Mannich reaction. Emulsion droplets encapsulated with IL aqueous solution were stabilized with modified SiO2 nanoparticles and dispersed in cyclohexane, which could be observed as numerous reactors. The properties of SiO2 stabilizer, such as wettability, surface groups, and the effect on interfacial tension were investigated. The characteristics of emulsion influenced by stabilizer properties and content were systematically studied. The droplet size, IL concentration and liquid hourly space velocity were optimized. The droplets were evaluated at 0.5 hr−1 for 150 hr without IL leakage and obvious activity decreasing, indicating the excellent stability of the emulsion system. The continuous process showed a 1.25‐fold enhancement in catalysis efficiency and less equipment compared to batch process.

Multiphase Microreactors Based on Liquid–Liquid and Gas–Liquid Dispersions Stabilized by Colloidal Catalytic Particles

“…The reactor is built with water‐in‐cyclohexane emulsions stabilized by hydrophobic silica particles and monoglyceride using diethanolamine acetate as the catalyst hosted in the water phase with an ionic liquid. [161] This continuous process exhibits a 1.25‐fold increase of catalytic activity compared to a batch reactor, and the emulsion shows good stability in eight runs with neither ionic liquid leakage nor activity decrease. Besides, a continuous flow system based on a packed oil‐in‐water emulsion stabilized by aldehyde cellulose nanofibers decorated with Pd nanoparticles has been applied to 4‐nitrophenol hydrogenation with dissolved H 2 for 55 h operation.…”

Pickering Emulsion Catalysis: Interfacial Chemistry, Catalyst Design, Challenges, and Perspectives

“…The homogeneous catalysts of enzymes were distributed in the IL droplets, with the concentration gradient‐driven diffusion of the reactant molecules into the IL droplets, thus, allowing the reaction to happen within the micro‐sized IL droplets (Figure 10b). This ionic liquid‐based emulsion fixed bed platform could also be extended to the ionic liquid‐catalyzed cyanosilylation reaction [129] and the secondary amine‐catalyzed methacrolein production [130] with excellent operational stability.…”

Multiphase Microreactors Based on Liquid–Liquid and Gas–Liquid Dispersions Stabilized by Colloidal Catalytic Particles

“…Finally, methacrolein has been synthesized by the aldol condensation of propionaldehyde and formaldehyde by the Mannich reaction in a continuous flow process. The reactor is built with water‐in‐cyclohexane emulsions stabilized by hydrophobic silica particles and monoglyceride using diethanolamine acetate as the catalyst hosted in the water phase with an ionic liquid [161] . This continuous process exhibits a 1.25‐fold increase of catalytic activity compared to a batch reactor, and the emulsion shows good stability in eight runs with neither ionic liquid leakage nor activity decrease.…”