Population balance modeling and simulation of liquid–liquid–liquid phase transfer catalyzed synthesis of mandelic acid from benzaldehyde
Mandelic acid has cosmetic, pharmaceutical, and antibacterial activities and is used in urinary antiseptic medicines. An attractive process for the production of mandelic acid is through reaction between benzaldehyde, sodium hydroxide, and chloroform in the presence of polyethylene glycol 4000 as a phase transfer catalyst. The liquid–liquid phase transfer catalyzed (L–L PTC) reaction can be intensified by converting it into three-liquid phases (L–L–L PTC). We address the modeling of a well-stirred reactor for the foregoing process, in which organic droplets surrounded by a thin film of catalyst-rich phase are suspended in the aqueous phase. A population balance model is formulated for the L–L–L PTC reaction and solved by Monte Carlo simulation using interval of quiescence technique. Transport processes and intrinsic reaction kinetics are extracted from the experiments. This population balance model serves to assess and interpret the relative roles of various processes in L–L–L PTC reaction, such as diffusive transport, reaction, and interaction between dispersed phase droplets. The model is expected to be an effective tool for reactor design and scale up. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Novelties of liquid–liquid–liquid phase transfer catalysis: Alkoxylation of p-chloronitrobenzene
Abstract Liquid–liquid–liquid phase transfer catalysis (L–L–L PTC) offers orders of magnitude intensification of rates of reaction and better selectivities than the biphasic PTC. The catalyst-rich middle phase is the main reaction phase. The etherification or alkoxylation of p-chloronitrobenzene (PCNB) was conducted by using alkanol and alkali instead of the metal alkoxide. A kinetic model is presented and validated.
A Monte Carlo coalescence model for reaction with dispersion in a tubular reactor
Abstract Deviations from plug flow are handled by a Monte Carlo model which simulates mixing and segregation effects in a tubular chemical reactor. The model superimposes dispersion, which is simulated by local droplet coalescence, on the plug-flow mean velocity. Both the residence time distribution and the micromixing details are determined by the local coalescence-mixing phenomena. The model is applied with success to the experiments of Vassilatos and Toor. Comparisons are drawn between this and other models. Use of the model is suggested whenever deviations from plug flow are present in conjunction with segregation effects and rapid of two miscible fluids with mixed or unmixed feed. Further use should be possible with coalescence two-phase extraction and reaction systems.