Cycloaddition of Isoamylene and ?-Methylstyrene in a Microreactor using Filtrol-24 catalyst: Microreactor Performance Study and Comparison with Semi-Batch Reactor Performance

Abstract

The cycloaddition reaction between isoamylene and ?-methylstyrene yields indane compounds 1,1,2,3,3,-pentamethylindane and 3-ethyl-1,1,3-trimethylindane, which are intermediate cyclic products used in the synthesis of musk fragrances. This exothermic reaction is conventionally carried out industrially in large semibatch reactors, which have high heat and mass transfer resistances, are difficult to optimize, and scale-up. Aqueous sulfuric acid is conventionally used as the catalyst for the cycloaddition reaction, but solid catalysts offer many advantages over the corrosive aqueous sulfuric acid catalyst including the elimination of expensive separation and purification steps, and the need to use corrosion resistant materials of construction. A microreactor, which has enhanced heat and mass transfer characteristics, high surface to volume ratio, and improved fluid mixing, was used for the reaction using an acidic solid catalyst, Filtrol-24. A parametric study to obtain the dependence of product yield, reactant conversion and space-time yield on process variables such as catalyst particle size, residence time, velocity, temperature, pressure and the molar ratio of the reactants in the feed, was conducted. Through this study the optimum reaction conditions were obtained. The cycloaddition reaction was also performed in the semi-batch reactor using Filtrol-24 catalyst in order to compare its performance to that of the microreactor. Higher product yields were obtained in the microreactor compared to the semi-batch reactor, and the space-time yield in the microreactor was 4.8 times larger than that obtained in * The financial and technical support from International Flavors and Fragrances, Inc.; and Graduate Tuition support from the Stevens Institute of Technology are gratefully acknowledged. The authors wish to thank all the members of NJCMCS at Stevens who provided valuable help during different stages of this project.Brought to you by | Gazi Universitesi Kutuphane ve Dokumanta Authenticated Download Date | 2/5/15 4:47 PM the semi-batch reactor at optimum reaction conditions in both reactors.

Hydrodeoxygenation of 4-Propylguaiacol (2-Methoxy-4-propylphenol) in a Microreactor: Performance and Kinetic Studies

“…Better selectivity, high yield, improved product quality, and safe operation are attainable in microreactors because of very fast heat and mass transfer. − Studies have shown that, because of laminar flow, mixing in microchannels occurs predominantly by interdiffusion of reactants . However, because of short transverse diffusional distance, rapid and effective mixing is attainable in a microreactor that can quickly bring reactants into contact with catalyst in a heterogeneous reaction .…”

Microreactortechnology: Real-Time Flow Measurements in Organic Synthesis

“…Microreactor technology enables increased process control due to inherently excellent heat dissipation, especially in scale up, and often shows beneficial effect when batchwise syntheses turn out to be low yielded [7,8]. There are three main types of reactions described in literature that show enhanced efficiency when performed in a continuous flow: (i) -instantaneous‖ reactions (t r < 1 s) which are controlled by mixing efficiency; (ii) -fast‖ reactions (1 s < t r < 10 min) which are predominantly kinetically controlled and ii) slow reactions (t r > 10 min) [9].…”

Microreactor Performance Studies of the Cycloaddition of Isoamylene and α-Methylstyrene

“…[20][21][22][23][24] Since rapid microfluidic mixing is difficult to achieve with laminar flow on account of the low Reynolds number in microchannels, mixing in microchannels is principally limited to molecular interdiffusion through the fluid interface. 14,25,26 Rapid and effective mixing due to the short transverse diffusional time obtained in the microreactor can quickly bring reactants in contact with the aqueous sulfuric acid catalyst to increase conversion. 27 Various methods for contacting immiscible liquids have been proposed.…”

“…The use of the microreactor for the cycloaddition reaction has the potential to offer a number of benefits. Better heat and mass transfer in a microreactor can improve selectivity, safety, yield, product quality, and also improve energy efficiency. − The use of the microreactor for the cycloaddition reaction could lead to significant cost savings arising from faster transfer of research to production scale by the numbering-up approach, which increases throughput by parallel operation of a multitude of microreactors, rather than the complex and cost intensive scaling up approach. Complex liquid−liquid reactions like the cycloaddition reaction also present some of the most difficult scale-up problems because of complexities of drop formation and coalescence that change with scale .…”