Enhanced Hydroformylation in a Continuous Flow Microreactor System

Abstract

A microreactor system consisting of a honeycomb microreactor and microtubing was proposed to enhance the Rh-biphephos catalyzed hydroformylation of 1-hexene. The effects of various reaction parameters were investigated. The isomerization, which turned the terminal olefins into isoolefins, occurred first in the beginning of the reaction. The increasing residence time, gas-to-liquid ratio, pressure, temperature, and biphephos/Rh ratio favored the catalytic cycle of hydroformylation, resulting in the increasing formation of aldehydes. A satisfactory yield (>90%) of aldehydes (heptanal, 2-methylhexanal) with a very high ratio between linear and branched aldehydes (L/B ratio) could be obtained in the present microreactor system under optimized conditions. Compared with the batch reactor, the used microreactor system shortened the reaction time from 3 h of the batch reactor to 30 min for a comparable aldehyde yield with higher regioselectivity to linear aldehyde. This promoting effect was attributed to the enhanced gas–liquid mass transfer in a continuous flow microreactor, which could be applied in other gas–liquid multiphase reactions.

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

“…Recently, Zhang et al developed a nature-inspired microreactor which is capable of increasing the gas–liquid mixing [ 563 ]. The reactor consists of an honeycombed microchannel reactor in which the channel cappilaries and branches assist with breaking the gas slugs up, enhancing the contact area in the mixture.…”

Enhanced Hydroformylation in a Continuous-Flow Microreactor with a Water-Soluble Phosphine Rhodium Catalyst

“…In order to overcome these hurdles to meet industrial production demands, researchers turned to investigate hydroformylation in microreactors due to a high surface-to-volume ratio, efficient heat and mass transfer, as well as precise control and enhanced safety in the process. − Vorholt and coworkers have improved reactor designs, enhancing the stirring structure to speed up the reaction rate in kettle reactors and using jet loop and microbubble reactors to improve mass transfer in gas–liquid–liquid systems. , Wiese and coworkers optimized the surface-to-volume ratio using a packed tube reactor with Sulzer SMV internals for hydroformylation in water-soluble rhodium–phosphine multiphase, achieving a 10-fold performance increase, suggesting its potential as a replacement for traditional stirred vessels. However, the complexity of the equipment and substantial investment costs should be taken into consideration for industrial production …”

In Situ XAS Diagnostics of Reductive Hydroformylation Reaction in Segmented Flow Under Elevated Pressure and Temperature

“…For example, in ref , the highest known hydroformylation TOF of 75,000 h –1 was reached in an MF unit. The authors of ref showed that under similar conditions, a flow system provided more effective hydroformylation compared to a classical batch reactor. In addition, the application of classical Rh/phosphine complexes and a Rh complex with water-soluble ligand TPPTS (tris(3-sulfophenyl)phosphine trisodium salt) for intensified biphasic HF using the MF system was recently demonstrated.…”