Hydrodynamics study of a fast liquid–liquid oxidation process with in situ gas production in microreactors

Abstract

Hydrodynamics characteristics of a fast and highly exothermic liquid–liquid oxidation process with in situ gas production in microreactors were studied using a newly developed experimental method. In the adipic acid synthesis through the K/A oil (the mixture of cyclohexanol and cyclohexanone) oxidation with nitric acid, bubble generation modes were divided into four categories. The gas production became more intensive, unstable, even explosive with increasing the oil phase feed rate and the temperature. A novel automatic image processing method was developed to monitor the instantaneous velocity online by tracking the gas–liquid interface. The axial velocity at the same location was unstable due to the changing gas production rate. Furthermore, the actual residence time was obtained easily with being only 36% of the space–time minimally, beneficial for establishing accurate kinetics and mass transfer models with time participation. Finally, an empirical correlation was developed to predict the actual residence time under different conditions.

Permeability and selectivity analysis for affinity‐based nanoparticle separation through nanochannels

“…Here, we use the equilibrium density functional theory 47 to calculate S nid i and the calculation details are presented in the Supporting Information. In Figure 7, the ordinate values of the cross symbols correspond to the calculation results of DDFT and the abscissa values correspond to the predictions by using either Equation (14) or Equation (20). As can be seen the improvement of Equation ( 20) over Equation ( 14) in predicting permeability is remarkable, which highlights the superiority of the extended model.…”

“…Briefly, Equations ( 20) and ( 21) constitute our extended model. In the Supporting Information, we provide the detailed derivation for Equation (20) and show that Equation ( 14) can be recovered when applying Equation (20) to a system involving no particle-particle interaction. The extended model shows that both the permeability and selectivity depend on the thermodynamic states of the HD-and LD-reservoirs, including the particle density, while this dependence is not reflected in Equation (14).…”

“…Before using Equations ( 14) and (20) to analyze permeability, we compare their predictions with DDFT results in Figure 7. By applying the square-well like external potential given by Equation (3), the integration in Equation ( 15) can be simplified as:…”

“…Both Equations ( 14) and (20) give linear relationship between permeability and equilibrium partition coefficient. Because the equilibrium partition coefficients for the systems with various pairwise interactions, including the Lennard-Jones and electrostatic interactions, have been widely investigated and are readily accessible, the permeability and selectivity of these systems can then be conveniently computed by the extended model.…”

“…18 Another advanced technique for the separation of nanoparticles with distinct surface chemical properties is the affinity-based separation operated in a nanochannel which exhibits a variety of advantages, including less sample consumption, rapid analysis speed, in situ characterization, and good portability. 19,20 During a typical nanofluidic affinity-based separation process, the affinity between channel inner-surface and nanoparticles induces noticeable adsorption of particles near the channel surface and, consequently, a difference between the quantities of particles that pass through the nanochannel. 21,22 This macroscopically observable affinity is a direct consequence of the microscopic channel-particle interaction which is mainly determined by the surface properties of both nanochannel and nanoparticles.…”