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Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min–1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d32) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d32 of 25–63 μm at a liquid flow rate of 1025 L·h–1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d32, and the predicted d32 was in good agreement with the experimental data with a deviation within ±15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

Selective hydrogenation plays an important role in chemical industries, yet its selectivity is usually limited by the mass transfer. In this work, the enhanced hydrogenation selectivity was achieved in a rotating packed bed (RPB) reactor with excellent mass transfer efficiency. Aiming to be used under the centrifugal filed, a monolithic catalyst Pd/γ-Al2O3/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition method. The mechanical strength of the catalyst can meet the requirement of high centrifugal force in the RPB. The hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3 ∼ 8 times higher than that in a stirred tank reactor under similar conditions. This work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.

The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensification device, exhibiting excellent mass transfer enhancement characteristics. However, the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods. In the past two decades, Computational Fluid Dynamics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design. This article covers the development of the CFD simulation of gas-liquid flow in RPB. Firstly, the improvement of the simulation method in the aspect of mathematical models, geometric models, and solving methods is introduced. Secondly, new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed, including pressure drop, velocity distribution, flow pattern, and concentration distribution, etc. Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works. In addition, the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications. The defects of current research and future development directions are also discussed at last.

Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue. Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue. In this work, a plasma-assisted rotating disk reactor (plasma-RDR) and a photocatalyst—namely, titanium dioxide (TiO2)—were coupled for the treatment of metronidazole (MNZ). Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR, which contributed to the utilization of ultraviolet (UV) light radiation in the presence of TiO2. The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41% and 2.954 mg·L−1 as the rotational speed increased from 0 to 500 r·min−1. The synergistic effect of plasma-RDR plus TiO2 on the generation of hydroxyl radicals was evaluated. Major intermediate products were identified using three-dimensional (3D) excitation emission fluorescence matrices (EEFMs) and liquid chromatography–mass spectrometry (LC-MS), and a possible degradation pathway is proposed herein. This plasma-catalytic process has bright prospects in the field of antibiotics degradation.

This work presents the study on solid-liquid mass transfer performance of suspension in a rotating packed bed (RPB). The calculation model of solid-liquid mass transfer coefficient (ks) is deduced on the basis of the mass conversation law. The ks in RPB is measured using the suspension of cation exchange resin particle reaction with NaOH. The effects of different operating parameters such as pre-dispersion time (t), rotating speed (N), mesh packing thickness (w), liquid volume flow rate (LT), and solid loading (e) are investigated. The results show that the ks increases with the increase of N and w, and increases first and then tends to remain constant with the increase of t and LT. However, the e has no influence on ks. The obtained ks ranges from 1.00×10-5 m/s to 2.60×10-4 m/s which is higher than that in microreactor (MR) under the similar experimental conditions.

In this paper, ZSM-5@MnOx catalyst was firstly prepared by in situ growth for the selective oxidation of benzyl alcohol to benzaldehyde. The coating effects of MnOx on ZSM-5 and OV formation mechanism at the ZSM-5-MnOx interface were investigated. Results showed that the sodium ions of ZSM-5 are found to be conducive to the better coating for MnOx. Hydrogen protons of zeolite can dehydrate with the OH groups on MnOx to generate the OVs where the oxidation of benzyl alcohol occurs. Besides, the deep dehydration at the ZSM-5-MnOx interface via increasing post-treatment temperature can further enrich the OV concentrations. The ~100% benzyl alcohol conversion and ~100% benzaldehyde selectivity over the ZSM-5@MnOx catalyst can be obtained within 3 h at 383 K. The findings of the structure-activity relationship of zeolite’s surface properties and OVs over MnOx can provide important guiding principles for the rational design of oxidation catalysts.

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (kLS) have been investigated. The correlation for predicting kLS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (kLSaLS) ranged from 0.04–0.14 1−1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.

Wire mesh packing has been extensively utilized in laboratory and industry applications in rotating packed bed (RPB) because of the high mass transfer performance and low cost. Conventional wire me...

This work presented experimental and modeling studies on the simultaneous absorption of H2S and CO2 into the N-methyldiethanolamine (MDEA) and piperazine (PZ) solution in a rotating packed bed (RPB...

Spent caustic from the desulfurization of liquefied petroleum gas has been proved to be effectively regenerated in a rotating packed bed (RPB) with classic wire mesh packing. However, the influence of the packing’s surface wettability on regeneration performance in the RPB was not clear with this oil-water two-phase system. In this work, the surface-modified packing was proposed to be used in the RPB to estimate the regeneration performance, including oxidation and separation efficiency. Three different surface-modified packings of hydrophilic surface-modified wire mesh packing (ISP), non-surface-modified wire mesh packing (NSP), and hydrophobic surface-modified wire mesh packing (OSP) were prepared and employed in the RPB for regeneration experiments. Results show that regeneration performance is in order of ISP＞NSP＞OSP. Compared with OSP, the NaSR conversion, RSSR removal efficiency, and number of transfer units of ISP increased nearly by 34%, 13%, and 21% at 1000 r/min rotational speed and 25 mm packing thickness, respectively. For the view of different packing combination, not only in the inner layer but also in the outer layer, ISP had noticeable superior regeneration performance, which displays the bright future of advanced surface-modified packing used in the RPB for process intensification of reaction and separation.

The rotating packed bed (RPB) reactor with a lab-scale mesh-pin rotor (MPR) displays the great potential for the chemical processes with viscosity reactants or solid products. However, the scale-up...

A systematic scale-up study on a rotating packed bed (RPB) reactor is essential before the industrial application. However, the mass transfer and application performance of the RPB reactor with a s...

The work herein employed COMSOL Multiphysics simulation and experiment to study the temperature distribution of water in a specially designed cylindrical microwave (MW) reactor with two magnetrons....

Liquid dispersion by impacting on wire mesh benefits many mass transfer processes. However, most of studies focused on the dispersion behaviors of liquid impacting on a one-layer wire mesh. In this...