| 1. |
Nikolay Cherkasov, Shusaku Asano, Yuta Tsuji, Kazuki Okazawa, Kazunari Yoshizawa, Hiroyuki Miyamura, Jun-ichiro Hayashi, Alexander A. Kunitsa, Samuel Jackson, Mechanistic origins of accelerated hydrogenation of mixed alkylaromatics by synchronised adsorption over Rh/SiO2, Reaction Chemistry & Engineering, 10.1039/d3re00032j, 8, 6, 1341-1348, 2023.03, We have studied the unique reaction acceleration phenomenon in the mixture and discussed the limitations of the Langmuir–Hinshelwood model for a solid-catalysed reaction. . |
| 2. |
Shusaku Asano, Yosuke Muranaka, Taisuke Maki, Koki Ikeda, Kazuhiro Mae, Kinetic Modeling of an Enzyme Membrane Reactor for the Selective Production of Oligosaccharides, Fermentation, 10.3390/fermentation8120701, 8, 12, 701-701, 2022.12, An enzyme membrane reactor is an attractive tool for producing oligosaccharides from biomass-based polysaccharides. However, kinetic modeling and reactor design based on the rate equations have rarely been reported for enzyme membrane reactors because of the difficulty in tracing the depolymerization process. In this study, a simplified reaction model based on Michaelis–Menten-type kinetics has been built to simulate the enzyme membrane reactor. Ramping various species into reactant, target, and byproduct worked well for discussing reactor performance. The use of a membrane with a molecular weight cut-off (MWCO) of 10 kDa with continuous feeding of the reactant was suggested for the efficient production of chitosan hexamer and pentamer by enzymatic hydrolysis of chitosan. . |
| 3. |
Shusaku Asano, Yu Takahashi, Taisuke Maki, Yosuke Muranaka, Nikolay Cherkasov, Kazuhiro Mae, Contactless mass transfer for intra-droplet extraction, Scientific Reports, 10.1038/s41598-020-64520-4, 10, 1, 2020.12, This study demonstrates the possibility of “contactless” mass transfer between two aqueous slugs (droplets) separated by an oil slug in Taylor flow inside milli-channels. Separation of the alternating aqueous slugs at the outlet was performed by switching a couple of solenoid valves at branched outlets according to signals obtained by an optical sensor at the branch. Transfer of bromothymol blue (BTB) from acidic to basic aqueous slugs was performed for demonstration. In some cases, aqueous slugs separated by oil, merged catching on each other due to the velocity difference. Interfacial tension which was affected by the solute concentration was responsible for the velocity difference. Position-specific mass transfer activity at the rear end of the aqueous slugs was found on the course of the experiment. A meandering channel decreased the velocity difference and enhanced mass transfer. Almost complete (93%) transfer of BTB was achieved within a short residence time of several minutes under optimized conditions. The presented system opens a way for advanced separation using minimum amounts of the oil phase and allows concentrating the solute by altering relative lengths of the sender and receiver slugs.. |
| 4. |
Nurulhuda Halim, Akira Tajima, Shusaku Asano, Shinji Kudo, Jun Ichiro Hayashi, Change in Catalytic Activity of Potassium during CO2 Gasification of Char, Energy and Fuels, 10.1021/acs.energyfuels.9b03630, 34, 1, 225-234, 2020.01, Potassium (K)-catalyzed CO gasification of lignite char was studied with a particular focus on the change in catalyst activity with the char conversion (X) at 800-900 °C. Char samples were prepared from an Indonesian lignite by a sequence of complete removal of inherent metallic species and mineral matter, K-loading by ion-exchange, and pyrolysis. The catalytic activity of K (kcat′) was defined as the rate of catalytic gasification (after elimination of the rate of non-catalytic gasification and that of K volatilization from total mass release rate from char) per amount of K retained by the gasifying char. kcat′ increased by a factor of 5-20 with X over its range up to 0.98-0.99, depending on the initial K concentration in the char (m ), ranging 0.16-1.4 wt %-daf. Such significant increase in kcat′ was due to the change in not the intrinsic reactivity of char but its porous nature, that is, the size and volume of pores that retained the K catalyst. At X 0.4, the gasification created greater mesopores (width >2.0 nm), providing spaces for growth in the size of the K catalyst and allowing promotion of its activity. However, for low m , its major portion continued to stay in micropores with a limited increase in kcat′. 2 cat,0 cat,0. |
| 5. |
U. P.M. Ashik, Shusaku Asano, Shinji Kudo, Doan Pham Minh, Srinivas Appari, Einaga Hisahiro, Jun Ichiro Hayashi, The distinctive effects of glucose-derived carbon on the performance of ni-based catalysts in methane dry reforming, Catalysts, 10.3390/catal10010021, 10, 1, 2020.01, This study aimed to investigate the effect of carbon derived from glucose (C) on the physicochemical characteristics and catalytic activity of Ni, supported over SiO , ZSM-5, and TiO in methane dry reforming. Among the Ni catalysts without C, Ni/SiO exhibited the highest CH -CO conversion and stability at all experimented temperatures. On the other hand, the C-incorporated catalysts prepared by glucose impregnation, followed by pyrolysis, showed dissimilar performances. C improved the stability of Ni/SiO in the reforming at 650 C and 750 C and increased the CH and CO conversion to the level close to the thermodynamic equilibrium at 850 C. However, this element did not substantially affect the activity of Ni/ZSM-5 and exerted a retarding effect on Ni/TiO . Characterizations with H -TPD, XRD, EXAFS, and STEM-EDS revealed that the different influences of C by the supports were attributed to the extent of metal dispersion and metal-support interaction. 2 2 2 4 2 2 4 2 2 2 ◦ ◦ ◦. |
| 6. |
KUDO Shinji, OKADA Jun, IKEDA Shiho, YOSHIDA Takuya, ASANO Shusaku, HAYASHI Jun-ichiro, Improvement of Pelletability of Woody Biomass by Torrefaction
under Pressurized Steam, Energy & Fuels, 10.1021/acs.energyfuels.9b02939, 33, 11, 11253-11262, 2019.12. |
| 7. |
S. Asano, S. Yamada, T. Maki, Y. Muranaka, K. Mae, Design protocol of microjet mixers for achieving desirable mixing times with arbitrary flow rate ratios, Reaction Chemistry and Engineering, 10.1039/c7re00051k, 2, 6, 830-841, 2017.12, We extensively examined and discussed the performance of microjet mixers that consisted of two concentrically arranged tubes. The orientation of the feed streams with respect to the inner and outer inlets was the crucial factor for promoting the desired reaction. The Reynolds number after jetting and the velocity ratio of the inner and outer fluids were the key variables for promoting vigorous jetting and efficient mixing. By choosing the appropriate operating conditions, the microjet mixers exhibited excellent performance. The design protocol for microjet mixers was established based on mixing time measurements. We successfully maximized the throughput in one channel and numbered-up the microjet mixers. The microjet mixers also proved to be useful for treating viscous fluids with the appropriate choice of the feed orientation. The complete mixing of water with a 200 times more viscous fluid was achieved in 20 ms.. |
| 8. |
Shusaku Asano, Taisuke Maki, Kazuhiro Mae, Evaluation of mixing profiles for a new micromixer design strategy, AIChE Journal, 10.1002/aic.15082, 62, 4, 1154-1161, 2016.04, The relationship between mixing history and reaction performance in microreactors using computational fluid dynamics (CFD) simulations is identified. In the idealized, simplified mixing model, mixing proceeds linearly and only the mixing time determined the reaction performance. However, in the case of realistic models where mixing proceeds unequally, the partial rapid progression of mixing, more than the mixing time, significantly impacts the reaction. The use of the fluid segment size distribution to capture this effect is proposed. The effective Damköhler number derived from the fluid segment size distribution predicted the reaction yield well. To demonstrate the utility of the mixing profile design strategy, we fabricated a novel micromixer with multiple partial rapid mixing zones. This micromixer achieved excellent results both in a CFD simulation and an experiment.. |
