@article { ISI:000328437300022, title = {Large centimeter-sized macroporous ferritin gels as versatile nanoreactors}, journal = {Chemistry of Materials}, volume = {25}, number = {23}, year = {2013}, month = {DEC}, pages = {4813-4819}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Organized assemblies of bionanoparticles such as ferritin provides templates that can be exploited for nanotechnological applications. Organization of ferritin into well-defined three-dimensional assemblies is challenging and has attracted considerable attention recently. We have synthesized, for the first time, large (centimeter-sized) self-standing macroporous scaffold monoliths from ferritin bionanoparticles, using dynamic templating of surfactant H-1 domains. These scaffolds comprise three-dimensionally connected strands of ferritin, organized as a porous gel with porosity similar to 55 mu m. The iron oxide inside the ferritin scaffold can be easily replaced with catalytically active monodisperse zerovalent transition metal nanoparticles using a very simple protocol. Since the ferritin is cross-linked in the scaffold, it is significantly robust with enhanced thermal stability and better tolerance toward several organic solvents in Comparison to the native ferritin bionanoparticle. In addition, the scaffold macropores facilitate substrate and reagent transport and hence the monoliths containing active Pd or iron oxide nanoparticles inside apo-ferritin bionanoparticles were used as a recyclable heterogeneous catalyst for the oxidation of 2,3,6-trimethyl phenol to 2,3,6-trimethyl-1,4-benzoquinone (precursor for Vitamin E synthesis) and for Suzuki-Miyaura cross-coupling reaction in both aqueous and organic solvents. The protein shell around the nanoparticles protects them from agglomeration, a phenomenon that otherwise plagues nanoparticles-based catalysis. The presence of macropores allow the ferritin scaffold to act as catalytic monolith for continuous flow reactions having rapid reaction rates, while offering a low pressure drop. Finally, the Pd@apo-ferritin scaffold was immobilized inside a steel cartridge and used for the continuous flow hydrogenation of alkenes to their corresponding alkanes for 15 cycles without any loss of activity.

}, keywords = {catalysis, continuous flow, ferritin, gel, macroporous materials, Self-assembly}, issn = {0897-4756}, doi = {10.1021/cm403240j}, author = {Kumari, Sushma and Kulkarni, Amol and Kumaraswamy, Guruswamy and Sen Gupta, Sayam} } @article { ISI:000332784900001, title = {Continuous flow nitration in miniaturized devices}, journal = {Beilstein Journal of Organic Chemistry}, volume = {10}, year = {2014}, month = {FEB}, pages = {405-424}, publisher = {BEILSTEIN-INSTITUT}, type = {Review}, address = {TRAKEHNER STRASSE 7-9, FRANKFURT AM MAIN, 60487, GERMANY}, abstract = {

This review highlights the state of the art in the field of continuous flow nitration with miniaturized devices. Although nitration has been one of the oldest and most important unit reactions, the advent of miniaturized devices has paved the way for new opportunities to reconsider the conventional approach for exothermic and selectivity sensitive nitration reactions. Four different approaches to flow nitration with microreactors are presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed.

}, keywords = {continuous flow, flow chemistry, microreactors, nitration, nitric acid, Tubular reactor}, issn = {1860-5397}, doi = {10.3762/bjoc.10.38}, author = {Kulkarni, Amol A.} } @article {46003, title = {Antisolvent based precipitation: batch, capillary flow reactor and impinging jet reactor}, journal = {Chemical Engineering Journal}, volume = {369}, year = {2019}, month = {AUG }, pages = {1161-1171}, type = {Article}, abstract = {

A method for continuous antisolvent precipitation of ammonium perchlorate (AP) using a confined impinging jet reactor (CIJR) is studied. The geometry of the CIJR was optimized to achieve excellent mixing with a significant reduction in the particle deposition on walls. Initially, the experimental conditions were optimized in a batch system and then in a continuous capillary reactor. Later those conditions extended for antisolvent precipitation of AP in an impinging jet reactor using water and n-butyl alcohol as a solvent and antisolvent, respectively for optimum performance. The performance was compared with the experiments in batch mode as well as and in a continuous capillary reactor. Over a range of inlet jet velocity that corresponded to 1792 \< Re \< 7193 for the saturated aqueous solution of AP and 1135 \< Re \< 4553 for the antisolvent butanol phase, 8.98-16.98 mu m Ammonium perchlorate particles were attained.

}, keywords = {Ammonium perchlorate, Antisolvent precipitation, CFD, continuous flow, Impinging jet reactor, microparticles}, issn = {1385-8947}, doi = {10.1016/j.cej.2019.03.107}, author = {Pal, Sayan and Madane, Ketan and Kulkarni, Amol A.} } @article {47591, title = {Design and scale-up of continuous di-nitration reaction using pinched tube flow reactor}, journal = {Journal of Flow Chemistry}, volume = {11}, year = {2021}, month = {SEP}, pages = {611-624}, type = {Article}, abstract = {Scale-up of the di-nitration reaction for synthesis of selective herbicide pendimethalin using only nitric acid in continuous flow is presented in this work. This work showcases an approach for smooth scale-up for an herbicide for a production capacity of 50 kg/day using a pinched tube reactor. The approach begins with the batch experiments followed by flow synthesis using a 1/8-inchSS316 helical coil tube where kinetics of the di-nitration was determined, and process optimization was done. Systematic approach was followed for quantification of heat transfer, mass transfer and residence time distribution and scale-up. Detailed scale-up methodology is presented with effect of relevant parameters for successful scale-up. Modular pilot plant with inline quenching, extraction and separation are some of the salient features presented in this work.}, keywords = {continuous flow, nitration, Pinched tube, RTD, scale-up}, issn = {2062-249X}, doi = {10.1007/s41981-021-00182-1}, author = {Hussain, Arshad and Sharma, Mrityunjay and Patil, Suneha and Acharya, Roopashree B. and Kute, Mahesh and Waghchaure, Aishwarya and Kulkarni, Amol A.} } @article {47615, title = {Multi-step synthesis of miltefosine: integration of flow chemistry with continuous mechanochemistry}, journal = {Chemistry-A European Journal}, volume = {27}, year = {2021}, month = {DEC }, pages = {17695-17699}, type = {Article}, abstract = {Herein we report for the first time, an advanced continuous flow synthesis of the blockbuster Leishmaniasis drug miltefosine from simple starting materials by a sequence involving four steps of chemical transformation including a continuous mechanochemical step. First three reaction steps were performed in simple tubular reactors in a telescopic mode, while in the last step the product precipitated from the 3(rd) step was used for a continuous mechanochemical synthesis of miltefosine. When compared to a typical batch protocol that takes 15 h, miltefosine was obtained in 58 \% overall yield in flow synthesis mode at the laboratory scale in a total residence time 34 min at synthesis rate of 10 g/hr, which is sufficient to treat 4800 patients per day.}, keywords = {continuous flow, continuous mechanochemistry, miltefosine, multistep synthesis, reactive intermediates}, issn = {0947-6539}, doi = {10.1002/chem.202103499}, author = {Patil, Niteen B. and Atapalkar, Ranjit S. and Chavan, Subhash P. and Kulkarni, Amol A.} } @article {49187, title = {Continuous flow ozonolysis of cardanol for greener synthesis of bio-based monomers}, journal = {Journal of Flow Chemistry}, volume = {14}, year = {2024}, month = {JUN}, pages = {417-426}, type = {Article}, abstract = {

Synthesis of bio-based monomers via continuous flow ozonolysis of cardanol using a simple tubular reactor is demonstrated. The direct ozonolysis of cardanol produces unique monomer 8-(3-hydroxyphenyl) octanal (HPOA) and heptanal along with several other oxidation products. Maximum 47\% yield of HPOA with 54.3\% conversion of cardanol was obtained at 0 degrees C in 9 s. The complete conversion of cardanol was obtained at the ozone to cardanol molar flow ratios greater than 2 at all temperatures varied in the range of -10 degrees C to 20 degrees C. Owing to large gas-liquid ratios, the mass transfer limitation for transfer of ozone from gas to liquid was negligible; however, the extent of axial dispersion in the liquid phase was significant at lower liquid flow rates. The non-ideal behavior was incorporated in the axial dispersion model to predict the conversion of cardanol. Examination of kinetic rates by both ideal plug-flow model and plug-flow with axial dispersion model revealed that the reaction is fast and is least influenced by the axial-dispersion in the reactor at prevailing operating conditions. The findings of the current study show that continuous flow technique enables a simple and safer synthesis of high-value bio-based monomers via ozonolysis of cardanol compared to traditional batch methods.

}, keywords = {Axial-dispersion model, Cardanol, continuous flow, Helical coil, Ozonolysis}, issn = {2062-249X}, doi = {10.1007/s41981-024-00308-1}, author = {Kulkarni, Sphurti P. and Kulkarni, Amol A.} } @article {49295, title = {Continuous flow synthesis of hierarchical low silica X zeolite}, journal = {Materials Today Communications}, volume = {39}, year = {2024}, month = {JUN}, pages = {109047}, type = {Article}, abstract = {

Zeolites, renowned for their versatile applications in catalysis, adsorption, and ion exchange, have long been synthesized using conventional batch processes. However, the inherent limitations of these methods, such as resource-intensive conditions and inconsistent product quality, underscore the need for a sustainable and efficient approach. In this study, a continuous flow synthesis process was established for the synthesis of industrially important low silica X (LSX) zeolite using a tubular reactor. The synthesis gel was subjected to aging for 5 days at room temperature to facilitate nucleation and crystal growth combined with the fast-heating rate in a tubular reactor at 363 K \& 1.1 atm., which in turn produces LSX after 40 min. The synthesized product was confirmed by the XRD, FE-SEM, EDS, XRF, TEM, and N2 adsorption-desorption; the data was compared with the LSX sample synthesized by batch process. The result implies that LSX prepared by continuous flow has a pure phase of LSX with the hierarchical structure, which provides better adsorption capacity of CO2 at 298 K up to 20 bar. Due to continuous flow synthesis, the crystallization time was reduced and faster kinetics which may be helpful for scale-up the process for LSX synthesis.

}, keywords = {Adsorption, Carbon dioxide, continuous flow, Low silica X, Tubular reactor, zeolites}, doi = {10.1016/j.mtcomm.2024.109047}, author = {Adarsh, V. K. and Shrotri, Aadesh R. and Birje, Amit R. and Nandanwar, Sachin U.} }