5 research outputs found
Rapid continuous microwave-assisted synthesis of silver nanoparticles to achieve very high productivity and full yield: from mechanistic study to optimal fabrication strategy
Systematic studies of silver nanoparticle synthesis in a continuous-flow single-mode microwave reactor using polyol process were performed, revealing that the synthesis is exceptionally effective to give very small metal particles at full reaction yield and very high productivity. Inlet concentration of silver nitrate or silver acetate, applied as metal precursors, varied between 10 and 50 mM, and flow rates ranged from 0.635 to 2.5 dm3/h, to give 3–24 s reaction time. Owing to its much higher reactivity, silver acetate was shown to be far superior substrate for the synthesis of small (10–20 nm) spherical silver nanoparticles within a few seconds. Its restricted solubility in ethylene glycol, applied as the solvent and reducing agent, appeared to be vital for effective separation of the stage of particle growth from its nucleation to enable rapid synthesis of small particles in a highly loaded system. This was not possible to obtain using silver nitrate. All the observations could perfectly be explained by a classical LaMer–Dinegar model of NPs’ formation, but taking into account also nonisothermal character of the continuous-flow process and acetate dissolution in the reaction system. The performed studies indicate an optimal strategy for the high-yield fabrication of metal particles using polyol method
Review on hierarchically microstructured monolithic reactors for high yield continuous production of fine chemicals
Preparation and properties of hierarchically structured porous silica monoliths have been discussed from the viewpoint of their application as continuous microreactors for liquid-phase synthesis of fine chemical in multi kilogram scales. The results of recent topical papers published by two research teams of Institute of Chemical Engineering Polish Academy of Sciences (ICE) and Department of Chemical Engineering and Process Design, Chemical Faculty, Silesian University of Technology (SUT) have been analyzed to specify the governing traits of microreactors. It was concluded that even enhancement factor of 100 in activity, seen in enzyme catalyzed reactions, can be explained by a proportional reduction of its physical constraints, i.e. huge enhancement of external mass transfer and micromixing. It is induced by very chaotic flows of liquid in tens of thousands of waving connected channels of ca. 25–50 mm in diameter, present in the skeleton. The scale of enhancement in the caseof less active catalysts was smaller, but still large enough to consider the most practical applications
Kinetyka reakcji estryfikacji kwasu octowego metanolemwobecności katalizatora mcf funkcjonalizowanego grupami kwasowymi
The esterification of acetic acid with methanol was studied in the presence of heterogeneous acidic catalyst - sulfonic acid functionalized silica mesoporous cellular foam (MCF) in order to determine its potentials. The effects of catalyst loading, molar ratio of substrates and temperature on the reaction rate were discussed. The kinetic model for this reaction was proposed.Przedstawiono wyniki badań kinetycznych reakcji estryfikacji kwasu octowego metanolem w obecności stałego kwasowego katalizatora – mezoporowatowego materiału krzemionkowego o strukturze piankowej, funkcjonalizowanego grupami sulfonowymi. Określono wpływ ilości katalizatora, stosunku molowego substratów oraz temperatury na szybkość reakcji. Zaproponowano model kinetyczny reakcji przeprowadzonej w obecności otrzymanego katalizatora