Microreactors

Flows in manifolds are of great importance in quite diverse fields of science and technology, including
fuel cells, spargers, solar collectors, microchannels, porous infiltration and irrigation. Theory of flow distribution
and pressure drop is vital to predict process performance and efficiency of manifold systems. In
this paper, we examined research and development of theoretical models and methodology of solutions
in flow in manifolds and highlight remarkable advances in the past fifty years. The main existing models
and solution methods were unified further to one theoretical framework, including Bernoulli theory and
momentum theory, and discrete and continuum methodologies. The generalised model was applicable
to not only designs of continuum manifolds but also those of discrete manifolds with constant or varying
factors. The procedure of design calculation is in reality straightforward without requirements of iteration,
successive approximation and computer programme. The theoretical model provides easy-to-use
design guidance to investigate the interactions among structures, operating conditions and manufacturing
tolerance under a wide variety of combination of flow conditions and geometries through three
general characteristic parameters (E, M and ) and to minimize the impact on manifold operability.

Teniendo en cuenta el desarrollo alcanzado mundialmente en la elaboración de vacunas, medicamentos y otros, en nuestros días se ha dado un mayor peso a los conceptos de microreactores, Microsistemas de Análisis Total (Micro Total Analysis Systems / µTAS) y Laboratorios en un chip (Lab-on-a-chip / LOC). La microfluídica promete ser el segmento más dinámico del impulso que tienen los MEMS , como lo demuestra el creciente número de publicaciones que atienden este tema (Rivas, 2011). Además de esto, la tecnología de micromecanizado ofrece oportunidades únicas no solo para el análisis químico sino también para la producción química. La miniaturización de reactores y la integración de diferentes componentes proveen nuevas capacidades y funcionalidades que no pueden ser llevadas a cabo por sus contrapartes a macroescala, ofreciendo potencialmente altos rendimientos y un bajo costo de producción másica (Nguyen & Wereley, 2002).
La importancia de los microsistemas para la ingeniería química ha sido percibida al menos desde 1996. Hoy en día, los microsistemas son vistos como una importante fuente de innovación (Tabeling, 2006), donde ha sido vital la información y superación gradual de personas capacitadas y en particular de grupos multidisciplinarios de científicos en numerosos centros de investigación del mundo entero (Rivas, 2011).
Para que en Colombia se pueda lograr algún avance en este fascinante y novedoso campo de la ciencia y estar a la vanguardia de las tecnologías mundiales más recientes, es necesario juntar esfuerzos y tratar objetivos comunes entre diversos grupos a lo largo del país, así como apuntarle al desarrollo de la investigación en dicho campo.

A B S T R A C T The corning ® Advanced Flow™ Reactor (AFR) was used for continuous synthesis of biodiesel from fresh oil and used cooking oil. All Experiments were carried out in AFR at different parameters such as feed flow rates, temperature and concentration of catalyst to study the optimum operating conditions for synthesis of biodiesel. Two different oils (fresh oil (FO) and used cooking Oil (CO)) were used for continuous flow synthesis of bio-diesel. The maximum oil conversion of 99 and 93% were achieved in presence of 2 wt.% of catalyst (sulfuric acid) at 80 °C and feed flow rate of 30 mL/h in AFR™ for FO and CO respectively. The composition of fatty acid methyl esters (FAMEs) in finished biodiesel product was found to be 0.2788 mol/L and 0.2742 mol/L for FO and CO respectively. A mathematical model was developed, assuming that the AFR™ module behave as a PFR. The model consists of ordinary differential equations, which were solved by Euler's method in MATLAB to study the change of concentration of oils against time at different parameters. The simulation results shown good agreement with the experimental results.

An experimentally easy to perform method for the generation of alumina-supported Fe3O4 nanoparticles [(6±1) nm size, 0.67 wt %]and the use of this material in hydrazine-mediated heterogeneously catalyzed reductions of nitroarenes to anilines under batch and continuous-flow conditions is presented. The bench-stable, reusable nano-Fe3O4@Al2O3 catalyst can selectively reduce functionalized nitroarenes at 1 mol % catalyst loading by using a 20 mol % excess of hydrazine hydrate in an elevated temperature regime (150 °C, reaction time 2-6 min in batch). For continuous-flow processing, the catalyst material is packed into dedicated cartridges and used in a commercially available high-temperature/-pressure flow device. In continuous mode, reaction times can be reduced to less than 1 min at 150 °C (30 bar back pressure) in a highly intensified process. The nano-Fe3O4@Al2O3 catalyst demonstrated stable reduction of nitrobenzene (0.5 M in MeOH) for more than 10 h on stream at a productivity of...

Many attempts to obtain a clean stream of COF2 have been carried out in the past by means of the direct fluorination of carbon monoxide with elemental fluorine or by electrochemical fluorination. The reaction is highly exothermic, therefore difficult to control. It can easily develop into a thermal runaway with a poor selectivity. We have successfully circumvented these critical issues by using a stainless steel parallel channel microreactor (surface/volume ratio ≈ 1 × 104 m−1, residence time τ ≈ 0.1 s) for the direct fluorination of carbon monoxide. Its performance in terms of operability and selectivity is compared to that of a standard reactor assembly, namely a fluorine burner reactor coupled with a water cooled heat exchanger. While the microreactor assembly succeeded to control the exothermic reaction, in the same experimental conditions the standard assembly reactor underwent serious corrosion issues that lead to nozzle meltdown lack of selectivity and consequent plant shutdowns.

A B S T R A C T The continuous production of performic acid is getting significant importance due to it's versatile oxidizing properties in various applications such as in the food, oil and chemical industries. In this work, an attempt has been made for synthesis of performic acid in a continuous flow microreator in polytetrafluoroethylene spiral capillary microreactor (PSCMR) with and without homogeneous catalyst. The effect of catalyst concentration, hydrogen peroxide concentration, temperature and radius of curvature on formation of perfomic acid was studied. The maximum conversion of FA was obtained within 6 min at 30 °C and 4 mol% catalyst. The maximum PFA was obtained (5.175 mol/L) when the reaction was performed in spiral capillary microreactor having 13.25 mm radius of curvature (Number of turns = 21). However, in the radius of curvature of 18.25 mm (Number of turns = 15) and 23.25 mm (Number of turns = 12) of the PSCMR gave 3.393 mol/L and 3.105 mol/L of PFA respectively at residence time of 9 min. Based on the kinetic equations and experimental data, the kinetic constants were determined. Thus, the average rate constants for forward and backward reaction are 0.0097 and 0.04354 L/(mol min) respectively. Based on the kinetic data, it was found that the activation energies of PFA synthesis and hydrolysis were 31.716 and 13.701 kJ/mol respectively.

Pt-USY-712 (Si/Al = 6) and three SBA-15 catalysts (metal-loaded with 1 wt% Pt, 1 wt% Ni or 0.5 wt% Pt and 0.5 wt% Ni) were prepared and characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), N$$_{2}$$2 adsorption porosimetry / BET and transmission electron microscopy (TEM). The catalysts were then tested in the hydroisomerisation and hydrocracking of $$n$$n-heptane using a micro-reactor at atmospheric pressure, and the products were analysed by GC-FID. Reaction temperatures ranged from 250–$$400\,\,^{\circ }\hbox {C}$$400∘C while the W/F values of $$n\hbox {-C}_{7}$$n-C7 varied from 224.70–550.57 kg $$\hbox {mol}^{-1}$$mol-1. The coke content of each catalyst was measured using thermo gravimetric analysis (TGA). The catalytic activity was highest on Pt-USY-712 at the lowest reaction temperatures due to (a) the presence of strong Brønsted acids sites on the zeolite and (b) the smaller and more highly dispersed metal clusters on Pt-USY-712, relative to Pt-SBA-15. The activity was higher on the bimetallic Pt/Ni-SBA-15 than on mono-metallic Pt-SBA-15 as the co-impregnation of Ni with Pt enhanced the distribution of the metal clusters on the catalyst and resulted in improved surface area for reaction. The Pt-SBA-15 and Pt/Ni-SBA-15 catalysts both had the lowest and approximately equal coke percentages with 0.116 and 0.119 wt%, respectively.