Abstract
AbstractIn this work, we report, for the first time, the continuous flow synthesis of zeolite NaX successfully accomplished in a pilot‐scale (up to 100 L/h) continuous oscillatory baffled reactor (COBR). The continuous synthesis was achieved by combining the seed‐assisted method, in‐line mixing of reactants at high temperature and COBR. The use of a COBR not only allowed the same residence time as the batch system, but also a controlled temperature profile, thanks to the plug flow behavior and effective heat transfer. A stable continuous operation was maintained during 5 hours owing to an effective mixing, preventing any hydrodynamic failure caused by the sedimentation of zeolite crystals. The results showed that zeolite NaX was obtained after 99 minutes and crystals between 0.6 and 0.7 μm were observed by scanning electron microscopy. The effect of frequency and amplitude on crystal properties was assessed. Sampling at three points along the COBR allowed the study of steady states of the zeolite concentration in temporal and spatial domains.
Highlights
Zeolites are crystalline aluminosilicates composed of AlO4 and SiO4 tetrahedrons to form 3D porous structures.[1]
In this work, we report, for the first time, the continuous flow synthesis of zeolite NaX successfully accomplished in a pilot-scale continuous oscillatory baffled reactor (COBR)
The X-ray diffraction (XRD) patterns for samples taken at different points along the COBR during the run 1 are shown in Figure 2A (30 L/h, 1 Hz-64 mm), which demonstrate that the product of the continuous flow system was single phase NaX
Summary
Zeolites are crystalline aluminosilicates composed of AlO4 and SiO4 tetrahedrons to form 3D porous structures.[1]. (a) An effective seeding to avoid aging stage and heterogeneous nucleation, (b) a well-tuned synthesis precursor to enable fast crystal growth, (c) fast heating to avoid decomposition of the organic structure-directing agent, and (d) high temperature to accelerate the crystal growth rate of the target structure.[17,22] Another approach was proposed by the same group[23] using pressurized hot water (370C) to increase the reaction mixture temperature (240C300C) They demonstrated, for the first time, the crystallization of ZSM-5 zeolite in the order of seconds. Jiang et al.[35] reported for the first time reactive seeded cooling crystallization of paracetamol in a COBR at different seed content, enabling smooth, and encrustation-free runs These results in the field of crystallization herald that a COBR can potentially benefit the synthesis of zeolite materials from the viewpoint of handling of solid particles. The steady state of zeolite concentration in both temporal and spatial domains was studied
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