Single Synthesis Method Research Articles

An eco-friendly method for the scale-up synthesis of ZSM-5 Zeolite

Scaling-up is the key step of the commercialisation of ZSM-5 zeolite, and the cost-effectiveness and greenness of the synthesis strategy is a decisive factor that cannot be ignored in the scale-up process. Herein, we present a template-free and solid-state-like crystallisation method for the synthesis of ZSM-5 zeolite by mechanical mixing of starting material components, which can be used for the scale-up production of ZSM-5 zeolite. The crystallisation range of ZSM-5 zeolite was obtained by this mechanical mixing of anhydrous starting materials. We have analyzed the kinetics study of three different Na2O/Al2O3/SiO2 systems in the range, and obtained the trends of nucleation and growth activation energy. The results show that mechanical mixing can effectively achieve a high degree of homogenous dispersion of the starting material, which is conducive to obtaining ZSM-5 with high crystallinity and size uniformity. We have synthesised monolithic ZSM-5 with high crystallinity and uniform grain size of about 2 g, 30 g and 120 g in different sizes (2.5 ml/50 ml/200 ml) of Teflon lined high pressure reactors in a single synthesis method. This study affirms the possibility of achieving the scale-up of ZSM-5 zeolite synthesis through the synthetic pathway proposed, presenting a cost-effective, eco-friendly strategy for the industrial preparation of ZSM-5 zeolite.

Magnetic multi-granule nanoclusters: A model system that exhibits universal size effect of magnetic coercivity.

It is well known that the coercivity of magnetic nanomaterials increases up to a maximum and then decreases to zero with decreasing particle size. However, until now, no single synthesis method has been able to produce magnetic nanoparticles with a wide range of sizes, i.e., from 10 to 500 nm, in order to uncover the coercivity evolution. Here we report the characterization of magnetite (Fe3O4) multi-granule nanoclusters (MGNCs) to demonstrate the transitional behaviour of coercivity. The M–H curves indicate that our samples had a relatively high saturation magnetization (MS) value of ~70 emu/g and that the coercivity (Hc) increased to the maximum value of ~48 Oe until the nanoclusters reached a size of ~120 nm; the coercivity then gradually decreased to zero.

Morphology oriented surfactant dependent CoO and reaction time dependent Co3O4 nanocrystals from single synthesis method and their optical and magnetic properties

A simple solvothermal strategy has been developed to synthesize highly stable, pure phased CoO and Co3O4 nanoparticles from Co(CH3COO)2·4H2O precursor in ethanol solvent at 220 °C. The various phases of cobalt oxide (cubic CoO and Co3O4) with controlled size and morphologies viz, nanocubes, hexagonal platelets and nanospheres could be obtained via varying only one parameter (either surfactant or reaction time) in this single synthesis method. XRD and HRTEM analyses revealed pure cubic phase CoO and Co3O4 nanoparticles. The formation and shapes of CoO nanoparticles are surfactant dependent, whereas the formation and morphologies of Co3O4 are time dependent. The optical absorbance studies showed two distinct broad absorption peaks and hence two optical band gaps for both CoO and Co3O4 nanoparticles. CoO nanoparticles showed a wide band gap difference of 2.36 eV, while Co3O4 nanoparticles were found to be semiconducting in nature with a 0.6 eV–1 eV band gap difference, which showed characteristic features of CoO and Co3O4 nanoparticles, respectively. CoO nanoparticles showed interesting magnetic behaviour due to intrinsic antiferromagnetic structure and uncompensated surface spins, which was confirmed by VSM and EPR studies.