Arumugam Pandurangan

The key challenges in selective oxidation of biomass derived 5-hydroxymethylfurfural (HMF) to 2,5-diformyl furan (DFF), a sustainable source for producing polymers, surfactants etc., are the selective catalyst and optimum process conditions. SBA-16(B) synthesized using bamboo leaves derived sodium silicate was impregnated with 20 weight% each of cobalt, tungsten and their mixture, characterized by XRD, XPS, SEM, TEM and N2 adsorption studies, confirmed the formation of cubic Co3O4 and monoclinic WO3. HMF conversion and DFF selectivity observed over Co3O4/SBA-16(B), WO3/SBA-16(B) and Co3O4-WO3/SBA-16(B), indicated that Co3O4 is active while WO3 is selective whereas Co3O4-WO3 is more active and selective owing to synergism creating more reactive lattice oxygen thus enhancing the adsorption and activation of HMF and the oxidant, tert-butyl hydroperoxide (TBHP). All the other mesoporous supports viz. FDU-5, KIT-6, MCM-41, MCM-48, SBA-15 and TUD-1 impregnated with Co3O4-WO3, have shown higher selectivity for DFF except MCM-48 and KIT-6 owing to the difference in their pore architecture. The optimum temperature, catalyst amount, HMF/TBHP mole ratio and solvent were found to be 80oC, 75 mg, 1:10 and acetonitrile respectively. The retention of HMF conversion and DFF selectivity of 95 and 100% respectively for five cycles by Co3O4-WO3/SBA-16(B) catalyst confirmed its recyclability.

The catalytic synthesis of carbon nanotubes (CNTs) using CeFeMgO catalysts represents a promising avenue for achieving efficient and controlled carbon nanotube growth. The CeFeMgO catalysts were prepared by solution combustion techniques and the growth of CNTs was obtained from the chemical vapour deposition (CVD) method. The X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM),w energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), BET, particle size distribution. were employed to characterize the morphology, crystallinity and composition of the synthesized CNTs. Results indicate that the study reveals the robust catalytic activity that facilitates the formation of high-quality carbon nanotubes (CNTs), highlighting the efficiency of CeFeMgO catalysts in promoting CNT growth and elucidating the structural aspects crucial for optimizing carbon nanotube production. The results demonstrate uniform carbon nanotube dimensions, excellent crystallinity and minimal defects, highlighting the efficacy of catalyst in achieving controlled and efficient carbon nanotube synthesis. This study enhances the comprehension and utilization of CeFeMgO catalysts in the synthesis of carbon nanomaterials.