Preparation, characterisation of pure aluminophosphate and aluminophosphate modified with different transition metals (V, Fe, Co Ni & Cu) and their catalytic activity in mono/dibenzyl substituted malonates synthesis are explained. The materials were prepared by the coprecipitation method in the absence of any structure-directing species and characterized for their composition, crystalline nature, total surface acidity, specific surface area pore diameter and pore volume by different techniques. Catalytic activity of the materials was investigated in transesterification of diethylmalonate with benzyl alcohol in liquid phase. Pure aluminophosphate resulted only in benzyl ethylmalonate whereas the incorporation of transition metals favored the formation of both benzyl ethylmalonate and dibenzylmalonate. Catalytic activity parallels the surface acidity and mesoporosity of the catalysts. The effect of the molar ratio of reactants, amount of catalyst, and reaction time on the conversion of diethyl malonate and transester yield has been studied. The highest activity of iron aluminophosphate is attributed to its mesoporous nature with uniform pore size distribution, higher surface acidity and surface area. Further, the scope and generality of iron aluminophosphate as a catalyst in the transesterification was studied using various aliphatic, alicyclic and aromatic alcohols. The catalysts could be recycled by retaining most of its initial activity. 2011 Acadie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Polymer composites have attracted considerable attention as potential light weight and cost-effective shielding materials which could be used for applications in nuclear reactors, nuclear waste transportation, as protective cloth/apron for personnel in hospitals, and shielding instruments on-board satellites from space radiations. In this context, we have developed diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin composites loaded with tungsten carbide (WC) for J-ray shielding. Epoxy composites containing different loadings (0, 10, 30 and 50 wt%) of WC were synthesized by room temperature solution casting technique. Structural and morphological studies of the composites were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal and tensile properties of epoxy were enhanced in the presence of WC fillers. Thermogravimetric analysis revealed the major degradation temperature occurring between 430C and 580C for all epoxy/WC composites. The tensile strength and Youngs modulus of the composites enhanced with loading, owing to greater intermolecular reinforcing effect, uniform stress distribution and enhanced energy-absorbing capacity. J-Ray attenuation studies performed in the energy region of 0.356 1.332 MeV using NaI(Tl) detector spectrometer showed the 50 wt% tungsten carbide/epoxy composites to have highest radiation attenuation at all the energies. The overall enhancement in thermal, mechanical, and radiation shielding characteristics of the composites may be attributed to the uniformity in distribution of the fillers in epoxy matrix. These nontoxic tungsten carbide/epoxy composites may be suitable as materials for shielding in radiation environments. 2022 American Institute of Physics Inc.. All rights reserved.
This work describes how to easily make NiO hollow sphere composites using waste sugarcane bagasse for use in supercapacitor applications. NiO hollow spheres (NOHSs) nanomaterialis effectively synthesized through the nano carbon sphere (CS) template. A core-shell structure was created on the carbon spheres surface by NiO nanoparticles that were several nanometers in size. The structural and morphological of the synthesized materials were investigated by X-ray diffraction (XRD) and Scanning electron microscope (SEM). The energy-dispersive X-ray spectroscopy (EDS) was used to confirm the presence of the elements in NOHS. The electrochemical behaviour of hierarchical CSs and NOHSs electrode was examined through cyclic voltammetry (CV), Galvanostatic charge/discharge (SC) and electrochemical impedance spectroscopy (EIS). In GCD analysis, NOHSs electrode showed a concentrated specific capacitance (Csp) of 913.79F/g at 5A/g current density. The porous conductive carbon with macro pores that speeds up the transit of electron and electrolyte ions causes noticeably better capacitive behavior. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
