Novel Preparation and Physicochemical Characterization of a Nanocrystalline Cobalt Ferrite System

Abstract

Well-defined CoFe 2 O 4 nanoparticles with an average grain size of about 50 nm were successfully synthesized by a combustion method employing different ratios of fuel to cations within the range 0-2.67. The as-prepared powders were characterized and investigated by TG, XRD, IR, SEM, TEM and VSM methods, and via isopropanol conversion at 250-450The results showed that increasing the ratio between fuel and cations stimulated the formation of cobalt ferrite due to the increasing flame temperature. Changing the fuel/cation ratio brought about modifications in the structure, surface activity, selectivity and magnetic properties of the investigated solids. A fuel/cation ratio of 2 led to the formation of catalyst having a high activity (49%) and magnetization (77.54 emu/g). All the solids investigated behaved as dehydrogenation catalysts leading to the formation of acetone as the major product. The fuel/cation ratio did not alter the mechanism of dehydrogenation of isopropanol, but increased the concentration of active sites involved in the catalyzed reaction.

Synthesis, non-isothermal crystallization and magnetic properties of Co0·75Zn0·25Fe2O4/poly(ethylene-co-vinyl alcohol) nanocomposite

“…Co 0•75 Zn 0•25 Fe 2 O 4 (cobalt-zinc ferrite) powder having a coercive force of 500 kOe, magnetization, 58 emu/g and 30-70 nm particle size were prepared by a combustion route. Detailed procedure was reported elsewhere (Deraz et al 2009). This sample was prepared by mixing calculated proportions of cobalt, zinc and iron nitrates with a certain amount of urea.…”

Study of Structural, Optical, Dielectric and Magnetic Properties of Zinc Ferrite Synthesized by Co-Precipitation

“…Ferrites are sparingly viable due to their electrical, magnetic and mechanical properties that can be bespoke as per the proviso for device fabrication and biological applications [1]. When spanned to electrical industries, their sheer electrical resistivity is subjugated for preventing induction of eddy currents and the resultant loss of energy [2].…”

Characterization and Catalytic Activity of Ni, Mo and Ni-Mo Supported on Al2O3 Systems

“…(iv)The upward deviation of Vt plot indicates the existing of wide pores (mesopores) (33)(34)(35) confirmed by the shape of isotherms. spinel may be referred to the increase in Mo loading which acts as catalyst for formation of NiAl 2 O 4 spinel confirming solid -solid interaction (36)(37)(38) .…”

“…(iii) Ni-Mo/AlO V catalyst is the most selective one for propene at 280, 340 o C where Mo/AlO VI catalyst is the most selective at 300, 340 and 360 o C due to the presence of MoO 3 species which has acidic character. (v) For bimetallic catalysts Ni-Mo/AlO (II-V), increasing of Mo loading resulted in a progressive increase in propene selectivity % reaching to its maximum value for Ni-Mo/AlO V catalyst which may be attributed to the formation of NiAl 2 O 4 phase (37,38) . So, the observed increase in the dehydration % may be attributed to the increase in the degree of dispersion of MoO 3 phase (4,5) .…”