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Abstract  

Kaolinic and bentonitic-clays are selected to prepare transition metals, iron, cobalt and nickel catalysts. The metals are incorporated into two supports through new impregnation technique. The original clays and the prepared catalysts were subjected to different techniques. The crystallite size (X-ray diffraction analysis) increases from iron to cobalt then to nickel upon heating and the increase for bentonitic-catalysts is higher than that for kaolinic-ones. Infrared spectra show the appearance of bands signifying the presence of iron, cobalt and nickel bonded to OH group constituting the silica-silica tetrahedral sheets inside the clay structure. The enthalpy (ΔH) andentropy (ΔS) values (differential scanning calorimetric) are lower for bentonitic-catalysts than for kaolinic-catalysts. Thus, the incorporation of the metal hydroxide in the interlamella of the silicate-silicate bentonite clay structure facilitates the interaction between the unpaired electrons on the adjacent atoms and the support which enables the prepared catalysts to be more active for catalytic conversion.

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The thermal decomposition studies on nitrophenates of copper, nickel and cobalt have been undertaken,α-t curves show dehydration of these compounds at lower temperatures whereas dehydration cum decomposition seem to occur at higher temperatures leading to oxidative combustion of aromatic part. NO2 gas is evolved during decomposition which seems to be responsible for oxidative reactions leading to detonation. The explosion temperature and velocity of detonation have been found to be linearly related with the number of nitro groups. The mechanism of thermal explosion has also been discussed.

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Abstract  

Bis-piperidine complexes of benzoylacetonates of Mn(II), Co(II), Cd(II) and Ni(II) were prepared. Thermogravimetric analysis (TG) demonstrated that Mn(II) bis-piperidine benzoylacetonate was stable up to 90°C, while Co(II) bis-piperidine benzoylacetonate was stable up to 100°C, whereas Cd(II) bis-piperidine benzoylacetonate was stable up to only 50°C. Its first decomposition step was completed at 110°C. Ni(II) bis-piperidine benzoylacetonate found to be stable up to 110°C. The stabilities of the complexes of these metals therefore follow the sequence Cd2+<Mn2+<Co2+<Ni2+. The complex of Cd(II) was the least stable of all the compounds studied.

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Abstract  

The thermal behaviour of Co(II), Ni(II) and Zn(II)-containing zirconium phosphate of α type was investigated. XRPD analysis revealed that, for the samples containing Co(II) or Ni(II), the first reflection of the solid phase is split into a doublet. In contrast, when Zn(II) is present, a single solid phase system is formed. The thermal behaviour of the materials followed this sequence. For the samples containing Co(II) or Ni(II), phase-transition processes were found and there was also a loss of crystal water, but for the sample containing Zn(II) there was only one endothermic effect, which corresponded to the decomposition of phosphate groups.

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Abstract  

The thermal behaviours of the Ti(II), Mn(II), Fe(II), Ni(II), Cu(II) and Zn(II) complexes of triethanolamine were studied by means of thermogravimetry, differential thermogravimetry, differential thermal analysis infrared spectrophotometry and elemental analysis. The sequence of thermal stability of the metal complexes, determined by using the initial decomposition temperature, was found to be Ti(II)≅Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Some of the kinetic parameters, such as the activation energy and order of reaction for the initial decomposition reaction, were calculated and the relationship between the thermal stability and the chemical structure of the complexes is discussed.

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Journal of Thermal Analysis and Calorimetry
Authors: Gurdip Singh, A. K. Shrimal, Inder Pal Singh Kapoor, Chandra Prakash Singh, Dinesh Kumar, and Manan S. Mudi

propellants compositions. Nickel hydrazine nitrate has been prepared and found insensitive to impact, friction, or electrostatic charge, but more sensitive to flame [ 5 ]. Transition metal complexes are also used to obtain nano size metal oxides, which can

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Abstract  

Transition metal dithiocarbamate complexes, [M(S2CN(C2H5)(CH2CH2OH)] (M=Co, Ni, Cu, Zn and Cd) have been prepared and characterized by elemental analysis and infrared spectra. Thermal decomposition of all the complexes occurs in two or three stages. The first stage in all the complexes is always fast with 65-70% mass loss. In all cases the end product is metal oxide except in the case of cobalt complex which gives Co metal as an end product. During decomposition of copper complex, first CuS is formed at ~300C which is converted into CuSO4 and finally CuO is formed. However, decomposition in helium atmosphere yields CuS. SEM studies of transition metal dithiocarbamates reveal needle shape crystalline phase at room temperature and formation of metal sulphide/oxide at higher temperatures. The activation energy varies in a large range of 33.8-188.3 kJ mol-1, being minimum for the Cu complex and maximum for the Zn complex possibly due to d 10 configuration. In the case of Ni, Zn and Cd complexes the order of reaction is two suggesting bimolecular process involving intermolecular rearrangement. However, in other cases it is a unimolecular process. Large negative values of ΔS # for all the complexes suggest that the decomposition process involves rearrangement.

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have been used to characterize complexes of bivalent transition metal ions [ 9 , 10 ]. However, they are not found in the literature thermal studies involving all metal-ions with oxamates, as well as the characterization of the gaseous products

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Abstract  

Mixed zirconium-titanium phosphates were synthesized by various methods and under various conditions. The effect of these conditions on the selectivity of synthetized samples toward the transition metal ions was investigated. It was found that the kd values are independent of the metal concentration and they give the selectivity order Zn2+>Cu2+ Co2+, Ni2+>Mn2+.

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