<報文>遷移金属硫酸塩の熱分解の速度と機構

概要

論文の詳細を見る
The thermal decomposition of sulfates of Fe2（SO4）3, CoSO4, CuSO4 and ZnSO4 was kinetically, isothermally studied in flowing high-purity-nitrogen by use of at hermobalance. Disk-like pellets compacting the anhydrous sulfate powders were used. The decomposition occurred at the phase boundary between the undecomposed sulfate and the oxide product, and the boundary proceeded uniformly from the surface towards the interior. The thickness, x, of the oxide product layer was proportional to the time, t, for Fe2（SO4）3, C0SO4 and NiSO4 : the rate equation was x=kct. The x vs t curves for CuSO4 and ZnSO4 were shown to become two straight lines with a break point. From the kinetic data and the results of X－ray diffraction, it was known that the break is due to the formation of their oxyysulfate as the intermediate. The in k vs 1/T relationship moves from lower to higher temperatures in the order : Fe2（SO4）3, CuSO4, CoSO4, NiSO4, ZnSO4. The activation energies of the decomposition for sulfates of iron（III）, cobalt, nickel, copper and zinc were 212, 217, 257, 211 and 238 kJ mo1-1, and those for oxysulfates of copper and zinc at the later stage after the break were 221 and 275 kJmo1-1, respectively, The activation energies were shown to be close to the enthalpies of decomposition for the sulfates, ⊿H゜d298
横浜国立大学の論文