Solid-state kinetics of thermal release of pyridine and morphological study of [Ni(ampy)2(NO3)2]; ampy = 2-picolylamine

The re-examined X-ray crystal structure of [Ni(ampy)2(NO3)2]; ampy = 2-picolylamine belongs to monoclinic P21/c space group having, a = 8.73510(10) Å, b = 8.73690(10) Å, c = 10.26480(10) Å and β = 101.5610(10)°. The microscopic feature calcined at 600 °C displays a thread type fiber of NiO. The thermogravimetric analysis shows that the thermal decomposition occurs in three steps where the removal of ligand occurs in an exothermic process. The activation energy was estimated with both iso-conversional and multivariate non-linear-regression methods. Friedman method agrees with a first-order kinetics having activation energy E and logarithmic pre-exponential factor A, 41 ± 1 kJ mol−1 and 2.54, respectively. Multivariate non-linear-regression methods show expanded Prout–Tompkins Bna model is the best fit model with highest correlation coefficient 0.999998 followed by Cn which corresponds to the nth order reaction with auto catalysis through the reactants. The calculated apparent activation energies are consistent with iso-conversional methods. The corresponding function f(α), activation energy E and logarithmic pre-exponential factor A of Bna model, are (1 − α)2.08α1.0236E−3, 42 kJ mol−1and 3.12, respectively, and those of Cn model are (1 − α)2.07(1 + 0.0144α), 42 kJ mol−1 and 3.11, respectively. The calculated rate constant and half-life time from iso-concentration plot are 2.381 × 10–3 s−1 and 291 s, respectively.