Thermal Decomposition of Ammonium Bicarbonate

Abstract

The thermal decomposition of ammonium bicarbonate (NH4HCO3) is relevant in numerous industrial and technological applications due to its ability to release gaseous products without leaving solid residues. This work presents a comprehensive kinetic and morphological study of its decomposition using non-isothermal differential scanning calorimetry (DSC) and complementary characterization techniques. Multiple heating programs were analyzed using the Friedman isoconversional method and combined kinetic analysis to build a predictive kinetic model. The results indicate that decomposition proceeds from ~75°C through a single endothermic step, releasing NH3, CO2, and H2O. The kinetic parameters obtained were an apparent activation energy of 101 kJ/mol and a ln⁡(A/s^(-1)) = 28.1. The optimized truncated Šesták–Berggren kinetic model, (1-α)^0.54 α^0.17, suggests a mechanism dominated by nucleation and growth. Scanning electron microscopy of partially decomposed particles confirmed the morphological evolution consistent with the proposed kinetic pathway. The verified model accurately reproduced experimental results and successfully predicted decomposition behavior under conditions beyond the experimental range, demonstrating its robustness and potential usefulness for industrial use.