Kinetic and Thermodynamic Analysis of the Non‐Catalytic Esterification of 2‐Butanol by Propionic Anhydride

This study aims to unambiguously resolve the controversy over the reaction mechanism (second‐order vs. autocatalytic) of the esterification between propionic anhydride (PAh) and 2‐butanol (2‐B) without concentrated sulfuric acid catalysis. A core strategy coupling reaction calorimetry (RC1e) with gas chromatography (GC) was employed. Isothermal experiments with different initial additions of product propionic acid (PAc) qualitatively confirmed the absence of autocatalytic behavior for this reaction, supporting the second‐order kinetic model. Kinetic parameters were acquired by fitting six sets of isothermal SBR experimental data using both second‐order and autocatalytic models. Comparative analysis of fitting performance (SSE, RMSE, R 2 , AIC and BIC), together with statistical validation (parameter correlation and residual diagnostics), further quantitatively demonstrated that the second‐order model was statistically superior to the autocatalytic model, thereby resolving the long‐standing controversy in the literature. The fitted kinetic parameters were validated via independent isoperibolic SBR, isothermal and isoperibolic BR experiments, as well as literature data, and the results showed that these parameters enabled accurate prediction of PAh conversion, temperature, and heat flow profiles across different operational modes. Key quantitative results are as follows: The fitted molar reaction enthalpy ΔHr, rate constant k ( T R ) ( T R = 80°C), and activation energy E are –63.6 kJ·mol − 1 , (8.18 ± 0.03) × 10 − 5 L·mol − 1 ·s − 1 , and 68.01 ± 0.44 kJ·mol − 1 , respectively. The derived kinetic parameters are slightly lower than literature results, owing to the superior heat transfer of the Hastelloy reactor, which provides more intrinsic kinetic data compared with conventional glass reactors.