Comprehensive study on the combustion mechanism of starch: Insights from TGA, DRIFTS, Hartmann tube, and ReaxFF simulation

The investigation of the microscopic characteristics and mechanisms underlying starch combustion is pivotal for facilitating the green transformation of energy systems under the framework of carbon neutrality. This study systematically examined the pyrolysis behavior of wheat starch through thermogravimetric analysis (TG). In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was utilized to track the evolution of functional groups during the combustion process of wheat starch. The combustion properties of wheat starch, corn starch, and sweet potato starch were further analyzed using the Hartmann tube method. Additionally, the ReaxFF molecular dynamics simulation approach was employed to elucidate the detailed combustion reaction mechanism of wheat starch. The TG-DTG results revealed that the pyrolysis of wheat starch can be categorized into four distinct stages: dehydration, transition, intense pyrolysis, and carbonization. DRIFTS observations demonstrated that as temperature increased, significant transformations occurred in key functional groups, including -OH, -CH/-CH 2 /-CH 3 , C=O, and C-O-C. Hartmann tube experiments indicated that the flame propagation velocities of corn starch and sweet potato starch reached their respective maxima at a concentration of 750 g•m −3 , with values of 10.45 ms and 8.875 m•s −1 . For wheat starch, the maximum flame velocity within the tube was observed to be 5.49 m•s −1 at a concentration of 500 g•m −3 . ReaxFF molecular dynamics simulations illustrated that the cleavage of C-O bonds in wheat starch leads to the formation of glucose, which subsequently undergoes ring-opening reactions to generate carbon chains of varying lengths. These chains ultimately fragment into CO, CO 2 , and H 2 O. Collectively, this study offers valuable theoretical insights and practical guidance for enhancing the efficient utilization of starch-based resources.