Reaction mechanism of stearic acid pyrolysis via reactive molecular dynamics simulation and TG-IR technology

Abstract

Stearic acid provides a basis for developing renewable energy, such as solar energy and biomass energy. A thermogravimetric-infrared spectroscopy (TG-IR) experimental test is conducted to obtain the thermal decomposition progress and the main gaseous products of stearic acid. The result shows that small gaseous products (H2O, CO2, CO, alkanes, olefins, etc.) are released. Furthermore, the method of reactive molecular dynamics simulation (ReaxFF-MD) is utilized to look into the pyrolysis reaction mechanism of stearic acid. The main pyrolysis products of stearic acid received by ReaxFF-MD are C2H4, H2, C2H2, CH4, H2O, CO2, and CO, consisting of the result of the TG-IR test. The effect of the simulated system density and temperature on the distribution of main products is also explored. Also, the thermal kinetic analysis is conducted by the initial consumption of stearic acid under different temperatures. The primary reaction mechanism of stearic acid pyrolysis is that the stearic acid molecules dissociate through C–C bonds break to generate C2H4, CH4, C2H2, C3H6, and other small molecules and radicals, and a typical reaction mechanism scheme of stearic acid pyrolysis is presented. The results provide a reference for explaining the macroscopic explosion characteristics of dust at the microscopic mechanism level.