Optimization of Pyrolysis Kinetics and Blending Ratio of Salix psammophila and Corn Stover Under a Nitrogen Atmosphere Based on TG-DTG and SEM

Understanding the thermal decomposition behavior and kinetic characteristics of blended biomass is crucial for optimizing thermochemical conversion processes. This study systematically investigates the synergistic pyrolysis (thermal decomposition) behavior of Salix psammophila (SP) and corn stover (CS) under a nitrogen atmosphere, with particular emphasis on process behavior and reaction kinetics (and thermodynamic feasibility). Based on elemental and proximate analyses, SP provides high calorific value and lignin content, while CS contributes high volatile matter and cellulose, enabling complementary interaction during thermal conversion. Three blending ratios (CS:SP = 2:1, 3:1, and 5:2) were analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and kinetic evaluation via the Coats–Redfern, Flynn–Wall–Ozawa (FWO), and Kissinger–Akahira–Sunose (KAS) methods, together with thermodynamic parameter estimation (ΔH, ΔS, and ΔG). The results indicate that the 3:1 blend forms an optimized “continuous phase–dispersed phase” structure with an interfacial transition layer of 11–15 μm and uniformly distributed fine pores, promoting effective heat and mass transfer and facilitating volatile-release pathways across the blend interface. At a heating rate of 15 °C·min−1, this blend exhibits the lowest onset temperature of rapid mass loss (Tonset, 209 °C), the highest comprehensive pyrolysis performance index (SN, 3.01), and stable DTG profiles. Kinetic analysis confirmed that the 3:1 blend exhibits the lowest activation energy during the devolatilization stage, indicating enhanced reaction feasibility under inert conditions. The results provide mechanistic insight into biomass blending effects and offer guidance for process optimization in inert-atmosphere thermochemical conversion systems.