Ternary Co-Pyrolysis of Soma Lignite, Sugar Beet Pulp, and Hazelnut Husk: Synergistic Effects, Pseudo-Component Behavior, and Optimal Blend Design

This study investigates the ternary co-pyrolysis behavior of Soma lignite (SL), sugar beet pulp (SBP), and hazelnut husk (HH) at four blending ratios (80:10:10, 60:20:20, 40:30:30, and 20:40:40 wt.%) using thermogravimetric analysis under a nitrogen atmosphere. Synergistic interactions were quantified through mass-based (ΔW) and rate-based (Ψ) deviation indices, and the contributions of individual pseudo-components were resolved by Gaussian deconvolution of DTG curves. Among the blends investigated, the 40:30:30 (SL:SBP:HH) composition exhibited the most consistent and intense synergistic effect across all temperature zones, with the strongest promotion concentrated in the high-temperature region associated with CaCO3 mineral decomposition. Deconvolution analysis revealed that increasing the biomass fraction systematically shifted coal-related pseudo-component peaks to lower temperatures and enhanced the hemicellulose/pectin contribution, confirming that biomass-derived volatiles accelerate lignite devolatilization. These findings demonstrate that ternary co-pyrolysis of low-rank coal with two complementary agricultural by-products is a viable and sustainable strategy to enhance pyrolysis performance, valorize agro-industrial waste, and reduce the environmental footprint of lignite utilization, providing fundamental thermochemical data for the design of integrated lignite–biomass co-processing systems.