Synergistic co-pyrolysis of pumpkin seed shell and low-rank coal and catalytic tar cracking over Fe–Ni-loaded char

Pumpkin seed shell (PSS), a representative biomass resource, can exert synergistic effects during co-pyrolysis with low-rank coal (LRC), thereby enhancing LRC utilization efficiency and reducing environmental impacts. In this study, the weight-loss behavior and kinetic mechanism of PSS/LRC co-pyrolysis were investigated using a thermogravimetric analyzer, and the gaseous and liquid products generated during co-pyrolysis were further analyzed in a tubular furnace. The results demonstrated a pronounced positive synergistic effect between PSS and LRC, which improved the thermal conversion efficiency of LRC and promoted the formation of light phenols and aromatic compounds. Among the blends, P7L3 exhibited higher reactivity, with a maximum weight-loss rate of 3.56%/min, whereas P3L7 showed better thermal stability, with a char yield of 39.61%, indicating its suitability as a catalyst precursor (LPC) and metal support. After further loading with Fe and Ni, the Fe-Ni/LPC bimetallic catalyst exhibited superior catalytic performance compared with the corresponding monometallic catalysts. In particular, 5Fe-5Ni/LPC-20 was most favorable for the generation of small-molecule gases, with H 2 and CO yields reaching 24.76% and 23.37%, respectively. The synergistic effect of Fe–Ni bimetals promoted tar cracking and reforming, accelerating the cleavage of oxygen-containing functional groups as well as C-C and C-H bonds. Consequently, the gas yield was enhanced, while the tar peak area and the number of components were significantly reduced, leading to improved tar quality. This study provides a theoretical basis for the synergistic high-value utilization of biomass and low-rank coal and for the preparation of carbon-based catalysts.