Study on the synergistic effect of co-pyrolysis gasification of low-grade non-cohesive coal and waste biomass

Abstract

The co-pyrolysis gasification technology of low-grade non-cohesive coal (NC) and biomass can promote the clean and efficient utilization of coal. This study investigated co-pyrolysis gasification experiments using three typical kinds of waste biomass (macadamia nut shells [MS], peanut shells [PS], and rice shells [RS]) mixed with NC in varying proportions. The results indicated that as the proportion of biomass in the mixture increased, the overall reactivity enhanced. Specifically, the activation energy in the low-temperature stage (S1, 200–450 °C) increased, whereas in the high-temperature stage (S2, 800–1050 °C), the activation energy decreased, demonstrating a synergistic effect across a broad spectrum. In summary, the synergistic effect of the three biomass types ranked as RS > PS > MS. The NC:RS50:50 mixture exhibited R, At0.5, and comprehensive pyrolysis index values of 1.78, 0.84, and 23.21, respectively. In contrast, the values for NC alone were 0.85, 0.63, and 14.77, respectively. The strength of the synergistic effect was indirectly reflected by the weakest covalent bond, d002, graphitization degree, and activation energy. Additionally, the content of alkali metal K in the biomass mixture was a primary factor directly influencing reactivity and synergistic effects. This research offers new insights for expanding biomass utilization and holds significant implications for developing various biomass-based carbon materials.