Efficient pyrolysis of biomass tar and tunable carbon deposition on FeNi-composited biochar surfaces under microwave heating

Abstract

There are significant challenges in utilizing biomass tar and other harmful substances to produce more efficient and cleaner syngas energy. In this study, a microwave reactor and a biochar composite FeNi bimetallic catalyst were employed to enhance the production of syngas and high-value carbon nanomaterials. Through various characterization methods, we investigated the synergistic mechanism between microwave metal biochar and the evolution mechanism of carbon nanomaterials under microwave fields, correlating the pyrolysis performance of naphthalene with these processes. The results indicated that the gas phase yield reached 91.7%, with a hydrogen yield of 82.38% when the FeNi ratio was 1. The key component Fe_0.65Ni_0.35, as the catalytic active phase, effectively cracked naphthalene and maintained over 80% hydrogen yield, thereby directly promoting the conversion of hydrogen-rich syngas. The high proportion of syngas suggests that microwaves enhance the metal biochar heterostructure and lower the activation energy required for C-C and C-H bond cleavage. Furthermore, the presence of transition metals iron (Fe) and nickel (Ni) influences the morphology of the deposited carbon, while their solubility and fluidity facilitate the formation of multi-defect three-dimensional CNFs. The proposed low-cost catalyst was integrated into the mechanism model of the microwave pyrolysis chemical vapor deposition process, providing an innovative solution and theoretical foundation for the high-value conversion of tar.