Microwave-Induced One-Pot Preparation of Bifunctional N-Fe/BC Catalysts and Oriented Production of Phenol-Enriched Bio-Oil from Biomass Pyrolysis: Catalyst Synthesis, Performance Evaluation, and Mechanism Insight via Theoretical Calculations

To recover valuable products from biomass, bifunctional catalysts (N-Fe/BC) capable of microwave absorption and oriented production of phenolics were prepared by a one-pot method involving the microwave-induced K2FeO4. Its catalytic performances were evaluated, and the catalytic mechanism was explored using a model compound and DFT calculations. The cycle performance and deactivation mechanism were investigated. N-Fe/BC possessed a large S-BET value (265.21 m(2) g(-1)), good pore distribution, and abundant Fe and N species, resulting in good dielectric and catalytic properties. After catalysis, the heating rates reached 63.78-107.84 degrees C min(-1), and the selectivity and yield of phenol-enriched bio-oil improved significantly, reaching maximum values of 80.28% and 38.09 wt % at 550 degrees C with 20 wt % N-Fe/BC, respectively. Model compound experiments and DFT calculations showed that N-Fe/BC directionally generated phenolics by changing the reaction path and forming "hot spots" that stimulated the catalytic reforming of oxygen-containing compounds. The catalytic performance decreased slightly after five cycles, due to active site loss, carbon deposition, and pore collapse.