A study on the thermochemical conversion characteristics of biomass mixed blast furnace slag catalyst coupled in supercritical CO₂/H₂O atmosphere

To reduce excessive CO₂ in the environment and reutilize waste blast furnace slag, thermochemical reduction methods have become a focus of attention. The waste blast furnace slag as the catalyst, thermochemical conversion of biomass and its mixed catalyst under supercritical CO₂ (scCO₂)/scCO₂ mixed H₂O atmosphere were compared to explore the best CO₂ consumed condition. The composition and thermal stability of the raw materials were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectrometer (XRF), thermogravimetric analysis (TGA) and simultaneous thermal analysis (STA), while gas chromatograph (GC), gas chromatography mass spectrometer (GC-MS), scanning electron microscope (SEM), brunauer emmette teller (BET), fourier transform infrared spectrometer (FT-IR) and X-ray diffractometer (XRD) were used to analyze the properties of the products. As a result, the scCO₂ atmosphere increased the consumption of CO₂ during the reaction process compared to the N₂ atmosphere. Under the scCO₂ mixed H₂O atmosphere, the addition of the catalyst resulted in the highest H₂ yield of 5.90 ± 0.01 mol/kg, led to an increase in HE from 58.17 % to 69.16 %, and also greatly facilitated the phenolic hydroxyl groups -OH and carboxyl groups C=O on the solid products to be detached from the aromatic ring. The specific surface area of the biomass reached the optimum value of 240.83 m²/g in the CHE7 when the characteristic peaks 002 and 100 intensities displayed high stack height and lateral dimensions.