Renewable biomass resources have become increasingly attractive in recent years. In this study, the pyrolysis of waste navel orange peels was carried out with different metal oxides (Cu ₂ O, CaO, V ₂ O ₅ , Fe ₂ O ₃ , and ZnO) in a tube furnace to obtain high-quality bio-oil, from which high-value chemicals such as 3-furaldehyde could be well recovered to enhance the economic value of waste navel orange peels. The effects of different metal oxides on bio-oil were analyzed by GC/MS. The results showed that Cu ₂ O and Fe ₂ O ₃ , as catalysts for slow pyrolysis, promoted the production of 3-furaldehyde compounds at a scale of approximately 5.69 and 4.82 times higher than that of pyrolysis without the addition of metal oxides, respectively. High-value chemicals such as 3-furaldehyde obtained from bio-oil can enhance the economic value of waste navel orange peels for full recovery and reuse.

Fly ash is a by-product from burning of coal. Utilization of fly ash by carbothermic reduction is an effective way to recover aluminum, silicon, and iron to enhance product-added value. This work is focused on the phase transformation of Al₂O₃, SiO₂ and Fe₂O₃ during carbothermic reduction of fly ash in air. A comparative analysis of carbothermic reduction of fly ash in air and in nitrogen was made. Thermodynamics analysis was performed to illustrate the possible reactions for residue and condensate. X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectrometry (EDS) were employed to characterize the phase composition, surface morphology, and microstructure of the reduced products. Results show that Fe₃Si and Fe₂Si appear sequentially with increasing of temperature. Al₅O₆N is an intermediate compound. Residue of Al₉FeSi₃, Al, and Si, and condensate of SiC, AlN and C are obtained. β-SiAlON was not found in the residue. Nitrogen is involved in the reduction of Al₂O₃ but not in the reduction of SiO₂ and Fe₂O₃. Carbothermic reduction of fly ash in air did not behave the same as fly ash in nitrogen.

Fly ash (FA) is a porous solid waste produced by coal-fired power plants that can be used as a carrier for solid–liquid phase change materials (PCM). Due to the disadvantages of FA, including small adsorption capacity and poor thermal performance, its application range is limited. Therefore, FA modification methods have received increasing attention. Two modification methods were used to improve the adsorption capacity of FA. After the modification experiments, the surface structure of modified fly ash (MFA) was eroded, revealing a three-dimensional porous structure. The Al/Si mass ratio of the alkali-modified sample increased from 0.67 to 1.28, and the specific surface area and pore volume increased from 3.82 m²/g and 0.008 cm³/g to 40.86 m²/g and 0.026 cm³/g, respectively. The shape-stable phase change material (SSPCM) prepared using the hybrid sintering method of Al-12Si alloy and alkali-modified fly ash (MFA-OH) exhibits excellent thermal properties and thermal cycling stability. The results showed that the heat storage density and thermal conductivity of SSPCM increased with an increase in PCM content. The thermal conductivity and latent heat of phase change in the composite with the highest latent heat of phase change in the sample were 18.24 W/(m·K) and 124.10 J/g, respectively. The optimum loading rate for the alloy is 65 wt%. After 100 thermal cycles, the latent heat and thermal conductivity of the phase change at SSPCM were 93.3% and 94.6% of the initial values, respectively. The research findings provide a feasible process for FA as a phase change carrier, and the application scope is extended.

In this study, we investigated the preparation process of lithium metal using a novel carbothermic reduction process. Herein, thermodynamic calculations and experimental research methods were used to investigate the novel carbothermal reduction process of LiAlO₂ for preparing lithium metal in a vacuum. The results suggest that the temperature of the chemical reaction can be significantly reduced by reducing the pressure in the system. When the system pressure was 10 Pa, the reduction temperature, reduction time, molar ratio of C/LiAlO₂, and reduction rate were 1623 K, 120 min, 0.9, and 79.01%, respectively. Furthermore, the lithium content in the reduction residue was 2.1 wt%, suggesting the presence of the LiAl₅O₈ phase. Under these conditions, when 20% CaO was added, the reduction rate of lithium increased to 99.38%, and the lithium in the reduction residue takes the form of CaAl₂O₄. This shows that CaO, as an additive, can promote reduction, compromise the effect of LiAl₅O₈, and increase the reduction rate of lithium.