Yanguo Zhang

CO₂ gasification-reforming facilitates CO₂ utilization and yields CO-rich syngas for municipal waste management. Catalysts are essential for enhancing syngas production via catalytic tar reforming.

The temperature and pressure of the hydrothermal process occurring in a batch reactor are typically coupled. Herein, we develop a decoupled temperature and pressure hydrothermal system that can heat the cellulose at a constant pressure, thus lowering the degradation temperature of cellulose significantly and enabling the fast production of carbon sub-micron spheres. Carbon sub-micron spheres can be produced without any isothermal time, much faster compared to the conventional hydrothermal process. High-pressure water can help to cleave the hydrogen bonds in cellulose and facilitate dehydration reactions, thus promoting cellulose carbonization at low temperatures. A life cycle assessment based on a conceptual biorefinery design reveals that this technology leads to a substantial reduction in carbon emissions when hydrochar replacing fuel or used for soil amendment. Overall, the decoupled temperature and pressure hydrothermal treatment in this study provides a promising method to produce sustainable carbon materials from cellulose with a carbon-negative effect.

Response surface method (RSM) was proposed to investigate the conversion of scrap tire via hydrothermal treatment. Temperature was the dominant factor in the process. The liquefaction rate increased sharply with temperature and exceeds 40 wt.% in the supercritical region ( >374.3°C). A maximum of more than 40 wt.% liquefaction rate was obtained when the tire was kept at 399°C for 60 min with the water/tire mass ratio of 10.8/1. Subsequently, the analysis of solid phase and liquid products at 360 and 400°C was carried out. The thermal stability of natural rubber in tire is significantly deteriorated after hydrothermal treatment. The hydrothermal process of rubber includes chain cleavage, particle hydrolysis, and carbon nanospheres formation, growth and agglomeration. The liquid products including carotenoids, ketones, and aromatic compounds, the ratio of which can be adjusted according to the temperature.

This paper reports an experimental study on the changes in the equivalent diameter and sphericity of flying molten slag particles in terms of heating temperature and nitrogen injection pressure. A high‐speed camera is used to continuously take images of the flying molten particles. Then the images are analyzed by mathematical image processing. With increasing heating temperature, the lower the viscosity, the stronger the fluidity, and the easier it is to be granulated into small particles under the spray of nitrogen. The results show that the equivalent diameter and sphericity of the particles with equivalent diameters remain the same during the flight. During the granulation of the particles, however, rod‐shaped particles gradually change to spherical ones, and the sphericity keeps increasing until it reaches a level. The average flying speed of the studied slag particles at the temperatures of 1400, 1450, 1475, 1500, and 1510°C is 4.0, 4.3, 4.5, 4.3, and 4.2 m/s, respectively. In addition, the higher the temperature, the longer the flight distance of the particles. By changing the gas injection pressure to 0.2, 0.3, 0.4, and 0.5 MPa, the average flying speeds of the studied slag particles are 2.8, 3.7, 5.5, and 8.4 m/s, respectively. This result proves that the higher the injection pressure, the greater the average flying speed of the particles.

The interaction between various municipal solid waste components is very important for the actual solid waste treatment process. Microcrystalline cellulose (MC) and styrene–butadiene–styrene triblock copolymer (SBS) are important components of municipal solid waste. In this paper, co-pyrolysis characteristics and kinetics of MC and SBS with different heating rates were investigated using a thermogravimetric analyzer. The overlap ratio was defined to evaluate the interaction between MC and SBS. The results showed that the decomposition temperature of MC was lower than that of SBS during pyrolysis. The interaction between MC and SBS, an inhibitory effect, was most significant when the MC mass fraction was 70% with an overlap ratio of 0.9764. SBS had almost no effect on the pyrolysis temperature of MC, while MC delayed the pyrolysis of SBS. Adding MC in SBS can significantly reduce the energy required for the reaction.