Synthesis of kinetic analysis and regression optimization for highly efficient conversion of pig manure in supercritical water

Supercritical water gasification (SCWG¹) is a promising technology, effectively employing biomass waste to generate value-added hydrogen-rich products. However, the gasification and optimization mechanisms still require further research to employ biomass waste to realize waste-to-energy in SCWG. This work investigates pig manure as a representative first to explore the effects of temperatures (580–660 °C) and residence times (1–45min) on the gasification characteristics. The results show that temperature and residence time positively correlate with gasification performance. The highest H₂ output and carbon gasification efficiency (CE) at 660°C‒45 min (temperature-residence time) are 19.73 mol/kg and 82.22 %, respectively. Subsequently, a double-intermediates kinetic model is developed to obtain transformation mechanisms and yield predictions of gasification products. The dehydrogenation, decarboxylation, and decarbonization of aniline, phenolic, and N-heterocyclic compounds to gaseous products mainly through pyrolysis and steam reforming reactions at the 1–20 min of the gasification process. Finally, with the average relative error of 3.82 %, 6.74 %, and 2.04 %, the optimization mechanism is researched by the regression equation and three-dimensional response surface plots of the regression model. The magnitude of the influence of the independent parameters is statistically determined from the correlation coefficients of the regression model for the first time, rather than merely from restricted experiments.