• LiOH catalysis enhances H₂ yield by 47–62% and suppresses CO by 65–87% in SCWG of equine manure at 560°C/25 MPa. • Residual alkali precipitates sustain catalytic activity during subsequent non-catalytic operation, reducing catalyst consumption. • Four-lump kinetic model reveals a 1.5 reaction order for heterogeneous feedstock decomposition. • Total gas yield increases by 33% via alkali-promoted water-gas shift and char suppression mechanisms. The efficient treatment and resource utilization of agricultural waste, such as equine manure, represents a significant challenge due to its high ammonia nitrogen content, which poses serious environmental and ecological risks. Conventional methods like anaerobic digestion are often inhibited by high ammonia levels and slow kinetics. This study demonstrates the efficacy of lithium hydroxide as a homogeneous catalyst in supercritical water gasificationat (SCWG) 560°C and 25 MPa to enhance hydrogen production while simultaneously removing ammonia nitrogen. Experimental results show that LiOH addition increased H₂ yield by 47–62%, suppressed CO formation by 65–87%, and improved total gas yield by 33%. Precipitated alkali residues retained notable catalytic activity in subsequent non-catalytic cycles. A four-lump kinetic model accurately described the reaction network, revealing a 1.5-order dependence for the heterogeneous feedstock phase. These findings provide both mechanistic insight and a practical strategy for the sustainable valorization of high-nitrogen organic wastes, advancing SCWG applications for simultaneous energy recovery and pollution mitigation.
Gai et al. (Sun,) studied this question.