Enhancing combustion performance and emission reduction in ammonium hydroxide-diesel blends: A comparative study of metal-based and carbon-based nanocatalysts for hydrogen separation

This study explores the effects of metal-based and carbon-based nanocatalysts on ammonia decomposition and hydrogen separation in ammonium hydroxide (AH)-blended diesel fuels. Blends of conventional diesel fuel (CDF) with 30% AH were prepared, with 100 ppm of aluminum oxide (Al₂O₃) or carbon nanotube (CNT) nanoparticles separately added. Characterization revealed that CNTs exhibited superior catalytic efficiency for hydrogen separation and ammonia decomposition compared to Al₂O₃. Combustion performance analysis showed that while AH blends increased brake-specific fuel consumption (BSFC) and reduced brake thermal efficiency (BTE), the addition of nanocatalysts mitigated these effects. CNTs reduced BSFC by 9.1% and increased BTE by 9.1%, outperforming Al₂O₃, which achieved reductions of 6.4% and improvements of 6.5%. Emission analysis showed CNTs reduced hydrocarbons (15.72%), carbon monoxide (13.94%), and smoke opacity (8.8%) by promoting more complete combustion. Al₂O₃, on the other hand, effectively reduced nitrogen oxides emissions (20.5%) by stabilizing combustion temperatures.