Cascade catalysts from heavy bio-oil for plasma-catalytic NH3 synthesis

Abstract

Plasma-assisted ammonia synthesis (PAAS) enables the production of ammonia at ambient temperature and pressure by utilizing high-energy free electrons to break N≡N and H-H bonds. This process leverages green electricity and hydrogen, offering an efficient and distributed alternative for renewable energy storage. However, conventional catalysts used in PAAS (Al2O3, metal-organic frameworks, molecular sieves, etc.) suffer from low efficiency, poor cycling performance, and high cost. Herein, we design and develop novel cascade porous biochar-based catalysts (Co-PB) derived from waste heavy bio-oil through catalytic pyrolysis by using cobalt nitrate as a pyrolysis catalyst, giving rise to a highly porous structure with uniformly distributed Co in Co-PB. The good mobility of heavy bio-oil ensures homogeneous C-Co bonds, which further enhances the transfer kinetics of the interfacial electron and the radical. As a result, Co-PB achieves a high PAAS rate of 1.605 mmol/g·h and exhibits excellent stability and cyclability under harsh electric fields. Economic and environmental assessments highlight the significant potential of PAAS for sustainable hydrogen and electricity storage.