Theoretical Study on the Evolution Mechanism of <scp>NO_X</scp> and <scp>CO_X</scp> During the Pyrolysis of Nitric Acid and Glucopyranose

ABSTRACT Sugar, as a denitration agent, has broad application prospects in the field of high‐level radioactive liquid waste (HLLW) treatment. Understanding the interaction mechanism between nitric acid and sugar is crucial for the development of HLLW treatment. This study presents a detailed reaction mechanism, revealing key intermediates (HNO 2 ) and pathways (generation of carboxyl groups) leading to critical products (NO 2 , NO, CO 2 , and CO). The work shows five different paths leading to the ring‐opening of β‐D‐glucopyranose. The results indicate that the ring‐opening path involving the interaction of H 3 O + with glycosidic oxygen has the greatest kinetic advantage, with lower energy of highest point (EHP) (63.6 kJ/mol) and lower highest energy barrier (HEB) (49.2 kJ/mol). Furthermore, carbon oxides, as key gaseous products, exhibit a synergistic relationship with the generation pathways of nitrogen oxides, promoting each other. In addition, through thermodynamic analysis of the four reaction products (NO 2 , NO, CO 2 , and CO), the study shows that the reactions producing NO 2 and NO are spontaneous exothermic reactions, while the reactions generating CO 2 and CO are non‐spontaneous endothermic reactions. The study aims to elucidate the atomic‐scale interaction mechanism between sugar‐based denitration agents and nitric acid, providing a theoretical basis for the application of natural polysaccharides in HLLW, while also opening new avenues for the design of reducing agents and byproduct control strategies in industrial denitration processes.