Synthesis of uniform-sized spherical monodisperse K2Ba[Ni(NO2)6] via polymer-assisted anti-solvent crystallization method for the enhanced catalytic pyrolysis of HNIW

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2025-01, Vol.704, p.135458, Article 135458
• Main Authors: Zhu, Fengdan, Liu, Chang, Yang, Desheng, Bai, Chaofei, Zeng, Xinlong, Niu, Ziteng, Li, Guoping, Luo, Yunjun
• Format: Article
• Language: English
• Subjects: barium; catalytic activity; combustion; crystallization; emulsions; heat production; Hexanitro complexes; HNIW; Monodisperse spherical crystals; particle size; Polymer-assisted anti-solvent crystallization; potassium; pyrolysis; solvents; surface area
• ISSN: 0927-7757
• DOI: 10.1016/j.colsurfa.2024.135458

Nitro complexes (NCs) have been selected as combustion catalysts for propellants due to their synergistic behavior. However, NCs prepared by traditional methods suffer from poor dispersion and irregular shape, which limit their catalytic potential. Hence, a polymer-assisted anti-solvent crystallization (PAASC) strategy was developed to fabricate potassium barium hexanitronickelate (K2Ba[Ni(NO2)6], PBHNN) crystals. In this method, emulsion particles created by mixing the solvent with the poor solvent serve as spherical templates. The particle size and monodispersity of PBHNN are controlled by PVP content. With 0.042 mol/L PVP, PBHNN were monodisperse with a particle size of 1.05±0.03 μm, which showed the best catalytic behavior for increasing the exothermic amount of hexanitrohexaazaisowurtzitane (HNIW) by 100.6 %. The high catalytic performance is due to the large specific surface area and improved contact efficiency. The in-situ TG-FTIR-MS test revealed that the procedure of PBHNN enhanced the pyrolysis of HNIW. The N-NO2 bonds of HNIW are weakened by the strong attraction of metal oxides to electrons, which accelerates the formation of NO2. Consequently, increased NO2 promotes subsequent oxidation reactions and improves the pyrolysis efficiency of individual HNIW. Therefore, the PAASC method is crucial for the fabrication of spherical monodisperse NCs with uniform particle size and high catalytic activity. [Display omitted] •Uniform-sized spherical monodisperse PBHNN crystals are prepared via PAASC.•0.042 mol/L of PVP is the optimum concentration for monodisperse crystals.•Emulsion particles serve as templates for spherical crystals.•The exothermic amount of HNIW lifts by 100.6 % when mixed with 2 wt% PBHNN.•Metal oxides weaken the N-NO2 bonds, and promote the pyrolysis of individual HNIW particles.