Cu Substitution at Co Td  In Spinel Oxide Cuco 2 O 4  Improving Nh 3  Absorption Capacity and Accelerating Ammonium Perchlorate Thermolysis

Abstract

As one of main components of solid propellant, ammonium perchlorate (AP) shows slow sluggish decomposition kinetics with unconcentrated heat release. In the past, researchers have done a lot of work using spinel oxides as combustion modifiers to improve the combustion performance of AP. However, AP decomposition process is very complicated, and the relationship between intrinsic activity of cobalt-based spinel catalysts and AP combustion process is still unclear. In this paper, a series of cobalt-based spinel structure catalysts, MCo2O4/C, were prepared by pyrolysis of cobalt-containing bimetal MOF-74 and used as AP combustion catalysts. All of them showed excellent catalytic performance, among which CuCo2O4/C had the best catalytic activity. It effectively reduces the activation energy of the reaction, speeds up the reaction rate, and reduces the peak temperature of the AP decomposition reaction by 161.2 ℃, and the reaction rate k is 10.28 times of Co3O4/C. XPS and NH3-TPD tests indicate that substitution CoTd2+ with Cu2+ increases the ratio of Co3+/Co2+ and enhance NH3 adsorption capacity. The essential reason is that Cu-O-Co corner sharing effect changes electron distribution and enhances CoOh3+ Lewis acidity accompanied with the proximity of d-band center to EF by density functional theory calculations.

Keywords: Cobalt-based spinel structure, AP combustion catalysts, d-band center, Cu-O-Co interaction