Study on Adsorption and Decomposition Kinetics of Hydrazine Nitrate on Different Transition Metal Surfaces

In the field of space propulsion, compared with the traditional hydrazine propellant, hydrazine nitrate-based propellant has attracted wide attention from scholars all over the world because of its green and nontoxic advantages and is often used as an additive of hydroxylamine nitrate-based propellant. In this paper, the adsorption and decomposition mechanisms of hydrazine nitrate (HN) on the surfaces of different face-centered cubic metals (Cu, Rh, Pd, Ir, Pt) are studied by using the density functional theory (DFT) calculation method under generalized gradient approximation, and the catalytic combustion reaction kinetics of this system is studied. By calculating the structural parameters of hydrazine nitrate in the stable state, the adsorption stability and reaction energy barrier of hydrazine nitrate on different transition metal surfaces are compared, and the kinetic model of the catalytic combustion reaction is established. The results show that hydrazine nitrate has the strongest adsorption capacity for Ir and the worst adsorption capacity for Cu on the surface of the active metals. The adsorption and decomposition trend of hydrazine nitrate on the transition metal surface was verified from the point of charge transfer, and the relationship between the rate constant and temperature of the two main reactions was calculated according to the Arrhenius formula. It was found that the reactivity of Rh was generally greater than that of Ir at lower temperatures, and the reactivity of hydrazine nitrate on Ir metal was greater than that of Rh metal at higher temperatures. The rate constant curves of hydrazine nitrate in Pd metal and Pt metal are almost the same, and the reaction rate is approximately the same. It can be concluded that Pd and Pt have similar reactivities, and the worst is Cu metal. A comprehensive comparison shows that the reactivity of hydrazine nitrate on five transition metal surfaces is Ir > Rh > Pt ⩾ Pd > Cu.