Porous cobaltate: Structure, active sites, thermocatalytic properties for ammonium perchlorate decomposition

Abstract

Co3O4 is an excellent catalyst for the thermal decomposition of ammonium perchlorate (AP) due to its spinel structure and more Co3+ as catalytically active sites. In this work, MCo2O4 (M=Fe, Cu, Ni and Zn) with different Co species substituted with transition metal ion were prepared using triblock copolymer F127 as soft template by simple solvothermal and subsequent heat treatment. The porous MCo2O4 samples have higher Co3+ / Co2+ ratio than Co3O4, and exhibits better catalytic performance for thermal decomposition of AP. Especially with the addition of FeCo2O4, the high decomposition temperature (HDT) of AP decreases by an amazing 196.25 °C, showing the most excellent catalytic performance. The activation energy (Ea) decreases from 290.19 kJ·mol−1 for pure AP to 203.05 kJ·mol−1, while the reaction rate (k) increases from 0.499 s−1 to 1.699 s−1. Based on the electron transfer theory, the catalytic mechanism and active site of porous MCo2O4 series cobaltate materials are discussed. The results show that the porous FeCo2O4 not only has highest specific surface, but also has the highest Co3+/ Co2+ ratio, which suggest that the Co3+ on octahedral coordination sites is known as the catalytic active site for AP thermal decomposition.