碳基材料负载高分散钴元素催化高氯酸铵热分解研究OA

The number and exposure of active sites can significantly affect the catalytic performance of catalysts in heterogeneous catalysis.Atomically dispersed catalysts are a good choice for heterogeneous catalysts due to their fully exposed active sites and superior catalytic efficiency,which are expected to play a good role in the typical heterogeneous catalytic reaction of ammonium perchlorate(AP)thermal decomposition.A series of graphitic carbon nitride(CN)-supported cobalt atomic-level dispersed catalysts SACo-CN-X with different cobalt loadings were fabricated by using pyrolysis method,and the structure was analyzed by FT-IR,XPS and AC-STEM.The results show that SACo-CN-X inherits the characteristics of CN framework,and Cobalt species are highly dispersed and anchored in CN substrate mainly in the form of Co-Nx.The Cobalt mass fractions of SACo-CN-1,SACo-CN-2 and SACo-CN-3 are 1.34%,2.41%and 3.65%,respectively.The catalytic performance increases with Co introduction amount.In particular,5%SACo-CN-3 reduces the main decomposition peak of AP from 431.2℃to 292.5℃,with a decrease of 138.7℃,while the actual Co mass fraction in the reaction system is lower than 0.2%.TG-IR results show that the NOCl content decreases and NO2 maintains high proportion in the SACo-CN-3 catalytic system,indicating that Co-Nx sites promotes the cleavage of HClO4-related intermediates and the oxidative conversion of nitrogen-containing intermediates.The apparent activation energy calculated by the Ozawa method is about 42～67 kJ·mol-1.These results indicate that highly dispersed Co-Nx sites anchored by the CN framework can effectively lower the energy barrier of AP decomposition at low Cobalt dosage,providing a catalyst design strategy for regulating AP thermal decomposition.