Preparation And Catalytic Properties Of Bimetallic Oxide Composites

As a kind of material that can release huge energy and gas quickly,energetic material is the basic energy for projectile launching,carrier missile rocket,warhead damage and drive control of all kinds of weapon systems,and is an important part of the formula of military explosives,propellant and rocket propellant.As an energetic ionic compound,TKX-50 has shown great development potential and application prospect in the field of energetic materials.With the improvement of weapon and equipment performance,the pursuit of higher energy targets and better combustion performance has become a permanent goal in the field of propellant.The method of adding catalysts is one of the most promising approaches at present.Among them,composite bimetallic oxides and carbon nanotubes can play a better catalytic role.In this paper,Eight kinds of cobaltate-type bimetallic oxide MCo₂O₄（M=Fe,Cu,Ni）and carbon-based supported composite combustion catalyst MCo₂O₄/MWCNTs（M=Fe,Cu,Ni,Zn,Mn）were prepared by hydrothermal method.The morphology and structure of the catalyst were characterized and tested by means of SEM,XRD,XPS,BET and Raman.And the successful preparation of the catalyst was demonstrated.TG-DSC was used to study the thermal decomposition characteristics of TKX-50 by adding different amounts of MCo₂O₄（M=Fe,Cu,Ni）and MCo₂O₄/MWCNTs（M=Fe,Cu,Ni,Zn,Mn）at different heating rates.（1）When the MCo₂O₄/MWCNTs（M=Fe,Cu,Ni）incorporation amount was 10 wt%,the catalytic effect was the best,and the initial decomposition temperature and low temperature decomposition temperature of TKX-50 could be advanced by 33.8℃,18.8℃,11.6℃and 34.6℃,17.0℃,9.1℃respectively.After adding bimetallic oxide,the catalyst accelerates the decomposition weight loss of TKX-50.Fe Co₂O₄showed the best catalytic activity,Cu Co₂O₄followed by Ni Co₂O₄.（2）Similarly,it was found that the compound bimetallic catalyst MCo₂O₄/MWCNTs（M=Fe,Cu,Ni,Zn,Mn）had the best catalytic effect when the dosage was 10 wt%,and Fe Co₂O₄/MWCNTs could advance the initial decomposition temperature and low temperature decomposition peak temperature of energetic material TKX-50 by 42.0℃and 42.8℃at the highest.The catalytic effects was the Fe Co₂O₄/MWCNTs>Cu Co₂O₄/MWCNTs>Ni Co₂O₄/MWCNTs>Zn Co₂O₄/MWCNTs≈Mn Co₂O₄/MWCNTs.When carbon nanotubes were loaded with bimetallic oxide,the catalytic performance of MCo₂O₄/MWCNTs was significantly improved compared with the simple bimetallic oxide MCo₂O₄,forming a"metal-metal-carbon"co-catalytic effect,and the"metal-metal"co-catalytic effect played a major role.Carbon nanotubes（CNTs）play an auxiliary catalytic role in carbon-based supported composite combustion catalysts.（3）To further confirm the catalytic effect of the catalyst,the Kissinger,Ozawa and Starink methods were used to study the influence of catalysts on the kinetic parameters of the non-isothermal decomposition of TKX-50.The thermal decomposition activation parametersΔS^≠,ΔH^≠andΔG^≠were calculated.The apparent activation energy of TKX-50 after adding catalyst is significantly lower than that of pure TKX-50,which promotes the thermal decomposition reaction.The activation enthalpiesΔS^≠,ΔH^≠andΔG^≠are mostly positive values after the addition of catalysts,and they are thermodynamically stable in some cases.The kinetic parameters of thermal decomposition and activation characteristics of thermal decomposition showed that MCo₂O₄（M=Fe,Cu,Ni）and MCo₂O₄/MWCNTs（M=Fe,Cu,Ni,Zn,Mn）had good catalytic effects.On this basis,the thermal decomposition mechanism and catalytic mechanism of TKX-50 were analyzed and studied.It has important research significance in the application of solid propellant.