Influence of V2O5 and AlF3 on Microstructure of Acicular Mullite Diesel Particulate Filter Along with Soot Oxidation Kinetics

In current research, aluminium oxide and silicon dioxide are used as raw materials for fabricating main structures of mullite diesel particulate filters. The variable substances applied to develop acicular mullite structure are titanium dioxide, aluminium fluoride, and vanadium oxide. Carbon black was used to create pores in mullite diesel particulate filters with 35 to 45% porosity based on the sintering temperature of 1300°C. The images of the filter’s porous surface microstructure were investigated using scanning electron microscopy. Vanadium oxide and aluminium fluoride play important roles in growth of acicular shape and acicular size for membrane, respectively. Acicular size of membrane varies from a hundred nano-meters to the submicron in needle diameter. The relation of all factors between pore size, porosity, surface roughness, and pin-shape microstructure can be controlled by additional amounts of additives. From Raman spectroscopy analysis, the soot formation of carbon black’s micro and nanostructure are acceptable to simulate diesel soot particles. In line with these results, carbon black was successfully used as a substitute of real engine soot in soot kinetics reactivity. In addition, the oxidation kinetics of soot particles on mullite and acicular mullite membrane were investigated by using tight contact in isothermal and loose contact in non-isothermal thermo-gravimetric analysis. The calculated apparent activation energies of soot oxidation with isothermal technique on mullite and acicular mullite membrane are approximately 213 and 141 kJ/mol while those values calculated with non-isothermal technique are 118 and 76 kJ/mol, respectively.