Synthesis of high performance diesel oxidation catalyst using novel mesoporous AlLaZrTiOx mixed oxides by a modified sol-gel method

Abstract

High performance diesel oxidation catalyst (DOC) is achieved using novel Al2O3-LaAlO3-ZrO2-TiO2 (AlLaZrTiOx) mixed oxides and has been successfully fabricated by a modified sol-gel method. It is worth noting that novel AlLaZrTiOx mixed oxides own outstanding properties, such as mesoporous structure, high specific surface area, and thermal stability, which are confirmed by N2 adsorption-desorption, TEM, small-angle x-ray diffraction, and XRD spectrum. For these mixed oxides, temperature has a significant effect on their properties, for example, high specific surface area (206.5 m2/g) with a pore volume of 0.5 cc/g can be obtained by calcining at 700 °C for 4 h. Meanwhile, the possible synthesis mechanism of mesoporous AlLaZrTiOx mixed oxides was also discussed. Finally, the catalytic performances of Pt-Pd/AlLaZrTiOx catalyst and commercial catalyst were compared under the same simulated clean diesel combustion. Pt-Pd/AlLaZrTiOx catalyst demonstrated an excellent low temperature oxidation catalytic activity with the conversion of CO and total hydrocarbon (C3H6) reaching 90% at 196 °C and 200 °C, respectively. Specially, the conversion of NO reached 75% when the temperature was at around 200 °C.