Elimination of soot particles from diesel exhaust remains one of the most pressing environmental issues. During the NOx-assisted soot catalytic oxidation process, it is proposed that the enhanced adsorption of NOx species (including NO and NO2) on the catalyst plays an important role in soot combustion. In this work, the 3DOM mullite catalysts with distinct NOx adsorption properties were designed, and the effect of NOx adsorption intensity on soot combustion behavior was investigated. It is proven that the soot combustion activity of 3DOM SmMn2O5 (SMO) catalyst was greatly improved when the adsorption of NOx on the catalyst was strengthened by the modification of K2Mn4O8 (KMO). Among all the as-prepared catalysts, the 5% KMO-SMO catalyst stands out with the best performance with the T-10, T-50, T-90 and S-CO2 of 299 degrees C, 336 degrees C, 383 degrees C and 99%, which represents one of the best catalysts for soot combustion application. Besides, our reaction mechanism analysis illustrates the importance of balancing the NOx adsorption and NO oxidation on modified SMO catalyst for NOx-assisted soot combustion reaction. (C) 2020 Elsevier Inc. All rights reserved.