Insights of MOF-derived bimetallic PVP/Ce-Ru nanocomposites for diesel soot oxidation

Novel MOF derived Ce-Ru mixed metal oxides were synthesized with addition of different amounts of PVP substance and investigated its catalytic effect towards the oxidation of diesel soot particles. These nano materials were characterized by XRD, BET Surface area, FESEM/EDS, HRTEM, Raman, UV–vis-DRS, XPS, H2-TPR and soot-TPR analysis. The structural characterization of CeO2@MOF reveals the formation of cubic crystalline phase; however, structural distortions were observed after attempting to incorporate Ru4+ cation into the crystal lattice. Besides, the samples' structural and surface characteristics were strongly influenced by the addition of PVP polymeric substance. FESEM images reveal the formation of nano-bar shaped particles with cracks and fissures on the surface of the as-synthesized samples. Indeed, the average particle diameters obtained from HRTEM analysis were in the range of 5 to 9 nm, signifying there was a reduction of particle sizes after addition of PVP substance. The spectra of Raman analysis evidenced the formation of oxygen vacancies for RuO2/PVP added samples, leading to a generation of active oxygen species (O2x-) that can be utilized during the oxidation reactions. The presence of Ce3+/Ce4+, Ru4+/Ru0 cations on the surface of oxides were noticed using XPS and H2-TPR analysis. In addition, O1s analysis attributes the higher mobility of surface chemisorbed oxygen species from the surface of the catalyst. Thus, Ce-Ru@MOF sample exhibited higher soot oxidation activity among the prepared samples with T50% and T90% were recorded as 336 °C and 387 °C respectively.