Loofa sponage derived multi-tubular CuO/CeO2-ZrO2 with hierarchical porous structure for effective soot catalytic oxidation. (15th December 2019) - Zhang, Guanglei
Graphical abstract: Highlights: Loofa sponage derived multi-tubular CuO/CeO2 -ZrO2 catalyst for soot oxidation is proposed. Multi-channels and many fractured sheets are favorable to enlarged soot/catalyst contact degree. Enhanced catalytic performance (T50 = 396–411 °C) and good reusability are achieved. Abstract: In this work, a series of multi-tubular CuO/CeO2 -ZrO2 catalysts (denoted as xHc@CZs) with hierarchical porous structure were obtained by using loofah sponage as biotemplate. The morphology and surface chemical environments were analyzed by SEM, TG-DSC, N2 -adsorption-desorption, XRD, H2 -TPR, and XPS measurements. The removal of biotemplate can lead to brittle multi-channels and many fractured sheets that were favorable to the enlarged soot/catalyst contact degree and enhanced catalytic performance ( T 50 = 396–411 °C). With increased copper ions entered the cubic lattice of ceria-zirconia, the separation of Ce-rich (Ce0.75 Zr0.25 O2 ) and Zr-rich (Ce0.16 Zr0.84 O2 ) tetragonal phases was accelerated, which was negative for the catalytic performance. The redox equilibrium Cu 2+ + Ce 3+ ↔ Cu + + Ce 4+ existed on the surface and lattice of the catalysts, which lead to the highest surface oxygen species (Osurf, 44.0%) for 1Hc@CZs. The higher degree of phase separation, as well as cracked multi-tubular structure could be the main reasons for the relative low catalytic activities with higher contents of copper ions. The sample 1Hc@CZs represented good reusability ( T 50 maintained at 435 °C under five recycles), which displayed excellent prospects in the practical applications.