In situ pyrolysis of Ce-MOF to prepare CeO2 catalyst with obviously improved catalytic performance for toluene combustion.

Mesoporous CeO 2 catalysts (CeO 2 -MOF) were synthesized by pyrolysis of Ce-MOF precursor (Ce-(1,3,5-benzenetricarboxylic acid) (H 2 O) 6 ). Physicochemical properties of the samples were investigated by means of various techniques including XRD, SEM, TEM, BET, Raman, XPS, H 2 -TPR, O 2 -TPD and NH 3 -TPD, and their catalytic performance were evaluated by toluene combustion compared with commercial CeO 2 (CeO 2 -C) and CeO 2 prepared by precipitation method (CeO 2 -P). The results show that CeO 2 -MOF/350 catalyst (pyrolyzed at 350 °C) presents enhanced catalytic activity for toluene oxidation with the conversion of T 10% , T 50% and T 90% at 180, 211, and 223 °C, respectively (SV = 20,000 mL/(g h), toluene concentration = 1000 ppm). Especially for high-temperature region, CeO 2 -MOF/350 catalyst displays much superior ability to rapidly reach to 100% conversion compared to CeO 2 -C and CeO 2 -P catalysts which usually result in a much broader temperature region to achieve complete conversion of toluene. The high catalytic performance of CeO 2 -MOF/350 can be reasonably ascribed to a series of better properties, such as three-dimensional penetrating mesoporous channels, larger specific surface area, smaller average grain size, higher relative percentages of Ce 3+ /Ce 4+ and O Sur /O Latt , higher oxygen storage capacity, higher oxygen vacancy concentration, better low temperature reducibility, more active oxygen species and more acid sites. Furthermore, CeO 2 -MOF/350 catalyst presented excellent resistance to H 2 O deactivation and temperature change, and in situ DRIFTs study on CeO 2 -MOF/350 catalyst suggests that toluene degradation is proceeded in consecutive steps via rapid transformation to aldehydic and benzoate species to finally form CO 2 and H 2 O. [ABSTRACT FROM AUTHOR]