Selectively creating oxygen vacancies on PrCe/SiO2 catalysts for the transformation of a furfural–acetone adduct into a functionalized 1,3-diene†
The production of valuable chemicals from renewable resources has attracted wide interest, and the present work focuses on the transformation of a furfural–acetone adduct into a functionalized 1,3-diene which can purposefully improve the interfacial properties of resulting polymer materials. Pr modified CeO2 catalysts supported on silica were prepared, and the correlation between catalyst nature and catalytic performance (conversion, selectivity and formation rate) was extensively investigated. A yield of 94% was obtained over the optimized catalyst (PrCe2.11/SiO2), and the yield still remained at >89% after 10 h on stream. Low-temperature adsorption of nitrogen, inductively coupled plasma (ICP), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to clarify the catalyst structure. The results indicated that Ce and Pr species exist as CeO2 and Pr6O11, respectively, without the formation of a PrCe solid solution. The migration of Pr leads to its enrichment on the catalyst surface, and the interaction between Pr and Ce plays a crucial role in the uniform dispersion of nanoparticles. More importantly, this suggested that the modification of ceria with Pr can selectively create oxygen vacancies instead of lattice distortions. The correlation between the catalytic performance and catalyst nature implies that the improvement in catalytic performance is linearly correlated with the oxygen vacancy concentration. Besides, a plausible reaction pathway for the transformation of a furfural–acetone adduct over PrCe/SiO2 was proposed involving a radical mechanism.