Preparation of silica supported ceria–lanthana solid solutions useful for synthesis of 4-methylpent-1-ene and dehydroacetic acid

Abstract

The intriguing research toward the exploitation of ceria-based materials for various applications has been growing significantly. In the present investigation, we describe the preparation, characterization and utilization of CeO 2 -La 2 O 3 (CL) and CeO 2 -La 2 O 3 /SiO 2 (CLS) solid solutions for the synthesis of two industrially useful chemicals namely 4-methylpent-1-ene and dehydroacetic acid. Coprecipitation and deposition coprecipitation from ultrahigh dilute solutions were used for the synthesis of CL and CLS catalysts, respectively. The physicochemical characterization has been achieved with the help of various techniques namely X-ray diffraction (XRD), BET surface area, transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), Raman spectroscopy (UV-RS and Vis-RS), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) measurements. The structure-activity relationships helped to correlate different parameters that are necessary for obtaining desired products in good yields. The inclusion of silica support has an optimistic influence on the acid-base properties of the ceria-lanthana, in terms of both amount and strength of sites. The presence of silica not only manipulates the acid-base properties but also causes numerous benefits, for instance, it improves the dispersion, stabilizes the active component against sintering and enriches the oxygen vacancy concentration. The meticulous analysis of characterization and activity studies revealed the significant role of acid-base sites in directing the desired products. Interestingly, the CLS catalyst has shown better performance in the production of both 4-methylpent-1-ene and dehydroacetic acid compared to the unsupported CL sample due to well-balanced acid-base sites.

Development of cerium promoted copper–magnesium catalysts for biomass valorization: Selective hydrogenolysis of bioglycerol

“…2. All the samples exhibited a major Raman peak at ~ 450 cm ˗1 , which indicates the triply degenerate F 2g mode of oxygen anions around the cerium cations [39,40]. This result reveals the formation of cubic structured CeO 2 in the synthesized samples, in line with the XRD results ( Fig.…”

“…A close observation of the XPS spectra reveals that the u /// peak area of Cu/Ce3/Mg sample is quite lower compared to other samples. This observation indicates that the Cu/Ce3/Mg sample contains more number of Ce 3+ ions [39][40][41]. The formation of oxygen vacancies in the synthesized samples is the key reason for the reduction of Ce 4+ ions to Ce 3+ [48,49].…”

“…2, the F 2g band is shifted to lower wavenumbers for all the Cu/Mg based catalysts compared with the pure ceria. The variation in the F 2g position could be attributed to several factors, including phonon confinement, defects, strain, and variations in the particle size [39][40][41]. In addition, the Ce-promoted Cu/Mg samples showed a weak peak at 585 cm ˗1 , which indicates the presence of oxygen vacancy defects (O v ) in the ceria lattice.…”

Enhancement in CO oxidation activity of nanosized CexZr1−xO2 solid solutions by incorporation of additional dopants

“…This broad feature can be deconvoluted into two peaks with a lower peak at around $590 cm À1 . The deconvoluted peaks can be easily observed with a higher excitation source of 632.81 and 785 nm [45,46]. In the present study, an excitation laser source of only 325 nm has been used hence an extended broad peak is observed.…”

“…The peak at 590 cm À1 could be assigned to the oxygen vacancies introduced into the ceria due to charge neutralization when Ce 4+ ions are replaced with trivalent cations. Besides, the 630 cm À1 band is ascribed to the intrinsic oxygen vacancies because of the presence of Ce 3+ in the solid solutions [45,46]. The weak bands observed at $320 and $180 cm À1 have been assigned to the displacement of the oxygen atoms from their ideal fluorite lattice positions and the presence of oxygen vacancies, respectively [47].…”