Wenxing Kuang

Catalytic properties of ultrafine molybdenum-cerium oxide particles prepared by the sol-gel method

The structure and catalytic properties of ultrafine Mo-Ce oxide particles prepared by the sol-gel method have been studied by using X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, laser Raman spectroscopy and microreactor tests. It has been shown that for selective oxidation of toluene to benzaldehyde the ultrafine Mo-Ce oxide particles exhibit higher catalytic activity than the larger oxide particles prepared by a conventional coprecipitation method. The unique catalytic properties of ultrafine Mo-Ce oxide particles may be correlated not only to the interaction between molybdenum oxide and cerium oxide, but also to the higher reactivity of lattice oxygen species in the ultrafine oxide matrix.

Ultrafine La-Mo and Ce-Mo complex oxide particle catalysts for selective oxidation of toluene

It has been found that by decreasing the particle size of La–Mo and Ce–Mo complex oxides to nanoscale, the reactivity of lattice oxygen ions and thus the selectivity for oxidation of toluene to benzaldehyde can be remarkably improved.

Structure and reactivity of ultrafine Ce-Mo oxide particles

Abstract Two series of the Ce–Mo oxide catalysts for the partial oxidation of toluene to benzaldehyde have been prepared, respectively, by the sol–gel and coprecipitation methods and characterized by using various techniques. The results have shown that the catalytic reactivity is strongly composition related; and ultrafine Ce–Mo oxide particles prepared by the sol–gel process are apparently a better catalyst than large Ce–Mo oxide particles with a same composition but prepared by the coprecipitation method. The highest yield of benzaldehyde is obtained when the composition of the ultrafine particles reaches the vicinity of Ce/(Ce+Mo)=0.50, corresponding to a catalyst consists of both CeO2 and Ce2(MoO4)3. The reaction mechanism and the promotion effect of the excess CeO2 in the ultrafine Ce–Mo oxide are discussed to explain why ultrafine Ce–Mo oxide particles prepared by the sol–gel method are good for the partial oxidation of toluene.

Study on the reactivity of ultrafine cerium–molybdenum oxide particles in the absence of molecular oxygen

The state and reactivity of lattice oxygen ions in the ultrafine Ce–Mo oxide particles prepared by the sol–gel method are studied by using X‐ray diffraction, laser Raman spectroscopy, temperature‐programmed reduction, X‐ray photoelectron spectroscopy and pulse microreactor tests. It is found that the lattice oxygen ions in the ultrafine Ce–Mo oxides are the main active species for partial oxidation of toluene to benzaldehyde. By decreasing the size of complex Ce–Mo oxide particles to nanometric scale, the reactivity of lattice oxygen ions can be remarkably improved.

Promotional effect of oxygen spillove in the ultrafine Mo-Ce oxide particle catalysts for selective oxidation of toluene

Publisher Summary This chapter describes the structure and catalytic properties of ultrafine Mo-Ce oxide particle catalysts for selective oxidation of toluene to benzaldehyde by using TEM, XRD, TPR, FTIR, XPS, and micro-reactor tests. It has been found that the ultrafine Mo-Ce composite oxide particles exhibit higher catalytic selectivity than the large particles. The unique catalytic properties of ultrafine Mo-Ce complex oxide particles are correlated not only to the higher mobility of lattice oxygen ions in the ultrafine Mo-Ce oxide particles but also to the promotional effect of oxygen spillover from Ce ions to Mo ions in the composite oxide catalysts.

Selective Oxidation of Toluene over Complex Fe–Mo Oxides in the Absence of Molecular Oxygen

Fe–Mo catalysts prepared by a sol–gel method for selective oxidation of toluene are studied in the absence of molecular oxygen; a high benzaldehyde yield and high specific activity are achieved at an atomic ratio (Mo∶Fe) of about 1.0.

The Role of Terminal MoO Bonds in Selective Oxidation of Toluene over a Complex Ce–Mo Oxide in the Absence of Molecular Oxygen

The role of terminal MoO bonds in selective oxidation of toluene over a complex Ce–Mo oxide is studied by using a pulse microreactor in the absence of molecular oxygen together with in situ Raman spectroscopy, and it is found that the terminal MoO bonds are mainly responsible for the formation of benzaldehyde.

Selective Oxidation of Toluene Catalysed by Ultrafine Fe–Mo Oxide Particles

It has been found that by decreasing the size of both Fe2O3 and Fe2(MoO4)3 particles in complex Fe–Mo oxide to nanometric order, the catalytic activity of the mixed oxide in toluene oxidation is remarkably improved.