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CoFe2O4 prepared by sol-gel has been examined with respect to its catalytic performance for preferential CO oxidation in a H2-rich stream. In turn, the promoting effects of incorporation of Ce, Co, Cu, and Zr by impregnation on the surface of CoFe2O4 on the process are examined as well. The catalysts have been characterized by N2 adsorption, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), temperature programmed reduction (TPR), and X-ray photoelectron spectra (XPS), as well as diffuse reflectance infrared DRIFTS under reaction conditions with the aim of establishing structure/activity relationships for the mentioned catalyst/process. It is shown that while the presence of the various metals on CoFe2O4 hinders a low temperature CO oxidation process, it appreciably enhances the activity above 125 °C. This is basically attributed to the surface modifications, i.e. cobalt oxidation, induced in CoFe2O4 upon introduction of the metals. In turn, no methanation activity is observed in any case except for the copper-containing catalyst, in which achievement of reduced states of cobalt appears most favored.

Magnesium aluminate nanoparticles have been synthesized by a citrate sol-gel route. X-ray diffraction and IR spectroscopy study confirmed the formation of MgAl2O4 cubic spinel structure without presence of any secondary phase. Crystallite size of the synthesized nanoparticles was found to be equal to 24 nm. The ac conductivity of MgAl2O4 was studied using complex impedance spectroscopy technique in the frequency range from 5 Hz to 13 MHz and temperature range from 673 to 798 K. The temperature and frequency dependence of ac conductivity were highlighted and the activation energies of, respectively, ac conduction and relaxation processes were also calculated.

The effect of process and composition parameters of inorganic aluminosilicate gels on the particle size of zeolite LTA were studied. The samples were characterized using Xray diffraction, scanning electron microscopy, and transmission electron microscopy. The crystallization domain of zeolite LTA around synthesis gel with composition 1.8 SiO 2 :1 Al 2 O 3 :12 Na 2 O:214 H 2 O was found to be narrow, with slight changes in composition leading to the crystallization of other zeolite phases, without a significant decrease in LTA particle size. Slightly increasing the Si/Al ratio of the synthesis gel results in the crystallization of a second population of nanosized crystals (down to 50 nm), which were revealed to be mostly FAU/EMT crystals from transmission electron microscopy imaging. FAU/EMT was found to exist as separate crystals or intergrown with LTA in the same particle, providing the first evidence of FAU/EMT and LTA intergrowth at this scale. Based on structural study using high resolution transmission electron microscopy imaging and comparison to simulations, we propose that the connection at the interface between LTA and Faujasite could be either by inversion or mirror symmetries across double six-membered rings, and both cases have been observed.