Aluminum Sec Research Articles

One-step synthesis of a structurally organized mesoporous CuO-CeO2-Al2O3 system for the preferential CO oxidation

Abstract A mesoporous Cu-Ce-Al-based material was prepared by a single-step synthesis, performed in n -propanol using aluminum sec -butoxide as Al precursor and metal stearates, both as Cu-Ce sources and structural directing agents. This type of synthetic approach appears to be very efficient for the preparation of highly dispersed Cu-Ce containing particles supported on a structurally ordered alumina with high surface area (>400 m 2 g −1 ) and quite narrow pore size distribution, as confirmed by X-ray powder diffraction, TPR and dispersion data and N 2 physisorption. The catalyst was also characterized by XPS and FT-IR measurements of adsorbed CO. The catalytic activity for the preferential oxidation of CO to CO 2 (PROX) in H 2 -rich streams was tested in the 75–200 °C temperature range.

New Gelation Process for Pt/Al2O3 Catalysts Preparation

Gel of platinum and aluminum was prepared by an anhydrous gelation process using a mixture of aluminum sec butoxid, platinum acetylacetonate and Butanol-2. The investigation of this gelation by FTIR, UV-vis and 27Al NMR spectroscopies suggest that a slow polymerization of aluminum precursors occurs according to an etheration mecanism likely catalysed by metallic platinum which could be formed by the reduction of platinum in Pt(acac)2 by sBuOH in the mixture during aging.

Synthesis and characterization of zinc aluminum oxide thin films by sol–gel technique

Crack free, and dense ZnAl 2 O 4 thin films have been prepared by a sol–gel method using aluminum sec -butoxide and zinc acetate. The complete single phase cubic structure of ZnAl 2 O 4 was formed on a silicon (1 0 0) substrate at an annealing temperature of 700°C for 5 h. As the annealing temperature increased from 700 to 800°C, we did not observe any kind of diffusion of Si in the formation of silicate phase at the interface of Si and ZnAl 2 O 4 phase as observed by grazing angle XRD. Structural, morphological and elemental evolution of these ZnAl 2 O 4 thin films produced by sol–gel synthesis were characterized by grazing incidence X-ray diffraction (GIXRD), tapping mode atomic force microscopy (TMAFM), and X-ray photoelectron spectroscopy (XPS), respectively.

Theory for Aerosol Generation in Laminar Flow Condensers

Generation of aerosols in laminar flow condensers is investigated theoretically. A model is developed for simultaneous heat and vapor mass transfer, aerosol nucleation, condensation, coagulation, thermophoresis, and diffusion representing the aerosol size distribution by a lognormal function throughout the process. The importance of the above physical phenomena and the effect of process parameters (reheater and boiler temperature, seed nuclei concentration) on product aerosol characteristics (average particle size and concentration, polydispersity, and yield) and condenser length are investigated. The effects of the classical Becker-Doering and the Lothe-Pound theories for homogeneous nucleation on product aerosol characteristics are examined. Nucleation and condensation are the controlling aerosol phenomena in production of aluminum sec butoxide and dibutylphthalate aerosols in laminar flow condensers. This theory is in good agreement with theoretical and experimental results in literature.

Mechanical and Thermo-Mechanical Protection by Alumina Sol-Gel Coatings

ABSTRACTAlumina coatings made by the sol-gel process using aluminum sec butox-ide can be made with variable surface area and porosity by firing on dense alumina substrates in the firing range 700 to 1000 C. These coatings are found to have large (over 100 MPa) compressive stresses and to cause a small but significant strengthening of the substrates. Within this firing range the surface area decreases while both the internal stress and strengthening effect increase with increasing firing temperature. Wear rate values are high but decrease with increasing firing temperature.

Super-Amorphous Alumina Gels

ABSTRACTThe structures of alumina gels made from aluminum sec butoxide have been studied by X-ray diffraction and scanning electron microscopy as a function of pH as well as of the temperature of peptization and gelling. The structures of these gels appear to be very sensitive to the conditions of preparation, and lead to a variety of gelled products and transformation behaviors on firing. Specific attention is directed to preferential orientation and to structures which are X-ray super-amorphous.