Javier Rivera De la Rosa

Low Concentration Fe-Doped Alumina Catalysts Using Sol-Gel and Impregnation Methods: The Synthesis, Characterization and Catalytic Performance during the Combustion of Trichloroethylene

The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques were used to study the level of Fe modification in the γ-Al2O3 phase formed and to correlate the catalytic properties during trichloroethylene (TCE) combustion. The introduction of Fe in situ during the sol-gel process influenced the crystallite size, and three iron species were generated, namely, magnetite, maghemite and hematite. The impregnated Fe-alumina formed hematite and maghemite, which were highly dispersed on the γ-Al2O3 surface. The X-ray photoelectron spectra (XPS), FT-IR and Mössbauer spectroscopy analyses revealed how Fe interacted with the γ-Al2O3 lattice in both catalysts. The impregnated Fe-catalyst showed the best catalytic performance compared to the catalyst that was Fe-doped in situ by the sol-gel method; both had better catalytic activity than pure alumina. This difference in activity was correlated with the accessibility of the reactants to the hematite iron species on the surface. The chlorine poisoning for all three catalysts was less than 1.8%.

Preparation and Characterization of Cu and Ni on Alumina Supports and Their Use in the Synthesis of Low-Temperature Metal-Phthalocyanine Using a Parallel-Plate Reactor

Ni- and Cu/alumina powders were prepared and characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), and N2 physisorption isotherms were also determined. The Ni/Al2O3 sample reveled agglomerated (1 μm) of nanoparticles of Ni (30–80 nm) however, NiO particles were also identified, probably for the low temperature during the H2 reduction treatment (350 °C), the Cu/Al2O3 sample presented agglomerates (1–1.5 μm) of nanoparticles (70–150 nm), but only of pure copper. Both surface morphologies were different, but resulted in mesoporous material, with a higher specificity for the Ni sample. The surfaces were used in a new proposal for producing copper and nickel phthalocyanines using a parallel-plate reactor. Phthalonitrile was used and metallic particles were deposited on alumina in ethanol solution with CH3ONa at low temperatures; ≤60 °C. The mass-transfer was evaluated in reaction testing with a recent three-resistance model. The kinetics were studied with a Langmuir-Hinshelwood model. The activation energy and Thiele modulus revealed a slow surface reaction. The nickel sample was the most active, influenced by the NiO morphology and phthalonitrile adsorption.

Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

Use of zeolites for phthalocyanine synthesis at low temperature

Non-substituted phthalocyanines have been synthesised starting from phthalonitrile in various non-aqueous solvents in the presence of two different zeolites of the clinoptilolite type is studied. The zeolites are shown to be effective matrices for phthalonitrile cyclisation at relatively low temperatures (0–40°C).

Nonsubstituted Phthalocyanine Nanostructures Obtained Using Activated Metals and Unstable Complexes at Ambient Temperature

Metal phthalocyanines were obtained at room temperature with the use of supported Cun/Al2O3 nanoparticles and active unstable complex Mg(anthracene)·3THF in a series of protic and aprotic nonaqueous solvents (yields 5-11%). The properties of copper-alumina aggregates were studied by morphological, atomic force microscopy, and X-ray diffraction studies. The phthalocyanines as shown exist in the form of nanorods and nanowires having 80-120 nm diameters, as shown by scanning electron microscopy studies.

Applications of Heterometallic Complexes in Catalysis

Abstract Direct synthesis of coordination compounds has become an active area of chemical research due to its ability to generate organometallic complexes starting from elemental metals. Some advantages of direct synthesis are its use as a facile experimental technique, shorter synthesis time, and more convenient control over the whole process. The main advantage of the direct synthesis method is one-pot preparation of the target compounds from cheap reagents with high yields in one technological stage under mild synthetic conditions. Some organometallic complexes obtained by direct synthesis have been applied in the catalysis field. For example, heterometallic coordination compounds with CuII/CoIII/FeIII and CuII/CoIII/CoII cores have been shown to act as remarkably active and selective catalysts for oxidation of cycloalkanes with hydrogen peroxide under mild conditions. Heterometallic complexes can also be used as intermediaries in catalyst synthesis by using heterometallic nano oxides, simplifying the synthesis and providing special features that promote a higher activity. The objective of this chapter is to present the application of heterometallic complexes prepared via direct synthesis, as reagents to obtain catalysts or as catalysts themselves.

Carbon tape as a convenient electrode material for electrochemical paper-based microfluidic devices (ePADs)

Electrochemical paper-based analytical devices represent an innovative and versatile platform for fluid handling and analysis. Nevertheless, the intrinsic structure of the paper can impose limitations to both the selection of the electrode material and the method selected to attach the electrodes to the device, potentially affecting the analytical performance of the device. To address these limitations, we herein propose carbon tape as a simple and low cost alternative to develop ePADs. The proposed material (in the form of tape or tabs) was first characterized using a combination of contact angle analysis, resistivity, Raman spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Upon this initial assessment, carbon tape was selected and modified with carbon nanotubes, to provide not only a better surface for proteins to adhere to, but also an enhanced electroactive surface. The analytical performance of the resulting device was assessed by integrating three enzymes that facilitate the oxidation of ethanol, glucose, and phenol, and by performing the detection of these analytes in beer samples. The resulting device, for which materials cost less than a dollar, represents a simple alternative material for ePADs, applied in this case to monitor three of the most important parameters during the production of beers.

La-, Mn- and Fe-Doped Zirconia Washcoats Deposited on Monolithic Reactors via Sol-Gel Method: Characterization and Evaluation of their Mass Transfer Phenomena and Kinetics in Trichloroethylene Combustion

Abstract La-, Mn- and Fe-doped ZrO2 was synthesized using the sol-gel method, washcoated on cordierite monoliths and used in trichloroethylene (TCE) combustion. A sol from sol-gel synthesis method was used to obtain the zirconia washcoatings. The washcoatings deposited on the cordierite monolith materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and N2 physisorption measurements, being the crystalline phase determination the most correlate with the catalytic activity. The washcoat properties were correlated to their performance in trichloroethylene combustion. The catalytic washcoatings contained a mixture of crystalline tetragonal ZrO2 and monoclinic ZrO2, and the monoclinic phase exhibited strong interactions with the α-cordierite crystalline phase. For the kinetic tests, the mass transfer into the washcoated monolith channels was evaluated using a recently developed model for the internal mass transfer coefficients for diffusion and reactions in catalytic monoliths. This model involves three resistances. In a plot of the overall resistance as function of the Thiele modulus was determinate that he reaction occurred in the kinetically controlled regime. The kinetic data were fit to two Langmuir–Hinshelwood (LH) models, and the reaction rate was fitted as a function of the trichloroethylene inlet concentration. The adsorption parameters obtained with both LH models were validated based on thermodynamic criteria for the changes in the standard enthalpy of adsorption(

Determination of the Solubility of Copper with Three Commercial Ligands and One Novel Ligand in Supercritical CO2

{\Delta}H_{ads}^0

Morphological Study of Supported Copper Particles on the Alumina Surface

ΔHads0) and standard total entropy of adsorption (