Mexican Institute of Petroleum

About: Mexican Institute of Petroleum is a government organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Catalysis & Asphaltene. The organization has 3273 authors who have published 4170 publications receiving 87269 citations.

Antibacterial activity of montmorillonites modified with silver

Abstract: The antibacterial properties of silver modified montmorillonites from Pellegrini Lake, Argentina were tested in growth inhibition of Escherichia coli bacteria. Montmorillonite was first submitted to different treatments: (a) calcination at 550 °C for 3 h and (b) grinding during 300 s. After that, the samples were loaded with silver by ion exchange. Structural characterization was performed by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and BET specific surface area measurements. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTM) showed that metallic silver nanoparticles precipitates over the clay surface after silver modification. Nevertheless, the displacement of the (0 0 1) reflection observed by XRD in the calcined sample, and the diminution in Na + content evaluated by energy dispersive X-ray spectroscopy (EDXS), indicate that Ag ions were interchanged in the structure of the clays. Both samples showed good antibacterial activity against E. coli , measured by the disk susceptibility and the minimum inhibitory concentration (MIC) tests. The ground montmorillonite required a lower MIC than the thermally treated, although the last one presented a bigger inhibition zone in the disk method. The results shows that the antibacterial activity is generated by the Ag + present in the clay, as confirmed by X-ray photoelectronic spectroscopy (XPS); however the overall antibacterial properties are affected by the availability of the ionic silver to be in contact with the bacteria.

Chemical functionalization of carbon nanotubes through an organosilane

Abstract: A novel chemical functionalization method for multiwalled carbon nanotubes (MWNTs), through an oxidation and silanization process, is presented. The method allows us to have different organo-functional groups attached to the MWNTs, which improves their chemical compatibility with specific polymers for producing new nanotube-based composites. The corresponding moieties were characterized by infrared, Raman and energy dispersion spectroscopies.

The overriding chemical principles that define asphaltenes

Abstract: Asphaltenes are defined in terms of their solubility classification. This operational definition combined with the previous controversy over asphaltene molecular weight have obscured the governing chemical and structural parameters that define the asphaltene fraction. Here, asphaltenes are investigated by several techniques to elucidate relations between structure and properties. In particular, the asphaltene molecular size is compared to the ratio of aromatic to saturated carbon. The conclusion is obtained that asphaltene molecular structure is governed by the balance between the propensity of fused aromatic ring systems to stack via π-bonding, reducing solubility, vs the steric disruption of stacking due alkane groups, increasing solubility.

Catalytic decomposition of methane over Ni-Al2O3 coprecipitated catalysts: Reaction and regeneration studies

Abstract: The catalytic decomposition of methane over nickel catalysts is a potential alternative route to steam reforming or partial oxidation for the production of hydrogen from natural gas and other feedstocks. In the present paper, we report the results of characterization and catalytic behaviour of a Ni(30%)/Al2O3 catalyst during the catalytic decomposition of methane. The influence of the operating and reduction temperatures and feed composition on the methane conversion, hydrogen production and coking rate has been studied. The effects of the regeneration cycles with oxygen on activity and carbon formation are also investigated. It has been shown that H2 inhibits both the carbon filament formation and the encapsulation of metallic particles by coke. An increase in the reaction temperature increases both the deactivation rate and the growth rate of filaments. However, at high reduction temperatures, there is a decrease in the number of filaments formed due to sintering of the Ni particles. A kinetic model has been developed for the prediction of H2 production and of carbon, taking into account both stages of carbon formation, nucleation and filament growth.