Modificación superficial de nanotubos de carbono mediante un plasma de CO2

En el presente trabajo se estudió la funcionalización de nanotubos de carbono de pared múltiple (NTCPM) con un plasma de CO2, donde se determinó el efecto del tiempo de tratamiento por plasma sobre las propiedades de los NTCPM. Para determinar el cambio en la hibridación de los NTCPM se utilizó espectroscopia Raman y espectroscopia de infrarrojo para identificar los grupos funcionales. Adicionalmente se determinó el ángulo de contacto y se hicieron dispersiones en agua para corroborar el cambio de polaridad de los NTCPM. Se encontró que a medida que se incrementa el tiempo de exposición al plasma de CO2, se observan dos incrementos, uno en la banda de infrarrojo de 1070 cm-1 asociada al grupo C-O y otro en la relación de intensidades D/G del espectro Raman asociado a la hibridación sp3, los cuales corroboran el injerto de oxígeno en la superficie de los NTCPM

The Silicon on the Catalysis: Hydrodesulfurization of Petroleum Fractions

The use of silicon in hydrodesulfurization (HDS) catalysts has had an impact on some of the fundamental parameters for the performance of the HDS catalyst, such as dispersion of the active phase, the extent of sulfidation, or the level of promotion. Mesoporous silicates such as MCM-41, SBA-15, the modified surface of γ-alumina with silica, or mixed Al2O3-SiO2 support have showed to affect the metal-support interaction, favoring the so-called type II Co(Ni)–Mo(W)–S structures. The aim of this chapter is to elaborate an analysis on the recent advances in the synthesis design of silicon catalyst support for the hydrodesulfurization of petroleum fractions

Problemas y soluciones en el diseño de reactores enzimáticos

Enzymatic reactors are a class of reactors that use an enzyme as catalyst during the reaction process. They have received attention because they are environmentally friendly and they have applications in chemical, food, pharmaceutical, biotechnological and other industries. The present review analyzes the most common problems related to the design of those, as well as the solutions to overcome them and the operation type.Los reactores enzimáticos utilizan como catalizador una enzima durante el proceso de reacción. Han recibido atención tanto en el ámbito de investigación como industrial ya que son amigables con el medio ambiente y tienen aplicaciones tanto en la industria química como alimentaria, farmacéutica, biotecnológica, entre otras. En la presente revisión se analizan los problemas más comunes en el diseño de reactores enzimáticos, así como las soluciones reportadas y el tipo de operación

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications

Film forming, stable hybrid latexes made of methyl metacrylate (MMA), butyl acrylate (BA) and 2-hydroxyethyl methacrylate (HEMA) copolymer reinforced with modified multiwalled carbon nanotubes (MWCNTs) were synthesized by in situ miniemulsion polymerization. The MWCNTs were pretreated by an air sonication process and stabilized by polyvinylpyrrolidone. The presence of the MWCNTs had no significant effect on the polymerization kinetics, but strongly affected the polymer characteristics (Tg and insoluble polymer fraction). The performance of the in situ composites was compared with that of the neat polymer dispersion as well as with those of the polymer/MWCNT physical blends. The in situ composites showed the presence of an additional phase likely due to the strong interaction between the polymer and MWNCTs (including grafting) that reduced the mobility of the polymer chains. As a result, a substantial increase of both the storage and the loss moduli was achieved. At 60 °C, which is above the main transition region of the polymer, the in situ composites maintained the reinforcement, whereas the blends behaved as a liquid-like material. This suggests the formation of a 3D network, in good agreement with the high content of insoluble polymer in the in situ composites