Relevant changes in the properties of Co(Ni)Mo/Al2O3 HDS catalysts modified by small amounts of SiO2

The changes in hydrodesulfurization activity, selectivity, dispersion, sulfidation, and extent of promotion of Co(Ni)Mo catalysts were investigated when the alumina support surface is modified by grafting 4 wt% silica. Adding SiO2 eliminates the most reactive hydroxyl groups on the alumina surface (IR band at 3775 cm 1) decreasing the possibility of generating tetrahedral Mo species difficult to sulfide in favor of octahedral ones capable of contributing to the sulfided active phase. The catalysts were evaluated in the hydrodesulfurization of 4,6-dimethyldibenzothiophene. Incorporating SiO2 to alumina increases the hydrogenation rate constant and therefore the global hydrodesulfurization rate of 4,6-dimethyldibenzothiophene and enhances the promotion of Mo by Co (or Ni). The global sulfidation of Ni is not affected by the addition of silica but the sulfidation of cobalt is significantly improved. The extent of promotion of the NiMo/Al2O3 and NiMo/SiO2/ Al2O3 catalysts was greater than the one achieved in their Co-promoted counterpartsCB-168827, beca posdoctoral otorgada por CONACyT al Dr. Adolfo Romero Galarza from DGAPA-UNAM, project PAPIIT-IN-113015. We thank Mariela Bravo-Sanchez (Universidad de Guadalajara) for her discussion about the XPS results, Ivan Puente for the TEM work, and Alberto Herrera-Gómez (CINVESTAV-Unidad Querétaro, Mexico) for providing computer program AANALYZER version 1.2

Quantification of the sulfidation extent of Mo in CoMo HDS catalyst through XPS

Background removal in X-ray photoelectron spectroscopy (XPS) spectra was carried out in Co–Mo hydrodesulfurization (HDS) catalysts supported alumina using traditional and recent methods. The sulfidation extent, expressed by the XPS area ratio AMo3d-MoS2/AMo3d-Total, which is a fundamental parameter in the performance of a hydrodesulfurization catalyst, was obtained using different methodologies. The methods include the use of the background active approach, in which the background is optimized during peak-fitting. The method allows for the use of several types of backgrounds, which proved crucial for fitting the Mo 3d-S 2s and the S 2p–Si 2p regions. Both regions contain two overlapped elements, making fundamental a distinction between them. In these cases, a slope background subtraction was used in conjunction with the Shirley-Vegh-Salvi-Castle (SVSC) method to have a clear distinction between the different strengths of backgrounds arising from the overlapped peaks Mo 3d-S 2s and S 2p–Si 2p. From the resulting fitting, the relative percentage (% rel.) of each species present in Mo and S in the catalyst CoMoAl was obtained. The results were compared with those obtained using the static (traditional) approach. With these results, the sulfidation extent, an important parameter in the performance of the HDS catalyst was determined.Adolfo-Romero Galarza thanks Consejo Nacional de Ciencia y Tecnologia (CONACyT), Mexico for their postdoctoral fellowship (ID. 1908/2010C ) . We acknowledge financial support from Direccion General de Asuntos del Personal Academico ( DGAPA) Mexico, UNAM , project PAPIIT-IN-113015 . The authors appreciate the support provided by Gustavo Gomez-Sosa (CINVESTAV-Qro.) for the acquisition of the XPS data and Alberto Herrera-Gómez (CINVESTAV-Unidad Queretaro, Mexico) for engaging in useful discussion regarding the spectra fitting and for providing computer program AANALYZER version 1.2

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

Secuencia didáctica aplicada al proyecto terminal de la unidad de aprendizaje: tratamiento del agua

El propósito de este proyecto es promover la participación de alumnos, directivos, docentes, así como cualquier miembro de la comunidad local, en el cuidado del agua, sensibilizando a toda esta comunidad, mediante campañas de difusión y distribución de folletos, sobre el uso y cuidado responsable del agua, se pretende lograr a través de la aplicación de una secuencia didáctica enfocada a un proyecto final, haciendo uso de material didáctico, trabajo teórico y experimental hecho por los estudiantes y la ciencia como herramienta en el desarrollo de algunas habilidades y lograr el aprendizaje de los alumnos. Se pretende hacer el trabajo por equipo en el que harán diversas propuestas para solucionar algunos problemas que se relacionan con el desperdicio del agua, la contaminación del agua y la falta de conciencia de la sociedad.The purpose of this project is to promote the participation of students, directors, teachers, as well as any member of the local community, in caring for water, raising awareness in the entire community, through dissemination campaigns and distribution of brochures, on the use and Responsible care of water, is intended to be achieved through the application of a didactic sequence focused on a final project, making use of didactic material, theoretical and experimental work done by students and science as a tool in the development of some skills and achieve student learning. It is intended to work as a team in which they will make various proposals to solve some problems related to water waste, water pollution and lack of awareness in society

Relevant changes in the properties of Co(Ni)Mo/Al2O3 HDS catalysts modified by small amounts of SiO2

The changes in hydrodesulfurization activity, selectivity, dispersion, sulfidation, and extent of promotion of Co(Ni)Mo catalysts were investigated when the alumina support surface is modified by grafting 4 wt% silica. Adding SiO2 eliminates the most reactive hydroxyl groups on the alumina surface (IR band at 3775 cm 1) decreasing the possibility of generating tetrahedral Mo species difficult to sulfide in favor of octahedral ones capable of contributing to the sulfided active phase. The catalysts were evaluated in the hydrodesulfurization of 4,6-dimethyldibenzothiophene. Incorporating SiO2 to alumina increases the hydrogenation rate constant and therefore the global hydrodesulfurization rate of 4,6-dimethyldibenzothiophene and enhances the promotion of Mo by Co (or Ni). The global sulfidation of Ni is not affected by the addition of silica but the sulfidation of cobalt is significantly improved. The extent of promotion of the NiMo/Al2O3 and NiMo/SiO2/ Al2O3 catalysts was greater than the one achieved in their Co-promoted counterpartsCB-168827, beca posdoctoral otorgada por CONACyT al Dr. Adolfo Romero Galarza from DGAPA-UNAM, project PAPIIT-IN-113015. We thank Mariela Bravo-Sanchez (Universidad de Guadalajara) for her discussion about the XPS results, Ivan Puente for the TEM work, and Alberto Herrera-Gómez (CINVESTAV-Unidad Querétaro, Mexico) for providing computer program AANALYZER version 1.2

Quadratic Non-Linear Optical Properties of the poly(2,5-bis(but-2-ynyloxy) Benzoate Containing the 2-(ethyl(4-((4-nitrophenyl)buta-1,3-diynyl)phenyl)amino)ethanol) Chromophore

Excellent quadratic non-linear optical (ONL-2) properties of the poly(2,5-bis(but-2-ynyloxy) benzoate, containing a polar diacetylene as a chromophore, were found. According with the Maker fringes method, oriented polymer films showing an order parameter of ∼0.23 can display outstanding and stable Second Harmonic Generation (SHG) effects under off-resonant conditions (SHG-532 nm). Also, the macroscopic non-linear optical (NLO)-coefficients were evaluated under the rod-like molecular approximation, obtaining: χzzz(2) and χzxx(2) in the order of 280 ± 10 and 100 ± 10 pm V−1, respectively. The mechanical and chemical properties, in addition to the large ONL-2 coefficients exhibited by this polymer, make it a promising organic material in the development of optoelectronic/photonic devices

Recomendaciones latinoamericanas para el manejo de la hipertensión arterial en adultos (RELAHTA 2)

Se presenta la segunda parte de las recomendaciones latinoamericanas para el manejo de la Hipertensión Arterial (HTA) en adultos. En una primera fase se han descripto los aspectos más relevantes de la epidemiología, aspectos fisiopatológicos, cómo hacer diagnóstico, pautas terapéuticas, urgencias y emergencias hipertensivas, poblaciones especiales, hipertensión refractaria y la aplicación de las guías en la vida real. En esta segunda parte, se emiten recomendaciones respondiendo a preguntas específicas para prevención primaria, secundaria, terciaria y cuaternaria. En general pocas recomendaciones al respecto del manejo de la hipertensión arterial surgen desde la clínica médica/ medicina interna, a pesar de dos situaciones: la mayoría de los pacientes con hipertensión arterial son evaluados y manejados por los clínicos, y la clínica médica es la especialidad que permite la mirada holística e integrada de los problemas de salud del adulto, permitiendo agregar el enfoque biográfico al biológico, comprender e interpretar no solo el problema de salud sino sus causas y consecuencias (que muchas veces suelen corresponder a diferentes parénquimas, lo cual en el modelo fragmentado haría transitar al paciente por distintas especialidades). El bajo porcentaje de pacientes hipertensos controlados obliga a todos los profesionales involucrados en el manejo de los mismos a  optimizar recursos y detectar problemas que se asocien a un control deficitario como la sub utilización del tratamiento farmacológico, baja tasa de pacientes tratados con estrategia combinada (la mayoría de los pacientes actualmente recibe monoterapia),  falta de prescripción adecuada de los cambios en el estilo de vida,  baja adherencia terapéutica e inercia clínica. En la presente publicación se presentan recomendaciones efectuadas por especialistas en clínica médica / medicina interna para el manejo de la hipertensión arterial en adultos, respondiendo preguntas de prevención primaria, secundaria, terciaria, y cuaternaria