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3 results, page 1 of 1

Catalytic Steam Gasification of Glucose for Hydrogen Production Using Stable Based Ni on a γ–Alumina Fluidizable Catalyst

BENITO SERRANO ROSALES (2019)

Six different Ni-based fluidizable catalysts were synthesized using both incipient impregnation and co-

impregnation. Ni-based catalysts were also promoted with 2.0 wt% La or alternatively with 2 wt% Ce. The

preparation procedure included catalysts treated at high temperatures and under free of oxygen conditions.

Catalysts were characterized using BET, XRD, AA, PSD, TPR, TPD, H2-chemisorption. TPR and H2 chemisorp-tion showed good metal dispersion with 10 nm- 40 nm metal crystallites.

Glucose catalytic gasification runs were performed in a CREC Riser Simulator to evaluate the following cata-

lysts: (a) 5 %Ni/γ-Al2O3, (b) 5 %Ni-2 %La/γ-Al2O3 and (c) 5 %Ni-2 %Ce/γ-Al2O3. In all cases, the preparation

steps involved acid solutions with pHs of 1 and 4. In between consecutive runs, different approaches were

considered: (a) A catalyst was regenerated by air, (b) A catalyst was regenerated by air followed by hydrogen

pretreatment, (c) A catalyst was reused directly without any regeneration or hydrogen pretreatment. It was

observed that Ni-based catalysts, which were subjected after every run, to both, air regeneration and hydro-

gen pretreatment, displayed the best yields in close agreement with thermodynamic equilibrium. On the other

hand, Ni-based catalysts regenerated with air only, showed the worst hydrogen yields. In between these two-

hydrogen yield limits, where catalysts not contacted with air nor hydrogen, with these yields being moderately

below chemical equilibrium.

This shows that Ni-based fluidizable catalysts can perform on stream for extended periods, requiring limited

reactivation with air and H2. This makes of gasification using the catalysts of the present study, a viable process alternative that could be implemented at industrial scale.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

INGENIERÍA Y TECNOLOGÍA hydrogen glucose nickel cerium lanthanum gasification

Strong Ferromagnetic Exchange Coupling Mediated by a Bridging Tetrazine Radical in a Dinuclear Nickel Complex.

Toby James Woods Heather Stout-Delgado Brian Dolinar Vignesh Kuduva Radhakrishnan MARIA FERNANDA BALLESTEROS RIVAS Catalina Achim Kim Renee Dunbar (2017)

The radical bridged compound [(Ni- (TPMA))2-μ-bmtz•−](BF4)3·3CH3CN (bmtz = 3,6-bis- (2′-pyrimidyl)-1,2,4,5-tetrazine, TPMA = tris(2- pyridylmethyl)amine) exhibits strong ferromagnetic exchange between the S = 1 NiII centers and the bridging S = 1/2 bmtz radical with J = 96 ± 5 cm−1 (−2JNi‑radSNiSrad). DFT calculations support the existence of strong ferromagnetic exchange.

Department of Energy Office of Science Graduate Fellowship, Instituto de Ciencia y Tecnología del Distrito Federal (ICyTDF) National Science Foundation (CHE-1310574) and the Robert A. Welch Foundation (A-1449).

Article

Bridging Tetrazine Dinuclear Nickel Complex Ferromagnetic BIOLOGÍA Y QUÍMICA

Distribución espacial y temporal del níquel y cadmio en relación a la abundancia de Synechococcus spp y Prochlorococcus spp en la región mexicana del Golfo de México

Spatial and temporal distribution of nickel and cadmium related to Synechococcus spp and Prochlorococcus spp abundance in the Mexican region of the Gulf of Mexico

Denice Alejandra Naranjo Ortiz (2022)

En la región oceánica y oligotrófica del golfo de México dominan las poblaciones de Synechococcus spp. y Prochlorococcus spp., las cuales han mostrado en otros ecosistemas una estrecha asociación con Cd y Ni, sugiriendo que estos picoautótrofos son actores importantes para la biogeoquímica de estos metales en la columna de agua. El objetivo de este estudio fue conocer la asociación entre las abundancias de estas cianobacterias y la concentración disuelta de Cd y Ni en la región de aguas profundas del golfo de México durante tres campañas oceanográficas: XIXIMI-4 (agosto - septiembre 2015), XIXIMI-5 (junio 2016) y XIXIMI-6 (agosto - septiembre 2017). Los resultados mostraron que la concentración de Cd y Ni tienen una gran variabilidad regional y temporal, influenciada en mayor medida por la actividad de mesoescala, y por otros forzantes físicos como los aportes continentales hacia la plataforma y la interacción de estructuras anticiclónicas con el talud, que permiten un transporte costa-océano. La distribución de Cd y Ni en la columna de agua también se vio influenciada por los procesos locales de remineralización de los metales que fueron consumidos en la zona eufótica por diversos grupos fitoplanctónicos. Las relaciones estequiométricas de metal:nutriente, evidenciaron una variabilidad temporal entre las campañas, proponiendo que los cambios estacionales de la columna de agua, así como la cantidad y el origen de la materia orgánica, pueden estar influyendo en el cambio de estas razones. Comparativamente con la región norte del Atlántico oeste (~19 - 21°N), las aguas del golfo mostraron características fisicoquímicas similares. Los análisis estadísticos de este estudio revelaron una tendencia generalmente opuesta de ambas cianobacterias con el Cd y Ni, sugiriendo un cierto control de estos metales en el crecimiento de estos organismos, ya sea por un consumo inmediato o por un efecto tóxico después de un cierto umbral de concentración. Los resultados de este estudio destacaron la importancia de los factores físicos, químicos y biológicos en la distribución de Cd y Ni en el golfo y particularmente, el papel que ejercen las poblaciones de cianobacterias en modificar sus concentraciones dentro de la zona eufótica.

Picoautotrophs like, Synechococcus spp. and Prochlorococcus spp. are dominant populations in the oceanic and oligotrophic region of the Gulf of Mexico. They exhibit a close relationship with Cd and Ni, hence, they are important actors on the biogeochemistry of these metals in the water column. The objective of this research was to study the association between the abundance of these cyanobacterial populations and the dissolved concentrations of Cd and Ni at the deep region of the Gulf of Mexico during three oceanographic campaigns: XIXIMI-4 (August - September 2015), XIXIMI-5 (June 2016) and XIXIMI-6 (August - September 2017). The results showed regional and temporal variability in the Cd and Ni concentrations, mainly influenced by the mesoscale activity and other physical forcing such as, river inputs to the continental shelf and the interaction between anticyclonic structures and the continental slope, allowing a cross-shelf transport. Local processes like, metal remineralization after consumption in the euphotic zone by different phytoplankton groups, also influenced the Cd and Ni distributions in the water column. The metal:nutrient stoichiometry displayed a temporal variability among campaigns, associated to the seasonal changes in the water column, and also the amount and origin of the organic matter. Comparisons made with the northern region of the Western Atlantic (~19 - 21°N), indicated that the Gulf of Mexico waters presented similar physicochemical characteristics. Statistical analyses revealed a generally opposed trend between both cyanobacterial populations and the two metals, suggesting a control over their growth, by immediate consuming or by a toxic effect after surpassing a concentration threshold. The results of this study highlights the importance of the physical, chemical, and biological factors on the Cd and Ni distributions in the Gulf of Mexico and, in particular, the role of the cyanobacterial populations to modify the concentrations of these metals into the euphotic zone.

Master thesis

Cadmio (Cd), níquel (Ni), cianobacterias, Golfo de México Cadmium (Cd), nickel (Ni), cianobacteria, Gulf of Mexico CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PECES Y FAUNA SILVESTRE PROTECCIÓN DE LOS PECES PROTECCIÓN DE LOS PECES