Examinando por Autor "Gomez-Pozuelo, Gema"

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Effective management of work groups through the behavioural roles applied in higher education students
(Elsevier, 2023) Martín-Sómer, Miguel; Linares, María; Gomez-Pozuelo, Gema
One of the most in-demand skills for engineers is working effectively in a team. However, divergences inside the group often lead to the unsuccessful progress of the task. Therefore, creating a methodology that allows overcoming this obstacle and promotes successful teamwork seems fundamental. In this work, we present a novel questionnaire that we have designed and implemented to form balanced work teams based on the behaviour and personality of the group members. Concretely, the roles selected were Leader, Collaborative, Thoughtful and Creative. The role assignment was performed using a questionary and applied to different subjects and degrees. The role of Leader was predominant, but when analysing the group mates’ opinions, a relevant decrease was observed, indicating that the students answered the questionary as a leader but did not show leadership capacities. The second role majority was Collaborator, and Creative and Thoughtful roles obtained the fewest percentages. Finally, the academic results of different courses and the students’ feedback experience have been analysed, getting an upbeat assessment of the new methodology for forming groups, and it has also been observed an improvement in the average marks of the subjects.
Evaluating fractional pyrolysis for bio-oil speciation into holocellulose and lignin derived compounds
(Elsevier, 2021-03) Hernando, Hector; Gomez-Pozuelo, Gema; Botas, Juan Angel; Serrano, David Pedro
Fractional pyrolysis of lignocellulosic biomass, by staged thermal treatment, has been assessed as an in-situ speciation method of the bio-oil components that could be highly beneficial for extracting valuable compounds or for their subsequent catalytic upgrading. Wheat straw and pine woodchips were used as representative biomasses. Based on the results of TG analyses in an inert atmosphere, 350 and 700 °C were selected, respectively, as operational temperatures for the fractional pyrolysis. Compared to single-step pyrolysis, fractional thermal treatment of both biomasses led to some reduction of the bio-oil yield but with improved properties due to their lower oxygen content. Sharp differences were observed in the bio-oil composition obtained at the two steps of fractional pyrolysis. GC-MS analyses revealed that most of the compounds detected in the bio-oil obtained at 350 °C were products formed by the decomposition of polysaccharides, such as carboxylic acids, furans, sugars, and light oxygenates. In contrast, the organic liquid phase obtained during the subsequent treatment at 700 °C was rich in aromatic oxygenated compounds, coming from the lignin conversion. The content of oligomeric and heavy species, not detected by GC-MS, was much higher in the bio-oils obtained in the high-temperature step of fractional pyrolysis, denoting that they are largely formed from lignin. Significant changes were also observed in the relative contribution of the deoxygenation pathways during the two steps of fractional pyrolysis. Thus, dehydration was the predominant deoxygenation route during the degradation of the holocellulose biopolymers at the low-temperature step, whereas the decomposition of the lignin-rich solid at the high-temperature treatment proceeded with a significant contribution of decarbonylation and decarboxylation. These results evidence the great potential of lignocellulose fractional pyrolysis to generate bio-oil streams with high speciation of the components, facilitating sharply their further processing and upgrading.
Hydrogen production by catalytic methane decomposition over rice husk derived silica
(Elsevier, 2021-12-15) Gomez-Pozuelo, Gema; Pizarro, Patricia; Botas, Juan Angel; Serrano, David Pedro
Methane decomposition (DeCH4) over solid catalysts is an interesting route for the production of hydrogen free of CO2 emissions. Moreover, it could lead to a negative carbon balance if biogas/biomethane is used as feedstock. However, it is limited by the huge amounts of carbon that are deposited over the catalyst causing its deactivation and hindering its regeneration, which makes necessary the development of low-cost and durable catalytic systems. This work reports the use of different silica materials fully produced from rice husk, i.e. without incorporating any external phase or component, as DeCH4 catalysts. The highest catalytic activity has been found for the silica samples showing large BET surface area and amorphous nature. These properties favor the generation of the actual DeCH4 active sites (-Si-C- species), shortening the induction time detected at the beginning of the reaction tests. The nano-silica materials produced from acid-washed rice husk exhibit a remarkable resistance against deactivation, affording an almost constant reaction rate at long times on stream. This fact is assigned to the presence of large mesopores that facilitate the growth of the carbons deposits towards the outer part of the catalyst particles. The results here reported show the great potential of rice husk-derived nano-silica to overcome several of the most relevant limitations that currently exist for the commercial deployment of hydrogen production by catalytic DeCH4, as a consequence of the low cost and durable activity of these sustainable materials.