1,720,978 research outputs found
Investigation of the catalytic activity of Rh-LaCoO3 catalyst in the conversion of tar from biomass devolatilization products
No full textControlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation
No full textFluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds
Regeneration strategies of deactivated catalysts for thermo-catalytic decomposition process in a fluidized bed reactor
No full textWaste-derived tuff for CO2 Capture: Enhanced CO2 adsorption performances by Cation-Exchange tailoring
No full textMitigating greenhouse gas emissions through CO2 capture from industrial flue gases is imperative for addressing climate change. This article delves into the potential of natural tuff, derived from construction and demolition (C&D) waste, as an affordable and sustainable CO2 adsorbent for post-combustion capture. By tailoring the tuff structure and chemical composition through cation-exchange, the crucial role of cation type in enhancing its textural properties, particularly its microporosity and specific surface area, has been highlighted. Notably, Li- and Na-exchanges greatly enhance these properties, indicating a heightened potential for CO2 capture. The work further explores the dynamic CO2 adsorption of both untreated and modified tuff in a fixed-bed reactor under low CO2 partial pressures (< 0.2 atm), particularly examining the effects of extra-framework cation nature (Na+, Li+) and composition, and the influence of NH4+ pre-treatment. Results show that Na- and Li-exchanged tuff exhibit enhanced CO2 uptake (up to 1 mmol g−1) compared to untreated tuff (0.54 mmol g−1), with Li-exchange resulting in the highest capacity due to both superior textural properties and stronger ion-quadrupole interactions with CO2 molecules. The multi-cyclic stability of the synthesized samples has been also assessed; regardless of the specific cation-exchange type, all the samples provide stable performances over 10 consecutive adsorption/desorption cycles
Production of hydrogen from thermo-catalytic decomposition of methane in a fluidized bed reactor
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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