669 research outputs found

    Intensified production of zeolite A: Life cycle assessment of a continuous flow pilot plant and comparison with a conventional batch plant

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    This study investigates on the environmental impact of an intensified technology for the manufacturing of Zeolite A, one of the largest zeolites employed worldwide by volume and value. The technology under consideration is an oscillatory continuous-flow synthesis, developed industrially by Arkema, and currently at pilot-scale. Life cycle assessment (LCA) is used in this work to measure the sustainability of this emerging technology in an anticipatory fashion, before its full deployment, with the aim of driving the process development toward the minimization of the environmental footprint. The assessment explores the full life-cycle of the production system and comprises comparative analysis, scenario analysis, and a hotspot analysis. Finally, the continuous-flow technology is benchmarked against the environmental impact of a conventional batch production of zeolite A, based on a full-scale commercial plant. The results evidence that significant benefits would stem from shifting from batch to continuous-flow production. The comparative analysis reveals that the extent of the latter advantages depends on the impact category under consideration and directs the next steps of CF system's process development toward pivotal aspects such as the recirculation system to further reduce the system's environmental impacts. Regardless of the chosen production technology, a large share of the total environmental impact hinges on the production of NaOH, a building block of the synthesis, and hence is hardly mitigatable. On the whole, the findings of this work emphasize the need of prioritizing LCA during the development phase of emerging technologies and underline its efficacy to prevent waste of resources and capitals

    Can the use of captured CO2 lower the environmental impacts of formate production?

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    The majority of bulk chemicals (e.g. olefins and alcohols) are organic compounds that are almost exclusively produced from fossil feedstocks such as natural gas. Utilisation of carbon dioxide captured from anthropogenic sources, which are both inexpensive and abundantly available, represents an alternative pathway that is drawing increasing attention, mainly for its potential to decreasing emissions of greenhouse gases and resource depletion of chemicals production. Notably, carbon utilisation does not represent an approach to CO2 mitigation because it only delays its emissions rather than removing it over a long timescale; hence, the relevant question that we aim to address is: "Can captured CO2 be used as feedstock to reduce the environmental impacts of chemicals' production?". As a case study, this work focuses on the production of formate and presents a prospective comparative life cycle assessment (LCA) between the conventional fossil-based pathway and an innovative, CO2-based process, that involves the electro-catalytic reduction of CO2 using an ionic liquid as solvent. CO2 is assumed to originate from a natural gas-fired power plant and captured after combustion, through a conventional monoethanolamine absorption system. Ionic liquids are used to enanche the reduction of CO2 and its conversion to formate. The study adopts a cradle-to-gate perspective and analyses multiple impact categories including, but not limited to, global warming and resources depletion

    The life-cycle environmental performance of producing formate via electrochemical reduction of CO_{2} in ionic liquid

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    Carbon capture and utilisation provide a means to mitigate climate change caused by anthropogenic greenhouse gas emissions by delaying carbon emissions via temporary storage in goods. This article presents a comprehensive Life Cycle Assessment (LCA) study of a novel process that generates formate via electrochemical reduction of CO_{2} in ionic liquid. We performed a scenario analysis, covering uncertain parameters like the recycling rate of unreacted reagents and the market price of CO_{2}, and compared the environmental performance of the carbon utilisation system with that of the conventional process, which relies on fossil sources. Inventory data is obtained from a mix of literature sources and commercial LCA databases. Our analysis indicates that (i) the system needs to attain a 99.9% recycling rate to be competitive with the conventional process; (ii) a future negative market price of CO_{2} would substantially reduce the environmental impacts associated with formate; (iii) there are significant environmental trade-offs between the carbon utilisation system and the conventional process, with the former outperforming the latter in 6/8 out of the 14 impact categories investigated. It should be noted that our results are conservative because inventory data for the electrochemical reduction process is obtained from laboratory experiments

    Application of acoustic techniques to fluid-particle systems – A review

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    Acoustic methods applied to opaque systems have attracted the attention of researchers in fluid mechanics. In particular, owing to their ability to characterise in real-time, non-transparent and highly concentrated fluid-particle systems, they have been applied to the study of complex multiphase flows such as fluidised beds. This paper gives an overview of the physical principles and typical challenges of ultrasound and acoustic emission AE methods when applied to fluid-particle systems. The principles of ultrasound imaging are explained first. The measurement techniques and signal processing methodologies for obtaining velocity profiles, size distribution of the dispersed phases, and solid volume fraction are then discussed. The techniques are based on the measurement of attenuation, sound speed, frequency shift, and transit time of the propagated sound wave. A description of the acoustic emission technique and applications to fluid-particle systems are then discussed. Finally, extensions and future opportunities of the acoustic techniques are presented

    Unconventional ratiometric-enhanced optical sensing of oxygen by mixed-phase TiO2

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    We show that mixed-phase titanium dioxide (TiO2) can be effectively employed as an unconventional, inorganic, dual-emitting and ratiometric optical sensor of O2. Simultaneous availability of rutile and anatase TiO2 PL and their peculiar anti-correlated PL responses to O2 allow using their ratio as measurement parameter associated to O2 concentration, leading to an experimental responsivity being by construction larger than the one obtainable for single-phase PL detection. A proof of this concept in given, showing a two-fold enhancement of the optical responsivity provided by the ratiometric approach. Besides the peculiar ratiometric-enhanced responsivity, other characteristics of mixed phase TiO2 can be envisaged as favorable for O2 optical probing, namely: a) low production costs, b) absence of heterogeneous components, c) self-supporting properties. These characteristics encourage experimenting its use for applications requiring high indicator quantities at competitive price, possibly also tackling the need to develop supporting matrixes that carry the luminescent probes and avoiding issues related to the use of different components for ratiometric sensing.Comment: 12 pages, 5 figure

    Performance-based assessment of seismic-resilient steel moment resisting frames equipped with innovative column base connections

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    Low-damage and self-centring column base connections have been proposed in the last two decades as innovative solutions able to provide the seismic resilience in Moment Resisting Frames (MRFs). Although many works have demonstrated the benefits deriving from the adoption of these systems, only a few research studies investigated the significant parameters influencing their self-centring capability. This paper investigates the influence of the frame layout (i.e., sto-reys and bays number) on the seismic performance of perimeter MRFs equipped with damage-free self-centring column bases previously studied by the authors. Nine case-study perimeter steel MRFs are designed and modelled in OpenSees. Incremental Dynamic Analyses are per-formed monitoring both global and storey-level Engineering Demand Parameters, including peak and residual interstorey drifts. Fragility curves are successively used to evaluate the self-centring capability of the structures. The present study provides insights on the use of the adopted con-nections for the residual drift reduction of MRFs and defines the boundaries of the investigated parameters for their application. Results highlight that the self-centring behaviour is particularly sensitive to the number of storeys and tends to reduce with the increasing height of MRFs equipped with the proposed connections
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