Search results for " carbon dioxide"
showing 10 items of 200 documents
Premio di Laurea “Ametek Scientific Instruments”: Electrochemical Conversion of Carbon Dioxide to Formic Acid. Study of the Effect of the Operating P…
2017
Electrochemical conversion of CO2 is considered one of the more appealing approaches to introduce renewable energy in the chemical and energy chain and to mitigate the greenhouse gases effect. In this work, the reduction of carbon dioxide was performed in undivided electrochemical cell to produce formic acid, which is one of the highest value-added chemicals and economically feasible for large-scale applications (1). It is well known that the main hurdle of the reduction of CO2 from water solution is the low CO2 solubility in water. In order to overcome this obstacle, a specific investigation on the effect of the CO2 pressure and other operating parameters at tin flat cathodes was carried o…
NOVEL PROCESSES FOR THE MODIFICATION AND THE STERILIZATION OF MACROMOLECULAR MATRICES
The duality of ocean acidification as a resource and a stressor
2018
Ecologically dominant species often define ecosystem states, but as human disturbances intensify, their subordinate counterparts increasingly displace them. We consider the duality of disturbance by examining how environmental drivers can simultaneously act as a stressor to dominant species and as a resource to subordinates. Using a model ecosystem, we demonstrate that CO2-driven interactions between species can account for such reversals in dominance; i.e., the displacement of dominants (kelp forests) by subordinates (turf algae). We established that CO2 enrichment had a direct positive effect on productivity of turfs, but a negligible effect on kelp. CO2 enrichment further suppressed the …
Exploring CO2 volcanic vents at Vulcano Island, Mediterranean Sea, to study the planktonic calcifier response to long-term changes in carbonate chemi…
2011
Design of novel imidazolium based nanostructures for sustainable catalytic applications
2019
Ventilation rates and unsatisfied percentage from indoor CO2 concentration.
2011
This work reports the results of a survey carried out on a hall in a historic building in Palermo (Italy) with the aim of assessing the air quality by means of objective measurement of carbon dioxide (CO2) concentration and its subjective evaluation through a questionnaire. The measured values of CO2 concentration were compared with those evaluated using the Meckler equation under steady-state conditions, having verified necessary parameters such as the constancy of the indoor and outdoor CO2 levels and the uniformity of the CO2 generation rate for all the occupants. The positive correspondence between measured and calculated results allowed us to utilise, under differing circum- stances, t…
Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide
2014
International audience; The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10−3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, prop…
Diffuse and focused carbon dioxide and methane emissions from the Sousaki geothermal system, Greece
2006
[1] We report first data on chemical composition of the gas emitted by the geothermal system of Sousaki, Greece. Gas manifestations display typical geothermal gas composition with CO2 as the main component and CH4 and H2S as minor species. Soil gas composition derives from the mixing of two end-members (atmospheric air and geothermal gas). Soil CO2 fluxes range from<2 to 33,400 g m−2 d−1. The estimated diffuse output of hydrothermal CO2, estimated for an area of 0.015 km2, is about 630 g s−1, while a tentative estimation of CH4 diffuse output gave a value of about 1.15 g s−1. Point sources accounted for lower flux values of ∼26 g s−1 of CO2, ∼0.1 g s−1 of CH4 and ∼0.02 g s−1 of H2S.
On the ionizing properties of supercritical carbon dioxide: uncatalyzed electrophilic bromination of aromatics
2014
Supercritical carbon dioxide (scCO2), a solvent with a zero dipole moment, low dielectric constant, and no hydrogen bonding behavior, is a suitable medium to perform the uncatalyzed electrophilic bromination of weakly activated aromatics with no interference of radical pathways. The ability of scCO2 to promote these reactions matches those of strongly ionizing solvents such as aqueous acetic and trifluoroacetic acids. Conversely, carbon tetrachloride, with similar polarity parameters to scCO2, leads exclusively to side chain functionalization. The strong quadrupole moment, and the acidic, but non basic, Lewis character of carbon dioxide, are proposed as key factors for the singular performa…
ChemInform Abstract: Epoxidation of Olefins with a Silica-Supported Peracid in Supercritical Carbon Dioxide under Flow Conditions.
2012
Anhydrous 2-percarboxyethyl-functionalized silica (2b), a recyclable supported peracid, is a suitable reagent to perform the epoxidation of alkenes 1 in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions. This procedure simplifies the isolation of the reaction products and uses only carbon dioxide as a solvent under mild conditions. The solid reagent 2b can be easily recycled by a reaction with 30% hydrogen peroxide in an acid medium.