1,355,543 research outputs found
Reattività non usuali di olefine coordinate in complessi di platino con leganti carrier azotati ed ossigenati. Nuovi strumenti di base per strategie innovative ecocompatibili di sintesi catalitica di sistemi molecolari complessi.
No full textProgramma dell’Unità di Ricerca di chimica generale ed inorganica, nell’ambito dei Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale, ammesso per il biennio 2006-2007 a cofinanziamento del MIUR; coordinato a livello nazionale dal Prof. Aresta Michele. Responsabile Scientifico: Prof. Fanizzi Francesco Paolo
Reattività di olefine coordinate in complessi di platino con leganti carrier azotati ed ossigenati. Alla ricerca di strumenti di base per nuove strategie di sintesi catalitica di sistemi molecolari complessi
No full textProgramma dell’Unità di Ricerca di chimica generale ed inorganica, nell’ambito dei Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale, ammesso per il biennio 2003-2004 a cofinanziamento del MIUR; coordinato a livello nazionale dal Prof. Aresta Michele. Responsabile Scientifico: Prof. Fanizzi Francesco Paolo
Synthesis, characterization and use of Nb(V)/Ce(IV)-mixed oxides in the direct carboxylation of ethanol by using pervaporation membranes for water removal.
No full textNew catalytic systems based on ceria have been used in the direct carboxylation of ethanol. The catalytic behaviour of Al2O3 or Nb2O5 loaded ceria are compared, the latter showing a better performance. A morphological and structural study has been carried out on Nb2O5/CeO2 catalysts in order to explain their behaviour in catalysis. Pervaporation membranes have been used for water separation. The synthesis of diethylcarbonate-DEC has been carried out either in a liquid phase (ethanol) pressurized with CO2 or in supercritical conditions. A set-up has been developed that allows the production of quite pure DEC (>90%) with recycling of CO2 and ethanol
Carbon Recycling Through CO2-Conversion for Stepping Toward a Cyclic-C Economy. A Perspective
No full textThe conversion of CO2 into added value chemicals, materials and fuels is a case of transition from the linear to the cyclic-C economy, a necessary change for stopping the putative negative effect of CO2 on climate and the environment. Several strategies can be implemented for CO2 conversion and their potential and timeframe is discussed in this perspective paper. The overall amount of avoided CO2 is evaluated in the short-, medium-, and long-term. The distinct contribution of Catalysis, Solar Chemistry and integrated Chemocatalysis-Biosystems is discussed
Industrial utilization of carbon dioxide (CO2)
No full textThe chapter presents the various aspects of the utilization of CO2 (technological, chemical, biotechnological) together with an analysis of the benefits derived from such practice. Conditions for correct use of CO2 are defined, and the potential of each technology is highlighted in terms of reducing emission into the atmosphere and lowering energy and/or material consumption, either directly (recycling of carbon) or indirectly, e.g. when the use of CO2 reduces the emission of products having a much higher climate change power (CCP) than CO2 itself. The potential utilization of CO2 as a tool to store excess or intermittent energies is also discussed, and the production of chemicals or energy products is presented, highlighting existing barriers to a full exploitation. The potential of enhanced fixation into aquatic biomass as a means of recyling CO2 and replacing fossil carbon in the production of chemicals or fuels for the transport sector is discussed. Emphasis is placed on the requirement for research into the potential for CO2 utilization to contribute to the reduction of its accumulation in the atmosphere. © 2010 Woodhead Publishing Limited All rights reserved
Merging the Green-H2 production with Carbon Recycling for stepping towards the Carbon Cyclic Economy
No full textHydrogen Economy and Cyclic Economy are advocated, together with the use of perennial (solar, wind, hydro, geo-power, SWHG) and renewable (biomass) energy sources, for defossilizing anthropic activities and mitigating climate change. Each option has intrinsic limits that prevent a stand-alone success in reaching the target. Humans have recycled goods (metals, water, paper, and now plastics) to a different extent since very long time. Recycling carbon (which is already performed at the industrial level in the form of CO2 utilization and with recycling paper and plastics) is a key point for the future. The conversion of CO2 into chemicals and materials is carried out since the late 1800s (Solvay process) and is today performed at scale of 230 Mt/y. It is time to implement on a scale of several Gt/y the conversion of CO2 into energy products, possibly mimicking Nature which does not use hydrogen. In the short term, a few conditions must be met to make operative on a large scale the production of fuels from recycled-C, namely the availability of low-cost: i. abundant, pure concentrated streams of CO2, ii. non-fossil primary energy sources, and iii. non-fossil-hydrogen. The large-scale production of hydrogen by Methane Steam Reforming with CO2 capture (Blue-H2) seems to be a realistic and sustainable solution. Green-H2 could in principle be produced on a large scale through the electrolysis of water powered by perennial primary sources, but hurdles such as the availability of materials for the construction of long-living, robust electrochemical cells (membranes, electrodes) must be abated for a substantial scale-up with respect to existing capacity. The actual political situation makes difficult to rely on external supplies. Supposed that cheap hydrogen will be available, its direct use in energy production can be confronted with the indirect use that implies the hydrogenation of CO2 into fuels (E-fuels), an almost ready technology. The two strategies have both pros and cons and can be integrated. E-Fuels can also represent an option for storing the energy of intermittent sources. In the medium-long term, the direct co-processing of CO2 and water via co-electrolysis may avoid the production/transport/ use of hydrogen. In the long term, coprocessing of CO2 and H2O to fuels via photochemical or photoelectrochemical processes can become a strategic technology
Transition from Fossil-C to Renewable-C (Biomass and CO2) Driven by Hybrid Catalysis
No full textHybrid catalysis, based on the integrated use of robust chemo- and selective bio-catalysts, is a recent but fast-growing discipline. Typical benefits of hybrid catalysis are: atom-saving, reduction of energy-demand, reduction in the number of steps, and waste-reduction at the source. It can be applied not only to the conversion of CO2 and biomass, but also to the efficient recycling of expensive co-substrates that therefore promotes the use of enzymes at the industrial level. In this chapter, we discuss some specific applications and highlight the advantages of applying hybrid-catalysis to both waste-biomass valorization and carbon recycling through CO2 conversion into chemicals or fuels for stepping towards the circular carbon economy (CCE). Hybrid-catalysis has a key role in both avoiding fossil-C and in maximizing the use of renewable carbon
Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Coffee Samples by DI-SPME-GC/MS
No full textRoasting is a crucial and essential step to produce quality coffee. However, it could lead to the formation of toxic and
suspected carcinogenic or procancerogenic compounds, such as polycyclic aromatic hydrocarbons. In this work, a simple and
easily automatable green procedure based on solid-phase microextraction coupled with gas chromatography for the analysis
of acenaphthene, anthracene, benzo[ghi]perylene, benzo[a]pyrene, chrysene, fluoranthene, fluorene, naphthalene, and pyrene,
in dark roasted and decaffeinated commercial coffees, was developed. The method was optimized for the determination of
the analytes both in solid samples, such as ground coffee or coffee grounds, and liquids, such as espresso coffee, using a
polyacrylate-coated fused silica fiber (85 μm) by direct immersion. The performance of the analytical method, developed
in terms of sensitivity, reproducibility, and recoveries, proved to be suitable for the applications. Among the 9 polycyclic
aromatic hydrocarbons investigated in the selected coffees, chrysene and pyrene were the most representative congeners
with values ranging from undetectable to 95.6 ± 11 ng/g for chrysene and from undetectable to 404.7 ± 42.0 ng/g for pyrene.
Benzo[a]pyrene was detected in two samples of dark roasted coffee which therefore had the highest toxicity/carcinogenicity
in terms of toxic equivalent. The estimated limit of detection for benzo[a]pyrene in ground coffee and coffee grounds was
9.0 ng/g. About 30% of the PAHs were transferred to the infusion while the remaining part was retained by the coffee grounds
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