1,720,997 research outputs found
Atmospheric CO2 mitigation technologies: carbon capture utilization and storage
Full text linkRecently, the utilization of carbon dioxide has gained in consideration as it may contribute to improve the economics of CO2 capture process by producing added value goods and is now considered a valid alternative to geological CO2 storage. Nowadays, the scientific community considers the integrated carbon capture, utilization and storage an important mitigation technology that involves the carbon dioxide sequestration from fuel combustion or industrial processes, its transport (via ship or pipeline) and conversion into valuable products or its permanent storage deep underground in geological formations. Noteworthy, CCS is functional to a linear economy, whereas utilization of carbon dioxide is at the hearth of a circular economy and its strategic role will grow in the future. In this mini review, the current state of the art in the field of capture, disposal, and reuse of CO2 as technologies for its overall reduction in the atmosphere will be discussed
Carboxylation Reaction Based on the Direct and Indirect Uses of CO2: Sustainable Syntheses of C—CO2, O—CO2, and N—CO2Bonds
No full textCarboxylation represents an important route to afford C-C bonds useful to make building block molecules for polymer chemistry. This chapter will focus on recent advances in the field of direct carboxylation reactions based on CO2. The use of urea and inorganic carbonate will be also discussed. Different kinds of synthetic approaches (electrochemical, photochemical, catalytic, and enzymatic) will be considered mainly as future perspectives from the point of view of possible industrial applications, focusing attention on the energy and atom economy. The use of heterogeneous catalytic species will be described, also with mechanistic considerations
Valorization of C5 polyols by direct carboxylation to FDCA: Synthesis and characterization of a key intermediate and role of carbon dioxide
No full textReplacing fossil-C based plastics with those derived from renewable-C is one of the goals of the modern polymer industry. 2,5-Furan dicarboxylic acid (2,5-FDCA) is a candidate to substitute terephthalic acid as comonomer for polyesters. 2,5-FDCA is usually produced from C6 sugars. Carboxylation of 2-furancarboxylic acid (2-FCA) to 2,5-FDCA is an alternative synthetic approach to such monomer for polyethene furoate (PEF) preparation. In this work, several inorganic carbonates have been tested in the 2-FCA carboxylation in presence and absence of CO 2 . A key copper intermediate has been synthesized and fully characterized that is able to increase the acidity and, thus, the reactivity of 5-H towards a carbonate species. Carboxylation occurs at 93% yield in absence of CO 2 . The role of metal salts and CO 2 were investigated. The conversion yield of 2-FCA into the dicarboxylic acid is related to the charge density on the metal cation, increasing with lower charge-density
The Future of Carbon Dioxide Chemistry
No full textThe utilization of carbon dioxide as building block for chemicals or source of carbon for energy products has been explored for over 40 years now, with varying allure. In correspondence with oil-crises, the use of CO2 has come into the spotlight, soon set aside when the crisis was over due to the low price of fossil carbon and the convenience of using established technologies. Nowadays, there is a continuous shift from fossil-C-based to perennial (solar, wind, geothermal, hydro-power) energy-driven processes that will also have a great potential to convert large amounts of carbon dioxide. The integration of biotechnology and catalysis will be a key player towards the utilization of CO2 in several different applications, reducing both the extraction of fossil carbon and the carbon transfer to the atmosphere
Towards New Sustainable Squalene Resources: Extraction from Apulian “Aged Extra-Virgin Olive Oil Sludge” (AEVOO-S). A Comparison Between Organic Solvent and Supercritical Fluid Techniques
No full textValorisation of agro-industry organic wastes has gained importance in the last decades since it pursues two major goals: environment protection and economic profit. Squalene that represents one the most important natural antioxidant for pharmaceutical and cosmeceutical industry, can be recovered from olive oil production wastes, playing a prominent role to substitute of the shark liver oil as main squalene resource, with great benefits from the marine species protection. The “Aged Extra Virgin Olive Oil-Sludge” (AEVOO-S) a less studied olive oil waste contains squalene in a good concentration depending by the starting Extra Virgin Olive Oil (EVOO) quality (cultivar, extraction processes) and storage conditions. In the present work, fresh EVOO, aged olive oil (AEVOO) and isolated sludge have been characterized and compared in some chemico/ physical properties that confirm the applicability of this waste as a further alternative squalene source. Organic solvent under different conditions and supercritical-CO2 extraction of squalene methodologies, were evaluated in order to optimize its recovery. The results showed that at room temperature, chloroform extracts the highest squalene amount (up to 500 mg/100 g of sludge) but with low selectivity (high amount of free fatty acids were also detected) whereas Microwave Assisted Extraction using n-hexane as solvent, provided high squalene yield (456 mg/100 g of sludge) but with less free fatty acid. Due to the high viscosity of the semi-solid sludge, supercritical carbon dioxide does not show the high squalene extraction ability showed using oils. Graphical Abstract: [Figure not available: see fulltext.]
What Catalysis Can Do for Boosting CO2 Utilization
No full textCarbon dioxide can be used as building block for chemicals and materials or source of carbon for fuels. The former application, if implemented at the correct scale, may boost the sustainability of the chemical industry. The latter is more relevant to the energy sector and requires cheap hydrogen from water or renewables for the hydrogenation of the cumulene. Both applications can, thus, render services to our society even if at different times and intensity. In this chapter, an analysis of possibilities is carried out, considering chemicals that have a market higher or close to 1 Mt/year, highlighting the pros and cons and which aspects (catalyst and process) must be further developed in order to have a successful exploitation of the technology. The integration of catalysis and biotechnology is discussed as a route to the utilization of large volumes of CO2. Letting Nature convert CO2 and using biomass in catalytic processes can be a win–win option in some cases
Selective Oxidation of 5-(Hydroxymethyl)furfural to DFF Using Water as Solvent and Oxygen as Oxidant with Earth-Crust-Abundant Mixed Oxides
Full text link5-Hydroxymethylfurfural (5-HMF) can be considered a prominent building block: because of the presence of the alcohol and aldehyde moieties, it can be used to generate useful molecules as chemicals of industrial interest with high added value, monomers for polymers, and even fuels. This article shows how building up mixed oxides of different complexities and properties may drive the selectivity toward one of the possible products generated from 5-HMF. In particular, mixed oxides based on cerium and other metals abundant on the earth-crust perform the selective oxidation of 5-HMF to 2,5-diformylfuran (94%), using oxygen as oxidant and water as solvent. The roles of the reaction conditions (temperature, reaction time, oxygen pressure, concentration of the substrate), the chemical composition, the acidic/basic properties, and redox properties of the catalysts are discussed
RU(II)-MEDIATED HYDROGEN TRANSFER FROM AQUEOUS GLYCEROL TO CO2: FROM WASTE TO VALUE-ADDED PRODUCTS
No full textAqueous glycerol was used as the hydrogen source for the reduction of CO2 to the hydrogen carrier formic acid in the presence of the catalyst [RuCl2(PPh3)3]. All intermediates were identified and characterized. Glycerol was converted into glycolic acid, HO-CH2-COOH, that was identified by using 1H and 13C NMR spectroscopy. In the face of wastefulness: Aqueous glycerol is used as a hydrogen source for the reduction of CO2 to formic acid. In the presence of RuCl2(PPh3)3, glycerol behaves as a four-hydrogen transfer agent affording glycolic acid
Synthesis and characterization of p-n junction ternary mixed oxides for photocatalytic coprocessing of CO2 and H2O
Full text linkIn the present paper, we report the synthesis and characterization of both binary (Cu2 O, Fe2 O3, and In2 O3 ) and ternary (Cu2 O-Fe2 O3 and Cu2 O-In2 O3 ) transition metal mixed-oxides that may find application as photocatalysts for solar driven CO2 conversion into energy rich species. Two different preparation techniques (High Energy Milling (HEM) and Co-Precipitation (CP)) are compared and materials properties are studied by means of a variety of characterization and analytical techniques UV-Visible Diffuse Reflectance Spectroscopy (UV-VIS DRS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray spectrometry (EDX). Appropriate data elaboration methods are used to extract materials bandgap for Cu2 O@Fe2 O3 and Cu2 O@In2 O3 prepared by HEM and CP, and foresee whether the newly prepared semiconductor mixed oxides pairs are useful for application in CO2-H2 O coprocessing. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2 O@In2 O3 shows positive results in CO2-H2 O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2 –H2 O. This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, EDX for the surface and bulk analytical characterization. Surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior. We show that a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps
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