Carbon-based honeycomb monoliths for environmental gas-phase applications

Honeycomb monoliths consist of a large number of parallel channels that provide high contact efficiencies between the monolith and gas flow streams. These structures are used as adsorbents or supports for catalysts when large gas volumes are treated, because they offer very low pressure drop, short diffusion lengths and no obstruction by particulate matter. Carbon-based honeycomb monoliths can be integral or carbon-coated ceramic monoliths, and they take advantage of the versatility of the surface area, pore texture and surface chemistry of carbon materials. Here, we review the preparation methods of these monoliths, their characteristics and environmental applications

Biomass-Derived Carbon Molecular Sieves Applied to an Enhanced Carbon Capture and Storage Process (e-CCS) for Flue Gas Streams in Shallow Reservoirs

The authors give thanks to Universidad Nacional de Colombia and the University of Granada for the logistical and financial support.It is possible to take advantage of shallow reservoirs (<300 m) for CO2 capture and storage in the post-combustion process. This process is called enhanced carbon capture and storage (e-CCS). In this process, it is necessary to use a nano-modifying agent to improve the chemical-physical properties of geological media, which allows the performance of CO2 selective adsorption to be enhanced. Therefore, this study presents the development and evaluation of carbon sphere molecular nano-sieves (CSMNS) from cane molasses for e-CSS. This is the first report in the scientific literature on CSMNS, due to their size and structure. In this study, sandstone was used as geological media, and was functionalized using a nanofluid, which was composed of CNMNS dispersed in deionized water. Finally, CO2 or N2 streams were used for evaluating the adsorption process at different conditions of pressure and temperature. As the main result, the nanomaterial allowed a natural selectivity towards CO2, and the sandstone enhanced the adsorption capacity by an incremental factor of 730 at reservoir conditions (50 ◦C and 2.5 MPa) using a nanoparticle mass fraction of 20%. These nanofluids applied to a new concept of carbon capture and storage for shallow reservoirs present a novel landscape for the control of industrial CO2 emissions.Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias 647-2014Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion "FRANCISCO JOSE DE CALDAS"Agencia Nacional de Hidrocarburos (ANH)Departamento Administrativo de Ciencia, Tecnologia e Innovacion ColcienciasUniversidad Nacional de ColombiaERDF/Ministry of Science, Innovation and Universities-State Research Agency RTI2018-099224-B-I0

Nickel Cobaltite Functionalized Silver Doped Carbon Xerogels as E cient Electrode Materials for High Performance Symmetric Supercapacitor

Introducing new inexpensive materials for supercapacitors application with high energy density and stability, is the current research challenge. In this work, Silver doped carbon xerogels have been synthesized via a simple sol-gel method. The silver doped carbon xerogels are further surface functionalized with di erent loadings of nickel cobaltite (1 wt.%, 5 wt.%, and 10 wt.%) using a facile impregnation process. The morphology and textural properties of the obtained composites are characterized by X-ray di raction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen physisorption analysis. The silver doped carbon xerogels display a higher surface area and larger mesopore volume compared to the un-doped carbon xerogels and hierarchically porous structure is obtained for all materials. The hybrid composites have been utilized as electrode materials for symmetric supercapacitors in 6 M KOH electrolyte. Among all the hybrid composites, silver doped carbon xerogel functionalized with 1 wt.% nickel cobaltite (NiCo1/Ag-CX) shows the best supercapacitor performance: high specific capacitance (368 F g(-1) at 0.1 A g(-1)), low equivalent series resistance (1.9 W), high rate capability (99% capacitance retention after 2000 cycles at 1 A g(-1)), and high energy and power densities (50 Wh/Kg, 200 W/Kg at 0.1 A g(-1)). It is found that the specific capacitance does not only depend on surface area, but also on others factors such as particle size, uniform particle distribution, micro-mesoporous structure, which contribute to abundant active sites and fast charge, and ion transfer rates between the electrolyte and the active sites.Deanship of Scientific Research at King Khalid University R.G.P.2/39/4

Carbon Xerogels Hydrothermally Doped with Bimetal Oxides for Oxygen Reduction Reaction

A total of two carbon xerogels doped with cobalt and nickel were prepared by the sol–gel method. The obtained carbon xerogels underwent further surface modification with three binary metal oxides namely: nickel cobaltite, nickel ferrite, and cobalt ferrite through the hydrothermal method. The mesopore volumes of these materials ranged between 0.24 and 0.40 cm3/g. Moreover, there was a morphology transformation for the carbon xerogels doped with nickel cobaltite, which is in the form of nano-needles after the hydrothermal process. Whereas the carbon xerogels doped with nickel ferrite and cobalt ferrite maintained the normal carbon xerogel structure after the hydrothermal process. The prepared materials were tested as electrocatalysts for oxygen reduction reaction using 0.1 M KOH. Among the prepared carbon xerogels cobalt-doped carbon xerogel had better electrocatalytic performance than the nickel-doped ones. Moreover, the carbon xerogels doped with nickel cobaltite showed excellent activity for oxygen reduction reaction due to mesoporosity development. NiCo2O4/Co-CX showed to be the best electrocatalyst of all the prepared electrocatalysts for oxygen reduction reaction application, exhibiting the highest electrocatalytic activity, lowest onset potential Eonset of -0.06 V, and the lowest equivalent series resistance (ESR) of 2.74 W.This research was funded by science and technology development fund [STDF] grant number [STF-25402] and from the project P12-RNM-2892 (Junta de Andalucía)

Electrodes Based on Carbon Aerogels Partially Graphitized by Doping with Transition Metals for Oxygen Reduction Reaction

A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of the metal loading. All aerogels have been characterized to analyze their textural properties, surface chemistry and crystal structures. These metal-doped aerogels have a very well-developed porosity, making their mesoporosity remarkable. Ni-doped aerogels are the ones with the largest surface area and the smallest graphitization. They also present larger mesopore volumes than Co- and Fe-doped aerogels. These materials are tested as electro-catalysts for the oxygen reduction reaction. Results show a clear and strong influence of the carbonaceous structure on the whole electro-catalytic behavior of the aerogels. Regarding the type of metal doping, aerogel doped with Co is the most active one, followed by Ni- and Fe-doped aerogels, respectively. As the Ni content is larger, the kinetic current densities increase. Comparatively, among the different doping metals, the results obtained with Ni are especially remarkable.This research is supported by the FEDER and Spanish projects CTQ2013-44789-R (MINECO) and P12-RNM-2892 (Junta de Andalucía). A.A. is grateful to the European Union for his Erasmus Mundus fellowship, Program ELEMENT. J. C.-Q. is grateful to the Junta de Andalucía for her research contract (P12-RNM-2892). We thank the “Unidad de Excelencia Química Aplicada a Biomedicina y Medioambiente” (UGR) for its technical assistance

Coupling Noble Metals and Carbon Supports in the Development of Combustion Catalysts for the Abatement of BTX Compounds in Air Streams

The catalytic combustion of volatile organic compounds (VOCs) is one of the most important techniques to remove these pollutants from the air stream, but it should be carried out at the lowest possible temperature, saving energy and avoiding the simultaneous formation of nitrogen oxides (NOx). Under these experimental conditions, the chemisorption of water generated from VOCs combustion may inhibit hydrophilic catalysts. Nowadays, a wide variety of carbon materials is available to be used in catalysis. The behavior of these hydrophobic materials in the development of highly active and selective combustion catalysts is analyzed in this manuscript. The support characteristics (porosity, hydrophobicity, structure, surface chemistry, etc.) and the active phase nature (noble metals: Pt, Pd) and dispersion were analyzed by several techniques and the results correlated with the dual adsorptive and/or catalytic performance of the corresponding catalysts. The coupling of highly active phases and carbon materials (activated carbons, honeycomb coated monoliths, carbon aerogels, etc.) with tuneable physicochemical properties leads to the complete abatement of benzene, toluene and xylenes (BTX) from dilute air streams, being selectively oxidized to CO2 at low temperatures

Revolutionizing Monolithic Catalysts: The Breakthroughs of Design Control through Computer-Aided-Manufacturing

Additive manufacturing (AM) presents a promising opportunity for the innovative design and production of structured catalytic materials. Given the critical role of catalysts in industrial catalytic processes, AM has the potential to contribute to the development of improved catalysts by reducing activation energy and enhancing selectivity. Conventional synthesis methods limit the choice of structural materials and composition for producing monoliths. Additionally, the deposition of catalytic compounds is also restricted by commonly applied techniques that may require prior coverage or treatments to improve adherence or do not achieve a homogenous coat. Moreover, production is limited to monoliths with straight and parallel channels. However, this format drives to laminar regime flow thus restricting the radial mass and heat transfer. Conversely, AM allows the production of a wider variety of compositions and more complex structures that have proven to rise their effectiveness by increasing reagents-catalyst interaction, making catalytic processes more cost-effective. Therefore, in this review an outline of the recent progress of AM methods in the development of monolithic catalysts is presented focusing on the requirements, advantages, and disadvantages of each technique, hence providing a practical overview of their novel opportunities to overcome current limitations in catalyst synthesis.Spanish project PID2021- 127803OB-I00 funded by MCIN/AEI/ 10.13039/501100011033/ and by “ERDF A way of making Europe”Universidad de Granada/CBUA (Funding for open access charge

From Polyethylene to Highly Graphitic and Magnetic Carbon Spheres Nanocomposites: Carbonization under Pressure

Carbon nanocomposites microspheres were synthesized from Low-Density Polyethylene (LDPE) by a facile one-step strategy under solvent-free conditions. The synthesis of these materials was carried out in a closed Hastelloy® reactor at 700 ºC. The treatment, during which autogenic pressure was generated, leads to highly graphitic materials with stunning properties, particularly concerning the oxidation resistance (compared to the graphite stability). The metallic doping triggers the growth of nanostructures with diverse morphologies around the spheres, obtaining samples with magnetic properties.This research is supported by the project P12-RNM-2892 and RMN-172 (Junta de Andalucía, Spain)

From CO2 to Value-Added Products: A Review about Carbon-Based Materials for Electro-Chemical CO2 Conversion

This research was funded by Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-099224-B-I00; and Junta de Andalucía, grant numbers P12-RNM-2892, P18- RTJ-2974 and RNM172. L.D.R.V. was funded by MINCIENCIAS.Data sharing not applicable.The authors thank the financial support of the Spanish Ministry of Science, Innovation and Universities (project RTI2018-099224-B-I00) and Junta de Andalucía (Project P12- RNM-2892, P18-RTJ-2974 and RNM172). L.D. Ramírez-Valencia is grateful to the Colombian Ministry of Sciences, Technology and Innovation (MINCIENCIAS) for supporting her PhD studies.The global warming and the dangerous climate change arising from the massive emission of CO2 from the burning of fossil fuels have motivated the search for alternative clean and sustainable energy sources. However, the industrial development and population necessities make the decoupling of economic growth from fossil fuels unimaginable and, consequently, the capture and conversion of CO2 to fuels seems to be, nowadays, one of the most promising and attractive solutions in a world with high energy demand. In this respect, the electrochemical CO2 conversion using renewable electricity provides a promising solution. However, faradaic efficiency of common electro-catalysts is low, and therefore, the design of highly selective, energy-efficient, and cost-effective electrocatalysts is critical. Carbon-based materials present some advantages such as relatively low cost and renewability, excellent electrical conductivity, and tunable textural and chemical surface, which show them as competitive materials for the electro-reduction of CO2. In this review, an overview of the recent progress of carbon-based electro-catalysts in the conversion of CO2 to valuable products is presented, focusing on the role of the different carbon properties, which provides a useful understanding for the materials design progress in this field. Development opportunities and challenges in the field are also summarized.Spanish Ministry of Science, Innovation and Universities RTI2018-099224-B-I00Junta de Andalucia P12-RNM-2892 P18RTJ-2974 RNM17

Metal-Carbon-CNF Composites Obtained by Catalytic Pyrolysis of Urban Plastic Residues as Electro-Catalysts for the Reduction of CO2

Metal–carbon–carbon nanofibers composites obtained by catalytic pyrolysis of urban plastic residues have been prepared using Fe, Co or Ni as pyrolitic catalysts. The composite materials have been fully characterized from a textural and chemical point of view. The proportion of carbon nanofibers and the final content of carbon phases depend on the used pyrolitic metal with Ni being the most active pyrolitic catalysts. The composites show the electro-catalyst activity in the CO2 reduction to hydrocarbons, favoring all the formation of C1 to C4 hydrocarbons. The tendency of this activity is in accordance with the apparent faradaic efficiencies and the linear sweep voltammetries. The cobalt-based composite shows high selectivity to C3 hydrocarbons within this group of compounds.This research is supported by the FEDER and Spanish projects CTQ2013-44789-R (MINECO) and P12-RNM-2892 (Junta de Andalucía). J.C.-Q. is grateful to the Junta de Andalucía for her research contract (P12-RNM-2892). A.E. acknowledges a predoctoral fellowship from Erasmus Mundus, Al-Idrissi, programme